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In this type of bone purchase 10 mg metoclopramide fast delivery, the matrix immediately surrounding the osteoblast is called osteoid and is not mineralized buy 10 mg metoclopramide overnight delivery. Immature bone is characterized by irregularly arranged, interwoven collagenous fibers within a matrix containing proteoglycans. There are two basic techniques for studying bone with the light microscope, and both of these types of preparations must be studied to appreciate the organic and inorganic components of bone. Haversian Systems (osteons) are distinctive structural units of compact bone that reflect the developmental and nutritive pattern of its lamellar configuration. Haversian systems consist of Haversian canals containing blood vessels and nerves surrounded by concentric lamellae of bone. Lacunae are connected with each other, and ultimately with the perivascular spaces of the Haversian canal, by canaliculi. This communicating system of canaliculi is essential for exchange of gases and metabolites between the osteocytes and the perivascular spaces of the Haversian canal. Note the gradation of the surrounding connective tissue with the periosteum and the increased cellularity of the periosteum. The reversal lines (also known as cementing lines) that delimit the Haversian systems may appear refractile or slightly basophilic. Trabeculae of bone extend into and partially subdivide the marrow cavity, which contains hematopoietic bone marrow. Osteoclasts (multinucleated giant cells with acidophilic cytoplasm, related to the process of bone resorption) may also be seen near the osteochondral junction. Calcifying cartilage and rows of hyaline cartilage cells are present and 20 extend into the cartilage of the proximal end of rib. Is the osseous lamella adjacent to the Haversian canal the youngest or the oldest lamella of a particular osteon? Be sure you know how cartilage and bone differ morphologically, functionally, and with respect to blood supply. Note the connective tissue has begun to condense as a fibrous periosteum on either side of the anastomosing trabeculae of the growing bone. The trabeculae surround large spaces (primitive marrow cavities) containing embryonic connective tissue, thin-walled blood vessels, and nerves. In active regions, a unicellular row of osteoblasts (each with an eccentric nucleus and strongly basophilic cytoplasm) lines the surface of the trabeculae. Within the trabeculae, notice osteocytes in their lacunae and the woven bone matrix, which, unlike that of mature bone, is unevenly stained pink and exhibits a patchy basophilia. Later, minerals are deposited as minute hydroxyapatite crystals (calcium phosphate salts) in close association with the collagenous fibers to form a solid rigid matrix. In a typical adult long bone, one can distinguish grossly a cylindrical shaft or diaphysis of compact bone (with a central marrow cavity) and, at the ends of the shaft, the epiphysis, each consisting of spongy bone covered by a thin peripheral shell of compact bone. In the growing long bone, the epiphysis and the diaphysis are united by a transitional zone called the metaphysis. A hollow cylinder called the periosteal collar forms through intramembranous ossification around the middle of the cartilage model. The primary center of ossification begins with calcification of matrix at the diaphysis and eroding by blood vessels. The osteoprogenitor cells differentiate into osteoblasts and begin depositing matrix, forming spicules. Secondary centers of ossification begin in the epiphysis at each end with invasion by blood vessels 22 23 Growth at the epiphyseal plate: Passing from the articular end of the cartilage toward the ossification center of the diaphysis, the following zones are encountered in succession in the growth plate: 1) zone of reserve cells: A thin layer (3-6 cells wide) of small, randomly oriented chondrocytes adjacent to the bony trabeculae on the articular side of the growth plate. Mitotic figures are present and the axis of the mitotic figure usually is perpendicular to that of the row of chondrocytes. In the epiphyses where growth in length is occurring, note the zones of reserve cells, proliferation, maturation, hypertrophy, calcification, ossification and resorption. The zone of endochondral ossification spreads from the primary ossification center toward the ends of the cartilage. Recall that this bone is growing in width by apposition and remodeling along the periosteum and the endosteum. This increase in length and extension of the primary ossification center results in a sequence of changes in the chondrocytes of the epiphyses, which is similar to that described for the establishment of the primary center. In the epiphyseal growth plate, observe the zones of reserve cells, proliferation, maturation, hypertrophy, calcification, ossification and resorption. When growth ceases, the epiphyseal disk is entirely replaced by spongy bone and marrow (“closure of the epiphyses”), resulting in a visible epiphyseal line. In synovial or diarthrodial joints, articular cartilage caps the ends of the bones, which are kept apart by a synovial cavity filled with synovial fluid. The articulation is enclosed by a dense fibrous capsule, which is continuous with the periosteum over the bones. Internal to this is the synovium, a secretory membrane formed by a layer of collagenous fibers interspersed with flattened fibroblasts (synovial cells). The connective tissue elements include the meninges, which surround the central nervous system; capsules surround some sense organs and ganglia; and the endo-, peri-, and epineurium of peripheral nerves. Meninges Dura mater Arachnoid mater Grey matter Subarachnoid space Cerebral cortex Pia mater White matter 26 The detailed structure and function of the nervous system will be studied during the neurosciences course.

