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How much pressure can human withstand if inner and outer pressure is balanced?

How much pressure can human withstand if inner and outer pressure is balanced?


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I know human can't dive too deep because there's pressure difference between inside and outside of the body. But how much pressure can human withstand if human is breathing components that is surrounding him?

So I have two questions: 1.How much pressure can human handle if he is surrounded by regular air (also breathing air)? 2. How much pressure can human handle if he is floating in oxygen-rich liquid and breathing it at the same time (Liquid Breathing, Wikipedia)?

There's a similar question, but it doesn't have answer that fully satisfies me. Highest Pressure Human Body Can Survive In?


Real and 3-D printed shells ability to withstand pressure

Mollusks got it right. They have soft innards, but their complex exteriors are engineered to protect them in harsh conditions. Engineers at the Indian Institute of Science and Rice University are beginning to understand why.

By modeling the average mollusk's mobile habitat, they are learning how shells stand up to extraordinary pressures at the bottom of the sea. The goal is to learn what drove these tough exoskeletons to evolve as they did and to see how their mechanical principles may be adapted for use in human-scale structures like vehicles and even buildings.

The team led by Chandra Sekhar Tiwary, a graduate student at the Indian Institute of Science and a visiting student at Rice, created computer simulations and printed 3-D variants of two types of shells to run stress tests alongside real shells that Tiwary collected from beaches in India.

The researchers discovered the structures that evolved over eons are not only generally effective at protecting their inhabitants, but also manage to redirect stress to locations where the soft creatures are least likely to be.

Their results appeared in a new online journal published by the American Association for the Advancement of Science, Science Advances.

Shells are made of nacre, also known as mother-of-pearl, a strong and resilient matrix of organic and inorganic materials recently studied by other Rice engineers as a model of strength, stiffness and toughness.

Tiwary and his colleagues took their research in a different direction to discover how seashells remain stable and redirect stress to minimize damage when failure is imminent. Their calculations showed their distinctive shapes make the shells nearly twice as good at bearing loads than nacre alone.

They examined two types of mollusk: Bivalves with two separate exoskeleton components joined at a hinge (as in clamshells) and terebridae that conceal themselves in screw-shaped shells. In the case of clamshells, the semicircular shape and curved ribs force stress to the hinge, while the screws direct the load toward the center and then the wide top.

They found such evolutionary optimization allows fractures to appear only where they're least likely to hurt the animal inside.

"Nature keeps on making things that look beautiful, but we don't really pay attention to why the shapes are what they are," said Tiwary, a member of Rice materials scientist Pulickel Ajayan's lab. Tiwary started the work with Kamanio Chattopadhyay, chair of mechanical sciences at the Indian Institute of Science, Bangalore.

The researchers noted engineers have made use of mechanical concepts from natural shapes like beak shells and shark teeth to design protective shields, automotive parts that dampen impacts and even buildings. But seashells, they wrote, represent one of the best examples of evolutionary optimization to handle varied mechanical loads.

While biologists, mathematicians and artists have contributed to the literature about seashells, materials scientists "haven't tried to think about these complex shapes because making them is not easy," Tiwary said. But the rapid development of 3-D printing has made it much easier to replicate the shapes with materials tough enough to put up a fight. "With the help of 3-D printing, these ideas can be extended to a larger reality," he said.

The researchers printed fan-shaped polymer shells, including some without their characteristic converging ribs. They also made cones that mimicked the screws but without the complexities.

They found the rib-less fans were far less effective at redirecting stress toward the base of the fan, spreading it to three separate regions across the shell. When cracks finally showed in the fans, they appeared in the same spots near the base in both the real shells and the realistic printed version.

Stress distribution in the more complex screws was "totally different," they wrote. The tough inner core of the shell took the most punishment, relieving stress from the outer surface and shunting it toward the top-most ring. In general, the researchers found the screw to be the better of the two shells at protecting its delicate contents.

"There are plenty of shapes that are even more complicated, and they may be even better than this for new structures," Tiwary said.

Co-authors are undergraduate Sharan Kishore, graduate students Suman Sarkar and Professor Debiprasad Roy Mahapatra at the Indian Institute of Science. Chattopadhyay is also a professor of materials engineering at the institute. Ajayan is chair of Rice's Department of Materials Science and NanoEngineering, the Benjamin M. and Mary Greenwood Anderson Professor in Engineering and a professor of chemistry.


Transport of Electrolytes across Cell Membranes

Ions cannot diffuse passively through membranes instead, their concentrations are regulated by facilitated diffusion and active transport.

Learning Objectives

Explain the relationship between osmotic pressure and the transport of electrolytes across cell membranes

Key Takeaways

Key Points

  • Important ions cannot pass through membranes by passive diffusion if they could, maintaining specific concentrations of ions would be impossible.
  • Osmotic pressure is directly proportional to the number of solute atoms or molecules ions exert more pressure per unit mass than do non- electrolytes.
  • Electrolyte ions require facilitated diffusion and active transport to cross the semi-permeable membranes.
  • Facilitated diffusion occurs through protein -based channels, which allow passage of the solute along a concentration gradient.
  • In active transport, energy from ATP changes the shape of membrane proteins that move ions against a concentration gradient.

Key Terms

  • facilitated diffusion: The spontaneous passage of molecules or ions across a biological membrane passing through specific transmembrane integral proteins.
  • passive diffusion: movement of water and other molecules across membranes along a concentration gradient
  • active transport: movement of a substance across a cell membrane against its concentration gradient (from low to high concentration) facilitated by ATP conversion

Transport of Electrolytes across Cell Membranes

A teaspoon of table salt readily dissolves in water. The solubility of sodium chloride results from its capacity to ionize in water. Salt and other compounds that dissociate into their component ions are called electrolytes. In water, sodium chloride (NaCl) dissociates into the sodium ion (Na + ) and the chloride ion (Cl – ). The most important ions, whose concentrations are very closely regulated in body fluids, are the cations sodium (Na+), potassium (K+), calcium (Ca+2),and magnesium (Mg+2) and the anions chloride (Cl-), carbonate (CO3-2), bicarbonate (HCO3-), and phosphate(PO3-). Electrolytes are lost from the body during urination and perspiration. For this reason, athletes are encouraged to replace electrolytes and fluids during periods of increased activity and perspiration.

