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Juicing for Your Manhood: Increase Testosterone Review

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Low Carb Weekly Meal Plans Review

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Face Engineering Exercises Review

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The Parkinson's-Reversing Breakthrough Review

Articles

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...

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,...

Twitch Summation and Tetanus

When the muscle is stimulated with a single electric shock of sufficient voltage, it quickly contracts and relaxes. This response is called a twitch. Increasing the stimulus voltage increases the strength of the twitch, up to a maximum. The strength of a muscle contraction can thus be graded, or varied an obvious requirement for the proper control of skeletal movements. If a second electric shock is delivered immediately after the first, it will produce a second twitch that may partially ride...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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,...

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,...

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....

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...

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...

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...

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...

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...

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...

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...

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...

Electrical Activity of the Heart

If the heart of a frog is removed from the body and all neural innervations are severed, it will still continue to beat as long as the myocardial cells remain alive. The automatic nature of the heartbeat is referred to as automaticity. As a result of experiments with isolated myocardial cells and clinical experience with patients who have specific heart disorders, many regions within the heart have been shown to be capable of originating action potentials and functioning as pacemakers. In a...

Significance of Blood PO and PCO2 Measurements

Since blood PO2 measurements are not directly affected by the oxygen in red blood cells, the PO2 does not provide a measurement of the total oxygen content of whole blood. It does, however, provide a good index of lung function. If the inspired air had a normal PO2 but the arterial PO2 was below normal, for example, you could conclude that gas exchange in the lungs was impaired. Measurements of arterial PO2 thus provide valuable information in treating people with pulmonary diseases, in...

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...

Nitric Oxide and Carbon Monoxide as Neurotransmitters

Nitric oxide NO was the first gas to be identified as a neuro-transmitter. Produced by nitric oxide synthetase in the cells of many organs from the amino acid L-arginine, nitric oxide's actions are very different from those of the more familiar nitrous oxide N2O , or laughing gas, sometimes used as a mild anesthetic in dentistry. Nitric oxide has a number of different roles in the body. Within blood vessels, it acts as a local tissue regulator that causes the smooth muscles of those vessels to...

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...

Memory and Learning Require the Cerebral Cortex and Limbic System

Memory and learning are inextricably linked because part of the learning process involves the assimilation of new information and its commitment to memory. The most likely sites of learning in the human brain are the large association areas of the cerebral cortex, in coordination with subcortical structures deep in the temporal lobe, including the hippocampus and amygdala. The association areas draw on sensory information received from the primary visual, auditory, somatic sensory, and...

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...

Atrial Stretch Reflexes

In addition to the baroreceptor reflex, several other reflexes help to regulate blood pressure. The reflex control of ADH release by osmoreceptors in the hypothalamus and the control of an-giotensin II production and aldosterone secretion by the juxta- glomerular apparatus of the kidneys have been previously discussed. Antidiuretic hormone and aldosterone increase blood pressure by increasing blood volume, and angiotensin II stimulates vasoconstriction to cause an increase in blood pressure....

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,...

Considerations for Esophageal Lengthening Procedures

It is essential that the gastroesophageal junction lie tension free in the abdomen before creating a fundic wrap. The length of tension-free intraabdominal esophagus should be measured after closing the crural defect. When the crura are closed from the caudal condensation of the crural fibers toward the anterior margin of the hiatus, the hiatal orifice is effectively displaced cephalad. This transposition of the hiatal orifice lengthens the intraabdominal segment of esophagus because the...

Feedforward Regulation

Another type of regulatory process frequently used in conjunction with negative-feedback systems is feedforward. Let us give an example of feedforward and then define it. The temperature-sensitive nerve cells that trigger negative-feedback regulation of body temperature when body temperature begins to fall are located inside the body. In addition, there are temperature-sensitive nerve cells in the skin, and these cells, in effect, monitor outside temperature. When outside temperature falls, as...

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...

Control of the Autonomic Nervous System by Higher Brain Centers

Visceral functions are largely regulated by autonomic reflexes. In most autonomic reflexes, sensory input is transmitted to brain centers that integrate this information and respond by modifying the activity of preganglionic autonomic neurons. The neural centers that directly control the activity of autonomic nerves are influenced by higher brain areas, as well as by sensory input. The medulla oblongata of the brain stem is the area that most directly controls the activity of the autonomic...

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,...

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...

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...

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...

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...

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...

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...

