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The Parkinson's-Reversing Breakthrough Review

Articles

Autonomic Nervous System

The efferent innervation of all tissues other than skeletal muscle is by way of the autonomic nervous system. A special case occurs in the gastrointestinal tract, where autonomic neurons innervate a nerve network in the wall of the intestinal tract. This network, termed the enteric nervous system, will be described in Chapter 17. In the autonomic nervous system, parallel chains, each with two neurons, connect the central nervous system and the effector cells Figure 8-43 . This is in contrast to...

Hormones That Use Second Messengers

Hormones that are catecholamines epinephrine and norepineph-rine , polypeptides, and glycoproteins cannot pass through the lipid barrier of the target cell's plasma membrane. Although some of these hormones may enter the cell by pinocytosis, most of their effects result from their binding to receptor proteins on the outer surface of the target cell membrane. Since they exert their effects without entering the target cells, the actions of these hormones must be mediated by other molecules within...

Spiral Organ Organ of Corti

The sensory hair cells are located on the basilar membrane, with their hairs actually stereocilia projecting into the endolymph of the cochlear duct. These hair cells are arranged to form one row of inner cells, which extends the length of the basilar membrane, and multiple rows of outer hair cells three rows in the basal turn, four in the middle turn, and five in the apical turn of the cochlea fig. 10.21 . The stereocilia of the outer hair cells are embedded in a gelatinous tectorial membrane...

Regulation of Blood Volume by the Kidneys

The formation of urine begins in the same manner as the formation of tissue fluid by filtration of plasma through capillary pores. These capillaries are known as glomeruli, and the filtrate they produce enters a system of tubules that transports and modifies the filtrate by mechanisms discussed in chapter 17 . The kidneys produce about 180 L per day of blood filtrate, but since there is only 5.5 L of blood in the body, it is clear that most of this filtrate must be returned to the vascular...

Muscle Cells Obtain ATP From Several Sources

Although ATP is the immediate fuel for the contraction process, its concentration in the muscle cell is never high enough to sustain a long series of contractions. Most of the immediate energy supply is held in an energy pool of the compound creatine phosphate or phosphocreatine PCr , which is in chemical equilibrium with ATP. After a molecule of ATP has been split and yielded its energy, the resulting ADP molecule is readily rephosphorylated to ATP by the high-energy phosphate group from a...

Effects of Blood PO2 on Ventilation

Under normal conditions, blood Po2 affects breathing only indirectly, by influencing the chemoreceptor sensitivity to changes in PcO2- Chemoreceptor sensitivity to PCO gt 2 is augmented by a low PO2 so ventilation is increased at a high altitude, for example and is decreased by a high PO2. If the blood PO2 is raised by breathing 100 oxygen, therefore, the breath can be held longer because the response to increased PCO2 is blunted. When the blood PCO2 is held constant by experimental techniques,...

Organization of the Respiratory System

There are two lungs, the right and left, each divided into several lobes. Pulmonary is the adjective referring to lungs. The lungs consist mainly of tiny air-containing sacs called alveoli singular, alveolus , which number approximately 300 million in the adult. The alveoli are the sites of gas exchange with the blood. The airways are all the tubes through which air flows between the external environment and the alveoli. Inspiration inhalation is the movement of air from the external...

Skeletal Muscle Action Potential

Brane potential to change after a stimulus is applied is called the time constant or t, and its relationship to capacitance C and resistance R is defined by the following equation In the absence of an action potential, a stimulus applied to the neuronal membrane results in a local potential change that decreases with distance away from the point of stimulation. The voltage change at any point is a function of current and resistance as defined by Ohm's law. If a lig-and-gated channel opens...

Exchange of Gases in Alveoli and Tissues

We have now completed our discussion of the lung mechanics that produce alveolar ventilation, but this is only the first step in the respiratory process. Oxygen must move across the alveolar membranes into the pulmonary capillaries, be transported by the blood to the tissues, leave the tissue capillaries and enter the extracellular fluid, and finally cross plasma membranes to gain entry into cells. Carbon dioxide must follow a similar path in reverse. In the steady state, the volume of oxygen...

The Internal Environment and Homeostasis

An amoeba and a human liver cell both obtain their energy by breaking down certain organic nutrients. The chemical reactions involved in this intracellular process are remarkably similar in the two types of cells and involve the utilization of oxygen and the production of carbon dioxide. The amoeba picks up oxygen directly from the fluid surrounding it its external environment and eliminates carbon dioxide into the same fluid. But how can the liver cell and all other internal parts of the body...

Abnormalities in the shape of the chest

Those of clinical importance are as follows. Increase in anteroposterior diameter. In some patients with emphysema, the posterior AP diameter is increased and the two measurements may approximate barrel chest . The degree of chest deformity in emphysema is not a reliable guide to the severity of the functional defect. An increase in anteroposterior diameter may also be due to thoracic kyphosis unrelated to respiratory disease Fig. 4.12 . Thoracic kyphoscoliosis. This ranges in degree from the...

Inspection And Palpation Of The Precordium

Inspection and palpation of the cardiac pulsations of the anterior chest have been practiced by physicians since ancient times and have a solid scientific basis. The results of precordial inspection and palpation have been correlated with noninvasive studies, hemodynamic data, and surgical and autopsy studies202,203 and remain an important part of the cardiovascular examination. Their usefulness depends on an understanding of cardiovascular physiology, the proficiency of the examiner, and his...

Organs without Dual Innervation

Although most organs are innervated by both sympathetic and parasympathetic nerves, some including the adrenal medulla, ar-rector pili muscles, sweat glands, and most blood vessels receive only sympathetic innervation. In these cases, regulation is achieved by increases or decreases in the tone firing rate of the sympathetic fibers. Constriction of cutaneous blood vessels, for example, is produced by increased sympathetic activity that stimulates alpha-adrenergic receptors, and vasodilation...