Osmotic pressure is influenced by the concentration of solutes in a solution. It is directly proportional to the number of solute atoms or molecules and not dependent on the size of the solute molecules. Because electrolytes dissociate into ions, adding relatively more solute molecules to a solution, they exert a greater osmotic pressure per unit mass than non-electrolytes such as glucose.

Water passes through semi-permeable membranes by passive diffusion, moving along a concentration gradient and equalizing the concentration on either side of the membrane. Electrolyte ions may not be able to passively diffuse across a membrane, but may instead require special mechanisms to cross the semi-permeable membrane. The mechanisms that transport ions across membranes are facilitated diffusion and active transport. Facilitated diffusion of solutes occurs through protein-based channels. Active transport requires energy in the form of ATP conversion, carrier proteins, or pumps in order to move ions against the concentration gradient.

Transport across cell membranes: Paul Andersen describes how cells move materials across the cell membrane. All movement can be classified as passive or active. Passive transport, such as diffusion, requires no energy as particles move along their gradient. Active transport requires additional energy as particles move against their gradient. Specific examples, such as GLUT and the Na/K, pump are included.


The Pressure of Family Expectations

Fulfilling the expectations of your family and society are not the same as being a useful member of society.

We live as social beings, and we derive immense benefit from the cumulative knowledge of other human beings, and from their labor in creating a comfortable and safe civilization for us all. Realizing this, a healthy person will want to flourish and prosper in a way that makes for a meaningful life, and which adds value for his fellow human beings, or to nature at large.

In fact, a strong argument can be made that a meaningful life has to be about more than oneself. A narcissist or a self-centered person lives for himself, but suffers from atomization, alienation, apathy and loneliness. His pleasures are short-lived, and he needs to continually validate his existence through consumerist possessions and by manipulating other human beings.

In contrast, a balanced human being has both inner and outer goals. He has meaningful relationships with other people, and uses his energy in ways which benefit his environment, while also having a strong inner emotional core that can withstand adversity and tragedy.

Understanding this, let us reflect on societal and familial expectations.

In India, community life is very much alive and potent. Kids live with their parents till their late twenties (unless the college or university is in another city). Parents therefore comprise a very large space in one’s emotional being. This attachment to one’s parents can wreak havoc when it is time to make important life choices.

At those times, an Indian man comes under intense pressure to become a conformant member of the society: to live according to the expectations of his parents and his extended social circle. From education to career choices to even one’s marriage, there is intense pressure and emotional manipulation to choose what others want you to choose. The expectation is: get educated, get a safe job, get married to a girl from a similar background, and spend the rest of your life supporting your wife and kids, and your parents and your brothers and sisters. There is nothing wrong with having a support system in one’s family in times of trouble, but these expectations of later support can quickly turn into pressures to do something or not in the present.

If you become a rich engineer, your parents feel safer about their old age, your brother and sister feel safer that you are their safety net. On the other hand, if you become a world-class rock-climber, what will they get out of you? So, for their future, they will try to manipulate you in the present.

Someone who follows the dictates of his family and society is considered a “good man”, and someone who seeks to chart his own path might be name-called as “selfish”, “ungrateful” or “disrespectful”. This internalization of equating goodness with fulfilling others’ expectations is a serious neurosis, and we have seen many men fall prey to this and finally succumb to getting on the traditional bandwagon. We believe that goodness is when you are fulfilling your full potential, and that can have myriad forms. Since each successive generation is presented with more knowledge and awareness of the world, and since the world is changing so fast these days, it is quite likely that the expectations of your parents and elders are archaic and make little sense and will thwart you from fulfillment.

Wise parents try to see what their child is capable of, and encourage him to become the best that he can. Unwise parents try to force their paradigms, prejudices and beliefs on the child.

If you have a natural talent for and wish to become a mountaineer, a writer or a musician, your family might protest that these “career choices” are risky and won’t pay. They are usually comparing abstract rewards of meaning and fulfillment of such a path to the money and status that comes with following an established path. New, untrodden paths are risky, and Indian society is extremely risk-averse.

In India, due to poverty, a long history of subjugation and a highly dysfunctional set of institutions, safety, survival and prosperity have attained extreme importance, to the detriment of creativity, exploration and enterprise.

In such an environment, you will be all alone if you want to do something “different”. You will have to be very strong to withstand the onslaught of criticism and to disobey your parents, and see them in tears or worse.

One of the strongest expectations is for Indian men to remain virgins or limit their interaction with the opposite sex, and if they have a girlfriend or a live-in partner, to get married to her. After all, a man who explores his sexuality, the strongest instinct of them all, might also explore other ways to live his life. This creates a nation of betas (no Hindi pun intended) who are cockblocked by their own families.

In this blog post on ReturnOfKings, an Indian man describes his struggle with these expectations. His post is titled “Taking the Red Pill Destroyed my Family“.

His parents desperately wanted to marry him off in his twenties, for their own reasons. When he resisted, all hell broke loose.

On a fortnightly basis my very traditional mother did her best, ringing me to ask if I had a girlfriend and why I wasn’t looking. She’d know of ‘some girl’ who is ‘only’ between 26-29. At 25 I had just started ‘game,’ but as that year went on I immersed myself more and more into the real reality of dating and what my value as a man was. Now I started to understand what I needed to do, with marriage nowhere on my list. Slowly I started to find more women interested in me compared to my barren years in my early 20s.

I got tired of my mother’s bitching, the woman whose siblings’ children were all getting married and having ‘fairytale’ Indian weddings. I knew that my mother wanted a wedding for herself in Indian culture, a status-showing occasion more for parents than an actual celebration of the marriage. She wanted to buy all the glamorous sarees, jewelry, and clothes. She wanted to pretty up a couple of banquet halls and show off my old man’s wealth.

He stuck to his guns, even enduring his father “disowning” him. And in the end, his family buckled.