Localized Inflammatory Response

The hallmarks of a localized acute inflammatory response, first described almost 2000 years ago, are swelling tumor , redness rubor , heat calor , pain dolor , and loss of function. Within minutes after tissue injury, there is an increase in vascular diameter vasodilation , resulting in an increase in the volume of blood in the area and a reduction in the flow of blood. The increased blood volume heats the tissue and causes it to redden. Vascular permeability also increases, leading to leakage...

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...

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...

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,...

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...

Reciprocal Innervation and the Crossed Extensor Reflex

In the knee-jerk and other stretch reflexes, the sensory neuron that stimulates the motor neuron of a muscle also stimulates interneu-rons within the spinal cord via collateral branches. These interneu-rons inhibit the motor neurons of antagonist muscles via inhibitory postsynaptic potentials IPSPs . This dual stimulatory and inhibitory activity is called reciprocal innervation fig. 12.29 . When a limb is flexed, for example, the antagonistic extensor muscles are passively stretched. Extension...

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...

Pulse Pressure and Mean Arterial Pressure

When someone takes a pulse, he or she palpates an artery for example, the radial artery and feels the expansion of the artery occur in response to the beating of the heart the pulse rate is thus a measure of the cardiac rate. The expansion of the artery with each pulse occurs as a result of the rise in blood pressure within the artery as the artery receives the volume of blood ejected by a stroke of the left ventricle. Since the pulse is produced by the rise in pressure from dia-stolic to...

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...

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...

Red Blood Cell Antigens and Blood Typing

There are certain molecules on the surfaces of all cells in the body that can be recognized as foreign by the immune system of another individual. These molecules are known as antigens. As part of the immune response, particular lymphocytes secrete a class of proteins called antibodies that bond in a specific fashion with antigens. The specificity of antibodies for antigens is analogous to the specificity of enzymes for their substrates, and of receptor proteins for neurotransmitters and...

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...

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...

Ankle Jerk Reflex

A neurological reflex depends on an arc which consists of an afferent pathway, which is activated by a specific receptor, an efferent system, which activates a stereotyped response, and a simple or complex pathway that interconnects the afferent and efferent systems. Since the reflex response to an appropriate stimulus is involuntary, disturbances of reflexes afford objective signs of neural dysfunction. The deep tendon reflexes of the limbs provide essential information about Lhe status of the...

Length Tension Relationship

The strength of a muscle's contraction is influenced by a variety of factors. These include the number of fibers within the muscle that are stimulated to contract, the frequency of stimulation, the thickness of each muscle fiber thicker fibers have more myofibrils and thus can exert more power , and the initial length of the muscle fibers when they are at rest. There is an ideal resting length for striated muscle fibers. This is the length at which they can generate maximum force. When the...

Triceps Tendon Injury

Rupture of the triceps tendon is a rare injury. Triceps tendon rupture occurs in both males and females and in individuals of all ages. Rupture of the triceps tendon is almost always the result of a single traumatic event. The mechanism of injury usually is a fall on an outstretched hand. Less common mechanisms of injury include a direct blow to the posterior elbow and a forceful eccentric contraction of the triceps muscle with the elbow flexed. Most tears of the triceps tendon occur at the...

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...

The Liver Is Important in Carbohydrate Metabolism

The liver is extremely important in maintaining an adequate supply of nutrients for cell metabolism and regulating blood glucose concentration Fig. 28.3 . After the ingestion of a meal, the blood glucose increases to a concentration of 120 to 150 mg dL, usually in 1 to 2 hours. Glucose is taken up by hepatocytes by a facilitated carrier-mediated process and is converted to glucose 6-phosphate and then UDP-glucose. UDP-glucose can be used for glycogen synthesis, or glycogenesis. It is generally...

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...

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...

Adrenergic and Cholinergic Synaptic Transmission

Acetylcholine ACh is the neurotransmitter of all preganglionic fibers both sympathetic and parasympathetic . Acetylcholine is also the transmitter released by most parasympathetic post- ganglionic fibers at their synapses with effector cells fig. 9.7 . Transmission at these synapses is thus said to be cholinergic. The neurotransmitter released by most postganglionic sympathetic nerve fibers is norepinephrine noradrenaline . Transmission at these synapses is thus said to be adrenergic. There are...

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...

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...

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...

Extrinsic Regulation of Blood Flow

The term extrinsic regulation refers to control by the autonomic nervous system and endocrine system. Angiotensin II, for example, directly stimulates vascular smooth muscle to produce generalized vasoconstriction. Antidiuretic hormone ADH also has a vasoconstrictor effect at high concentrations this is why it is also called vasopressin. This vasopressor effect of ADH is not believed to be significant under physiological conditions in humans. Stimulation of the sympathoadrenal system produces...