Circulatory Changes During Exercise

While the vascular resistance in skeletal muscles decreases during exercise, the resistance to flow through the visceral organs and skin increases. This increased resistance occurs because of vasoconstriction stimulated by adrenergic sympathetic fibers, and it results in decreased rates of blood flow through these organs. During exercise, therefore, the blood flow to skeletal muscles increases because of three simultaneous changes 1 increased total blood flow cardiac output 2 metabolic...

Digestion and Absorption in the Stomach

Proteins are only partially digested in the stomach by the action of pepsin, while carbohydrates and fats are not digested at all by pepsin. Digestion of starch begins in the mouth with the action of salivary amylase and continues for a time when the food enters the stomach, but amylase soon becomes inactivated by the strong acidity of gastric juice. The complete digestion of food molecules occurs later, when chyme enters the small intestine. Therefore, people who have had partial gastric...

Coupled Reactions Oxidation Reduction

When an atom or a molecule gains electrons, it is said to become reduced when it loses electrons, it is said to become oxidized. Reduction and oxidation are always coupled reactions an atom or a molecule cannot become oxidized unless it donates electrons to another, which therefore becomes reduced. The atom or molecule that donates electrons to another is a reducing agent, and the one that accepts electrons from another is an oxidizing agent. It is important to understand that a particular atom...

Providencia Stuartii Characteristics Alpha Hemolysis

Morello-Mizer-Granato I Back Matter I Figures I I The McGraw-Hill Laboratory Manual and Companies, 2003 Workbook in Microbiology, 7 e Plate 1 Staphylococcus aureus in a Gram-stained smear from a colony growing on agar medium left and from the sputum of a patient with staphylococcal pneumonia right . The organisms are gram-positive spheres, primarily in grapelike clusters. The pink cells in the right-hand photo are neutrophils. Plate 2 Streptococcus pyogenes in Gram-stained smears. From a...

Female sex organs produce eggs receive sperm and nurture the embryo

When a mammalian egg matures, it is released from the ovary directly into the body cavity. But the egg does not go far. Each ovary is enveloped by the undulating, fringed opening of an oviduct also known as a Fallopian tube , which sweeps the egg into that tube Figure 43.11 . Fertilization takes place in the oviduct. Whether or not the egg is fertilized, cilia lining the oviduct propel it slowly toward the uterus, a muscular, thick-walled cavity shaped in humans like an upside-down pear. The...

Carrier Mediated Transport

Molecules such as glucose are transported across plasma membranes by special protein carriers. Carrier-mediated transport in which the net movement is down a concentration gradient, and which is therefore passive, is called facilitated diffusion. Carrier-mediated transport that occurs against a concentration gradient, and which therefore requires metabolic energy, is called active transport. In order to sustain metabolism, cells must take up glucose, amino acids, and other organic molecules...

Retrovirus HIV1 Is the Causative Agent of AIDS

Within a few years after recognition of AIDS as an infectious disease, the causative agent was discovered and characterized by efforts in the laboratories of Luc Montagnier in Paris and Robert Gallo in Bethesda Figure 19-8 . This immunodeficiency syndrome was novel at the time in that the type of virus causing it was a retrovirus. Retroviruses carry their genetic information in the form of RNA. When the virus enters a cell, the RNA is reverse transcribed to DNA by a virally encoded enzyme,...

Clinical Significance Of Transverse Pericardial

Chapter 2 FUNCTIONAL ANATOMY OF THE HEART CORRELATIVE ANATOMY This section in this chapter is an illustrated review of applied cardiac anatomy. The clinical significance of the anatomy described is highlighted in italics. The fibrous parietal pericardium is a resilient sac that envelops the heart and attaches onto the great vessels. 5 Almost the entire ascending aorta and main pulmonary artery and portions of both venae cavae and all four pulmonary veins are intrapericardial Fig. 2-19 . These...

Endocrine Functions of the Placenta

The placenta secretes both steroid hormones and protein hormones. The protein hormones include chorionic gonadotropin hCG and chorionic somatomammotropin hCS , both of which have actions similar to those of some anterior pituitary hormones table 20.7 . Chorionic gonadotropin has LH-like effects, as previously described it also has thyroid-stimulating ability, like pituitary TSH. Chorionic somatomammotropin likewise has actions that are similar to two pituitary hormones growth hormone and...

Clinical Indications Background

Clinical indications for noninvasive vascular diagnostic modalities have increased in the last ten years due to rapid developments in technology and subsequent improvements of spatial resolution. Improvements in imaging of intracranial vessels have occurred in large part due the possibility to acquire larger volumes. Major advantages of MRA over CTA for the study of intracranial circulation are that it is less invasive, is not entirely dependent on the need for contrast media, and permits...

Lung Volumes Affect Pulmonary Vascular Resistance

Pulmonary vascular resistance is also significantly affected by lung volume. Because pulmonary capillaries have little , Measuring pulmonary wedge pressure. A catheter is threaded through a peripheral vein in the systemic circulation, through the right heart, and into the pulmonary artery. The wedged catheter temporarily occludes blood flow in a part of the vascular bed. The wedge pressure is a measure of downstream pressure, which is pulmonary venous pressure. Pulmonary venous pressure...

Transport of Lipids in the Blood

Once the chylomicrons are in the blood, their triglyceride content is removed by the enzyme lipoprotein lipase, which is attached to the endothelium of blood vessels. This enzyme hydrolyzes triglycerides and thus provides free fatty acids and Step 1 Emulsification of fat droplets by bile salts Step 2 Hydrolysis of triglycerides in emulsified fat droplets into fatty acid and monoglycerides Step 3 Dissolving of fatty acids and monoglycerides into micelles to produce mixed micelles Figure 18.35...

