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Articles

Medical Term Urine In Cavity

A semipermeable membrane richly supplied with small blood vessels lines the peritoneal cavity. With dialysate dwelling in the peritoneal cavity, waste products diffuse from the network of blood vessels into the dialysate. FIGURE 13-7. Peritoneal dialysis. A semipermeable membrane richly supplied with small blood vessels lines the peritoneal cavity. With dialysate dwelling in the peritoneal cavity, waste products diffuse from the network of blood vessels into...

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,...

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...

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...

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...

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...

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...

Ligand Operated Channels

This is the most direct mechanism by which chemically regulated gates can be opened. In this case, the ion channel runs through the receptor itself. The ion channel is opened by the binding of the receptor to the neurotransmitter ligand. Such is the case when ACh binds to its nicotinic ACh receptor. This receptor consists of five polypeptide subunits that enclose the ion channel. Two of these subunits contain ACh-binding sites, and the channel opens when both sites bind to ACh fig. 7.23 . The...

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...

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...

Functional Neuroanatomy Of Penile Function

Parasympathetic and Nonadrenergic and Noncholinergic Outflow Parasympathetic preganglionic input to the human penis originates in the sacral S2-S4 spinal cord 30 . In most men, S3 is the main source of erectogenic fibers, with a smaller supply provided by either S2 or S4. These preganglionic neurons are situated in the intermediolateral cell column and send dendritic projections to laminae V, VII, IX, and X of the spinal cord. These distributions for axonal processes imply that sacral...

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...

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...

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...

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...

Posterior Superior Iliac Spine

Tendon of flexor digitorum profundus Tendon of flexor digitorum superficialis Lumbricals Opponens digiti minimi Flexor digiti minimi brevis Abductor digiti minimi Flexor retinaculum Tendons of Flexor carpi ulnaris Flexor digitorum superficialis Palmaris longus C Adductor pollicis Flexor pollicis brevis Abductor pollicis brevis Tendons of Abductor pollicis longus Flexor carpi radialis Flexor pollicis longus Flexor retinaculum cut Carpal tunnel Tendons of Abductor pollicis longus Flexor carpi...

Where Are Seeds Developed In Figure 8.1

The concave side of an ordinary kidney bean a dicot has a small white scar called the hilum. The hilum marks the point at which the ovule was attached to the ovary wall. A tiny pore called the micropyle is located right next to the hilum. If this bean is placed in water for an hour or two, it may swell enough to split the seed coat. Once the seed coat is removed, the two halves, called cotyledons, can be distinguished Fig. 8.28 . The cotyledons, which have a tiny immature plantlet along one...

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...

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...

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...

Anterior Inferior Acetabular Hip Paralabral Cyst

Rectus femoris avulsion in an athlete. A Coronal inversion recovery, and B axial T2, fat-suppressed images demonstrate avulsion of the origin of the biceps femoris from the left anterior inferior iliac spine. Note prominence of avulsed tendon arrows with surrounding soft-tissue edema and hemorrhage. Fluid distending the iliopsoas bursa, resulting in symptoms, is a common clinical problem. There may be communication between hip joint and bursa, with bursal distension resulting from...

Anal Skin Tags and Haemorrhoids

Anal skin tags are typically asymptomatic and present problems only when they interfere with perianal hygiene Fig. 5 . They are more prominent with active intestinal disease. Approximately 25 resolve spontaneously, generally after remission of concomitant bowel disease. These tags should not be removed Fig. 5. Anal tags with ulceration and tissue inflammation Fig. 5. Anal tags with ulceration and tissue inflammation because that may result in an unhealed wound, a chronic ulcer or perianal...

Pancreatic Islets Islets of Langerhans

On a microscopic level, the most conspicuous cells in the islets are the alpha and beta cells fig. 11.30 . The alpha cells secrete the hormone glucagon, and the beta cells secrete insulin. Alpha cells secrete glucagon in response to a fall in blood glucose concentrations. Glucagon stimulates the liver to Figure 11.29 The actions of parathyroid hormone and the control of its secretion. An increased level of parathyroid hormone causes the bones to release calcium and the kidneys to conserve...

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,...

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,...

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...

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,...

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...

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...

Antigen Selection of Lymphocytes Causes Clonal Expansion

A mature immunocompetent animal contains a large number of antigen-reactive clones of T and B lymphocytes the antigenic specificity of each of these clones is determined by the specificity of the antigen-binding receptor on the mem- Processing and presentation of exogenous and endogenous antigens. a Exogenous antigen is ingested by endocytosis or phagocytosis and then enters the endocytic processing pathway. Here, within an acidic environment, the antigen is degraded into small peptides, which...