One day I sat them all down and sternly explained why I made the choices I made. I told them I would not yield. My father reluctantly accepted what I said while my mother put on a strained smile that showed her pain in having to let go of the magical wedding. My brother? He was just happy I was back and now “in charge.” I’m in charge? Yes, somehow I’m now king of my tribe. My mother is pacified and my father is going on about he’s happy if we’re happy. I thought taking the red pill caused me to lose my family for good, but the values it taught me helped me get them right back.

But there are many stories with an alternate, tragic ending, wherein a man or a woman got married or made a career choice just to keep their parents happy.

Never live your life on the emotional whims of another. Be a useful an upstanding member of society, but have a spine, and do not betray your own intelligence and potential. Resist emotional manipulation, and be willing to stand alone in your manliness.


Record high pressure squeezes secrets out of osmium

A schematic of the pressure chamber of the double-stage diamond anvil cell: The osmium sample is just 3 microns small and sits between two semi-balls made of nanocristalline diamond of extraordinary strength. Credit: Elena Bykova/University of Bayreuth

An international team of scientists led by the University of Bayreuth and with participation of DESY has created the highest static pressure ever achieved in a lab: Using a special high pressure device, the researchers investigated the behaviour of the metal osmium at pressures of up to 770 Gigapascals (GPa) - more than twice the pressure in the inner core of the Earth, and about 130 Gigapascals higher than the previous world record set by members of the same team. Surprisingly, osmium does not change its crystal structure even at the highest pressures, but the core electrons of the atoms come so close to each other that they can interact - contrary to what is usually known in chemistry.

This fundamental result published in the journal Nature has important implications for understanding physics and chemistry of highly compressed matter, for design of materials to be used at extreme conditions, and for modelling the interiors of giant planets and stars.

Metallic osmium (Os) is one of the most exceptional chemical elements, having at ambient pressure the highest known density of all elements, one of the highest cohesive energies, melting temperatures, and a very low compressibility - it is almost as incompressible as diamond. Due to its hardness, osmium finds applications in alloys used for instance as electrical contacts, wear-resistant machine parts and tips for high-quality ink pens.

"High pressure is known to radically affect properties of chemical elements: metals like sodium may become transparent insulators gases like oxygen solidify and become electrical conductors - and even superconductors," explains Natalia Dubrovinskaia from the University of Bayreuth, together with Leonid Dubrovinsky the main author of the study. "as any other material subjected to very high compression, osmium is expected to change its crystal structure."

For their experiments, the scientists used a device for generating ultra-high static pressures developed by Dubrovinsky and Dubrovinskaia at Bayreuth. The device uses micro-anvils of only 10 to 20 micrometres (a micrometre is a thousandths of a millimetre) in diameter which are made of nanocrystalline diamond. These nanocrystals, which are diamond grains of a nano-size, are bound together forming a bulk micro-anvil. The many grain boundaries make the nanocrystalline anvils even harder than single crystal diamonds, extending the range of static pressure in experiments from about 400 GPa to 770 GPa at room temperature.

A photo of the double-stage diamond cell developed at the University of Bayreuth. Credit: University of Bayreuth

For probing the samples under these extreme conditions, the team used high-brilliance X-rays from the synchrotron sources PETRA III at DESY, ESRF in France and APS in the U.S. The team found out that Osmium shows unprecedented structural stability and keeps its crystal structure even at huge pressures of about 770 GPa.

While the volume of the osmium unit cell steadily shrinks with rising pressure, very accurate X-ray diffraction experiments revealed anomalies in the behaviour of the lattice parameters describing the unit cell. Usually, changes in materials properties under pressure are associated with modifications in the configurations of the outer (valence) electrons. But in case of highly compressed osmium the reason for the observed structural anomaly is an interaction between the inner (core) electrons, as suggested by state-of-the-art theoretical calculations. "This work demonstrates that ultra-high static pressures can force the core electrons to interplay," explains Dubrovinsky. "The ability to affect the core electrons even in such incompressible metals as osmium in static high-pressure experiments opens up exciting opportunities in searching for new states of matter."

The experiments pave the way for investigating materials under conditions of the inner core of giant planets. "In the last 20 years, astronomers found more than thousand planets around other stars, nearly all of them bigger than our Earth," says co-author Hanns-Peter Liermann from DESY, responsible for the beamline P02 at PETRA III, where some of the experiments took place. "With the newly developed double-stage diamond anvil cell and with the very focused high intensity X-ray spot at PETRA III - or later at the X-ray laser European XFEL that is currently being constructed in the Hamburg area - we can probe a variety of rocky planet compositions under most extreme conditions and will learn a lot about the composition and evolution of such planets."


How much pressure can human withstand if inner and outer pressure is balanced? - Biology

Large quantities of water molecules constantly move across cell membranes by simple diffusion, often facilitated by movement through membrane proteins, including aquaporins. In general, net movement of water into or out of cells is negligible. For example, it has been estimated that an amount of water equivalent to roughly 100 times the volume of the cell diffuses across the red blood cell membrane every second the cell doesn't lose or gain water because equal amounts go in and out.

There are, however, many cases in which net flow of water occurs across cell membranes and sheets of cells. An example of great importance to you is the secretion of and absorption of water in your small intestine. In such situations, water still moves across membranes by simple diffusion, but the process is important enough to warrant a distinct name - osmosis.

Osmosis and Net Movement of Water

Osmosis is the net movement of water across a selectively permeable membrane driven by a difference in solute concentrations on the two sides of the membrane. A selectively permiable membrane is one that allows unrestricted passage of water, but not solute molecules or ions.

Different concentrations of solute molecules leads to different concentrations of free water molecules on either side of the membrane. On the side of the membrane with higher free water concentration (i.e. a lower concentration of solute), more water molecules will strike the pores in the membrane in a give interval of time. More strikes equates to more molecules passing through the pores, which in turn results in net diffusion of water from the compartment with high concentration of free water to that with low concentration of free water.

