Anatomy and Physiology – McGraw Hill Education

Glossary Click here to go to Prefixes and Suffixes.

Most of the words in this glossary are followed by a phonetic spelling that serves as a guide to pronunciation. The phonetic spellings reflect standard scientific usage and can be easily interpreted following a few basic rules.

abduction (ab-dukshun) The movement of a body part away from the axis or midline of the body; movement of a digit away from the axis of the limb.

ABO system The most common system of classification for red blood cell antigens. On the basis of antigens on the red blood cell surface, individuals can be type A, type B, type AB, or type O.

absorption (ab-sorpshun) The transport of molecules across epithelial membranes into the body fluids.

accessory organs (ak-sesuo-re) Organs that assist with the functioning of other organs within a system.

accommodation (ua-komuo-dashun) A process whereby the focal length of the eye is changed by automatic adjustment of the curvature of the lens to bring images of objects from various distances into focus on the retina.

acetabulum (asue-tabyuu-lum) A socket in the lateral surface of the hipbone (os coxa) with which the head of the femur articulates.

acetone (asue-t=on) A ketone body produced as a result of the oxidation of fats.

acetyl coenzyme A (acetyl CoA) (asue-tl, ua-setl) A coenzyme derivative in the metabolism of glucose and fatty acids that contributes substrates to the Krebs cycle.

acetylcholine (ACh) (ua-setl-kol=en) An acetic acid ester of choline-a substance that functions as a neurotransmitter in somatic motor nerve and parasympathetic nerve fibers.

acetylcholinesterase (ua-setl-kolu1-nestue-r=as) An enzyme in the membrane of postsynaptic cells that catalyzes the conversion of ACh into choline and acetic acid. This enzymatic reaction inactivates the neurotransmitter.

Achilles tendon (ua-kil=ez) See tendo calcaneous.

acid (asid) A substance that releases hydrogen ions when ionized in water.

acidosis (asu1-dosis) An abnormal increase in the H+ concentration of the blood that lowers the arterial pH to below 7.35.

acromegaly (akro-megua-le) A condition caused by the hypersecretion of growth hormone from the pituitary gland after maturity and characterized by enlargement of the extremities, such as the nose, jaws, fingers, and toes.

actin (aktin) A protein in muscle fibers that together with myosin is responsible for contraction.

action potential An all-or-none electrical event in an axon or muscle fiber in which the polarity of the membrane potential is rapidly reversed and reestablished.

active immunity (u1-myoonu1-te) Immunity involving sensitization, in which antibody production is stimulated by prior exposure to an antigen.

active transport The movement of molecules or ions across the cell membranes of epithelial cells by membrane carriers. An expenditure of cellular energy (ATP) is required.

adduction (au-dukshun) The movement of a body part toward the axis or midline of the body; movement of a digit toward the axis of the limb.

adenohypophysis (adn-o-hi-pofu1-sis) The anterior, glandular lobe of the pituitary gland that secretes FSH (follicle-stimulating hormone), LH (luteinizing hormone), ACTH (adrenocorticotropic hormone), TSH (thyroid-stimulating hormone), GH (growth hormone), and prolactin. Secretions of the adenohypophysis are controlled by hormones produced by the hypothalamus.

adenoids (adue-noidz) The tonsils located in the nasopharynx; pharyngeal tonsils.

adenylate cyclase (ua-denl-it sikl=as) An enzyme found in cell membranes that catalyzes the conversion of ATP to cyclic AMP and pyrophosphate (PP1). This enzyme is activated by an interaction between a specific hormone and its membrane receptor protein.

ADH Antidiuretic hormone; a hormone produced by the hypothalamus and released by the posterior pituitary that acts on the kidneys to promote water reabsorption; also known as vasopressin.