Pepsin and Hydrochloric Acid Secretion

The parietal cells secrete H , at a pH as low as 0.8, into the gastric lumen by primary active transport involving carriers that function as an ATPase . These carriers, known as H K ATPase pumps, transport H uphill against a million-to-one concentration gradient into the lumen of the stomach while they transport K in the opposite direction fig. 18.8 . At the same time, the parietal cell's basolateral membrane facing the blood in capillaries of the lamina propria take in Cl-against its...

Exchange of Fluid Between Capillaries and Tissues

The distribution of extracellular fluid between the plasma and interstitial compartments is in a state of dynamic equilibrium. Tissue fluid is not normally a stagnant pond rather, it is a continuously circulating medium, formed from and returning to the vascular system. In this way, the tissue cells receive a continuously fresh supply of glucose and other plasma solutes that are filtered through tiny endothelial channels in the capillary walls. Filtration results from blood pressure within the...

Slow and Fast Twitch Fibers

Skeletal muscle fibers can be divided on the basis of their contraction speed time required to reach maximum tension into slow-twitch, or type I, fibers, and fast-twitch, or type II, fibers. These differences are associated with different myosin ATPase isoenzymes, which can also be designated as slow and fast. The two fiber types can be distinguished by their ATPase isoenzyme when they are appropriately stained fig. 12.23 . The extraocular muscles that position the eyes, for example, have a...

Organs with Dual Innervation

Most visceral organs receive dual innervation they are innervated by both sympathetic and parasympathetic fibers. In this condition, the effects of the two divisions of the autonomic system may be antagonistic, complementary, or cooperative table 9.7 . The effects of sympathetic and parasympathetic innervation of the pacemaker region of the heart is the best example of the antagonism of these two systems. In this case, sympathetic and parasympathetic fibers innervate the same cells. Adrenergic...

The Liver Plays an Important Role in the Metabolism of Lipids

The liver plays a pivotal role in lipid metabolism Fig. 28.4 . It takes up free fatty acids and lipoproteins complexes of lipid and protein from the plasma. Lipid is circulated in the plasma as lipoproteins because lipid and water are not mis- The Metabolism of Monosaccharides. Monosaccharides are first phosphorylated by a reaction catalyzed by the enzyme hexokinase. In the liver but not in the muscle , there is a specific enzyme glucokinase for the phosphorylation of glucose to form glucose...

Bowel Obstruction In The Elderly

Causes of bowel obstruction usually specific to the elderly include sigmoid volvulus, Ogilvie's Syndrome, colon carcinoma, and gallstone ileus. These conditions in the elderly patient can lead to gangrene with resulting perforation. Sigmoid volvulus is 20 times more likely in the patient age 60 yr and greater 19 . This age association may be due to acquired redundancy of the sigmoid colon. High-residue diets are believed to be the causative factor in developing a redundant sigmoid 20 . Other...

Inspiration and Expiration

Between the bony portions of the rib cage are two layers of intercostal muscles the external intercostal muscles and the internal intercostal muscles fig. 16.14 . Between the costal cartilages, however, there is only one muscle layer, and its fibers are oriented in a manner similar to those of the internal inter-costals. These muscles are therefore called the interchondral part of the internal intercostals. Another name for them is the parasternal intercostals. An unforced, or quiet,...

Anterior Tibial Artery Palpation

The anatomy of he radial, brachial and carotid pulses have been described I p. 83 . Femoral artery. The I'emoral artery is situated just below the inguinal ligament, midway between the anterior superior iliac spine and the pubic symphysis mid-inguinal point . It is immediately lateral to the femoral vein and medial to the femoral nerve. In the obese it can be difficult to feel. Popliteal artery. At the level of the knee crease, the artery lies deep in the popliteal fossa and the pulse is...

Effects of Blood PCO2 and pH on Ventilation

Chemoreceptor input to the brain stem modifies the rate and depth of breathing so that, under normal conditions, arterial PCo2, pH, and Po2 remain relatively constant. If hypoventilation inadequate ventilation occurs, PCO2 quickly rises and pH falls. The fall in pH is due to the fact that carbon dioxide can combine Sensory nerve fibers in vagus nerve Sensory nerve fibers in vagus nerve Figure 16.26 Sensory input from the aortic and carotid bodies. The peripheral chemoreceptors aortic and...

CO2 is transported as bicarbonate ions in the blood

Delivering O2 to the tissues is only half of the respiratory function of the blood. The blood also must take carbon dioxide, a metabolic waste product, away from the tissues Figure 48.14 . CO2 is highly soluble and readily diffuses through cell membranes, moving from its site of production in the tissues into the blood, where the partial pressure of carbon dioxide Pco2 is lower. However, very little dissolved CO2 is transported by the blood. Most CO2 produced by the tissues is transported to...

Visual Acuity and Sensitivity

While reading or similarly viewing objects in daylight, each eye is oriented so that the image falls within a tiny area of the retina called the fovea centralis. The fovea is a pinhead-sized pit fovea pit within a yellow area of the retina called the macula lutea. The pit is formed as a result of the displacement of neural layers around the periphery therefore, light falls directly on photoreceptors in the center fig. 10.41 . Light falling on other areas, by contrast, must pass through several...

Insulin and Glucagon Postabsorptive State

The plasma glucose concentration is maintained surprisingly constant during the fasting, or postabsorptive, state because of the secretion of glucose from the liver. This glucose is derived from the processes of glycogenolysis and gluconeogenesis, which are promoted by a high secretion of glucagon coupled with a low secretion of insulin. Glucagon stimulates and insulin suppresses the hydrolysis of liver glycogen, or glycogenolysis. Thus during times of fasting, when glucagon secretion is high...

