All posts by medical

Cell Biology

Home > Cell Biology | Yale School of Medicine

When you express interest in a specific study, the information from your profile will be sent to the doctor conducting that study. If you're eligible to participate, you may be contacted by a nurse or study coordinator.

If you select a health category rather than a specific study, doctors who have active studies in that area may contact you to ask if you would like to participate.

In both cases, you will be contacted by the preferred method (email or phone) that you specified in your profile.

Read the rest here:

Home > Cell Biology | Yale School of Medicine

Anatomy

anatomy | biology | Britannica.com

Anatomy,a field in the biological sciences concerned with the identification and description of the body structures of living things. Gross anatomy involves the study of major body structures by dissection and observation and in its narrowest sense is concerned only with the human body. Gross anatomy customarily refers to the study of those body structures large enough to be examined without the help of magnifying devices, while microscopic anatomy is concerned with the study of structural units small enough to be seen only with a light microscope. Dissection is basic to all anatomical research. The earliest record of its use was made by the Greeks, and Theophrastus called dissection anatomy, from ana temnein, meaning to cut up.

Comparative anatomy, the other major subdivision of the field, compares similar body structures in different species of animals in order to understand the adaptive changes they have undergone in the course of evolution.

face: superficial arteries and veins in humansEncyclopdia Britannica, Inc.This ancient discipline reached its culmination between 1500 and 1850, by which time its subject matter was firmly established. None of the worlds oldest civilizations dissected a human body, which most people regarded with superstitious awe and associated with the spirit of the departed soul. Beliefs in life after death and a disquieting uncertainty concerning the possibility of bodily resurrection further inhibited systematic study. Nevertheless, knowledge of the body was acquired by treating wounds, aiding in childbirth, and setting broken limbs. The field remained speculative rather than descriptive, though, until the achievements of the Alexandrian medical school and its foremost figure, the Greek Herophilus (flourished 300 bce), who dissected human cadavers and thus gave anatomy a considerable factual basis for the first time. Herophilus made many important discoveries and was followed by his younger contemporary Erasistratus, who is sometimes regarded as the founder of physiology. In the 2nd century ce the Greek physician Galen assembled and arranged all the discoveries of the Greek anatomists, including with them his own concepts of physiology and his discoveries in experimental medicine. The many books Galen wrote became the unquestioned authority for anatomy and medicine in Europe because they were the only ancient Greek anatomical texts that survived the Dark Ages in the form of Arabic (and then Latin) translations.

Owing to church prohibitions against dissection, European medicine in the Middle Ages relied upon Galens mixture of fact and fancy rather than on direct observation for its anatomical knowledge, though some dissections were authorized for teaching purposes. In the early 16th century, the artist Leonardo da Vinci undertook his own dissections, and his beautiful and accurate anatomical drawings cleared the way for the Flemish physician Andreas Vesalius to restore the science of anatomy with his monumental De humani corporis fabrica libri septem (1543; The Seven Books on the Structure of the Human Body), which was the first comprehensive and illustrated textbook of anatomy. As a professor at the University of Padua, Vesalius encouraged younger scientists to accept traditional anatomy only after verifying it themselves, and this more critical and questioning attitude broke Galens authority and placed anatomy on a firm foundation of observed fact and demonstration.

From Vesaliuss exact descriptions of the skeleton, muscles, blood vessels, nervous system, and digestive tract, his successors in Padua progressed to studies of the digestive glands and the urinary and reproductive systems. Hieronymus Fabricius, Gabriello Fallopius, and Bartolomeo Eustachio were among the most important Italian anatomists, and their detailed studies led to fundamental progress in the related field of physiology. William Harveys discovery of the circulation of the blood, for instance, was based partly on Fabriciuss detailed descriptions of the venous valves.

The new application of magnifying glasses and compound microscopes to biological studies in the second half of the 17th century was the most important factor in the subsequent development of anatomical research. Primitive early microscopes enabled Marcello Malpighi to discover the system of tiny capillaries connecting the arterial and venous networks, Robert Hooke to first observe the small compartments in plants that he called cells, and Antonie van Leeuwenhoek to observe muscle fibres and spermatozoa. Thenceforth attention gradually shifted from the identification and understanding of bodily structures visible to the naked eye to those of microscopic size.