ADP Adenosine diphosphate; a molecule that together with inorganic phosphate is used to make ATP (adenosine triphosphate).

adrenal cortex (ua-drenal korteks) The outer part of the adrenal gland. Derived from embryonic mesoderm, the adrenal cortex secretes corticosteroid hormones (such as aldosterone and hydrocortisone).

adrenal medulla (mue-dulua) The inner part of the adrenal gland. Derived from embryonic postganglionic sympathetic neurons, the adrenal medulla secretes catecholamine hormones-epinephrine and (to a lesser degree) norepinephrine.

adrenergic (adreu-nerjik) A term used to describe the actions of epinephrine, norepinephrine, or other molecules with similar activity (as in adrenergic receptor and adrenergic stimulation).

adventitia (adven-tishua) The outermost epithelial layer of a visceral organ; also called serosa.

afferent (afer-ent) Conveying or transmitting to.

afferent arteriole (ar-tire-=ol) A blood vessel within the kidney that supplies blood to the glomerulus.

afferent neuron (nooron) See sensory neuron.

agglutinate (ua-glootn-=at) A clump of cells (usually erythrocytes) formed as a result of specific chemical interaction between surface antigens and antibodies.

agranular leukocytes (ua-granyuu-lar loo kuo-s1=tz) White blood cells (leukocytes) that do not contain cytoplasmic granules; specifically, lymphocytes and monocytes.

albumin (al-byoomin) A water-soluble protein produced in the liver; the major component of the plasma proteins.

aldosterone (al-doster-=on) The principal corticosteroid hormone involved in the regulation of electrolyte balance (mineralocorticoid).

alimentary canal The tubular portion of the digestive tract. See also gastrointestinal tract (GI tract).

allantois (ua-lanto-is) An extraembryonic membranous sac involved in the formation of blood cells. It gives rise to the fetal umbilical arteries and vein and also contributes to the formation of the urinary bladder.

allergens (aler-jenz) Antigens that evoke an allergic response rather than a normal immune response.

allergy (aler-je) A state of hypersensitivity caused by exposure to allergens. It results in the liberation of histamine and other molecules with histaminelike effects.

all-or-none principle The statement of the fact that muscle fibers of a motor unit contract to their maximum extent when exposed to a stimulus of threshold strength.

allosteric (aluo-sterik) A term used with reference to the alteration of an enzyme's activity as a result of its combination with a regulator molecule. Allosteric inhibition by an end product represents negative feedback control of an enzyme's activity.

alveolar sacs (al-veuo-lar) A cluster of alveoli that share a common chamber or central atrium.

alveolus (al-veuo-lus) 1.An individual air capsule within the lung. The alveoli are the basic functional units of respiration. 2.The socket that secures a tooth(tooth socket).

amniocentesis (amne-o-sen-tesis) A procedure in which a sample of amniotic fluid is aspirated to examine suspended cells for various genetic diseases.

amnion (amne-on) A developmental membrane surrounding the fetus that contains amniotic fluid.

amphiarthrosis (amfe-ar-throsis) A slightly movable articulation in a functional classification of joints.

amphoteric (am-fo-terik) Having both acidic and basic characteristics; used to denote a molecule that can be positively or negatively charged, depending on the pH of its environment.

ampulla (am-poolua) A saclike enlargement of a duct or tube.

ampulla of Vater (Fuater) See hepatopancreatic ampulla.

anabolic steroids (anua-bolik steroidz) Steroids with androgenlike stimulatory effects on protein synthesis.

anabolism (ua-nabuo-lizem) A phase of metabolism involving chemical reactions within cells that result in the production of larger molecules from smaller ones; specifically, the synthesis of protein, glycogen, and fat.

anaerobic respiration (an-ua-robik respu1-rashun) A form of cell respiration involving the conversion of glucose to lactic acid in which energy is obtained without the use of molecular oxygen.

anal canal (anal) The terminal tubular portion of the large intestine that opens through the anus of the GI tract.

anaphylaxis (anua-fu1-laksis) An unusually severe allergic reaction that can result in cardiovascular shock and death.

anastomosis (ua-nastuo-mosis) An interconnecting aggregation of blood vessels or nerves that form a network plexus.

anatomical position (anua-tomu1-kal) An erect body stance with the eyes directed interior, the arms at the sides, the palms of the hands facing interior, and the fingers pointing straight down.

anatomy (ua-natuo-me) The branch of science concerned with the structure of the body and the relationship of its organs.

androgens (andruo-jenz) Steroids containing 18 carbons that have masculinizing effects; primarily those hormones(such as testosterone) secreted by the testes, although weaker androgens are also secreted by the adrenal cortex.

anemia (ua-neme-ua) An abnormal reduction in the red blood cell count, hemoglobin concentration, or hematocrit, or any combination of these measurements. This condition is associated with a decreased ability of the blood to carry oxygen.

