Carla S. Dupree, MD, PhD
Biaxin dosages: 500 mg, 250 mg
Biaxin packs: 30 pills, 60 pills, 90 pills, 120 pills, 180 pills
The parallel arrangement of fibers is an adaptation to the fact that musculoskeletal stresses pull tendons and ligaments in predictable directions gastritis diet biaxin 500 mg amex. With minor exceptions such as blood vessels and sensory nerve fibers, the only cells in this tissue are fibroblasts, visible by their slender, violetstaining nuclei squeezed between bundles of collagen. This type of tissue has few blood vessels, so injured tendons and ligaments are slow to heal. The vocal cords and some spinal ligaments are made of a dense regular connective tissue called elastic tissue. In addition to the densely packed collagen fibers, it exhibits branching elastic fibers and more fibroblasts. The fibroblasts have larger, more conspicuous nuclei than seen in most dense regular connective tissue. When the heart pumps blood into the arteries, these sheets enable them to expand and relieve some of the pressure on smaller vessels downstream. When the heart relaxes, the arterial wall springs back and keeps the blood pressure from dropping too low between heartbeats. The importance of this elastic tissue becomes especially clear in diseases such as Marfan syndrome (see Deeper Insight 5. This tissue constitutes most of the dermis, where it binds the skin to the underlying muscle and connective tissue. It forms a protective capsule around organs such as the kidneys, testes, and spleen and a tough fibrous sheath around the bones, nerves, and most cartilages. It is sometimes difficult to judge whether a tissue is areolar or dense irregular. In the dermis, for example, these tissues occur side by side, and the transition from one to the other is not at all obvious (see fig. A relatively large amount of clear space suggests areolar tissue, and thicker bundles of collagen and relatively little clear space suggest dense irregular connective tissue. Fibrous connective tissue often forms a filler, or interstitium, around and between other structures such as blood vessels and gland ducts and within the walls of some organs. In some places, this interstitium is like a honeycomb of fluid-filled spaces supported by thick bundles of collagen. These are not seen in prepared slides, where the spaces are empty and the collagen is densely packed as in figure 5. Clinical signs of Marfan syndrome include hyperextensible joints, hernias of the groin, and visual problems resulting from abnormally elongated eyes and deformed lenses. People with Marfan syndrome typically show unusually tall stature, long limbs, spidery fingers, abnormal spinal curvature, and a protruding "pigeon breast. The aorta, where blood pressure is highest, is sometimes enormously dilated close to the heart and may rupture. Marfan syndrome is present in about 1 out of 20,000 live births, and most victims die by their mid-30s.
Syndromes
Thus gastritis diet amazon generic biaxin 250 mg buy on line, the shoulder became more mobile and enabled primates to reach out in any direction (even overhead, which few other mammals can do). The thumbs became fully opposable-they could cross the palm to touch the fingertips-and enabled primates to hold small objects and manipulate them more precisely than other mammals could. Opposable thumbs made the hands prehensile10-able to grasp objects by encircling them with the thumb and fingers (fig. The thumb is so important that it receives highest priority in the repair of hand injuries. If the thumb can be saved, the hand can be reasonably functional; if it is lost, hand functions are severely diminished. Some major aspects of primate evolution are the opposable thumb, prehensile hand, forward-facing eyes, and stereoscopic vision. In humans, the hand became refined for increasingly sophisticated manipulation of objects. Chimpanzee: Tim Davis/Science Source the eyes of primates moved to a more forward-facing position, which allowed for stereoscopic11 vision (depth perception). The ability to distinguish subtle shades of orange and red enables them to distinguish ripe, sugary fruits from unripe ones. Distinguishing subtle shades of green helps them to differentiate between tender young leaves and tough, more toxic older foliage. Various fruits ripen at different times and in widely separated places in the tropical forest. This requires a good memory of what will be available, when, and how to get there. Larger brains might have evolved in response to the challenge of efficient food finding and, in turn, laid the foundation for more sophisticated social organization. Our relationship is not like parent and child, but more like cousins who have the same grandparents. Observations of monkeys and apes provide insight into how primates adapt to the arboreal habitat and therefore how certain human adaptations probably originated. Some primates adapted to living on the savanna, but this was a dangerous place with more predators and less protection. Just as squirrels and monkeys stand briefly on their hind legs to look around for danger, so would these early ground dwellers. Being able to stand up not only helps an animal stay alert, but also frees the forelimbs for purposes other than walking. Chimpanzees sometimes walk upright to carry food, infants, or weapons (sticks and rocks), and it is reasonable to suppose that our early ancestors did so too. These advantages are so great that they favored skeletal modifications that made bipedalism12-standing and walking on two legs-easier.