Responses to Adrenergic Stimulation

Adrenergic stimulation by epinephrine in the blood and by norepinephrine released from sympathetic nerve endings has both excitatory and inhibitory effects. The heart, dilatory muscles of the iris, and the smooth muscles of many blood vessels are stimulated to contract. The smooth muscles of the bronchioles and of some blood vessels, however, are inhibited from contracting adrenergic chemicals, therefore, cause these structures to dilate. Since excitatory and inhibitory effects can be produced...

Renal Clearance of Inulin Measurement of GFR

If a substance is neither reabsorbed nor secreted by the tubules, the amount excreted in the urine per minute will be equal to the amount that is filtered out of the glomeruli per minute. There does not seem to be a single substance produced by the body, however, that is not reabsorbed or secreted to some degree. Plants such as artichokes, dahlias, onions, and garlic, fortunately, do produce such a compound. This compound, a polymer of the monosaccharide fructose, is inulin. Once injected into...

Hormones That Bind to Nuclear Receptor Proteins

Unlike the water-soluble hormones, the lipophilic steroid and thyroid hormones do not travel dissolved in the aqueous portion of the plasma rather, they are transported to their target cells attached to plasma carrier proteins. These hormones must then dissociate from their carrier proteins in the blood in order to pass through the lipid component of the plasma membrane and enter the target cell, within which their receptor proteins are located fig 11.4 . The receptors for the lipophilic...

Rupture Of The Patellar Tendon

Rupture of the patellar tendon after total knee replacement is a rare and typically devastating problem Fig. 13.1 . Unfortunately, the results of several methods of acute repair are almost uniformly Numerous theories have been postulated to explain the etiology of late rupture of the patellar tendon following TKA. As mentioned previously, improper surgical technique that malaligns the knee or the position of any single component can play a contributory role. Some authors have found its...

Digestion and Absorption of Carbohydrates Lipids and Proteins

Polysaccharides and polypeptides are hydrolyzed into their subunits. These subunits enter the epithelial cells of the intestinal villi and are secreted into blood capillaries. Fat is emulsified by the action of bile salts, hydrolyzed into fatty acids and monoglycerides,and absorbed into the intestinal epithelial cells. Once inside the cells, triglycerides are resynthesized and combined with proteins to form particles that are secreted into the lymphatic fluid. The caloric energy value of food...

Effects of Temperature and pH

An increase in temperature will increase the rate of non-enzyme-catalyzed reactions. A similar relationship between temperature and reaction rate occurs in enzyme-catalyzed reactions. At a temperature of 0 C the reaction rate is immeasurably slow. As the temperature is raised above 0 C the reaction rate increases, but only up to a point. At a few degrees above body temperature which is 37 C the reaction rate reaches a plateau further increases in temperature actually decrease the rate of the...

Motor Control Hierarchy

Throughout the central nervous system, the neurons involved in controlling the motor neurons to skeletal muscles can be thought of as being organized in a hierarchical fashion, each level of the hierarchy having a certain task in motor control Figure 12-1 . To begin a movement, a general intention such as pick up sweater or write signature or answer telephone is generated at the highest level of the motor control hierarchy. This highest level encompasses many regions of the brain, including...

Sequence of Excitation

To reiterate, the SA node is the normal pacemaker for the entire heart. Its depolarization normally generates the current that leads to depolarization of all other cardiac muscle cells, and so its discharge rate determines the heart rate, the number of times the heart contracts per minute. The action potential initiated in the SA node spreads throughout the myocardium, passing from cell to cell by way of gap junctions. The spread Vander et al. Human Physiology The Mechanism of Body Function,...

Bone Deposition and Resorption

The skeleton, in addition to providing support for the body, serves as a large store of calcium and phosphate in the form of crystals called hydroxyapatite, which has the formula Cajo PO4 6 OH 2. The calcium phosphate in these hydroxyap-atite crystals is derived from the blood by the action of bone-forming cells, or osteoblasts. The osteoblasts secrete an organic matrix composed largely of collagen protein, which becomes hardened by deposits of hydroxyapatite. This process is called bone...

Herpes Simplex Virus Type Ii Hsv2

Genital herpes simplex virus HSV infection is not a reportable disease but is considered to be extremely common in the U.S. with approximately 45 million adults approx 22 of the population aged 15-74 yr estimated to be infected in 1990, based on the serologic results of a random sampling of civilian adults examined as part of the National Health and Nutrition Examination Survey NHANES III 12 . This represents a 32 increase compared to 1978, when the seroprevalence of HSV-2 was 16 among the...

Palpation during inspiration

The liver, gallbladder, spleen and kidneys should be examined in turn during deep inspiration. The key to success is to keep the examining hand still and wait for the organ to descend. One common error is to begin palpation of the liver too close to the costal margin, thereby missing Place the hand flat on the abdomen with the lingers pointing upwards and position the sensing fingers index and middle lateral to the rectus muscle so that the fingertips lie on a line parallel to lhe expected...

Tyrosine Kinase Second Messenger System

Insulin promotes glucose and amino acid transport and stimulates glycogen, fat, and protein synthesis in its target organs primarily the liver, skeletal muscles, and adipose tissue. These effects are achieved by means of a mechanism of action that is quite complex, and in some ways still incompletely understood. Nevertheless, it is known that insulin's mechanism of action bears similarities to the mechanism of action of other regulatory molecules known as growth factors. These growth factors,...

Single Unit and Multiunit Smooth Muscles

Smooth muscles are often grouped into two functional categories single-unit and multiunit fig. 12.35 . Single-unit smooth muscles have numerous gap junctions electrical synapses between adjacent cells that weld them together electrically they thus behave as a single unit, much like cardiac muscle. Most smooth muscles including those in the digestive tract and uterus are single-unit. Only some cells of single-unit smooth muscles receive autonomic innervation, but the ACh released by the axon can...