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...

Glomerular Ultrafiltrate

The fluid that enters the glomerular capsule is called ultrafiltrate fig. 17.10 because it is formed under pressure the hydrostatic pressure of the blood. This process is similar to the formation of tissue fluid by other capillary beds in the body in response to Starling forces chapter 14 see fig. 14.9 . The force favoring filtration is opposed by a counterforce developed by the hydrostatic pressure of fluid in the glomerular capsule. Also, since the protein concentration of the tubular fluid...

Hormone Structures and Synthesis

Hormones fall into three chemical classes 1 amines, 2 peptides and proteins, and 3 steroids. The amine hormones are all derivatives of the amino acid tyrosine. They include the thyroid hormones, epinephrine and norepinephrine produced by the adrenal medulla , and dopamine produced by the hypothalamus . Thyroid Hormones The thyroid gland is located in the lower part of the neck wrapped around the front of the trachea windpipe . It is composed of many spherical structures called follicles, each...

Synergistic and Permissive Effects

When two or more hormones work together to produce a particular result, their effects are said to be synergistic. These effects may be additive or complementary. The action of epinephrine and norepinephrine on the heart is a good example of an additive effect. Each of these hormones separately produces an increase in cardiac rate acting together in the same concentrations, they stimulate an even greater increase in car- diac rate. The synergistic action of FSH and testosterone is an example of...

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...

There Are Several Phases of the DTH Response

The development of the DTH response begins with an initial sensitization phase of 1-2 weeks after primary contact with an antigen. During this period, TH cells are activated and clonally expanded by antigen presented together with the requisite class II MHC molecule on an appropriate antigen-presenting cell Figure 16-17a . A variety of antigen-presenting cells have been shown to be involved in the activation of a DTH response, including Langerhans cells and macrophages. Langerhans cells are...

Energy Requirements of Skeletal Muscles

Skeletal muscles generate ATP through aerobic and anaerobic respiration and through the use of phosphate groups donated by creatine phosphate.The aerobic and anaerobic abilities of skeletal muscle fibers differ according to muscle fiber type, which are described according to their speed of contraction, color,and major mode of energy metabolism. Skeletal muscles at rest obtain most of their energy from the aerobic respiration of fatty acids. During exercise, muscle glycogen and blood glucose are...

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...

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...

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...

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....

Female Reproductive System

1. any disease that affects women 7. gynecologist gi-ne-KOL-o-jist 8. anovulatory an-OV-u-1a-1o-re 11. dysmenorrhea DIS-men-o-re-a 12. oligomenorrhea ol-i-go-men-o-RE-a 14. ovariopexy o-var-e-o-PEK-se also oophoropexy o-of-o-ro-PEK-s e 15. ovariocentesis o-var-e-o-sen-TE-sis 16. oophorectomy o-of-o-REK-to-me 1. plastic repair of an oviduct 2. surgical removal of the uterus 4. pertaining to the uterus and bladder 5. instrument for measuring the vagina 7. salpingopexy sal-PING-go-pek-se 8....

Treatment For Intasubstance Tear Of The Extensor Carpi Ulnaris Tendon

Scapholunate instability is the most common carpal instability. It may occur after a traumatic extension injury to the wrist or result from repetitive stress, as in chronic crutch walking 65 . Weakness and pain about the dorsal radial aspect of the wrist are frequent complaints. On clinical examination, a positive scaphoid shift test may be found 66 . This result consists of a click elicited when bringing the wrist from ulnar to radial deviation while the scaphoid tuberosity is stabilized by...

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...

Indications for a vaginal examination

Surveillance for cervical carcinoma Symptoms of uterine prolapse Unexplained urinary tract obstruction P Ask the patient to empty Ihe bladder. Position the patient comfortably either on her back or in the left lateral position with her head on a pillow, hips and knees flexed and thighs abducted. P Use a lamp to illuminate the vulva adequately. P Use suitable gloves and lubricate the examining fingers. P Separate the labia minora with the forefinger and thumb of the left hand, bringing into...

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...

Fruit And Seed Dispersal

Why are so many species of orchids rare, while dandelions, shepherd's purse, and other weeds occur all over the world Why are some plants confined to single continents, mountain ranges, or small niches occupying less than a hectare 2.47 acres of land The answers to these questions involve many different factors, including climate, soil, the adaptability of the plant, and its means of seed dispersal. How fruits and seeds are transported from one place to another is the subject of the following...