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...

The Endomembrane System

Much of the volume of some eukaryotic cells is taken up by an extensive endomembrane system. This system includes two main components, the endoplasmic reticulum and the Golgi apparatus. Continuities between the nuclear envelope and the endomembrane system are visible under the electron microscope. Tiny, membrane-surrounded droplets called vesicles appear to shuttle between the various components of the endomembrane system. This system has various structures, but all of them are essentially...

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...

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...

Asexual Plant Propagation

In recent years, we have heard amazing stories about scientists who have cloned animals such as sheep and cows. Botanists are far ahead in that arena. They have been cloning plants for centuries Many plants are easy to propagate asexually, using vegetative parts rather than seeds. For example, crown division is a simple technique in which a plant is separated into several pieces, each of which contains a crown and a portion of the root system Fig. 14.17 . This is commonly used for many...

Gastrointestinal Tract Infection

A variety of organisms can infect the gastrointestinal tract, from viruses and bacteria to protozoa and worms. Some produce short-lived upsets with gastroenteritis, nausea, diarrhea, and emesis vomiting . Others, such as typhoid, cholera, and dysentery, are more serious, even fatal. An ulcer is a lesion of the skin or a mucous membrane marked by inflammation and tissue damage. Ulcers caused by the damaging action of gastric, or peptic, juices on the lining of the GI tract are termed peptic...

Development of Accessory Sex Organs and External Genitalia

In addition to testes and ovaries, various internal accessory sex organs are needed for reproductive function. Most of these are derived from two systems of embryonic ducts. Male accessory organs are derived from the wolffian mesonephric ducts, and female accessory organs are derived from the mullerian paramesonephric ducts fig. 20.5 . Interestingly, the two duct systems are present in both male and female embryos between day 25 and day 50, and so embryos of both sexes have the potential to...

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...

Belsey Fundoplication Technique

The total Nissen fundoplication is a 360-degree wrap of gastric fundus around the distal esophagus. After complete distal esophageal and proximal gastric mobilization including division of the proximal short gastric vessels left panel , the crura are approximated to close the hiatus to a normal caliber center panel . The proximal fundus is wrapped posteriorly around the esophagus and a portion of the fundus is brought anterior to the esophagus.The two edges are sutured together to...

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...

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...

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...

Gross Structure of the Urinary System

The paired kidneys lie on either side of the vertebral column below the diaphragm and liver. Each adult kidney weighs about 160 g and is about 11 cm 4 in. long and 5 to 7 cm 2 to 3 in. wide about the size of a fist. Urine produced in the kidneys is drained into a cavity known as the renal pelvis basin , and then it is channeled from each kidney via long ducts the ureters to the urinary bladder fig. 17.1 . Figure 17.1 The organs of the urinary system. The urinary system of a female is shown that...

Pronator Teres And Supinator

Semispinalis capitis Semispinalis cervicis Muscles of the Back and Neck. Deep muscles of the back and the neck help move the head and hold the torso erect. The splenius capitis and semispinalis capitis are removed on the left to show underlying muscles. The iliocostalis, longissimus, and spinalis muscles compose the erector spinae muscle. Thoracic and Abdominal Muscles. Superficial muscles. The left rectus sheath is cut away to expose the rectus abdominis muscle. Thoracic and Abdominal Muscles....

Tissue Patterns In Stems

Primary xylem, primary phloem, and the pith, if present, make up a central cylinder called the stele in most younger and a few older stems and roots. The simplest form of stele, called a protostele, consists of a solid core of conducting tissues in which the phloem usually surrounds the xylem. Protosteles were common in primitive seed plants that are now extinct and are also found in whisk ferns, club mosses see Chapter 21 , and other relatives of ferns. Siphonosteles, which are tubular with...

Clinical Features Of Klinefelters Syndrome

The clinical manifestations of KS are those of prepubertal androgen deficiency and infertility. Because testicular failure occurs before puberty, the developmental changes Fig. 2. An individual with Klinefelter's syndrome. Note tall body proportions, gynecomastia, relative paucity of facial and body hair, and small testis. Photos courtesy of Dr. C. Alvin Paulsen. Fig. 2. An individual with Klinefelter's syndrome. Note tall body proportions, gynecomastia, relative paucity of facial and body...

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,...

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...

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...

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....

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...

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...

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...

Medical Terminology Case Studies - Skin

Case Study 21-1 Basal Cell Carcinoma BSC K.B., a 32-year-old fitness instructor, had noticed a tiny hard lump at the base of her left nostril while cleansing her face. The lesion had been present for about 2 months when she consulted a dermatologist. She had recently moved north from Florida, where she had worked as a lifeguard. She thought the lump might have been triggered by the regular tanning salon sessions she had used to retain her tan because it did not resemble the acne pustules,...