Tests for nerve root compression

Prolapse of intervertebral discs occurs most frequently at the L4 5 or L5 SI level, producing compression of the L5 and SI nerve roots respectively. Tension can be applied to these nerve roots by flexing the hip with the knee straight -the so-called straight leg raising test. Normally, about 90 degrees of hip flexion should be possible but this varies considerably 70-120 degrees . When the root is stretched over a prolapsed disc, straight leg raising will be restricted and pain will usually be...

Sexual Dysfunction Secondary to Surgical Treatment

Sexual dysfunction following rectal surgery for IBD has been reported in 1-27 of cases but dysfunction is often partial and transient 119, 128, 132, 133, 142-148 . This is usually due to damage of neurological structures during pelvic dissection, although psychogenic or vasculogenic factors may contribute 149 . Normal sexual function in males is under the control of both the sympathetic and parasympathetic system erection is mainly mediated by parasympa-thetic fibres, while sympathetic fibres...

Intrinsic Regulation of Blood Flow

Intrinsic, or built-in, mechanisms within individual organs provide a localized regulation of vascular resistance and blood flow. Intrinsic mechanisms are classified as myogenic or metabolic. Some organs, the brain and kidneys in particular, utilize these intrinsic mechanisms to maintain relatively constant flow rates despite wide fluctuations in blood pressure. This ability is termed autoregulation. If the arterial blood pressure and flow through an organ are inadequate if the organ is...

Rectus Abdominis Myocutaneous Flap

This technique was described by Taylor et al. in 1983 35 . It is an excellent method for closing a large perineal defect. Based on the inferior epigastric artery and vein, it may be passed into the pelvis to close the pelvic floor and fill the dead space. It is best employed pro-phylactically in high risk patients at the time of proc-tectomy when potential perineal wound problems are anticipated 17 , or at the time of abdominoperineal excision for a large neoplasm 34 when extensive perineal...

Review Activities

TestYour Knowledge ofTerms and Facts a. rise in insulin rise in glucagon b. fall in insulin rise in glucagon c. rise in insulin fall in glucagon d. fall in insulin fall in glucagon 3. growth a. increased protein hormone synthesis increased 4. thyroxine cell respiration 5. hydrocortisone b. protein catabolism in muscles gluconeogenesis in liver c. protein synthesis in muscles decreased glucose utilization d. fall in blood glucose increased fat synthesis 6. A lowering of blood glucose...

Generator Receptor Potential

The electrical behavior of sensory nerve endings is similar to that of the dendrites of other neurons. In response to an environmental stimulus, the sensory endings produce local graded changes in the membrane potential. In most cases, these potential changes are depolarizations that are analogous to the excitatory postsynaptic potentials EPSPs described in chapter 7. In the sensory endings, however, these potential changes in response to environmental stimulation are called receptor, or...

Parasympathetic Division

The parasympathetic division is also known as the craniosacral division of the autonomic system. This is because its preganglionic fibers originate in the brain specifically, in the midbrain, medulla oblongata, and pons and in the second through fourth sacral levels of the spinal column. These pre-ganglionic parasympathetic fibers synapse in ganglia that are located next to or actually within the organs innervated. These parasympathetic ganglia, called terminal ganglia, supply the...

Chemoreceptors in the Medulla

The chemoreceptors most sensitive to changes in the arterial PCO2 are located in the ventral area of the medulla oblongata, near the exit of the ninth and tenth cranial nerves. These chemoreceptor neurons are anatomically separate from, but synaptically communicate with, the neurons of the respiratory control center in the medulla. An increase in arterial PCO2 causes a rise in the H concentration of the blood as a result of increased carbonic acid concentrations. The H in the blood, however,...

Effects Of Powerfull Magnet On Humanbeings

The Influence of Magnetic Fields on Man The human body is composed of atoms of different elements surrounded by water molecules. These atoms react to magnetic and electric forces and fields, and this may lead to, for example, a net-nuclear magnetization of a person when placed in a clinical MRI machine. It is therefore easy to imagine that magnetic and electromagnetic forces could alter physiologic functions, induce effects, or influence the organism in either a positive or negative way....

Monoamines as Neurotransmitters

A variety of chemicals in the CNS function as neurotransmitters. Among these are the monoamines,a chemical family that includes dopamine,norepinephrine,and serotonin. Although these molecules have similar mechanisms of action, they are used by different neurons for different functions. The regulatory molecules epinephrine, norepinephrine, dopamine, and serotonin are in the chemical family known as monoamines. Serotonin is derived from the amino acid tryptophan. Epinephrine, norepinephrine, and...

Hormone Production Sexual Development and Activity Hormone Production

Testosterone levels are generally normal in men with cryptorchidism, even those who were not treated 73,130 . Although testosterone levels are within the normal range in men who were formerly cryptorchid see Fig. 3 without other problems, a Fig. 4. Testosterone levels ng dL in men who were formerly cryptorchid plotted against age of orchidopexy. These data suggest lower levels in men with orchiopexy at older ages 1 . Fig. 4. Testosterone levels ng dL in men who were formerly cryptorchid plotted...

Childbirth is triggered by hormonal and mechanical stimuli

We traced the development of a human blastocyst into an embryo and then a fetus in Chapter 20. Throughout pregnancy, the muscles of the uterine wall periodically undergo slow, weak, rhythmic contractions called Braxton-Hicks contractions. These contractions become gradually stronger during the third trimester of pregnancy and are sometimes called false labor contractions. True labor contractions usually mark the beginning of childbirth. Both hormonal and mechanical stimuli contribute to the...

Digestion and Absorption of Proteins

Protein digestion begins in the stomach with the action of pepsin. Some amino acids are liberated in the stomach, but the major products of pepsin digestion are short-chain polypeptides. Figure 18.32 The action of pancreatic amylase. Pancreatic amylase digests starch into maltose, maltriose, and short oligosaccharides containing branch points in the chain of glucose molecules. Pepsin digestion helps to produce a more homogenous chyme, but it is not essential for the complete digestion of...