The use of the microscope in discovering minute, previously unknown features was pursued on a more systematic basis in the 18th century, but progress tended to be slow until technical improvements in the compound microscope itself, beginning in the 1830s with the gradual development of achromatic lenses, greatly increased that instruments resolving power. These technical advances enabled Matthias Jakob Schleiden and Theodor Schwann to recognize in 183839 that the cell is the fundamental unit of organization in all living things. The need for thinner, more transparent tissue specimens for study under the light microscope stimulated the development of improved methods of dissection, notably machines called microtomes that can slice specimens into extremely thin sections. In order to better distinguish the detail in these sections, synthetic dyes were used to stain tissues with different colours. Thin sections and staining had become standard tools for microscopic anatomists by the late 19th century. The field of cytology, which is the study of cells, and that of histology, which is the study of tissue organization from the cellular level up, both arose in the 19th century with the data and techniques of microscopic anatomy as their basis.

In the 20th century anatomists tended to scrutinize tinier and tinier units of structure as new technologies enabled them to discern details far beyond the limits of resolution of light microscopes. These advances were made possible by the electron microscope, which stimulated an enormous amount of research on subcellular structures beginning in the 1950s and became the prime tool of anatomical research. About the same time, the use of X-ray diffraction for studying the structures of many types of molecules present in living things gave rise to the new subspecialty of molecular anatomy.

Scientific names for the parts and structures of the human body are usually in Latin; for example, the name musculus biceps brachii denotes the biceps muscle of the upper arm. Some such names were bequeathed to Europe by ancient Greek and Roman writers, and many more were coined by European anatomists from the 16th century on. Expanding medical knowledge meant the discovery of many bodily structures and tissues, but there was no uniformity of nomenclature, and thousands of new names were added as medical writers followed their own fancies, usually expressing them in a Latin form.

By the end of the 19th century the confusion caused by the enormous number of names had become intolerable. Medical dictionaries sometimes listed as many as 20 synonyms for one name, and more than 50,000 names were in use throughout Europe. In 1887 the German Anatomical Society undertook the task of standardizing the nomenclature, and, with the help of other national anatomical societies, a complete list of anatomical terms and names was approved in 1895 that reduced the 50,000 names to 5,528. This list, the Basle Nomina Anatomica, had to be subsequently expanded, and in 1955 the Sixth International Anatomical Congress at Paris approved a major revision of it known as the Paris Nomina Anatomica.

View original post here:

anatomy | biology | Britannica.com

Physiology

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

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.

Read the original here:

Mechanics of Breathing - Breathing in Joy

Neuroscience

BMC Neuroscience – BioMed Central

Section Editors

Editorial Board | Editorial Team | Instructions for authors | FAQ

There has been an error retrieving the data. Please try again.

High fat diet can change brain

Acute intake of high fat diet resulted in a distinct response in specific functional regions of the hippocampus of the rat.

Our picky cat eaters with smart tongues

The analysis of two cat bitter receptors Tas2r38 and Tas2r43 by using a cellular functional assay reveals their different responsiveness to known human bitter compounds, comparing with their orthologous human receptors.

Kuramoto model simulation of neural hubs and dynamic synchrony in the human cerebral connectome

Schmidt R, LaFleur KJR, de Reus MA, van den Berg LH and van den Heuvel MP

BMC Neuroscience 2015, 16:54

Read the original here:

BMC Neuroscience - BioMed Central

Biochemistry

Harpers Illustrated Biochemistry (Lange Medical Book …

Gain a thorough understanding of the principles of biochemistry and molecular biology as they relate to modern medicine

Includes 16 case histories

Clear, concise, and in full color, Harpers Illustrated Biochemistry is unrivaled in its ability to clarify the link between biochemistry and the molecular basis of disease. Combining outstanding full-color illustrations with integrated coverage of biochemical diseases and clinical information, Harpers offers an organization and careful balance of detail and brevity not found in any other text on the subject.