A marked difference in pathogenesis and immune response induced by different Mycobacterium tuberculosis genotypes generic 10 mg metoclopramide with mastercard. Abnormalities in monocyte recruitment and cytokine expression in monocyte chemoattractant protein 1-deficient mice best 10mg metoclopramide. Human tyrosine kinase 2 deficiency reveals its requisite roles in multiple cytokine signals involved in innate and acquired immunity. The purinergic P2X7 receptor is not required for control of pulmonary Mycobacterium tuberculosis infection. Mannose-binding lectin binds to a range of clinically relevant microorganisms and promotes complement deposition. Intrapulmonary Mycobacterium avium infection as the first manifestation of chronic granulomatous disease. The effect of mannose-binding protein gene polymorphisms in recurrent respiratory system infections in children and lung tu- berculosis. Association of various genetic markers with tuberculosis and other lung diseases in Tuvinian children. Interferon-gamma receptor 1 promoter polymorphisms: population distribution and functional implications. Association between vitamin D receptor gene poly- morphisms and response to treatment of pulmonary tuberculosis. Vitamin D-receptor gene polymorphisms and bone density in prepubertal American girls of Mexican descent [see comments]. Phagocytosis of Mycobacterium tuberculosis is mediated by human monocyte complement receptors and complement component C3. Genetic predisposition to leprosy: A major gene reveals novel pathways of immunity to Mycobacterium leprae. Mycobacterium tuberculosis in chemokine receptor 2-deficient mice: influence of dose on disease progression. Association of functional mutant homozygotes of the mannose binding protein gene with susceptibility to pulmonary tuberculosis in In- dia. Association of vitamin D receptor genotypes with the susceptibility to pulmonary tuberculosis in female patients & resistance in female contacts. Analysis of the interleukin-12/interferon-gamma pathway in children with non-tuberculous mycobacterial cervical lymphadenitis. The association between common vita- min D receptor gene variations and osteoporosis: a participant-level meta-analysis. Current status and prospects of studies on human genetic alleles associated with hepatitis B virus infection. Influence of vitamin D deficiency and vitamin D receptor polymorphisms on tuberculosis among Gujarati Asians in west London: a case-control study [see comments]. Worldwide, one person out of three is infected with Mycobacterium tuberculosis – two billion peo- ple in total. Unless intensive efforts are made, it is likely to main- tain that position through to 2020, despite a substantial projected decline in disease burden from other infectious diseases (Dye 1999, Smith 2004). Ninety-five per cent of all cases and 99 % of deaths occur in developing countries, with the greatest burden in sub- Saharan Africa and South East Asia. This difference is partly due to the fact that women have less access to diagnostic facili- ties in some settings, but the broader pattern also reflects real epidemiological dif- ferences between men and women, both in exposure to infection and in suscepti- bility to disease. As transmis- sion falls, the caseload shifts to the older age groups, and a higher proportion of cases come from the reactivation of latent infection (Borgdorff 2000). Although the “direct costs” of diagnosis and treatment are significant for poor families, the greatest economic loss occurs as a result of “indirect” costs, such as loss of employment, travel to health facilities, sale of assets to pay for treatment- related costs, and in particular, lost productivity from illness and premature death (Smith 2004, Floyd 2003, World Health Organization 2005a). Global epidemiology of tuberculosis 265 count for half (48 %) of the new cases that arise every year (Figure 7-1). In Eastern Europe (mostly countries of the former Soviet Union), the incidence per capita increased during the ’90s, peaked around 2001, and has since fallen. The average downturn in case noti- fications in Eastern Europe is mainly due to data from Russia and the Baltic States of Estonia, Latvia, and Lithuania; however, incidence rates might still be increasing in the central Asian republics of Tajikistan and Uzbekistan (Dye 2006, World Health Organization 2006a). In all other regions (Table 7-1), the incidence rate was stable or decreasing con- tinuously between 1990 and 2003. The downfall was relatively quick in Latin America, Central Europe and the established market economies. If the trends suggested by the case notifica- tions are correct, and if these trends persist, the global incidence rate will reach about 150 per 100,000 in 2015, resulting in more than 10 million new cases in that year (Dye 2006, World Health Organization 2006a, World Health Organization 2006 b). Despite intensified efforts, these targets were not met; more than 80 % of known cases are successfully treated, but only 45 % of cases are detected (World Health Organization 1993, World Health Organization 1994, World Health Organi- zation 2006a).