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...

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...

And Mitochondrial Leukoencephalopathies

Leigh syndrome, also called subacute necrotizing encephalomyelopathy, is a neurodegenerative disorder mainly occurring in infancy and childhood. The disease often starts before 1 year of age and leads to death in months or years. Juvenile and adult-onset forms have also been described. In most cases the disease has an autosomal recessive inheritance in some cases inheritance is maternal or X-linked. Both sexes are affected, but among infants there is a 3 2 male predominance. The course can be...

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...

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...

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....

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...

Human Papilloma Virus

Human papilloma virus HPV infections have two important clinical manifestations external genital warts EGWs and squamous intraepithelial lesions 30 . A discussion of these neoplasms is beyond the scope of this chapter but screening and treatment issues can be found elsewhere 2 . The majority of newly acquired HPV infections are asymptomatic. EGWs are diagnosed when visible warts occur in the genital area they can be discrete or coalesce into confluent plaques 30 . The acetowhite test has not...

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...

Structure of Skeletal Muscles

The fibrous connective tissue proteins within the tendons extend around the muscle in an irregular arrangement, forming a sheath known as the epimysium epi above my muscle . Connective tissue from this outer sheath extends into the body of the muscle, subdividing it into columns, or fascicles these are the strings in stringy meat . Each of these fascicles is thus surrounded by its own connective tissue sheath, which is known as the perimysium peri around . Dissection of a muscle fascicle under...

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,...

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...

Steps Of Muscle Contraction

RESULTS Autonomic neurotransmitters alter membrane resting potential and thereby determine the rate that smooth muscle cells fire action potentials. Conclusion Smooth muscle contraction is stimulated by stretch and by the parasympathetic neurotransmitter acetylcholine. 47.2 Mechanisms of Smooth Muscle Activation Stretching depolarizes the membrane of smooth muscle cells, and this depolarization causes action potentials that activate the contractile mechanism.The neurotransmitters acetylcholine...

Labeling Exercise 174

Spinal Cord and Divisions of the Spinal Nerves Write the name of each numbered part on the corresponding line of the answer sheet. Brain Brainstem Cervical nerves Coccygeal nerve Lumbar nerves Sacral nerves Spinal cord Thoracic nerves Cross-Section of Spinal Cord and Reflex Arc Write the name of each numbered part on the corresponding line of the answer sheet. Cell body Central canal Dorsal horn Dorsal root Dorsal root ganglion Effector Gray matter Interneuron Motor neuron Receptor Sensory...

Craniospinal Radiation

This technique treats the entire craniospinal axis and frequently is utilized with a high rate of success in other malignant diseases of the craniospinal axis, such as medulloblastoma and central nervous system CNS germinoma. Because of the compartmental nature of leptomeningeal carcinomatosis, craniospinal irradiation is occasionally used in the treatment of this disease process. It involves a technically complex set-up of two opposed lateral brain fields and one or two posterior spine fields...

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...

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...

Multivalent Subunit Vaccines

One of the limitations of synthetic peptide vaccines and recombinant protein vaccines is that they tend to be poorly immunogenic in addition, they tend to induce a humoral antibody response but are less likely to induce a cell-mediated response. What is needed is a method for constructing synthetic peptide vaccines that contain both immunodominant B-cell and T-cell epitopes. Furthermore, if a CTL response is desired, the vaccine must be delivered intra-cellularly so that the peptides can be...

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...

The Indicator Dilution Method Measures Fluid Compartment Size

The indicator dilution method can be used to determine the size of body fluid compartments see Chapter 14 . A known amount of a substance the indicator , which should be confined to the compartment of interest, is administered. After allowing sufficient time for uniform distribution of the indicator throughout the compartment, a plasma sample is collected. The concentration of the indicator in the plasma at equilibrium is measured, and the distribution volume is calculated from this formula...

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...

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...

Molecular diagnosis of hepatitis B virus

Clinical applications of hepatitis B virus DNA assays The diagnosis of acute and chronic HBV infection can be made using the serologic tests described previously. However, the ability to perform quantitative tests in serum for HBV DNA is useful in several settings 1 to diagnose some cases of acute HBV infection 2 to distinguish replicative from non-replicative chronic HBV infection and 3 to monitor a patient's response to antiviral therapy. Determination of the HBV genotype will likely be used...

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...

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...