Regurgitation of blood through the incompetent valves creates turbulence that can be heard with a stethoscope as a heart murmur chronic gastritis message boards 500 mg biaxin visa. It is often hereditary and affects about 1 out of 40 people, especially young women. In many cases, it causes no serious dysfunction, but in some people it causes chest pain, fatigue, and shortness of breath. A defective valve can be surgically repaired or replaced with an artificial valve or a valve transplanted from a pig heart. Here, it is divided into colored and numbered bars to correspond to the following phases. Where to begin when describing a circular chain of events is somewhat arbitrary, but in this presentation, we begin with the filling of the ventricles. During diastole, the ventricles expand and their pressure drops below that of the atria. Ventricular filling occurs in three phases: (1a) the first one-third is rapid ventricular filling, when blood enters especially quickly. The P wave of the electrocardiogram occurs at the end of diastasis, marking the depolarization of the atria. The atria repolarize, relax, and remain in diastole for the rest of the cardiac cycle. Wave Q marks the end of ventricular filling; R marks the transition from atrial systole to isovolumetric contraction of the ventricles; and S occurs during isovolumetric contraction. Pressure in the ventricles rises sharply and reverses the pressure gradient between atria and ventricles. Heart sound S1 occurs at the beginning of this phase and is produced mainly by the left ventricle; the right ventricle is thought to make little contribution. Then as the ventricles relax again and their pressure falls below that in the arteries, arterial blood briefly flows backward and fills the pocketlike cusps of the semilunar valves. The first and second heart sounds, symbolized S1 and S2, are often described as a "lubb-dupp"-S1 is louder and longer and S2 a little softer and sharper. This is rarely audible in people older than 30, but when it is, the heartbeat is said to show a triple rhythm or gallop, which may indicate an enlarged and failing heart. If the normal sounds are roughly simulated by drumming two fingers on a table, a triple rhythm sounds a little like drumming with three fingers. This is because pressures in the aorta (80 mm Hg) and pulmonary trunk (10 mm Hg) are still greater than the pressures in the respective ventricles and thus oppose the opening of the semilunar valves. The ejection of blood begins when ventricular pressure exceeds arterial pressure and forces the semilunar valves open. The pressure peaks at typically 120 mm Hg in the left ventricle and 25 mm Hg in the right. Blood spurts out of each ventricle rapidly at first (rapid ejection), then flows out more slowly under less pressure (reduced ejection).