Immediately adjacent to the brain stem is the cervical region trusted metoclopramide 10 mg, followed by the thoracic cheap 10mg metoclopramide fast delivery, then the lumbar, and finally the sacral region. The spinal cord is not the full length of the vertebral column because the spinal cord does not grow significantly longer after the first or second year, but the skeleton continues to grow. The nerves that emerge from the spinal cord pass through the intervertebral formina at the respective levels. As the vertebral column grows, these nerves grow with it and result in a long bundle of nerves that resembles a horse’s tail and is named the cauda equina. Gray Horns In cross-section, the gray matter of the spinal cord has the appearance of an ink-blot test, with the spread of the gray matter on one side replicated on the other—a shape reminiscent of a bulbous capital “H. The lateral horn, which is only found in the thoracic, upper lumbar, and sacral regions, is the central component of the sympathetic division of the autonomic nervous system. The motor neuron that causes contraction of the big toe, for example, is located in the sacral spinal cord. The neuronal cell body that maintains that long fiber must be quite large, possibly several hundred micrometers in diameter, making it one of the largest cells in the body. Ascending tracts of nervous system fibers in these columns carry sensory information up to the brain, whereas descending tracts carry motor commands from the brain. Looking at the spinal cord longitudinally, the columns extend along its length as continuous bands of white matter. Between the two anterior horns, and bounded by the axons of motor neurons emerging from that gray matter area, are the anterior columns. The white matter on either side of the spinal cord, between the posterior horn and the axons of the anterior horn neurons, are the lateral columns. The anterior and lateral columns are composed of many different groups of axons of both ascending and descending tracts—the latter carrying motor commands down from the brain to the spinal cord to control output to the periphery. Basal Nuclei Parkinson’s disease is a disorder of the basal nuclei, specifically of the substantia nigra, that demonstrates the effects of the direct and indirect pathways. Without that modulatory influence, the basal nuclei are stuck in the indirect pathway, without the direct pathway being activated. The increased activity of the indirect pathway results in the hypokinetic disorder of Parkinson’s disease. Parkinson’s disease is neurodegenerative, meaning that neurons die that cannot be replaced, so there is no cure for the disorder. With levels of the precursor elevated, the remaining cells of the substantia nigra pars compacta can make more neurotransmitter and have a greater effect. According to one hypothesis about the expansion of brain size, what tissue might have been sacrificed so energy was available to grow our larger brain? Based on what you know about that tissue and nervous tissue, why would there be a trade-off between them in terms of energy use? To protect this region from the toxins and pathogens that may be traveling through the blood stream, there is strict control over what can move out of the general systems and into the brain and spinal cord. The next branches give rise to the common carotid arteries, which further branch into the internal carotid arteries. The bases of the common carotids contain stretch receptors that immediately respond to the drop in blood pressure upon standing. The orthostatic reflex is a reaction to this change in body position, so that blood pressure is maintained against the increasing effect of gravity (orthostatic means “standing up”). Heart rate increases—a reflex of the sympathetic division of the autonomic nervous system—and this raises blood pressure. Branches off the left and right vertebral arteries merge into the anterior spinal artery supplying the anterior aspect of the spinal cord, found along the anterior median fissure. The two vertebral arteries then merge into the basilar artery, which gives rise to branches to the brain stem and cerebellum. The left and right internal carotid arteries and branches of the basilar artery all become the circle of Willis, a confluence of arteries that can maintain perfusion of the brain even if narrowing or a blockage limits flow through one part (Figure 13. The circle of Willis is a specialized arrangement of arteries that ensure constant perfusion of the cerebrum even in the event of a blockage of one of the arteries in the circle. The animation shows the normal direction of flow through the circle of Willis to the middle cerebral artery. Where would the blood come from if there were a blockage just posterior to the middle cerebral artery on the left? The superior sagittal sinus drains to the confluence of sinuses, along with the occipital sinuses and straight sinus, to then drain into the transverse sinuses. The dura mater is a thick fibrous layer and a strong protective sheath over the entire brain and spinal cord. Beneath the arachnoid is a thin, filamentous mesh called the arachnoid trabeculae, which looks like a spider web, giving this layer its name. It is directly attached to the inner surface of the bones of the cranium and to the very end of the vertebral cavity. Two infoldings go through the midline separations of the cerebrum and cerebellum; one forms a shelf-like tent between the occipital lobes of the cerebrum and the cerebellum, and the other surrounds the pituitary gland.