The key to remember about osmosis is that water flows from the solution with the lower solute concentration into the solution with higher solute concentration. This means that water flows in response to differences in molarity across a membrane. The size of the solute particles does not influence osmosis . Equilibrium is reached once sufficient water has moved to equalize the solute concentration on both sides of the membrane, and at that point, net flow of water ceases. Here is a simple example to illustrate these principles:

Two containers of equal volume are separated by a membrane that allows free passage of water, but totally restricts passage of solute molecules. Solution A has 3 molecules of the protein albumin (molecular weight 66,000) and Solution B contains 15 molecules of glucose (molecular weight 180). Into which compartment will water flow, or will there be no net movement of water? [ answer ]

Additional examples are provided on how to determine which direction water will flow in different circumstances.

Tonicity

When thinking about osmosis, we are always comparing solute concentrations between two solutions, and some standard terminology is commonly used to describe these differences:

  • Isotonic: The solutions being compared have equal concentration of solutes.
  • Hypertonic: The solution with the higher concentration of solutes.
  • Hypotonic: The solution with the lower concentration of solutes.

In the examples above, Solutions A and B are isotonic (with each other), Solutions A and B are both hypertonic compared to Solution C, and Solution C is hypotonic relative to Solutions A and B.

Diffusion of water across a membrane generates a pressure called osmotic pressure. If the pressure in the compartment into which water is flowing is raised to the equivalent of the osmotic pressure, movement of water will stop. This pressure is often called hydrostatic ('water-stopping') pressure . The term osmolarity is used to describe the number of solute particles in a volume of fluid. Osmoles are used to describe the concentration in terms of number of particles - a 1 osmolar solution contains 1 mole of osmotically-active particles (molecules and ions) per liter.

The classic demonstration of osmosis and osmotic pressure is to immerse red blood cells in solutions of varying osmolarity and watch what happens. Blood serum is isotonic with respect to the cytoplasm, and red cells in that solution assume the shape of a biconcave disk. To prepare the images shown below, red cells from your intrepid author were suspended in three types of solutions:

  • Isotonic - the cells were diluted in serum: Note the beautiful biconcave shape of the cells as they circulate in blood.
  • Hypotonic - the cells in serum were diluted in water: At 200 milliosmols (mOs), the cells are visibly swollen and have lost their biconcave shape, and at 100 mOs, most have swollen so much that they have ruptured, leaving what are called red blood cell ghosts. In a hypotonic solution, water rushes into cells.
  • Hypertonic - A concentrated solution of NaCl was mixed with the cells and serum to increase osmolarity: At 400 mOs and especially at 500 mOs, water has flowed out of the cells, causing them to collapse and assume the spiky appearance you see.

Predict what would happen if you mixed sufficient water with the 500 mOs sample shown above to reduce its osmolarity to about 300 mOs.

Calculating Osmotic and Hydrostatic Pressure

The flow of water across a membrane in response to differing concentrations of solutes on either side - osmosis - generates a pressure across the membrane called osmotic pressure. Osmotic pressure is defined as the hydrostatic pressure required to stop the flow of water, and thus, osmotic and hydrostatic pressures are, for all intents and purposes, equivalent. The membrane being referred to here can be an artifical lipid bilayer, a plasma membrane or a layer of cells.

The osmotic pressure P of a dilute solution is approximated by the following:

where R is the gas constant (0.082 liter-atmosphere/degree-mole), T is the absolute temperature, and C1 . Cn are the molar concentrations of all solutes (ions and molecules).

Similarly, the osmotic pressure across of membrane separating two solutions is:

where &DeltaC is the difference in solute concentration between the two solutions. Thus, if the membrane is permeable to water and not solutes, osmotic pressure is proportional to the difference in solute concentration across the membrane (the proportionality factor is RT).


Intro to Human Body 46 Bi

The human body begins to take shape during the earliest stages of embryonic development. While the embryo is a tiny hallow ball of dividing cells, it begins forming the tissues and organs that compose the human body. By the end of its third week, human embryo has bilateral symmetry (a body plan in which the left and right sides mirror each other) and is developing vertebrate characteristics that will support an upright body.

OBJECTIVES: Define Anatomy and Physiology, and explain how they are related. List and describe the major characteristics of life. Define homeostasis, and explain its importance to survival. Describe a Homeostatic Mechanism.List and describe the four types of tissues that make up the human body. Explain how tissues, organs, and organ systems are organized. Summarize the functions of the primary organ systems in the human body. Name and locate four human body cavities, and describe the organs that each contain. Properly use terms that describe relative positions, body sections, and body regions.

1. The human body is a precisely structured container of Chemical Reactions.

2. Biology is the Study of Living Things including the Study of the Human Body.

3. The Study of BODY STRUCTURE, which includes Size, Shape, Composition, and perhaps even Coloration, is called ANATOMY.

4. The Study of HOW the BODY FUNCTIONS is called PHYSIOLOGY.

5. The purpose of this course is to enable you to gain an understanding of Anatomy and Physiology with the emphasis on Normal Structure and Function. You will examine the anatomy and physiology of the major body systems.

A. The Chemicals that make up the body may be divided into TWO major categories: INORGANIC AND ORGANIC.

B. INORGANIC CHEMICALS are usually simple molecules made of one or more elements other than CARBON. Examples: Water, Oxygen, Carbon Dioxide (an exception), and Minerals such as iron, calcium, and sodium.

C. ORGANIC CHEMICALS are often VERY Complex and ALWAYS CONTAIN THE ELEMENTS CARBON AND HYDROGEN. Examples: Carbohydrates, Fats, Proteins, and Nucleic Acids.

A. The SMALLEST LIVING UNITS OF STRUCTURE AND FUCTION ARE CELLS.

B. Cells are the smallest living subunits of a multicellular organism such as a human being.

C. There are many different types of cells each is made of chemicals and carries out specific chemical reactions.

A. A Tissue is a group of cells with similar structure and function.

B. There are FOUR Groups of Tissue.

C. EPITHELIAL TISSUE – Cover or line body surfaces some are capable of producing secretions with specific functions. The outer layer of the Skin and Sweat Glands are examples of Epithelial Tissue.