The necrosis worsens gastritis diet list order biaxin 500 mg otc, and is accompanied by another form of cell death, apoptosis. In as little as 4 hours, this second wave of destruction, called posttraumatic infarction, consumes about 40% of the cross-sectional area of the spinal cord; within 24 hours, it destroys 70%. As many as five segments of the cord become transformed into a fluid-filled cavity, which is replaced with collagenous scar tissue over the next 3 to 4 weeks. Effects of Injury Complete transection (severance) of the spinal cord causes immediate loss of motor control at and below the level of the injury. Victims also lose sensation from the level of injury and below, although some patients temporarily feel burning pain within one or two dermatomes of the level of the lesion. For 8 days to 8 weeks after the accident, the patient typically lacks bladder and bowel reflexes and thus retains urine and feces. Lacking sympathetic stimulation to the blood vessels, a patient may exhibit neurogenic shock in which the vessels dilate and blood pressure drops dangerously low. As spinal shock subsides, somatic reflexes begin to reappear, at first in the toes and progressing to the feet and legs. Contrary to the earlier urinary and fecal retention, a patient now has the opposite problem, incontinence, as the rectum and bladder empty reflexively in response to stretch. Both the somatic and autonomic nervous systems typically exhibit exaggerated reflexes, a state called hyperreflexia or the mass reflex reaction. Stimuli such as a full bladder or cutaneous touch can trigger an extreme cardiovascular reaction. The systolic blood pressure, normally about 120 mm Hg, jumps to as high as 300 mm Hg. Pressure receptors in the major arteries sense this rise in blood pressure and activate a reflex that slows the heart, sometimes to a rate as low as 30 or 40 beats/minute (bradycardia), compared with a normal rate of 70 to 80. They may recover these functions later and become capable of ejaculating and fathering children, but without sexual sensation. The flaccid paralysis of spinal shock later changes to spastic paralysis as spinal reflexes are regained but lack inhibitory control from the brain. Spastic paralysis typically starts with chronic flexion of the hips and knees (flexor spasms) and progresses to a state in which the limbs become straight and rigid (extensor spasms). Three forms of muscle paralysis are paraplegia, a paralysis of both lower limbs resulting from spinal cord lesions at levels T1 to L1; quadriplegia, the paralysis of all four limbs resulting from lesions above level C5; and hemiplegia, paralysis of one side of the body, usually resulting not from spinal cord injuries but from a stroke or other brain lesion. Spinal cord lesions from C5 to C7 can Treatment the first priority in treating a spinal injury patient is to immobilize the spine to prevent further trauma. Given within 3 hours of the trauma, it reduces injury to cell membranes and inhibits inflammation and apoptosis. After these immediate requirements are met, reduction (repair) of the fracture is important. Treatment strategies for spinal cord injuries are a vibrant field of contemporary medical research. Some current interests are the use of antioxidants to reduce free radical damage, and the implantation of pluripotent stem cells, which has produced significant (but not perfect) recovery from spinal cord lesions in rats.
If the prime mover worked alone at a joint gastritis diet v8 cheap biaxin 500 mg otc, it could cause rotation or other undesirable movements of a bone. A synergist may stabilize a joint and restrict these movements, or modify the direction of a movement so that the action of the prime mover is more coordinated and specific. In some cases, it relaxes to give the prime mover almost complete control over an action. More often, however, the antagonist maintains some tension on a joint and thus limits the speed or range of the prime mover, preventing excessive movement, joint injury, or inappropriate actions. If you extend your arm to reach out and pick up a cup of tea, for example, your triceps brachii serves as the prime mover of elbow extension, and your brachialis acts as an antagonist to slow the extension and stop it at the appropriate point. If you extend your arm rapidly to throw a dart, however, the brachialis must be quite relaxed. The brachialis and triceps represent an antagonistic pair of muscles that act on opposite sides of a joint. We need antagonistic pairs at a joint because a muscle can only pull, not push-for example, a single muscle cannot flex and extend the elbow. Which member of the pair acts as the prime mover depends on the motion under consideration. In flexion of the elbow, the brachialis is the prime mover and the triceps is the antagonist; when the elbow is extended, their roles are reversed. To fix a bone means to hold it steady, allowing another muscle attached to it to pull on something else. The biceps originates on the scapula, crosses both the shoulder and elbow joints, and inserts on the radius and forearm fascia. The scapula is loosely attached to the axial skeleton, so when the biceps contracts, it seems that it would pull the scapula 12 13 laterally. However, there are fixator muscles (the rhomboids) that attach the scapula to the vertebral column (see fig. They contract at the same time as the biceps, holding the scapula firmly in place and ensuring that the force generated by the biceps moves the radius rather than the scapula. Knowing the innervation to each muscle enables clinicians to diagnose nerve, spinal cord, and brainstem injuries from their effects on muscle function, and to set realistic goals for rehabilitation. The innervations described in this chapter will be more meaningful after you have studied the peripheral nervous system (chapters 13 and 14), but a brief orientation will be helpful here. Spinal nerves are identified by letters and numbers that refer to the adjacent vertebrae-for example, T6 for the sixth thoracic nerve and S2 for the second sacral nerve. Immediately after emerging from an intervertebral foramen, each spinal nerve branches into a posterior and anterior ramus. The term plexus in some of the tables refers to weblike networks of spinal nerves adjacent to the vertebral column. All of the spinal nerves named here are illustrated, and most are also discussed, in chapter 13 (see the four tables starting at table 13.