angina pectoris (an-jinua pektuo-ris) A thoracic pain, often referred to the left pectoral and arm area, caused by myocardial ischemia.

angiotensin II (anje-o-tensin) An 8-amino-acid polypeptide formed from angiotensin I(a 10-amino-acid precursor), which in turn is formed from cleavage of a protein(angiotensinogen) by the action of renin(an enzyme secreted by the kidneys). Angiotensin II is a powerful vasoconstrictor and a stimulator of aldosterone secretion from the adrenal cortex.

anions (ani-onz) Ions that are negatively charged, such as chloride, bicarbonate, and phosphate.

antagonist (an-taguo-nist) A muscle that acts in opposition to another muscle.

antebrachium (ante-brake-em) The forearm.

anterior (ventral) Toward the front; the opposite of posterior, or dorsal.

anterior pituitary (pu1-toou1-ter-e) See adenohypophysis.

anterior root The anterior projection of the spinal cord, composed of axons of motor neurons.

antibodies (antu1-bod=ez) Immunoglobin proteins secreted by B lymphocytes that have transformed into plasma cells. Antibodies are responsible for humoral immunity. Their synthesis is induced by specific antigens, and they combine with these specific antigens but not with unrelated antigens.

anticodon (antu1-kodon) A base triplet provided by three nucleotides within a loop of transfer RNA that is complementary in its base-pairing properties to a triplet(the codon) in mRNA. The matching of codon to anticodon provides the mechanism for translating the genetic code into a specific sequence of amino acids.

antigen (antu1-jen) A molecule that can induce the production of antibodies and react in a specific manner with antibodies.

antigenic determinant site (an-tu1-jenik) The region of an antigen molecule that specifically reacts with particular antibodies. A large antigen molecule may have a number of such sites.

antiserum (antu1-sirum) A serum that contains specific antibodies.

anus (anus) The terminal opening of the GI tract.

aorta (a-ortua) The major systemic vessel of the arterial system of the body, emerging from the left ventricle.

aortic arch The superior left bend of the aorta between the ascending and descending portions.

apex (apeks) The tip or pointed end of a conical structure.

aphasia (ua-fazhua) Defects in speech, writing, or in the comprehension of spoken or written language caused by brain damage or disease.

apneustic center (ap-noostik) A collection of nuclei(nerve cell bodies) in the brain stem that participates in the rhythmic control of breathing.

apocrine gland (apuo-krin) A type of sweat gland that functions in evaporative cooling. It may respond during periods of emotional stress.

aponeurosis (apuo-noo-rosis) A fibrous or membranous sheetlike tendon.

appendix A short pouch that attaches to the cecum.

aqueous humor (akwe-us) The watery fluid that fills the anterior and posterior chambers of the eye.

arachnoid mater (ua-raknoid) The weblike middle covering(meninx) of the central nervous system.

arbor vitae (arbor vite) The branching arrangement of white matter within the cerebellum.

arm (brachium) The portion of the upper extremity from the shoulder to the elbow.

arrector pili muscle (ah-rektor pihle) The smooth muscle attached to a hair follicle that, upon contraction, pulls the hair into a more vertical position, resulting in "goose bumps."

arteriole (ar-tire-=ol) A minute arterial branch.

arteriosclerosis (ar-tire-o-sklue-rosis) Any one of a group of diseases characterized by thickening and hardening of the artery wall and in the narrowing of its lumen.

arteriovenous anastomoses (ar-tire-o-venus ua-nastuo-mos=ez) Direct connections between arteries and veins that bypass capillary beds.

artery (artue-re) A blood vessel that carries blood away from the heart.

arthrology (ar-throluo-je) The scientific study of the structure and function of joints.

articular cartilage (ar-tikyuu-lar kartu1-lij) A hyaline cartilaginous covering over the articulating surface of the bones of synovial joints.

articulation (ar-tikyuu-lashun) A joint.

arytenoid cartilages (arue-tenoid) A pair of small cartilages located on the superior aspect of the larynx.

ascending colon (kolon) The portion of the large intestine between the cecum and the hepatic flexure.

association neuron (nooron) A nerve cell located completely within the central nervous system. It conveys impulses in an arc from sensory to motor neurons; also called interneuron or internuncial neuron.

astigmatism (ua-stigmua-tizem) Unequal curvature of the refractive surfaces of the eye (cornea and/or lens), so that light entering the eye along certain meridians does not focus on the retina.

atherosclerosis (athue-ro-sklue-rosis) A common type of arteriosclerosis found in medium and larger arteries in which raised areas within the tunica intima are formed from smooth muscle cells, cholesterol, and other lipids. These plaques occlude arteries and serve as sites for the formation of thrombi.