Following two introductory chapters, the text is divided into six main sections: Section I addresses the structures and functions of proteins and enzymes. Section II explains how various cellular reactions utilize or release energy and traces the pathways by which carbohydrates and lipids are synthesized and degraded. Section III covers the amino acids, their metabolic fates, certain features of protein catabolism, and the biochemistry of the porphyrins and bile pigments. Section IV describes the structure and function of nucleotides and nucleic acids, DNA replication and repair, RNA synthesis and modification, protein synthesis, the principles of recombinant DNA technology, and new understanding of how gene expression is regulated. Section V deals with aspects of extracellular and intracellular communication. Section VI includes fifteen special topics, ranging from nutrition, digestion and absorption to the biochemistry of aging

New to this edition:

See more here:

Harpers Illustrated Biochemistry (Lange Medical Book ...

Biochemistry

Biochemistry and Molecular Biology – Departments – Johns …

The Department of Biochemistry and Molecular Biology conducts research to discover and characterize the fundamental biological processes relevant to health and disease.

Faculty and students work together to increase knowledge of the biochemical and molecular bases of normal and abnormal cellular processes and to train highly qualified scientists whothrough research, teaching and servicecontinue to provide new insights into the biomedical issues that have a profound impact on public health.

Greetings and welcome to the Department of Biochemistry and Molecular Biology. I'd like to share a brief description of who we are, and a sense of how it feels to be part of this wonderful community.

Learn More

The Department of Biochemistry and Molecular Biology takes great pride in the fantastic students it attracts. Meet our current students. Learn the research theyre pursuing.

Learn More

Continue reading here:

Biochemistry and Molecular Biology - Departments - Johns ...

Physiology

Amazon.com: Anatomy and Physiology For Dummies …

Learn about the human body from the inside out

Every year, more than 100,000 degrees are completed in biologyor biomedical sciences. Anatomy and physiology classes are requiredfor these majors and others such as life sciences andchemistry, and also for students on a pre-medtrack. These classes also serve as valuableelectives because of the importance and relevance of this subject'scontent. Anatomy and Physiology For Dummies, 2ndEdition, appeals to students and life-learners alike, as acourse supplement or simply as a guide to this intriguingfield of science.

With 25 percent new and revised content, including updatedexamples and references throughout, readers of the new edition willcome to understand the meanings of terms in anatomy and physiology,get to know the body's anatomical structures, and gain insight intohow the structures and systems function in sickness and health. * New examples, references, and case studies * Updated information on how systems function in illness and inhealth * Newest health discovers and insights into how the bodyworks

Written in plain English and packed with dozens of beautifulillustrations, Anatomy & Physiology For Dummies is yourguide to a fantastic voyage of the human body.

Link:

Amazon.com: Anatomy and Physiology For Dummies ...

Physiology

Anatomy and Physiology Learning Modules – CEHD – U of M

Quiz Bowl and Timed Test were retired at the end of summer 2013. Quiz Bowl had always been buggy, as many people had pointed out, and it had become difficult to maintain. It also used technology that doesnt work on a lot of newer computers or tablets. Timed test depended on a browser add-on that both Microsoft and Apple have encouraged users to remove for security concerns. For these reasons, we took these two quizzes down at the end of the month. Thanks to everyone who has shown support for them, and we hope you continue to use the other quizzes on this site!

Looking for the Image Bank? We moved it up to the main Anatomy and Physiology page, which has all kinds of other cool resources.

Conference for High School Anatomy and Physiology Instructors - October 17 and 18, 2014 - Minneapolis, MN. Contact Murray Jensen for details.

Excerpt from:

Anatomy and Physiology Learning Modules - CEHD - U of M

Physiology

Human Physiology: An Integrated Approach (7th Edition …

Fulfillment by Amazon (FBA) is a service we offer sellers that lets them store their products in Amazon's fulfillment centers, and we directly pack, ship, and provide customer service for these products. Something we hope you'll especially enjoy: FBA items qualify for FREE Shipping and .

If you're a seller, Fulfillment by Amazon can help you increase your sales. We invite you to learn more about Fulfillment by Amazon .

Read this article:

Human Physiology: An Integrated Approach (7th Edition ...