Shou-Wu-Pian (Fo-Ti). Biaxin.
Source: http://www.rxlist.com/script/main/art.asp?articlekey=96750
They act like switches to turn certain metabolic pathways on or off when the hormones bind to them gastritis y embarazo 500 mg biaxin overnight delivery. Receptor defects lie at the heart of several endocrine diseases (see Deeper Insight 17. Unlike enzymes, receptors do not chemically change their ligands, but they do exhibit enzymelike specificity and saturation. Saturation is the condition in which all the receptor molecules are occupied by hormone molecules. Hormones fall into two broad classes according to where they act on their target cells-those that cannot enter the target cell but act through receptors at the cell surface, and those that can enter the target cell and act through receptors within it. Most of the monoamines and peptides are hydrophilic, so mixing with the blood plasma is no problem for them. To travel in the watery bloodstream, they must bind to hydrophilic transport proteins-albumins and globulins synthesized by the liver. A hormone attached to a transport protein is called a bound hormone, and one that is not attached is an unbound (free) hormone. Transport proteins not only carry the hydrophobic hormones, but also prolong their half-lives. They protect hormones from being broken down by enzymes in the blood plasma and liver and from being filtered out of the blood by the kidneys. Free hormone may be broken down or removed from the blood in a few minutes, whereas bound hormone may circulate for hours to weeks. For example, a defect or deficiency of insulin receptors causes type 2 diabetes mellitus. Androgen insensitivity syndrome is due to an androgen receptor defect or deficiency; it causes genetic males to develop feminine genitalia and other features (see Deeper Insight 27. For this reason, estrogen replacement therapy should not be used for women with estrogen-dependent cancer. They bind to cell surface receptors, which are linked to second-messenger systems on the other side of the membrane (fig. Two other second-messenger systems begin with one of the phospholipids in the plasma membrane. It can open Ca2+ channels in the plasma membrane, letting Ca2+ into the cell from the extracellular fluid, or it can open channels in the endoplasmic reticulum, causing it to release a flood of Ca2+ into the cytosol. It binds to certain calcium-dependent cytoplasmic enzymes that alter cell metabolism.
The opening and closing of the heart valves are governed by these pressure changes gastritis diet 900 generic biaxin 500 mg buy on-line. Blood flows freely from the atria into the ventricles even before the atria contract. As the ventricles fill with blood, the cusps float upward toward the closed position. This pushes the cusps together, seals the openings, and prevents blood from flowing back into the atria. The papillary muscles contract slightly before the rest of the ventricular myocardium and tug on the tendinous cords, preventing the valves from bulging excessively (prolapsing) into the atria or turning inside out like windblown umbrellas. When atrial pressure is greater than ventricular pressure, the valve opens and blood flows through (green arrows). When ventricular pressure rises above atrial pressure, the blood in the ventricle pushes the valve cusps closed. When the pressure in the ventricles is greater than the pressure in the great arteries, the semilunar valves are forced open and blood is ejected. When ventricular pressure is lower than arterial pressure, arterial blood holds these valves closed. Valvular stenosis25 is a form of insufficiency in which the cusps are stiffened and the opening is constricted by scar tissue. It frequently results from rheumatic fever, an autoimmune disease in which antibodies produced to fight a bacterial infection also attack the mitral and aortic valves. As the valves become scarred and constricted, the heart is overworked by the effort to force blood through the openings and may become enlarged. By analogy, suppose you were to shake up a bottle of carbonated beverage and remove the cap. The liquid would spurt out rapidly at high pressure and then more would dribble out at lower pressure, much like the blood leaving the ventricles. Ventricular ejection lasts about 200 to 250 ms, which corresponds to the plateau of the myocardial action potential but lags somewhat behind it (review the red tension curve in fig. The T wave occurs late in this phase, beginning at the moment of peak ventricular pressure. This is early ventricular diastole, when the T wave ends and the ventricles begin to expand. Another is that contraction of the ventricles deforms the fibrous skeleton, which subsequently springs back like the rubber bulb of a turkey baster that has been squeezed and released. This elastic recoil and expansion would cause pressure to drop rapidly and suck blood into the ventricles. At the beginning of ventricular diastole, blood from the aorta and pulmonary trunk briefly flows backward through the semilunar valves. The backflow, however, quickly fills the cusps and closes them, creating a slight pressure rebound that appears as the dicrotic notch of the aortic pressure curve (the top curve in the Wiggers diagram).