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Anatomy and Physiology - McGraw Hill Education

What is Physiology | Human Physiology | Understanding Life …

Physiology is the science of life. It is a broad science which aims to understand the mechanisms of living, from the molecular basis of cell function to the integrated behaviour of the whole body.

Research in physiology helps us to understand how the body works; it also helps us to realise what goes wrong in disease and to identify new treatments for disease.

Physiology forms an integral part of pre- and post-16 biology education, and can also be studied at university either as a stand-alone discipline or as part of an integrated degree, such as biomedical sciences. For more information about career paths in physiology, please visit the careers section of this website.

Pre-16, the study of physiology focuses primarily on how the body moves, and the structure and function of some of the major organ systems (including the cardiovascular and respiratory systems). Post-16, the study of physiology leans more towards the understanding of physiological processes such as homeostasis and excretion.

A degree in physiology will build on the knowledge and understanding developed at school/college: it will explore selected topics in greater detail and provide a holistic view of how the different cells, tissues, organs and systems of the body are integrated. Physiologists - scientists who have chosen to explore physiology as a career will continue to build on the knowledge they have gained during their degree and advance the science of life within an area of particular interest to them. It is important to highlight, however, that physiologists do not work in isolation: the sharing of information between scientists around the world is essential to continue developing our understanding of how the body works.

Physiology is an experimental science that underpins the biological and clinical sciences; it is key to the detection, prevention and treatment of disease. Without an understanding of basic physiology, progress made in other areas such as the sequencing of the human genome is limited because every biological advance must ultimately be related to the behaviour of the whole organism.

The Physiological Society recognises the importance of using animals in research in order to gain further knowledge of disease mechanisms in both animal and human diseases. We appreciate that this can be a difficult topic to understand and teach and have therefore developed supporting resources designed to address this area specifically.

To hear what physiology means to our members, listen to the podcasts available in our resources section.

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Mechanics of Breathing – Breathing in Joy

Mechanics of Breathing

This explanation of the physiology of breathing shows how our health improves through the conscious connected breathing that we do in Transformation Breathwork.

Humans need a continuous supply of oxygen for cellular respiration, and they must get rid of excess carbon dioxide, the poisonous waste product of this process. Gas exchange supports this cellular respiration by constantly supplying oxygen and removing carbon dioxide. The oxygen we need is derived from the Earth's atmosphere, which is 21% oxygen. This oxygen in the air is exchanged in the body by the respiratory surface. In humans, the alveoli in the lungs serve as the surface for gas exchange.

Gas exchange in humans can be divided into five steps:

Other factors involved with respiration are:

Structure of the Human Respiratory System

The Nose - Usually air will enter the respiratory system through the nostrils. The nostrils then lead to open spaces in the nose called the nasal passages. The nasal passages serve as a moistener, a filter, and to warm upthe air before it reaches the lungs. The hairs existing within the nostrils prevents various foreign particles from entering.Different air passageways and the nasal passages are covered with a mucous membrane. Many of the cells which produce the cells that make up the membrane contain cilia. Others secrete a type a sticky fluid called mucus. The mucus and cilia collect dust, bacteria, and other particles in the air. The mucus also helps in moistening the air. Under the mucous membrane there are a large number of capillaries. The blood within these capillaries helps to warm the air as it passes through the nose. The nose serves three purposes. It warms, filters, and moistens the air before it reaches the lungs. You will obviously lose these special advantages if you breath through your mouth.

Pharynx and Larynx - Air travels from the nasal passages to the pharynx, or more commonly known as the throat. When the air leaves the pharynx it passes into the larynx, or the voice box. The voice box is constructed mainly of cartilage, which is a flexible connective tissue. The vocal chords are two pairs of membranes that are stretched across the inside of the larynx. As the air is expired, the vocal chords vibrate. Humans can control the vibrations of the vocal chords, which enables us to make sounds. Food and liquids are blocked from entering the opening of the larynx by the epiglottis to prevent people from choking during swallowing.