Triscaphe Degenerative Arthritis

A 62-year-old right hand dominant woman who works as a polisher presented with right wrist pain progressively worsening over the last 6 months. She noted significant and progressive difficulty with strength and holding onto small objects. She denied any trauma and noted no specific previous treatment. The patient had specific localized tenderness and swelling of the scaphoid-trapezium-trapezoid STT triscaphe joint. This area is located by following the index meta-carpal proximally until a...

Hormone Metabolism and Excretion

A hormone's concentration in the plasma depends not only upon its rate of secretion by the endocrine gland but also upon its rate of removal from the blood, either by excretion or by metabolic transformation. The liver and the kidneys are the major organs that excrete or metabolize hormones. The liver and kidneys, however, are not the only routes for eliminating hormones. Sometimes the hormone is metabolized by the cells upon which it acts. Very importantly, in the case of peptide hormones,...

Neurilemma and Myelin Sheath

All axons in the PNS myelinated and unmyelinated are surrounded by a continuous, living sheath of Schwann cells, known as the neurilemma, or sheath of Schwann. The axons of the CNS, by contrast, lack a neurilemma Schwann cells are only found in the PNS . This is significant in terms of regeneration of damaged axons, as will be described shortly. Some axons in the PNS and CNS are surrounded by a myelin sheath. In the PNS, this insulating covering is formed by successive wrappings of the cell...

Structure of Proteins

Proteins consist of long chains of subunits called amino acids. As the name implies, each amino acid contains an amino group NH2 on one end of the molecule and a carboxyl group COOH on another end. There are about twenty different amino acids, each with a distinct structure and chemical properties, that are used to build proteins. The differences between the amino acids are due to differences in their functional groups. R is the abbreviation for functional group in the general formula for an...

Transport of Oxygen in Blood

Table 15-7 summarizes the oxygen content of systemic arterial blood we shall henceforth refer to systemic arterial blood simply as arterial blood . Each liter normally contains the number of oxygen molecules equivalent to 200 ml of pure gaseous oxygen at atmospheric pressure. The oxygen is present in two forms 1 dissolved in the plasma and erythrocyte water and 2 re-versibly combined with hemoglobin molecules in the erythrocytes. As predicted by Henry's law, the amount of oxygen dissolved in...

Anterolateral Pain Pathway

A stimulus that causes or is on the verge of causing tissue damage usually elicits a sensation of pain. Receptors for such stimuli are known as nociceptors. They respond to intense mechanical deformation, excessive heat, and many chemicals, including neuropeptide transmitters, bradykinin, histamine, cytokines, and prostaglandins, several of which are released by damaged cells. These substances act by combining with specific ligand-sensitive ion channels on the nociceptor plasma membrane. Vander...

Introduction to Physiology

Human physiology is the study of how the human body functions, with emphasis on specific cause-and-effect mechanisms. Knowledge of these mechanisms has been obtained experimentally through applications of the scientific method. Physiology from the Greek physis nature logos study is the study of biological function of how the body works, from cell to tissue, tissue to organ, organ to system, and of how the organism as a whole accomplishes particular tasks essential for life. In the study of...

Neural Control of Skeletal Muscles

Skeletal muscles contain stretch receptors called muscle spindles that stimulate the production of impulses in sensory neurons when a muscle is stretched.These sensory neurons can synapse with alpha motoneurons, which stimulate the muscle to contract in response to the stretch. Other motor neurons, called gamma motoneurons, stimulate the tightening of the spindles and thus increase their sensitivity. Motor neurons in the spinal cord, or lower motor neurons often shortened to motoneurons , are...

Transport of Carbon Dioxide in Blood

In a resting person, metabolism generates about 200 ml of carbon dioxide per minute. When arterial blood flows through tissue capillaries, this volume of carbon dioxide diffuses from the tissues into the blood Figure 15-27 . Carbon dioxide is much more soluble in water than is oxygen, and so more dissolved carbon dioxide than dissolved oxygen is carried in blood. Even so, only a relatively small amount of blood carbon dioxide is transported in this way only 10 percent of the carbon dioxide...

Adenylate Cyclase Cyclic AMP Second Messenger System

Cyclic adenosine monophosphate abbreviated cAMP was the first second messenger to be discovered and is the best understood. When epinephrine and norepinephrine bind to their P-adrenergic receptors chapter 9 , the effects of these hormones are due to cAMP production within the target cells. It was later discovered that the effects of many but not all polypeptide and glycoprotein hormones are also mediated by cAMP. When one of these hormones binds to its receptor protein, it causes the...

The Laboratory Guide to Human Physiology Concepts

And Clinical Applications, Tenth Edition, by Stuart I. Fox, is self-contained so students can prepare for laboratory exercises and quizzes without having to bring the textbook to the laboratory. The introduction to each exercise contains cross-references to the pages in this textbook where related information can be found. Similarly, those figures in the lab manual that correspond to full-color figures in the textbook are also cross-referenced. Both of these mechanisms help students better...

Prohormones and Prehormones

Hormone molecules that affect the metabolism of target cells are often derived from less active parent, or precursor, molecules. In the case of polypeptide hormones, the precursor may be a longer chained prohormone that is cut and spliced together to make the hormone. Insulin, for example, is produced from proinsulin within the beta cells of the islets of Langerhans of the pancreas see fig. 3.25 . In some cases, the prohormone itself is derived from an even larger precursor molecule in the case...