Stress Reaction Femur

Stress fractures of the femur in runners may occur in the femoral neck, trochan-teric and subtrochanteric region, and femoral shaft. These injuries are often not considered in the initial presentation, and a high index of suspicion must be maintained. Patients commonly present with hip, groin, gluteal, thigh, or knee pain, depending on the location of the injury 18,72,73 . In a study by Clement and colleagues 72 , 71 patients who had 74 stress fractures of the femur were studied. Nearly 95 were...

The Victim S Injured Extremities Were Immobilized Before Transport. Immobilized Means

During a triathlon, paramedics responded to a scene with multiple patients involved in a serious bicycle accident. B.R., a 20-year-old woman, lost control of her bike while descending a hill at approximately 40 mph. As she fell, two other cyclists collided with her, sending all three crashing to the ground. At the scene, B.R. complained of pain in her head, back, chest, and leg. She also had numbness and tingling in her legs and feet. Other injuries included a cut on her face and on her right...

External Form Of A Woody Twig

A woody twig consists of an axis with attached leaves Fig. 6.1 . If the leaves are attached to the twig alternately or in a spiral around the stem, they are said to be alternate, or alternately arranged. If the leaves are attached in pairs, they are said to be opposite, or oppositely arranged, or if they are in whorls groups of three or more , their arrangement is whorled. The area, or region not structure , of a stem where a leaf or leaves are attached is called a node, and a stem region...

Methods of Evaluation

Given the poor correlation between symptoms and anatomic failure, a careful and thorough evaluation is warranted. A complete history and physical should be performed with particular attention to the patient's current symptoms. Are the symptoms similar to those experienced before the original surgery Do symptoms of reflux or dysphagia predominate Was there a precipitating event Do antacid medications ameliorate the symptoms The patient's original operative report should be obtained to clarify...

Clinical Features of Infections

Infections in the elderly often present in an atypical, nonclassical fashion. Furthermore, the differential diagnosis of infectious diseases in the elderly differs from the young because it is dependent on both the clinical setting and the patient's underlying functional status. For example, free living, independent, healthy elderly are prone to respiratory infections, such as bacterial pneumonia, genitourinary infections and intraabdominal infections including cholecystitis, diverticulitis,...

The Complement System Clears Immune Complexes from Circulation

The importance of the complement system in clearing immune complexes is seen in patients with the autoimmune disease systemic lupus erythematosus SLE . These individuals produce large quantities of immune complexes and suffer tissue damage as a result of complement-mediated lysis and the induction of type II or type III hypersensitivity see Chapter 16 . Although complement plays a significant role in the development of tissue damage in SLE, the paradoxical finding is that deficiencies in C1,...

Hormone Transport in the Blood

Peptide and catecholamine hormones are water-soluble. Therefore, with the exception of a few peptides, these hormones are transported simply dissolved in plasma Table 10-2 . In contrast, the steroid hormones and the thyroid hormones circulate in the blood largely bound to plasma proteins. Even though the steroid and thyroid hormones exist in plasma mainly bound to large proteins, small concentrations of these hormones do exist dissolved in the plasma. The dissolved, or free, hormone is in...

Transition Point Between Distended And Collapsed Veins

There are no valves between the right atrium and the internal jugular vein. It follows that the degree of distension in the vein equates to the pressure in the right atrium and the venous waveform provides information about cardiac function. The internal jugular vein enters the neck behind the mastoid process. Il runs deep to the sternomastoid muscle before entering the thorax between its sternal and clavicular heads. Because of its deep position the internal jugular vein can only be examined...

Cubital Tunnel Syndrome

Physiologic and compressive cubital tunnel syndromes have been described. Compressive cubital syndrome may have acute, subacute, or chronic presentation. Normal loss in volume and increased pressure within the tunnel during elbow flexion result in physiologic cubital tunnel syndrome. This can be seen in ''sleep palsy,'' as the arm is held in flexion for prolonged periods of time. Blunt trauma to the cubital tunnel is a typical cause of acute external compression syndrome of the ulnar nerve....

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...

Dissociative Identity Disorder

The treatment of dissociative identity disorder is the subject of a voluminous literature, most of which addresses the role of hypnosis to some extent. Numerous articles by the author, summarized in Kluft 1992a,b , and a more recent text by Phillips and Frederick 1995 focus on hypnotic approaches. Dissociative identity disorder involves lesions of identity, consciousness, and memory. Ideally, treatment should help the patient achieve a subjective sense of a unified identity by integrating the...