Trachea - The larynx goes directly into the trachea or the windpipe. The trachea is a tube approximately 12 centimeters in length and 2.5 centimeters wide. The trachea is kept open by rings of cartilage within its walls. Similar to the nasal passages, the trachea is covered with a ciliated mucous membrane. Usually the cilia move mucus and trapped foreign matter to the pharynx. After that, they leave the air passages and are normally swallowed. The respiratory system cannot deal with tobacco smoke very keenly. Smoking stops the cilia from moving. Just one cigarette slows their motion for about 20 minutes. Thetobacco smokeincreases the amount of mucus in the air passages. When smokers cough, their body is attempting to dispose of the extra mucus.

Bronchi - Around the center of the chest, the trachea divides into two cartilage-ringed tubes called bronchi. Also, this section of the respiratory system is lined with ciliated cells. The bronchi enter the lungs and spread into a treelike fashion into smaller tubes calle bronchial tubes.

Bronchioles - The bronchial tubes divide and then subdivide. By doing this their walls become thinner and have less and less cartilage. Eventually, they become a tiny group of tubes called bronchioles.

Alveoli - Each bronchiole ends in a tiny air chamber that looks like a bunch of grapes. Each chamber contains many cup-shaped cavities known as alveoli. The walls of the alveoli, which are only about one cell thick, are the respiratory surface. They are thin, moist, and are surrounded by several numbers of capillaries. The exchange of oxygen and carbon dioxide between blood and air occurs through these walls. The estimation is that lungs contain about 300 million alveoli. Their total surface area would be about 70 square meters. That is 40 times the surface area of the skin. Smoking makes it difficult for oxygen to be taken through the alveoli. When the cigarette smoke is inhaled, about one-third of the particles will remain within the alveoli. There are too many particles from smoking or from other sources of air pollution which can damage the walls in the alveoli. This causes a certain tissue to form. This tissue reduces the working area of the respiratory surface and leads to the disease called emphysema.


Breathing consists of two phases, inspiration and expiration. During inspiration, the diaphragm and the intercostal muscles contract. The diaphragm moves downwards increasing the volume of the thoracic (chest) cavity, and the intercostal muscles pull the ribs up expanding the rib cage and further increasing this volume. This increase of volume lowers the air pressure in the alveoli to below atmospheric pressure. Because air always flows from a region of high pressure to a region of lower pressure, it rushes in through the respiratory tract and into the alveoli. This is called negative pressure breathing, changing the pressure inside the lungs relative to the pressure of the outside atmosphere. In contrast to inspiration, during expiration the diaphragm and intercostal muscles relax. This returns the thoracic cavity to it's original volume, increasing the air pressure in the lungs, and forcing the air out.

External Respiration

When a breath is taken, air passes in through the nostrils, through the nasal passages, into the pharynx, through the larynx, down the trachea, into one of the main bronchi, then into smaller bronchial tubules, through even smaller bronchioles, and into a microscopic air sac called an alveolus. It is here that external respiration occurs. Simply put, it is the exchange of oxygen and carbon dioxide between the air and the blood in the lungs. Blood enters the lungs via the pulmonary arteries. It then proceeds through arterioles and into the alveolar capillaries. Oxygen and carbon dioxide are exchanged between blood and the air. This blood then flows out of the alveolar capillaries, through venuoles, and back to the heart via the pulmonary veins. For an explanation as to why gasses are exchanged here, see partial pressure.

Gas Transport

If 100mL of plasma is exposed to an atmosphere with a pO2 of 100mm Hg, only 0.3mL of oxygen would be absorbed. However, if 100mL of bloodis exposed to the same atmosphere, about 19mL of oxygen would be absorbed. This is due to the presence of haemoglobin, the main means of oxygen transport in the body. The respiratory pigment haemoglobin is made up of an iron-containing porphyron, haem, combined with the protein globin. Each iron atom in haem is attached to four pyrole groups by covalent bonds. A fifth covalent bond of the iron is attached to the globin part of the molecule and the sixth covalent bond is available for combination with oxygen. There are four iron atoms in each hemoglobin molecule and therefore four heam groups.