D. CONNECTIVE TISSUE – Connects and supports parts of the body some transport or store materials. Blood, Bone, and Adipose Tissue (Fat) are examples.

E. MUSCLE TISSUE – Specialized for CONTRACTION, which brings about movement. Our Skeleton Muscles and the Heart are examples.

F. NERVE TISSUE – Specialized to generate and transmit Electrochemical Impulses that regulate body functions. The Brain and Optic Nerves are examples.

A. An Organ is a group of TWO or more different types of Tissues precisely arranged so as to accomplish Specific Functions and usually have recognizable shape.

B. Heart, Brain, Kidneys, Liver, Lungs are Examples.

5. ORGAN SYSTEMS (System Level)

A. An Organ System is a group of organs that all contribute to a Particular Function.

B. Examples are the Circulatory, Respiratory, and Digestive Systems.

C. Each organ system carries out its own specific function, but for the organism to survive the organ systems must work together- this is called INTEGRATION OF ORGAN SYSTEM.

B. ALL the Organ Systems of the body functioning with one another constitute the TOTAL ORGANISM – ONE LIVING INDIVIDUAL.

LIFE PROCESSES or CHARACTERISTICS OF LIFE

1. All living organisms carry on certain processes that set them apart from nonliving things.

2. The Following are Several of the more important life processes of Humans:

A. METABOLISM is the sum of all the chemical reactions that occur in the body. One phase of Metabolism called CATABOLISM provides the ENERGY needed to sustain life by BREAKING DOWN substances such as food molecules. The other phase called ANABOLISM uses the energy from catabolism to MAKE various substances that form body structures and enable them to function.

B. ASSIMILATION is the changing of Absorbed substances into forms that are chemically different from those that entered body fluids.

C. REPONSIVNESS is the ability to Detect and Respond to changes Outside or Inside the Body. Seeking Water to quench thirst is a response to water loss from body tissue.

D. MOVEMENT includes motion of the whole body, individual organs, single cells, or even structures inside cells.

E. GROWTH refers to an Increase in Body Size. It may be due to an increase in the size of existing cells, the number of cells, or the amount of substance surrounding cells. It occurs whenever an organism produces new body materials faster than old ones are worn out or replaced.

F. DIFFERENTIATION is the process whereby unspecialized cells become specialized cells. Specialized Cells differ in Structure and Function from the cells from which they originated.

G. REPRODUCTION refers either to the formation of new cells for Growth, Repair, or Replacement or to the making of a New Individual.

H. Others Include:
Respiration – obtaining Oxygen.
Digestion – Chemically and Mechanically breaking down food substances.
Absorption – The passage of substances through certain membranes.
Circulation – the movement of substances within the body in Body Fluids.
Excretion – Removal of wastes that the body produces.

MAINTENANCE OF LIFE OR SURVIVAL NEEDS

1. The structures and functions of almost all body parts help maintain the Life of the Organism. The ONLY Exceptions are an Organisms Reproductive Structures, which ensure that its species will continue into the future.

2. Life requires certain Environmental Factors, including the Following:

A. WATER – this is the most abundant chemical in the body and it is required for many Metabolic Processes and provides the environment in which Most of them take place. Water also transports substances within the organism and is important in regulating body temperature.

B. FOOD – the Substances that provide the body with necessary Chemicals (Nutrients) in addition to Water. Food is used for Energy, supply the raw materials for building new living matter, and still others help regulate vital chemical reactions.

C. OXYGEN – It is required to release Energy from food substances. This energy, in turn, drives metabolic processes. Approximately 20% of the air be breathe is oxygen.

D. HEAT (BODY TEMPERATURE) – a form of energy, it is a product of Metabolic Reactions. Normal Body Temperature is around 37 C or 98 F. both low or high body temperatures are dangerous to the organism.

E. PRESSURE (ATMOSPHERIC) – Necessary for our Breathing.

PRINCPAL ORGAN SYSTEMS OF THE HUMAN BODY (TABLE 46-1)

1. INTEGUMENTARY SYSTEM

A. The Skin and Structures derived from it, such as hair, nails, and sweat and oil glands.

B. Is a barrier to pathogens and chemicals (Protects the body), Helps regulate body temperature, Eliminates waste, Helps synthesize vitamin D, and receives certain stimuli such as Temperature, Pressure, and Pain.

A. All the Bones of the body (206), their associated Cartilage, and the Joints of the Body.

B. Bones Support and Protect the body, assist in body movement, They also house cells that produce blood cells, and they store minerals.

A. Specifically refers to Skeletal Muscle Tissue and Tendons.

B. Participates in bringing about movement, maintaining posture, and produces heat.

4. CIRCULATORY A nd CARDIOVASCULAR SYSTEM

A. The Heart, Blood and Blood Vessels.

B. Transports oxygen and nutrients to tissues and removes waste.

5. LYMPHATIC SYSTEM- Sometimes included with the Immune System or Circulatory System becuase it works closely with Both Systems.

A. The Lymph, Lymphatic Vessels, and Structures or Organs (Spleen and Lymph Nodes) containing Lymph Tissue.

B. Cleans and Returns tissue fluid to the blood and destroys pathogens that enter the body.

A. The Brain, Spinal Cord, Nerves, and Sense Organs, such as the eye and ear.

B. Interprets sensory information, Regulates body functions such as movement by means of Electrochemical Impulses.

A. ALL Hormone producing Glands and Cells such as the Pituitary Gland, Thyroid Gland, and Pancreas.

B. Regulates body functions by means of Hormones.

8. RESPIRATORY SYSTEM

A. The Lungs and a series of associated passageways such as the Pharynx (Throat), Larynx (Voice Box), Trachea (Windpipe), and Bronchial Tubes leading into and out of them.

B. Exchange oxygen and carbon dioxide between the air and blood.

A. A long tube called the Gastrointestinal (GI) Tract and associated organs such as the Salivary Glands, Liver, Gallbladder, and Pancreas.