Physiology Of Cortisol Metabolism

The principal metabolites of cortisol are shown in Figure 18.2. The enzymes directly metabolizing cor tisol include the A-ring reductases 5a- and 5P-reductases , 6 -hydroxylase, 20-reductase, and 11 -hydroxysteroid dehydrogenases. In rats and mice, which lack 17-hydroxylase in their adrenal cortex, the principal glucocorticoid is corticosterone, which is subject to analogous metabolism. 11 P-Hydroxysteroid Dehydrogenases 1ip-HSDs These enzymes catalyse the interconversion of cortisol or...

Xanthophyta The Yellowgreen Algae

The pigments in Xanthophyta are chlorophyll a, possibly chlorophyll e although there is some uncertainty related to a suspicion that its presence may be connected to limitations in extraction methods , and an abundance of carotenoid pigments. Motile cells have two unequal flagella a tinsel-type flagellum that extends anteriorly and a whiplash flagellum that trails posteriorly. There are approximately 400 species. The life cycle of Vaucheria is detailed as an example of this phyla. Vaucheria is...

Intrapulmonary and Intrapleural Pressures

The visceral and parietal pleurae are normally flush against each other, so that the lungs are stuck to the chest wall in the same manner as two wet pieces of glass sticking to each other. The intrapleural space contains only a film of fluid secreted by the two membranes. The pleural cavity in a healthy person is thus potential rather than real it can become real only in abnormal situations when air enters the intrapleural space. Since the lungs normally remain in contact with the chest wall,...

The Formed Elements of Blood

The formed elements of blood include two types of blood cells erythrocytes, or red blood cells, and leukocytes, or white blood cells. Erythrocytes are by far the more numerous of the two. A cubic millimeter of blood contains 5.1 million to 5.8 million erythrocytes in males and 4.3 million to 5.2 million erythrocytes in females. The same volume of blood, by contrast, contains only 5,000 to 9,000 leukocytes. Erythrocytes are flattened, biconcave discs, about 7 im in diameter and 2.2 im thick....

The Balance Between Heat Production And Heat Loss

All animals exchange energy with the environment. Some energy is exchanged as mechanical work, but most is exchanged as heat Fig. 29.4 . Heat is exchanged by conduction, convection, and radiation and as latent heat through evaporation or rarely condensation of water. If the sum of energy production and energy gain from the environment does not equal energy loss, the extra heat is stored in, or lost from, the body. This relationship is summarized in the heat balance equation Exchange of energy...

The Loading and Unloading Reactions

Deoxyhemoglobin and oxygen combine to form oxyhemoglo-bin this is called the loading reaction. Oxyhemoglobin, in turn, dissociates to yield deoxyhemoglobin and free oxygen molecules this is the unloading reaction. The loading reaction occurs in the lungs and the unloading reaction occurs in the systemic capillaries. Loading and unloading can thus be shown as a reversible reaction Deoxyhemoglobin O2 lt z gt Oxyhemoglobin tissues The extent to which the reaction will go in each direction depends...

Mechanism of Thyroid Hormone Action

As previously discussed, the major hormone secreted by the thyroid gland is thyroxine, or tetraiodothyronine T4 . Like steroid hormones, thyroxine travels in the blood attached to carrier proteins primarily to thyroxine-binding globulin, or TBG . The thyroid also secretes a small amount of triiodothyronine, or T3. The carrier proteins have a higher affinity for T4 than for T3, however, and, as a result, the amount of unbound or free T3 in the plasma is about ten times greater than the amount of...

Pressure Changes During the Cardiac Cycle

When the heart is in diastole, pressure in the systemic arteries averages about 80 mmHg millimeters of mercury . These events in the cardiac cycle then occur 1. As the ventricles begin their contraction, the intraventricular pressure rises, causing the AV valves to snap shut. At this time, the ventricles are neither being filled with blood because the AV valves are closed nor ejecting blood because the intraventricular pressure has not risen sufficiently to open the semilunar valves . This is...

Explain How Valves In Veins Breathing And Skeletal Muscle Contractions Help Venous Blood Return To The Heart

Most of the total blood volume is contained in the venous system. Unlike arteries, which provide resistance to the flow of blood from the heart, veins are able to expand as they accumulate additional amounts of blood. The average pressure in the veins is only 2 mmHg, compared to a much higher average arterial pressure of about 100 mmHg. These values, expressed in millimeters of mercury, represent the hydrostatic pressure that the blood exerts on the walls of the vessels. The low venous pressure...

Hall Drill And Saline Coolant

Case Study 19-1 Arthroplasty of the Right TMJ S.A., a 38-year-old teacher, was admitted for surgery for degenerative joint disease DJD of her right temporomandibular joint TMJ . She has experienced chronic pain in her right jaw, neck, and ear since her automobile accident the previous year. S.A.'s diagnosis was confirmed by CT scan and was followed up with conservative therapy, which included a bite plate, NSAIDs, and steroid injections. She had also tried hypnosis in an attempt to manage her...

Body Temperatures And Heat Transfer In The Body

The body is divided into a warm internal core and a cooler outer shell Fig. 29.2 . Because the temperature of the shell is strongly influenced by the environment, its temperature is not regulated within narrow limits as the internal body temperature is, even though thermoregulatory responses strongly affect the temperature of the shell, especially its outermost layer, the skin. The thickness of the shell depends on the environment and the body's need to conserve heat. In a warm environment, the...

Lateral Epicondylitis

Lateral epicondylitis is a pathologic condition of the common extensor tendon at its origin from the lateral epicondyle. Lateral epicondylitis also is known as tennis elbow because more than 50 of tennis players develop the condition at some time or another 36 . Lateral epicondylitis is far more common in Fig. 13. Normal ulnar band of the lateral collateral ligament. Coronal fat-suppressed T2-weighted fast spin-echo image of the elbow shows the normal low signal intensity ulnar band of the...