These depth cues purchase metoclopramide 10 mg with visa, both monocular and binocular buy generic metoclopramide 10 mg line, can be exploited to make the brain think there are three dimensions in two-dimensional information. The projected image on the screen is two dimensional, but it has disparate information embedded in it. The 3-D glasses that are available at the theater filter the information so that only one eye sees one version of what is on the screen, and the other eye sees the other version. If you take the glasses off, the image on the screen will have varying amounts of blur because both eyes are seeing both layers of information, and the third dimension will not be evident. Some optical illusions can take advantage of depth cues as well, though those are more often using monocular cues to fool the brain into seeing different parts of the scene as being at different depths. There are two main regions that surround the primary cortex that are usually referred to as areas V2 and V3 (the primary visual cortex is area V1). The visual association regions develop more complex visual perceptions by adding color and motion information. Visual processing has two separate streams of processing: one into the temporal lobe and one into the parietal lobe. Because the ventral stream uses temporal lobe structures, it begins to interact with the non-visual cortex and may be important in visual stimuli becoming part of memories. The dorsal stream locates objects in space and helps in guiding movements of the body in response to visual inputs. The dorsal stream 634 Chapter 14 | The Somatic Nervous System enters the parietal lobe, where it interacts with somatosensory cortical areas that are important for our perception of the body and its movements. A particular sensory deficit that inhibits an important social function of humans is prosopagnosia, or face blindness. The word comes from the Greek words prosopa, that means “faces,” and agnosia, that means “not knowing. However, a person with prosopagnosia cannot recognize the most recognizable people in their respective cultures. They would not recognize the face of a celebrity, an important historical figure, or even a family member like their mother. A study of the brains of people born with the deficit found that a specific region of the brain, the anterior fusiform gyrus of the temporal lobe, is often underdeveloped. This region of the brain is concerned with the recognition of visual stimuli and its possible association with memories. Though the evidence is not yet definitive, this region is likely to be where facial recognition occurs. Though this can be a devastating condition, people who suffer from it can get by—often by using other cues to recognize the people they see. Often, the sound of a person’s voice, or the presence of unique cues such as distinct facial features (a mole, for example) or hair color can help the sufferer recognize a familiar person. In the video on prosopagnosia provided in this section, a woman is shown having trouble recognizing celebrities, family members, and herself. What other information can a person suffering from prosopagnosia use to figure out whom they are seeing? Somatic senses inform the nervous system about the external environment, but the response to that is through voluntary muscle movement. One example is the ability of our breathing to switch to unconscious control while we are focused on another task. However, the muscles that are responsible for the basic process of breathing are also utilized for speech, which is entirely voluntary. In the cerebral cortex, the initial processing of sensory perception progresses to associative processing and then integration in multimodal areas of cortex. These levels of processing can lead to the incorporation of sensory perceptions into memory, but more importantly, they lead to a response. The completion of cortical processing through the primary, associative, and integrative sensory areas initiates a similar progression of motor processing, usually in different cortical areas. Whereas the sensory cortical areas are located in the occipital, temporal, and parietal lobes, motor functions are largely controlled by the frontal lobe. The most anterior regions of the frontal lobe—the prefrontal areas—are important for executive functions, which are those cognitive functions that lead to goal-directed behaviors. These higher cognitive processes include working memory, which has been called a “mental scratch pad,” that can help organize and represent information that is not in the immediate environment. The prefrontal lobe is responsible for aspects of attention, such as inhibiting distracting thoughts and actions so that a person can focus on a goal and direct behavior toward achieving that goal. The functions of the prefrontal cortex are integral to the personality of an individual, because it is largely responsible for what a person intends to do and how they accomplish those plans. Whereas he was a hardworking, amiable man before the accident, he turned into an irritable, temperamental, and lazy man after the accident. Many of the accounts of his change may have been inflated in the retelling, and some behavior was likely attributable to alcohol used as a pain medication.