B. Breaks down and absorbs food for use by cells and eliminates solid and other waste.

10. URINARY And EXCRETORY SYSTEMS

A. The Kidneys, Urinary Bladder, and Urethra that together produce, store, and eliminate Urine.

B. Removes waste products from the blood and regulates volume and pH of blood.

A. The Immune System Consists of Several Organs, as well as White Blood Cells in the Blood and Lymph.
Includes the Lymph Nodes, Spleen, Lymph Vessels,Blood Vessels, Bone Marrow, and White Blood Cells (Lymphocytes).

B. Provides protection against Infection and Disease.

12. REPRODUCTIVE SYSTEM

A. Organs that produce, store, and transport reproductive cells (Sperm and Eggs).

B. Produces eggs and sperm, in women, provides a site for the developing embryo-fetus.


Lesson Objectives

  • Describe the obstacles to studying the seafloor and methods for doing so.
  • Describe the features of the seafloor.

Ancient myth says that Atlantis was a powerful undersea city whose warriors conquered many parts of Europe. There is little proof that such a city existed, but human fascination with the world under the oceans certainly has existed for centuries. Not much was known about the aphotic zone of the ocean until scientists developed a system modeled after the way that bats and dolphins use echolocation to navigate in the dark (Figure 14.19). Prompted by the need to find submarines during World War II, scientists learned to bounce sound waves through the ocean to detect underwater objects. The sound waves bounce back like an echo off of whatever object may be in the ocean. The distance of the object can be calculated based on the time that it takes for the sound waves to return. Finally, scientists were able to map the ocean floor.

Three main obstacles have kept us from studying the depths of the ocean: absence of light, very cold temperatures, and high pressure. As you know, light only penetrates the top 200 meters of the ocean the depths of the ocean can be as much as 11,000 meters deep. Most places in the ocean are completely dark, which makes it impossible for humans to explore without bringing a source of light with them. Secondly, the ocean is very cold colder than 0°C (32°F) in many places. Such cold temperatures pose significant obstacles to human exploration of the oceans. Finally, the pressure in the ocean increases tremendously as you go deeper. Scuba divers can rarely go deeper than 40 meters due to the pressure. The pressure on a diver at 40 meters would be 4 kilograms/square centimeter (60 lbs/sq in). Even though we don’t think about it, the air in our atmosphere has weight. It presses down on us with a force of about 1 kilogram per square centimeter (14.7 lbs/ sq in). In the ocean, for every 10 meters of depth, the pressure increases by nearly 1 atmosphere! Imagine the pressure at 10,000 meters that would be 1,000 kilograms per square centimeter (14,700 lbs/sq in). Today’s submarines usually dive to only about 500 meters to go deeper than this they must be specially designed for greater depth (Figure 14.20).

Figure 14.20: Submarines are built to withstand great pressure under the sea, up to 680 atmospheres of pressure (10,000 pounds per square inch). They still rarely dive below 400 meters.

Figure 14.21: Alvin allows for a nine hour dive for up to two people and a pilot. It was commissioned in the 1960s.

In the 19th century, explorers mapped ocean floors by painstakingly dropping a line over the side of a ship to measure ocean depths, one tiny spot at a time. SONAR, which stands for Sound Navigation And Ranging, has enabled modern researchers to map the ocean floor much more quickly and easily. Researchers send a pulse of sound down to the ocean floor and calculate the depth based on how long it takes the sound to return. Of course, some scientific research requires actually traveling to the bottom of the ocean to collect samples or directly observe the ocean floor, but this is more expensive and can be dangerous.

In the late 1950s, the bathyscaphe (deep boat) Trieste was the first manned vehicle to venture to the deepest parts of the ocean, a region of the Marianas Trench named the Challenger Deep. It was built to withstand 1.2 metric tons per square centimeter and plunged to a depth of 10,900 meters. No vehicle has carried humans again to that depth, though robotic submarines have returned to collect sediment samples from the Challenger Deep. Alvin is a submersible used by the United States for a great number of studies it can dive up to 4,500 meters beneath the ocean surface (Figure 14.21).

In order to avoid the expense, dangers and limitations of human missions under the sea, remotely operated vehicles or ROVs, allow scientists to study the ocean’s depths by sending vehicles carrying cameras and special measuring devices. Scientists control them electronically with sophisticated operating systems (Figure 14.22).

Figure 14.22: Remotely-operated vehicles like this one allow scientists to study the seafloor.


The Urinary System - Workings: how the urinary system functions

The urinary system is not the sole system in the body concerned with excretion. Other systems and organs also play a part. The respiratory system eliminates water vapor and carbon dioxide through exhalation (the process of breathing out). The digestive system removes feces, the solid undigested wastes of digestion, by a process called defecation or elimination. The skin (the integumentary system see chapter 4) also acts as an organ of excretion by removing water and small amounts of urea and salts (as sweat).

Through its primary role of forming and eliminating urine, the urinary system also helps regulate blood volume and pressure. In addition, it regulates the concentrations of sodium, potassium, calcium, chloride, and other mineral ions (an ion is an atom or group of atoms that has an electrical charge) in the blood. These combined actions by the urinary system help the body maintain homeostasis or the balanced state of its internal functions.

Formation of urine

Urine is the fluid waste excreted by the kidneys. It can range in color from pale straw to amber (the deeper the color, the more concentrated the urine). Fresh urine is sterile (meaning it contains no bacteria) and has very little odor. Some drugs, vegetables (such as asparagus), and various diseases alter the normal smell of urine. Water forms approximately 95 percent of urine the remaining 5 percent is made up of urea, creatinine, uric acid, and various salts.

Urea, creatinine, and uric acid are nitrogen-containing compounds produced as wastes during cellular activity. When cells break down amino acids, they produce ammonia as a waste product. Ammonia is very toxic to the body's cells, so the liver combines ammonia with carbon dioxide to create the less toxic urea, the most abundant of the nitrogen-containing wastes. Creatinine is produced when skeletal muscle cells break down the compound creatine to generate energy for muscle contraction. Uric acid, which forms only a small portion of the urine, is a normal waste product of the breakdown of nucleic acids (complex organic molecules found in living cells).