Structure and Maintenance of Neurons

Neurons occur in a variety of sizes and shapes nevertheless, as shown in Figure 8-2, most of them contain four parts 1 a cell body, 2 dendrites, 3 an axon, and 4 axon terminals. As in other types of cells, a neuron's cell body contains the nucleus and ribosomes and thus has the genetic information and machinery necessary for protein synthesis. The dendrites form a series of highly branched outgrowths from the cell body. They and the cell body receive most of the inputs from other neurons, the...

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...

Fluid Movement In Capillaries

Hypoxia-Induced Pulmonary Hypertension Hypoxia has opposite effects on the pulmonary and systemic circulations. Hypoxia relaxes vascular smooth muscle in systemic vessels and elicits vasoconstriction in the pulmonary vasculature. Hypoxic pulmonary vasoconstriction is the major mechanism regulating the matching of regional blood flow to regional ventilation in the lungs. With regional hypoxia, the matching mechanism automatically adjusts regional pulmonary capillary blood flow in response to...

The Physical Examination

Fig. 4.3 Palpation of the right scalene lymph node. The patient should tilt the head forwards and to the right to relax the sternomastoid during the examination. Fig. 4.3 Palpation of the right scalene lymph node. The patient should tilt the head forwards and to the right to relax the sternomastoid during the examination. Abnormal findings. The speed with which a paiieni can dress or undress is often a useful index of respiratory disability. Evidence of recent w eight loss may suggest...

The Classical Pathway Begins with Antigen Antibody Binding

Complement activation by the classical pathway commonly begins with the formation of soluble antigen-antibody complexes immune complexes or with the binding of antibody to antigen on a suitable target, such as a bacterial cell. IgM and certain subclasses of IgG human IgG1, IgG2, and IgG3 can activate the classical complement pathway. The initial stage of activation involves C1, C2, C3, and C4, which are present in plasma in functionally inactive forms. Because the components were named in order...

Feedback Control of the Anterior Pituitary

In view of its secretion of releasing and inhibiting hormones, the hypothalamus might be considered the master gland. The chain of command, however, is not linear the hypothalamus and anterior pituitary are controlled by the effects of their own actions. In the endocrine system, to use an analogy, the general takes orders from the private. The hypothalamus and anterior pituitary are not master glands because their secretions are controlled by the target glands they regulate. Anterior pituitary...

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...

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...

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...

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...

The Challenges Of Working In The Transference

Not untypically, those new to the practice of psychoanalytic therapy are hesitant about making transference interpretations. When patients are encouraged to work directly with transference reactions, conflictual issues are identified and the patient's anxiety is heightened. The patient may perceive our behaviour as critical, attacking or intrusive. In these situations, we may find it difficult to be experienced as the bad, persecuting object. The interpersonal strain that is generated when...

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...

Functional Classes of Neurons

Neurons can be divided into three functional classes afferent neurons, efferent neurons, and interneurons. Afferent neurons convey information from the tissues and organs of the body into the central nervous system, efferent neurons transmit electric signals from the central nervous system out to effector cells particularly muscle or gland cells or other neurons , and interneurons connect neurons within the central nervous system Figure 8-4 . As a rough estimate, for each afferent neuron...

Cleavage and Blastocyst Formation

At about 30 to 36 hours after fertilization, the zygote divides by mitosis a process called cleavage into two smaller cells. The rate of cleavage is thereafter accelerated. A second cleavage, which occurs about 40 hours after fertilization, produces four cells. A third cleavage about 50 to 60 hours after fertilization produces a ball of eight cells called a morula mulberry . This very early embryo enters the uterus 3 days after ovulation has occurred fig. 20.43 . Continued cleavage produces a...

Types of Endocrine Disorders

Most endocrine disorders fall into one of four categories 1 too little hormone hyposecretion 2 too much hormone hypersecretion 3 reduced response of the target cells hyporesponsiveness and 4 increased response of the target cells hyperresponsive-ness . In the first two categories, the phrases too little hormone and too much hormone here mean too little or too much for any given physiological situation. For example, as we shall see, insulin secretion decreases during fasting, and this decrease...

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...

Endometrial Thickness and Pattern for Assessing Endometrial Receptivity

Ultrasonography has been used, with varying degrees of success, to correlate the probability of pregnancy in ovarian stimulation-ovulation induction cycles and IVF cycles 73-77 . Most imaging studies have been attempting to predict the probability of implantation. A thicker endometrium was observed on the day of oocyte retrieval in women who conceived during that cycle 74 . The IVF pregnancy rate increased in cycles when the endo-metrium was gt 9 mm but lt 14 mm 75 . In another study, no...

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...

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...

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...