The Pineal Gland The pineal gland order 10mg metoclopramide fast delivery, a small purchase metoclopramide 10 mg mastercard, flattened, cone-shaped structure located between the two parts of the thalamus, produces a hormone called melatonin in a number of animals and also in humans. Melatonin, or some other hormone from the pineal, is thought to regulate the release of certain substances from the hypothalamus, which may in turn regulate the secretion of gonadotropins from the pituitary. There is evidence from animal studies that the production of melatonin is regulated by the amount of light in the environment. Selected Key Terms The following key terms are defined in the Glossary: Anastomosis Diastole Leukaemia Systole Aorta Endocardium Leukocyte Valve Arteriole Endothelium Murmur Vein Artery Epicardium Myocardium Vena cava Atrium Erythrocyte Pericardium Ventricle Capillary Fibrin Plasma Venule Coagulation Haemoglobin Platelet Coronary Hematocrit Pulse Deptum Hemolysis Serum 244 Human Anatomy and Physiology The cardiovascular system is the transport system of the body by which food, oxygen, water and all other essentials are carried to the tissue cells and their waste products are carried away. The blood vessels, the routes by which the blood travels to and through the tissues and back to the heart. However, it differ from other connective tissues in that its cells are not fixed in position, instead they move freely in the liquid portion of the blood, the plasma. Blood is a viscous (thick) fluid that varies in colour from bright to dark red, depending on how much oxygen it is carrying. Its quantity differs with the size of the person; the average adult male, weighing 70 kg has about 5-6 litres of blood. The circulating blood is of fundamental importance in maintaining the internal environment in a constant state (homeaostasis). Oxygen- from inhaled air diffuses into the blood through the thin lung membranes and is carried to all the tissue of the body. Carbon dioxide, a waste product of cell metabolism, is carried from the tissues to the lungs, where it is breathed out. These materials may inter the blood from the digestive system or may be released into the blood from body stores. The kidney removes excess water, minerals, and urea from protein metabolism and maintains the acid-base balance of the blood. The blood serves to regulate the amount of fluid in the tissues by means of substances (mainly proteins) that maintain the proper osmotic pressure 246 Human Anatomy and Physiology C. The blood transports heat that is generated in the muscles to other parts of the body thus aiding in the regulation of body temperature by the blood, thus aiding in the regulation of body temperature. Composition of Blood The blood is composed of two prime elements: as already mentioned, the liquid element is called plasma; the cells and fragments of cells are called formed elements or corpuscles (Figure 9-1). Leukocytes, from leuko, meaning “white,” are the several types of white blood cells, which protect against infection. Blood cells (From Memmler and Wood: The Human Body in Health and Disease, ed 6, Philadelphia, 1987, J. The plasma content varies somewhat, since the substances carried by the blood to and from the organs get used and added to. For example, the level of glucose, a simple sugar, 248 Human Anatomy and Physiology is maintained at a remarkably constant level of about on tenth of a 1% solution. Proteins are the principal constituents of cytoplasm and are essential to the growth and the rebuilding of body tissues. Albumin, the most abundant protein in plasma, is important for maintaining the osmotic pressure of the blood. A system of enzymes made of several proteins, collectively known as complement, helps antibodies in their fight against pathogens. The principal form of carbohydrate found in the plasma is glucose, which is absorbed by the capillaries of the intestine following digestion. The 249 Human Anatomy and Physiology mineral salts in the plasma appear primarily as chloride, carbonate, or phosphate salts of sodium, potassium, and magnesium. These salts have a variety of functions, including the formation of bone (calcium and phosphorus), the production of hormones by certain glands (iodine for the production of thyroid hormone), the transportation of the gases oxygen and carbon dioxide (iron), and the maintenance of the acid base balance (sodium and potassium carbonates and phosphates). The Formed Elements Erythrocytes Erythrocytes, the red cells, are tiny, disk-shaped bodies with a central area that is thinner than the edges. They are different from other cells in that the mature form found in the circulating blood does not have a nucleus. These cells, like almost all the blood cells, live a much shorter time (120 days) than most other cells in the body, some of which last a lifetime. Haemoglobin that has given up its oxygen is able to carry hydrogen ions; in this way, haemoglobin acts as a buffer and plays an important role in acid-base balance. The red cells also carry a small amount of carbon dioxide from the tissues to the lings for elimination in exhalation. It displaces the oxygen that is normally carried by the haemoglobin and reduces the oxygen-carrying ability of the blood. Carbon monoxide may be produced by the incomplete burning of various fuels, such as gasoline, coal, wood, and other carbon containing materials. Leukocytes The leukocytes, or white blood cells, are very different from the erythrocytes in appearance, quantity, and function.