Urine is formed in the kidneys as a result of three processes: filtration, reabsorption, and secretion. Filtration takes place in the renal corpuscles reabsorption and secretion take place in the renal tubules.

FILTRATION. Filtration is the movement of water and dissolved materials through a membrane from an area of higher pressure to an area of lower

pressure. In the body, the pressure of blood in the capillaries is higher than the pressure of the interstitial fluid, or the fluid surrounding the body's cells. Thus, through filtration, blood plasma (fluid portion of blood) and nutrients such as amino acids, glucose, and vitamins are forced through the capillary walls into the surrounding interstitial fluid to be used by the cells.

The pressure of the blood in the glomeruli is higher than in other types of capillaries in the body. This high pressure forces plasma, dissolved waste substances, and small proteins out of the glomeruli and into the Bowman's capsules. The process is called glomerular filtration. Blood cells and larger proteins are too large to be forced out of the glomeruli, so they remain in the blood. The pressure in a Bowman's capsule is low and its inner membrane is permeable, so the material that filters out of a glomerulus passes into the capsule. The fluid and material in a Bowman's capsule is referred to as renal filtrate, which is very much like blood plasma, except it contains very little protein and no blood cells.

REABSORPTION. In an average twenty-four-hour period, the kidneys form 160 to 190 quarts (150 to 180 liters) of renal filtrate. Normal urinary output in that same time frame is only about 1.1 to 2.1 quarts (1 to 2 liters). Many factors (such as increased water intake or increased sweating) can significantly alter that output amount. Nonetheless, it is quite obvious that most of the renal filtrate does not become urine, but is reabsorbed or taken back into the blood. This is important because renal filtrate contains many useful substances—water, glucose, amino acids, and mineral ions—that are needed by the body.

Reabsorption is the return of water and other substances from the filtrate to the blood. The process begins as soon as the filtrate enters the renal tubule. Cells lining the tubule actively take up useful materials (such as glucose, amino acids, vitamins, proteins, and certain ions), move them through their cell bodies, then release them into the interstitial fluid outside the tubule.

As these materials collect in the interstitial fluid, water in the tubules is drawn out through the process of osmosis. Osmosis is the diffusion of water through a semipermeable membrane from an area where it is abundant to an area where it is scarce or less abundant. Once in the interstitial fluid, the materials and water then diffuse into or enter nearby capillaries, which empty into the renal vein.

The reabsorption process is selective. The cells of the renal tubules have been "programmed" to retain substances that are useful to the body, not those substances that are of no use (such as urea and uric acid). Also, the amount of a substance that is reabsorbed is dependent on its concentration in the blood. If it exists in a low concentration in the blood, a large amount of it will be reabsorbed from the renal tubules. Conversely, if it already exists in a high concentration, very little of it will be reabsorbed into the blood.

SECRETION. Secretion is the transport of materials from the interstitial fluid into the renal filtrate. It is essentially reabsorption in reverse. The process is important for getting rid of substances not already in the filtrate. Waste products such as ammonia, some creatinine, and the end products of medications move from the blood in the capillaries around the renal tubules into the interstitial fluid. They are then taken in by the cells of the tubules and deposited into the renal filtrate to be eliminated in the urine.

Hormones and the composition of urine

Hormones are chemical "messengers" secreted by endocrine glands that control or coordinate the activities of other tissues, organs, and organ systems in the body. Each type of hormone affects only specific tissue cells or organs, called target cells or target organs. Most hormones are composed of amino acids, the building blocks of proteins. The smaller class of hormones are steroids, which are built from molecules of cholesterol (fatlike substance produced by the liver).

The hormones that affect the urinary system help it regulate the amount of water and mineral ions in urine. By extension, this action also regulates the pressure in the bloodstream and the concentration of mineral ions in the blood.

Excessive water loss in the urine is controlled by the antidiuretic hormone (ADH), which is released by the pituitary gland (a small gland lying at the base of the skull). If an individual perspires a lot, fails to drink enough water, or loses water through diarrhea, special nerve cells in the hypothalamus (a region of the brain controlling body temperature, hunger, and thirst) detect the low water concentration in the blood. They then signal the pituitary gland to release ADH into the blood, where it travels to the kidneys. With ADH present, the renal tubules are stimulated to reabsorb more water from the renal filtrate and return it to the blood. The volume of water in the urine is thus reduced, and the urine becomes more concentrated. Harmful substances are still eliminated from the body, but necessary water is not.

In 1950, Ruth Tucker, a forty-nine-year-old American woman, was dying from chronic kidney failure. American surgeon Richard Lawler of Loyola University in Chicago transplanted a kidney from a cadaver (dead body) into Tucker. Although her body rejected the new kidney after only a short time, Tucker became the first human to survive an organ transplantation.

With the development of immunosuppressant drugs (those that hinder the body's immune response to ȯoreign" tissue), the success of kidney transplants has risen. Today, individuals who receive a kidney transplant from a living donor (who is often a close relative) have a survival rate of 80 percent.

The action of ADH also controls blood volume and pressure. As more water is removed from the urine and transported into the bloodstream, blood volume and pressure increase. This is an important safeguard against low blood volume and pressure, which might be brought about by an injury.

On the other hand, if an individual takes in too much water, production of ADH decreases. The renal tubules do not reabsorb as much water, and the volume of water in the urine is increased. Alcohol and liquids containing caffeine (coffee, tea, and cola drinks) inhibit ADH production (these substances are called diuretics). Large amounts of urine are consequently excreted from the body and blood pressure decreases. If that fluid is not replaced, an individual may feel dizzy due to low blood pressure.

Another hormone that helps to control blood volume by acting on the kidneys is aldosterone. Aldosterone is a steroid hormone secreted by the adrenal cortex (the outer layer of an adrenal gland, which sits like a cap on top of a kidney). A decrease in blood pressure or volume, a decrease in the sodium ion level in blood, and an increase in the potassium ion level in blood all stimulate the secretion of aldosterone. Once released, aldosterone spurs the cells of the renal tubules to reabsorb sodium from the urine and to excrete potassium instead. Sodium is then returned to the bloodstream. When sodium is reabsorbed into the blood, water in the body follows it, thus increasing blood volume and pressure.