Each beat of the heart produces a surge of pressure that can be felt by palpating a superficial artery with the fingertips gastritis diet purchase 500 mg biaxin mastercard. Heart rate can be obtained by counting the number of pulses in 15 seconds and multiplying by 4 to get beats per minute. It declines steadily with age, averaging 72 to 80 bpm in young adult females and 64 to 72 bpm in young adult males. Thus, the heart races when the body has lost a significant quantity of blood or when there is damage to the myocardium. Endurance training enlarges the heart and increases its stroke volume, enabling it to maintain the same output with fewer beats. Hypothermia (low body temperature) also slows the heart and may be deliberately induced in preparation for cardiac surgery. Diving mammals such as whales and seals exhibit bradycardia during the dive, as do humans to some extent when the face is immersed in cool water. Factors outside of the heart itself that raise the heart rate are called positive chronotropic29 agents, and factors that lower it are negative chronotropic agents. Such responses to fluctuations in blood chemistry and blood pressure, called chemoreflexes and baroreflexes, are good examples of negative feedback loops. The Central Nervous System There is a benefit to placing heart rate under the influence of cardiac centers in the medulla-these centers can receive input from many other sources and integrate it into a decision as to whether the heart should beat more quickly or slowly. Sensory and emotional stimuli can act on the cardiac centers by way of the cerebral cortex, limbic system, and hypothalamus; therefore, heart rate can climb even as you anticipate taking the first plunge on a roller coaster or competing in an athletic event, and it is influenced by emotions such as love and anger. The medulla also receives input from the following receptors in the muscles, joints, arteries, and brainstem: Hormones, Drugs, and Other Chronotropic Chemicals Heart rate is influenced by many other factors besides the autonomic nervous system. Thyroid hormone accelerates it by stimulating the up-regulation of -adrenergic receptors, making the heart more sensitive to sympathetic stimulation; this is why tachycardia is one of the signs of hyperthyroidism. Glucagon is sometimes given in cardiac emergencies to stimulate the heartbeat, and epinephrine is frequently given to support cardiac output and blood pressure in life-threatening allergic reactions. Hypertension is often treated with drugs called beta blockers, which inhibit the binding of catecholamines to the -adrenergic receptors and slow down the heart. Electrolyte concentrations also strongly influence heart rate and contraction strength. In hyperkalemia,30 a potassium excess, K+ diffuses into the cardiomyocytes and keeps the membrane voltage elevated, inhibiting cardiomyocyte repolarization. The myocardium becomes less excitable, the heart rate becomes slow and irregular, and the heart may arrest in diastole.