Parathyroid Hormone and Calcitonin

Whenever the plasma concentration of Ca2 begins to fall, the parathyroid glands are stimulated to secrete increased amounts of parathyroid hormone PTH , which acts to raise the blood Ca2 back to normal levels. As might be predicted from this action of PTH, people who have their parathyroid glands removed as may occur accidentally during surgical removal of the thyroid will experience hypocalcemia. This can cause severe muscle tetany, for reasons previously discussed, and serves as a dramatic...

Maintenance of Upright Posture and Balance

The skeleton supporting the body is a system of long bones and a many-jointed spine that cannot stand erect against the forces of gravity without the support given by coordinated muscle activity. The muscles that maintain upright posture that is, support the body's weight against gravity are controlled by the brain and by reflex mechanisms that are wired into the neural networks of the brainstem and spinal cord. Many of the reflex pathways previously introduced for example, the stretch and...

Ventilation and Acid Base Balance

The basic concepts and terminology relating to the acid-base balance of the blood were introduced in chapter 13. In brief review, acidosis refers to an arterial pH below 7.35, and alkalosis refers to an arterial pH above 7.45. There are two components of each respiratory and metabolic. The respiratory component refers to the carbon dioxide concentration of the blood, as measured by the PCO2. As implied by its name, the respiratory component is regulated by the respiratory system. The metabolic...

Lung Volumes and Capacities

An example of a spirogram is shown in figure 16.16, and the various lung volumes and capacities are defined in table 16.3. A lung capacity is equal to the sum of two or more lung volumes. During quiet breathing, for example, the amount of air expired in each breath is the tidal volume. The maximum amount of air that can be forcefully exhaled after a maximum inhalation is called the vital capacity, which is equal to the sum of the inspiratory reserve volume, tidal volume, and expiratory reserve...

Endothelial Cells Can Release Chemicals That Cause Relaxation or Constriction of Arterioles

An important contributor to local vascular regulation is released by endothelial cells. This substance, endothelium-derived relaxing factor EDRF , is released from all arteries, microvessels, veins, and lymphatic endothelial cells. EDRF is nitric oxide NO , which is formed by the action of nitric oxide synthase on the amino acid arginine. NO causes the relaxation of vascular smooth muscle by inducing an increase in cyclic guanosine monophosphate cGMP . When cGMP is increased, the smooth muscle...

Spermatogenesis Stimulation

The induction of spermatogenesis in patients with hypogonadotropic hypogonadism requires testicular stimulation with GnRH or gonadotropins. Various preparations are available see Table 1 to reach this goal, each with advantages and disadvantages. Because the maturation of spermatogonia to mature sperm takes approx 70 d, the first sperm usually do not appear in the ejaculate for at least 3 mo, but it may take 2 yr for patients with congenital hypogonadotropic hypogonadism to become sperm...

Delayed Treatment of Flexor Tendons Staged Tendon Reconstruction

Schneider History and Clinical Presentation An 18-year-old student lacerated both flexor tendons in zone 2 of his right dominant index finger on broken glass. His primary treatment was by direct repair of both flexor tendons 3 days postinjury, and he was started on a mobilization program in a hand therapy unit. Unfortunately, this did not result in functional pull-through of his flexor tendons. He then underwent flexor tenolysis in an attempt to salvage function, a procedure that...

Extracellular Osmolarity and Cell Volume

We can now apply the principles learned about osmosis to cells, which meet all the criteria necessary to produce an osmotic flow of water across a membrane. Both the intracellular and extracellular fluids contain water, and cells are surrounded by a membrane that is very permeable to water but impermeable to many substances nonpenetrating solutes . About 85 percent of the extracellular solute particles are sodium and chloride ions, which can diffuse into the cell through protein channels in the...

How To Prepare A Wet Mount

Using a pipette bulb, aspirate a small amount of the Proteus culture with a capillary pipette and place a small drop on a clean microscope slide fig. 3.2, step 1 . 2. Carefully place a clean cover glass see Experiment 3.1, procedure 1 over the drop, trying to avoid bubble formation fig. 3.2, step 2 . The fluid should not leak out from under the edges of the cover glass. If it does, wait until it dries before sealing. 3. If you examine the slide immediately, you need not seal the coverslip....

Refractory Period of the Heart

Ventricular muscle, unlike skeletal muscle, is incapable of any significant degree of summation of contractions, and this is a very good thing. Imagine that cardiac muscle were able to undergo a prolonged tetanic contraction. During this period, no ventricular filling could occur since filling can occur only when the ventricular muscle is relaxed, and the heart would therefore cease to function as a pump. The inability of the heart to generate tetanic contractions is the result of the long...

The Holding Environment

The frame that supports the analytic relationship is also referred to as the holding environment, an expression that highlights its containing function. Bion 1967 drew a parallel between the mother's capacity to receive the raw intensity of her baby's projections, to empathise and to bear them, thereby rendering them eventually manageable for the baby, and the therapist's function of receiving, containing and transforming the patient's communications. This helps the patient eventually to...

Velocity of Capillary Blood Flow

Figure 14-44 illustrates a simple mechanical model of a series of 1-cm-diameter balls being pushed down a single tube that branches into narrower tubes. Although each tributary tube has a smaller cross section than the wide tube, the sum of the tributary cross sections is three times greater than that of the wide tube. Let us assume that in the wide tube each ball moves 3 cm min. If the balls are 1 cm in diameter and they move two abreast, six balls leave the wide tube per minute and enter the...

Chemical Classification of Hormones

Hormones secreted by different endocrine glands vary widely in chemical structure. All hormones, however, can be divided into a few chemical classes. 1. Amines. These are hormones derived from the amino acids tyrosine and tryptophan. They include the hormones secreted by the adrenal medulla, thyroid, and pineal glands. 2. Polypeptides and proteins. Polypeptide hormones generally contain less than 100 amino acids an example is antidiuretic hormone table 11.2 . Protein hormones are polypeptides...