The kidneys themselves play a role in regulating blood pressure. When blood pressure around the kidneys decreases below normal, the cells of the renal tubules react by secreting the enzyme renin (an enzyme is a protein that speeds up the rate of chemical reactions). Renin, in turn, stimulates an inactive blood protein to change into a hormone that causes blood vessels to constrict or narrow, which immediately raises blood pressure.

Elimination of urine

The process of eliminating urine from the urinary bladder is known as urination. It is also called micturition or voiding. The sensation of having to urinate usually occurs after the urinary bladder has filled with about 7 ounces (200 milliliters) of urine. The bladder has stretched enough at this point to activate receptors within its walls. Once activated, these receptors send impulses to the spinal cord, which sends impulses back to the bladder, causing it to contract. The internal urethral sphincter (surrounding the opening of the urethra) relaxes and urine is forced into the upper portion of the urethra. This initiates the 𢿮ling" of having to urinate.

Urination occurs when an individual voluntarily relaxes his or her external urethral sphincter. Urine flows through the urethra and the bladder is emptied. Babies do not exert control over their external urethral sphincter and urine is automatically forced out of the body when it reaches a certain level. As children mature, they learn to control their external urethral sphincter, retaining their urine until it is appropriate to urinate.

If the external urethral sphincter is not relaxed, urine will continue to accumulate in the bladder. When it reaches a volume over 1 pint (475 milliliters), the pressure created will cause pain and the external urethral sphincter eventually will be forced open, regardless of an individual's desire.


3 Life-Changing Steps to Chill Your Stressed-Out Brain

If you’re like most people, you might not even know about your own brain, and yet your brain is who you are. It is the boss of your mind and body. So it’s important to know what it’s up to, especially when you’re under pressure. With modern imaging techniques, scientists have advanced our understanding of this amazing organ and how it functions under stress.
1. Meet Your Brain

Your brain is about the size of your fists and weighs about as much as a cantaloupe—around three pounds. Although it’s mostly made up of water, the human brain contains as many as 100 billion neurons. The neurons connect through long, spidery arms and communicate with each other through electrochemical signals. Your brain never shuts down. It’s your protector, active around the clock—even when you’re asleep—to keep you safe so you can survive this thing called life. Your brain is prewired to constantly scan your inner and outer worlds for threats and to react automatically to perceived threats—even if they’re not real.

2. Get in Touch with Your Lizard Brain

Are you waiting for the ax to fall or worrying that something bad might happen—even though there’s no good reason for it? That’s because your lizard brain (or survival memories in the limbic system) senses that a present situation is similar to a memory it has already recorded, so it kicks into survival mode to protect you. Let’s say you were dog bitten when you were four years old. And when friends introduce you to their friendly Goldendoodle, you freak out. Your lizard brain has a built-in negativity bias, designed to exaggerate fears and worries in order to protect you against threats at all costs. When a threat is perceived (real or imagined), its job is to throw your prefrontal cortex (decision making, executive functioning part of the brain) offline, even when there’s no rational reason for it.

Mother Nature is more interested in marinating you in stress juices to keep you alive than in reducing your stress to make you happy. Your lizard brain routinely assesses risks by making judgments about people and situations. And negative experiences grab your brain’s attention more than positive ones. In situations where your buttons are pushed, you can feel the moment your lizard brain dumps a tonic of heart-pounding enzymes into your bloodstream. The surging adrenaline and cortisol act like a tidal wave, hijacking your thoughts and leaving your emotions to rush to action.

3. Rewire Your Brain to Stay Cool Under Pressure

To complete Mother Nature’s work, your job is to go beyond survival mode and avoid taking the bait every time a negative thought clobbers you. Neuroscientists have an old saying: “Neurons that fire together, wire together.” By taking a different track under pressure, you can rewire current stressful events by taking a more positive action and getting a calmer outcome. With some dedication to changing your old stress responses, you can change the way your brain fires in the moment. This is known as neuroplasticity. In the same way that a cut on your hand regenerates new healing tissue, the pliability of the brain makes it possible to rewire connections of neurons to adapt more positively under stressful conditions. When you’re frazzled and start to sizzle, you can avoid hotheaded action and cool down your lizard brain by challenging perceived threats. As you bring your prefrontal cortex back online, it offers an impartial, objective perspective on the stressful situation. Here are some examples of how to do that:

* To gain more clarity, ask yourself questions such as, “What am I afraid of and where is that coming from?” or “What are the chances of that really happening?” or “What is the worst thing that could happen?”

* Pinpoint the upside of a downside situation. Look for the roses instead of the thorns. “I had to pay more taxes this year than I’ve ever paid” becomes “I made more money this year than I’ve ever made.”

* Be chancy and take small risks in new situations instead of predicting negative outcomes without sticking your neck out. “I don’t know anybody at the party, so I’m not going” becomes “If I go to the party, I might make a new friend.”

* Make an effort to focus on the good news wrapped around the bad news. “A tornado destroyed my neighbor’s house” becomes “Their house was destroyed, but everyone survived and nobody was injured.”

THE BASICS

* Avoid blowing things out of proportion and letting one negative experience rule your whole life pattern. “I didn’t get the promotion now I’ll never reach my career goals” becomes “I didn’t get the promotion, but there are many other steps I can take to reach my career goals.”

#Chill: It’s A No-Brainer

So next time you’re about to blast off, call on your brain’s prefrontal cortex to help you stay on the launch pad. Even when positive experiences outnumber negative ones, it can feel like your life is full of mostly negative events that make you feel on edge, pessimistic, and grim. The key is to look for the silver lining in unpleasant situations and to note and savor positive outcomes so you have a balanced perspective. Once you realize things are usually not as bad as your lizard brain registers them to be, you can take a breath, step back from stressors and hopefully relax. You don’t have to look through rose-colored glasses. But by intentionally bringing your prefrontal cortex to threatening situations, you create a more chilled life inside and out.