Oxygen Transport -

In the loading and unloading of oxygen, there is a cooperation between these four haem groups. When oxygen binds to one of the groups, the others change shape slightly and their attraction to oxygen increases. The loading of the first oxygen, results in the rapid loading of the next three (forming oxyhemoglobin). At the other end, when one group unloads it's oxygen, the other three rapidly unload as their groups change shape again having less attraction for oxygen. This method of cooperative binding and release can be seen in the dissociation curve for hemoglobin. Over the range of oxygen concentrations where the curve has a steep slope, the slightest change in concentration will cause hemoglobin to load or unload a substantial amount of oxygen. Notice that the steep part of the curve corresponds to the range of oxygen concentrations found in the tissues. When the cells in a particular location begin to work harder, e.g. during exercise, oxygen concentration dips in that location, as the oxygen is used in cellular respiration. Because of the cooperation between the haem groups, this slight change in concentration is enough to cause a large increase in the amount of oxygen unloaded.

As with all proteins, hemoglobin's shape shift is sensitive to a variety of environmental conditions. A drop in pH lowers the attraction of hemoglobin to oxygen, an effect known as the Bohr shift. Because carbon dioxide reacts with water to produce carbonic acid, an active tissue will lower the pH of it's surroundings and encourage hemoglobin to give up extra oxygen, to be used in cellular respiration. Hemoglobin is a notable molecule for it's ability to transport oxygen from regions of supply to regions of demand.

Carbon Dioxide Transport - Out of the carbon dioxide released from respiring cells, 7% dissolves into the plasma, 23% binds to the multiple amino groups of hemoglobin (Caroxyhemoglobin), and 70% is carried as bicarbonate ions. Carbon dioxide created by respiring cells diffuses into the blood plasma and then into the red blood cells, where most of it is converted to bicarbonate ions. It first reacts with water forming carbonic acid, which then breaks down into H+ and CO3-. Most of the hydrogen ions that are produced attach to hemoglobin or other proteins.

Internal Respiration

The body tissues need the oxygen and have to get rid of the carbon dioxide, so the blood carried throughout the body exchanges oxygen and carbon dioxide with the body's tissues. Internal respiration is basically the exchange of gasses between the blood in the capillaries and the body's cells.

The respiratory center is gray matter in the pons and the upper Medulla, which is responsible for rhythmic respiration. This center can be divided into an inspiratory center and an expiratory center in the Medulla, an apneustic center in the lower and midpons and a pneumotaxic center in the rostral-most part of the pons. This respiratory center is very sensitive to the pCO2 in the arteries and to the pH level of the blood.The CO2 can be brought back to the lungs in three different ways; dissolved in plasma, as carboxyhemoglobin, or as carbonic acid. That particular form of acid is almost broken down immediately by carbonic hydrase into bicarbonate and hydrogen ions. This process is then reversed in the lungs so that water and carbon dioxide are exhaled. The Medulla Oblongata reacts to both CO2 and pH levels which triggers the breathing process so that more oxygen can enter the body to replace the oxygen that has been utilized. The Medulla Oblongata sends neural impulses down through the spinal chord and into the diaphragm. The impulse contracts down to the floor of the chest cavity, and at the same time there is a message sent to the chest muscles to expand causing a partial vacuum to be formed in the lungs. The partial vacuum will draw air into the lungs.

There are two other ways the Medulla Oblongata can be stimulated. The first type is when there is an oxygen debt (lack of oxygen reaching the muscles), andthis produces lactic acid which lowers the pH level.The Medulla Oblongata is then stimulated. If the pH rises it begins a process known as the Bohr shift. The Bohr shift is affected when there are extremely high oxygen and carbon dioxide pressures present in the human body. This factor causes difficulty for the oxygen and carbon dioxide to attach to hemoglobin. When the body is exposed to higher altitudes the oxygen will not attach to the hemoglobin properly, causing the oxygen level to drop and the person will black out. This theory also applies to divers who go to great depths, and the pressure of the oxygen becomes poisonous. These pressures are known as pO2 and pCO2, or partial pressures. The second type occurswhen the major arteries in the body called theaortic and carotid bodies, sense a lack of oxygen within the blood and they send messages to the Medulla Oblongata.