Why not simply have one ossicle concentrating the mechanical energy of the tympanic membrane directly on the inner ear The answer is that the ossicles serve at times to lessen the transfer of energy to the inner ear gastritis diet 800 cheap biaxin 250 mg buy line. In response to a loud noise, the tensor tympani pulls the tympanic membrane inward and tenses it, while the stapedius reduces the motion of the stapes. The reflex probably evolved in part for protection from loud but slowly building natural sounds such as thunder. It is therefore imperative to wear the next step in hearing is based on movement of the cochlear hair cells relative to stationary structures nearby. In this section, we will see how movements of the inner-ear fluids and basilar membrane move the hair cells and why it is important that the tectorial membrane near the hair cells remains relatively still. A simple mechanical model of the ear can help in visualizing how this happens (fig. Perilymph, like other liquids, cannot be compressed, so it flows away from the stapes footplate. Why would high air pressure in the middle ear reduce the movements of the basilar membrane of the inner ear As the cycle of vibration continues, the stapes pulls back from the oval window and all of this happens in reverse. In short, as the stapes goes in-out-in, the secondary tympanic membrane goes out-in-out, and the basilar membrane goes downup-down. It is not difficult to see how this happens-the only thing hard to imagine is that it can happen as often as 20,000 times per second! The important thing about all this is that the hair cells, affixed to the basilar membrane, go along for the ride, bobbing up and down as the basilar membrane moves. To understand how all of this leads to electrical excitation of the hair cells, we must seemingly digress for a moment to examine the tips of the hair cells. Potassium ions (K+) are secreted into the endolymph by cells around the circumference of the cochlear duct (on the wall opposite from the modiolus). Thus there is an exceptionally strong electrochemical gradient from the endolymph to the hair cell cytoplasm. This gradient provides the potential energy that ultimately enables the hair cell to work. On the inner hair cells-the ones that generate all the signals we hear-each stereocilium has a single transmembrane protein at its tip that functions as a mechanically gated ion channel. A fine, stretchy protein filament called a tip link extends like a spring from the ion channel of one stereocilium to the sidewall of the taller stereocilium next to it (fig.
Extensors of the Neck the extensors are located mainly in the nuchal region (back of the neck; fig gastritis symptoms and back pain buy biaxin 250 mg on line. It is named for the fact that the right and left trapezii together form a diamond or trapezoidal shape (see fig. The splenius is a deeper, elongated muscle with splenius capitis and splenius cervicis regions in the head and neck, respectively. It is nicknamed the "bandage muscle" because of the way it wraps around still deeper neck muscles. One of those deeper muscles is the semispinalis, another elongated muscle with head, neck, and thoracic regions. Flexors of the Neck the prime mover of neck flexion is the sternocleidomastoid, a thick muscular cord that extends from the upper chest (sternum and clavicle) to the mastoid process behind the ear (fig. This is most easily seen when the head is rotated to one side and slightly extended. To visualize the action of a single sternocleidomastoid, place the index finger of your left hand on your left mastoid process and the index finger of your right hand on your suprasternal notch. Now contract your left sternocleidomastoid to bring your two fingertips as close together as possible. The three scalenes43 on the side of the neck are named for their staircase-like arrangement. Bilateral action draws the head straight forward and down, as when eating or reading. Unilateral contraction causes ipsilateral flexion or contralateral rotation (tilts head toward same shoulder, or rotates face away), depending on action of other muscles. Name the four paired muscles of mastication and state where they insert on the mandible. In the illustrations, you will note some major muscles that are not discussed in the associated tables-for example, the pectoralis major and serratus anterior. Although they are located in the trunk, they act upon the limbs and limb girdles, and are further discussed in sections 10. The diaphragm is a muscular dome between the thoracic and abdominal cavities, bulging upward against the base of the lungs. It has openings for passage of the esophagus, major blood and lymphatic vessels, and nerves between the two cavities. When the diaphragm contracts, it flattens slightly and enlarges the thoracic cavity, causing air intake (inspiration); when it relaxes, it rises and shrinks the thoracic cavity, expelling air (expiration). Three layers of muscle lie between the ribs: the external, internal, and innermost intercostal muscles.
Deckard, 27 years: Both the internal and external elastic laminae, however, are thick and often conspicuous.
Corwyn, 51 years: Red marrow is then limited to the skull, vertebrae, ribs, sternum, part of the pelvic (hip) girdle, and the proximal heads of the humerus and femur (fig.
Hauke, 43 years: Moving blood would exert no pressure against a vessel wall unless it encountered at least some downstream resistance.
References