Various marine mammals have been found to have adapted special abilities which help in their respiratory processes, enabling them to remain down at great depths for long periods of time. The Weddell seal possesses some amazing abilities. It only stores 5% of its oxygen in its lungs, and keeps the remaining 70% of its oxygen circulating throughout the blood stream. Humans are only able to keep a small 51% of their oxygen circulating throughout the blood stream, while 36% of the oxygen is stored in the lungs. The explanation for this is that the Weddell seal has approximately twice the volume of blood per kilogram as humans. As well, the Weddell seal's spleen has the ability to store up to 24L of blood. It is believed that when the seal dives the spleen contracts causing the stored oxygen enriched blood to enter the blood stream. Also, these seals have a higher concentration of a certain protein found within the muscles known as myoglobin, which stores oxygen. The Weddell seal contains 25% of its oxygen in the muscles, while humans only keep about 12% of their oxygen within the muscles.

Not only does the Weddell seal store oxygen for long dives, but they consume it wisely as well. A diving reflex slows the pulse, and an overall reduction in oxygen consumption occurs due to this reduced heart rate. Regulatory mechamisms reroute blood to where it is needed most (brain, spinal cord, eyes, adrenal glands, and in some cases placenta) by constricting blood flow where it is not needed (mainly in the digestive system). Blood flow is restricted to muscles during long dives and they rely on oxygen stored in their myoglobin and make their ATP from fermentation rather then from respiration.

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Mechanics of Breathing - Breathing in Joy

Renal System – Physiology – Part 4 – (Ureters, Bladder, Urethra, Obligatory Water Loss) – Video

Renal System - Physiology - Part 4 - (Ureters, Bladder, Urethra, Obligatory Water Loss)
Lecture series by G. Fuller, who has been teaching Physiology course for 35 years. This was the last semester teaching before he retired. In this lecture, yo...

By: Wizard of Science

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Renal System - Physiology - Part 4 - (Ureters, Bladder, Urethra, Obligatory Water Loss) - Video

Science Under Pressure: Inside the Hyperbaric Chamber

Guest post by Lauren Burianek, doctoral candidate in cell biology

The basement of the Duke Clinic (called Duke South by everyone around here) seems like the last place youd expect to dive for treasure, but researchers and physicians at the Center for Hyperbaric Medicine and Environmental Physiology are doing just that diving for a better understanding of the human body.

Medical Director Rich Moon (standing) and chamber engineer Eric Schinazi at the controls of the hyperbaric chambers.

The $10 million facility was built in 1968 to study the effects of diving, altitude, and compressed gasses on human physiology. It features seven large steel chambers capable of simulating the high pressure of 1,000 feet below sea water to the low pressure of 100,000 feet above sea level. To put that into perspective, 1000 feet is the deepest the Smithsonian exploratory submersible, DROP, can dive, and 100,000 feet above sea level is considered to be near-space (with the peak of Mt. Everest at a measly 30,000 feet).

The deadly physiology of atmospheric pressure first came to light during construction of the Brooklyn Bridge in New York and the Eads Bridge in St. Louis in the late 1800s. High pressure tunnels were designed to keep the water out as footings were set in river beds, but the pressure also dissolved gas molecules in the blood streams of tunnel workers. When they emerged from the pressurized conditions, the gas would bubble out of solution like a freshly opened can of soda, causing life-threatening conditions, including damage to the organs and lungs, and killing about a quarter of the workers.

A news photo of workers in the Lincoln Tunnel under construction in the mid-1930s.

A couple decades later, a decompression chamber was used during the building of the Lincoln Tunnel under the Hudson River to slow the depressurization and reduce the chance of injury. This change reduced the deaths relating to decompression from 25% to almost 0%.

Similarly, SCUBA divers must carefully watch their rate of ascent; otherwise, they too might experience what is now known as decompression sickness or the bends.

The Hyperbaric facility at Duke is dedicated to researching exactly how the human body deals with these extreme pressures.

The interior of one of the hyperbaric chambers. The stickers are souvenirs of decades of research projects.

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Science Under Pressure: Inside the Hyperbaric Chamber

A supplement to stop wrinkles?

The claim: Two new studies published Skin Pharmacology and Physiology find a daily regimen of a new type of collagen supplement improves skin elasticity and reduces wrinkles around the eyes by 20 percent after just eight weeks.

The research: Between the two studies, more than 200 women took Verisol, a collagen supplement that can be added to beauty vitamins and drinks to increase collagen in the skin. In the first study, 114 women between 45 and 65 took a daily oral dose and, after eight weeks, showed a 20 percent average decrease in wrinkle volume around the eyeand a reduction of nearly 50 percent in some subjects.

Four weeks after the women stopped their daily regimen, wrinkle volume was still 11.5 percent less than it was at the start, on average. The second study had 69 women in the same age group drink the substance dissolved in water for 8 weeks; the subjects older than 50 showed a significant improvement in skin elasticity, hydration, and skin roughness.

For more tips to keep your skin looking young, learn the 10 Best Ways To Prevent Wrinkles.

What it means: Collagen supplements are a point of debate among dermatologists and doctors because collagen is a protein that, when it enters your stomach, is largely broken down before ever making it to your skin. As a result, most derms would deem collagen supplements ineffective for anti-aging results. Instead, derms typically recommend a topical collagen cream to help boost collagen and achieve the firm, springy skin of decades past. But even creams have their limitations:

The topical stuff doesnt last long and it only penetrates the first layer of skin, says Dr. Shilpi Agarwal, boardcertified integrative medicine and family medicine physician in Los Angeles.

These studies, however, focus on a new type of ingestible collagen peptide that is more bioavailablemeaning, it's more easily absorbed by the body. As a result, it may boost collagen in the skin's deeper layers, where it helps reduce the look of wrinkles by plumping and firming the skin.

On a cellular level, this works, said Agarwal, who was not involved in the study but reviewed the research.

What really causes wrinkles? Find out here!

Bottom line: These initial studies only focus on one specific type of collagen peptide, but its a peek into the future of beauty-focused supplements that carry a serious bang for their buck.

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A supplement to stop wrinkles?

APS Elects New 2014 Officers

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Newswise Bethesda, MD (February 26, 2014) The American Physiological Society (APS) today announced the election of Patricia E. Molina, MD, PhD, as the new president-elect. Barbara Alexander, PhD, Rudy M. Ortiz, PhD, and Bill Yates, PhD, were also announced as new APS Councillors. The new officers were elected by the APS membership and will take office at the Experimental Biology meeting on April 30, 2014.

Dr. Patricia E. Molina is a Richard Ashman, PhD professor and head of the department of physiology at the Louisiana State University Health Sciences Center (LSUHSC) in New Orleans. She is also director of the Alcohol and Drug Abuse Center of Excellence at LSUHSC. Dr. Molina received her medical degree from the Universidad Francisco Marroquin in Guatemala and her PhD from LSUHSC. Dr. Molina completed her postdoctoral training at Vanderbilt University.

Dr. Molinas research focuses on the impact of alcohol and drug abuse on the cardiovascular, metabolic, and immune consequences of acute traumatic injury and hemorrhagic shock. Her laboratory also investigates the interaction of chronic alcohol and cannabinoid use on the behavioral, metabolic, and immune consequences of HIV/AIDS.

Active on a number of APS committees, Dr. Molina has served as chair of both the International and Porter Physiology Development and Minority Affairs committees and of the APS Gulf-Coast chapter.

Physiologists skills and knowledge have never been as relevant as today. They are the core of team science, render context to big data, and should lead the educational initiatives necessary for health literacy, essential in achieving health equity, Dr. Molina said. I am committed to the professional development of a diverse and inclusive APS membership body that will continue to evolve and embrace current and future scientific challenges.

Dr. Barbara T. Alexander is an associate professor and director of the Analytical and Assay Core at the University of Mississippi Medical Center (UMMC) in Jackson. She received her undergraduate degree from Mississippi State University before completing her graduate work and postdoctoral training at UMMC. Dr. Alexanders research focuses on the renal mechanisms linking low birth weight and hypertension. Utilizing an integrative approach, including whole animal and molecular and biochemical analysis, she investigates how poor fetal growth due to placental insufficiency leads to high blood pressure.

Dr. Alexander has served as secretary-treasurer of the Water and Electrolyte Homeostasis section and on the editorial board of AJPRegulatory, Integrative and Comparative Physiology; AJPRenal Physiology; and AJPHeart and Circulatory Physiology. She has also served as a member on the Women in Physiology and Communications committees and as an organizer for the APS conference Physiology of Cardiovascular Disease: Gender Disparities.

My involvement in the APS is driven by its strong commitment to foster education, scientific research, and communication of science to the public, Dr. Alexander wrote. I value these missions of the APS and believe that it is important for our council to continue to provide avenues of support to its members in order to not only enrich their science and career goals but to ensure the continuation of physiology as a science.

APS Elects New 2014 Officers