P. Topork. Pace University.
Extreme sprains may re- A synovial joint is a remarkable biologic system cheap kamagra soft 100 mg overnight delivery erectile dysfunction prescription medications. Its self-lubricating quire surgery and casting of the joint to facilitate healing generic kamagra soft 100 mg with visa causes of erectile dysfunction young males. Under normal circumstances and in most people,the many joints of the body perform without prob- Knowledge Check lems throughout life. Joints are not indestructible,however,and are subject to various forms of trauma and disease. Articulations © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 Chapter 8 Articulations 225 TABLE 8. Sprains are usually accompanied Joints are well adapted to withstand compression and tension forces. Torsion or sudden impact to the side of a joint, however, can be Luxation, or joint dislocation, is a derangement of the ar- devastating. Joint dislocation is more In a strained joint, unusual or excessive exertion stretches serious than a sprain and is usually accompanied by sprains. The damage is not shoulder and knee joints are the most vulnerable to dislocation. Strains are frequently caused by not “warming up” the muscles and not “stretching” the joints prior to exercise. Articulations © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 226 Unit 4 Support and Movement Self-healing of a dislocated joint may be incomplete, leaving the person with a “trick knee,” for example, that may unexpectedly give way. Subluxation of the hip joint is a common type of birth defect that can be treated by bracing or casting to promote suitable bone development. Because the bursa is close to the joint, the joint capsule may be affected as well. Bursitis may be caused by exces- sive stress on the bursa from overexertion, or it may be a local or systemic inflammatory process. Tendonitis involves inflamma- tion of a tendon; it usually comes about in the same way as bursitis. Not only do the individual vertebrae articulate one (a) (b) with another, but together they form the portion of the axial skeleton with which the head, ribs, and ossa coxae articulate. It may be congenital, disease-related, or idio- The vertebral column also encloses the spinal cord and provides pathic (of unknown cause). Our way of life causes Diseases of Joints many of the problems associated with the vertebral column. Im- proper shoes, athletic exertion, sudden stops in vehicles, or im- Arthritis is a generalized designation for over 50 different joint proper lifting can all cause the back to go awry. Some types are genetic The most common cause of back pain is strained muscles, and others result from hormonal or metabolic disorders. The second most frequent most common forms are rheumatoid arthritis, osteoarthritis, and back ailment is a herniated disc. The third most frequent back problem is a dislocated articu- mune attack against the joint tissues. The synovial membrane lar facet between two vertebrae, caused by sudden twisting of the thickens and becomes tender, and synovial fluid accumulates. The treatment of back ailments varies from This is generally followed by deterioration of the articular carti- bed rest to spinal manipulation to extensive surgery. When bone tissue is Curvature disorders are another problem of the vertebral unprotected, joint ossification produces the crippling effect of column. Lordosis (swayback) is an abnormal anterior disease usually begins between the ages of 30 and 50. If the right wrist or hip ness) is an abnormal lateral curvature of the vertebral column develops the disease, so does the left. It may be caused by abnormal vertebral structure, un- Osteoarthritis is a degenerative joint disease that results equal length of the legs, or uneven muscular development on the from aging and irritation of the joints.
Which of the following structures is insinuated between the ex- CT shows a hemorrhage into the head of the caudate nucleus that ternal and extreme capsules and is functionally related to the in- has ruptured into the anterior horn of the lateral ventricle generic 100mg kamagra soft with amex erectile dysfunction treatment atlanta ga. An 83-year-old man is brought to the emergency department by his (E) Thalamoperforating artery(ies) daughter 100mg kamagra soft overnight delivery effective erectile dysfunction drugs, who explains that her father started having “ﬁts”. The ex- amination reveals an alert, otherwise healthy, man who frequently Questions 5 and 6 are based on the following patient. Which of the A 23-year-old man is brought to the emergency department from the following structures is most likely involved in this lesion? The neurologic examination reveals (A) Cerebellar cortex plus nuclei weakness of the right lower extremity and a loss of pain and thermal (B) Lenticular nucleus sensations on the left side beginning at the level of the umbilicus. CT (C) Subthalamic nucleus shows a fracture of the vertebral column with displacement of bone (D) Ventral lateral nucleus fragments into the vertebral canal. Damage to which of the following tracts would correlate with mal sensations at the base of the neck (C3 dermatome) and ex- weakness of the lower extremity in this man? MRI shows a cavitation in the spinal (B) Reticulospinal ﬁbers on the right cord at these levels. Damage to which of the following structures (C) Right lateral corticospinal tract would most likely explain this deﬁcit? A 92-year-old woman is brought to the emergency department by of the medulla that is served by the anterior spinal artery? The examination revealed no cranial nerve deﬁcits and age- (A) Anterolateral system normal motor function, but a loss of pain, thermal, vibratory, and (B) Gracile fasciculus discriminative touch sensations on one side of the body excluding (C) Medial lemniscus the head. Which of the following (D) Rubrospinal tract structures is the most likely location of this lesion? A 59-year-old man complains to his family physician that he has (C) Subthalamic nucleus trouble chewing. The examination reveals a weakness of mastica- (D) Ventral posterolateral nucleus tory muscles on the left side. Which of the following nuclei is (E) Ventral posteromedial nucleus speciﬁcally related to the deﬁcit seen in this man? In its location immediately internal to the anterior spinocerebel- (A) Left facial motor lar tract, which of the following ﬁber bundles would most likely (B) Left hypoglossal be damaged in a lesion to this area of the spinal cord? A 15-year-old boy with signs of increased intracranial pressure (E) Lateral corticospinal tract (stupor, vomiting, headache) is referred to a neurologist. The ex- amination reveals a paralysis of upward gaze, and MRI shows a 19. A 37-year-old man is brought to the emergency department with large tumor of the pineal gland. Within a few hours he is decerebrate (upper ing structures would be most speciﬁcally related to the gaze and lower extremities extended) and comatose. A 61-year-old man is brought to the emergency department after (E) Intermediate zone a fall from his garage roof. The examination reveals a hemiplegia on the left, a loss of vibratory sense on the left, and a loss of pain Question 20 and 21 are based on the following patient. These deﬁcits are characteristically seen in A 71-year-old woman presents to her family physician with the com- which of the following syndromes? The examina- tion reveals a unilateral weakness of muscles around the eye (palpebral (A) Benedikt ﬁssure) and the opening of the mouth (oral ﬁssure). She also has a loss (B) Brown-Séquard of pain and thermal sensations on the opposite side of the body ex- (C) Claude cluding the head. CT shows an infarcted area in the lateral portion of (D) Wallenberg the pontine tegmentum. Damage to which of the following nuclei would most likely ex- plain the muscle weakness experienced by this woman? Based on their relative locations in the spinal cord, which of the following tracts or ﬁber bundles would most likely be involved in (A) Abducens a lesion located in the immediate vicinity of the lateral corti- (B) Arcuate cospinal tract? The loss of pain and thermal sensations experienced by this woman (D) Medial longitudinal fasciculus would most likely correlate with a lesion involving which of the (E) Rubrospinal tract following structures? The examination reveals a drowsy somewhat stuporous stem; CT conﬁrms this. Damage to which of the following within the brain medial to the internal medullary lamina. Which of tracts or ﬁber bundles in the pons or medulla would most likely the following structures is most likely involved in this lesion?
Numerous enzymes are local- Electron micrographs show the cell nucleus ized in the inner membrane and in the (A–C1) to be enclosed by a double-layered matrix discount 100mg kamagra soft with visa erectile dysfunction is often associated with, among others the enzymes of the membrane(A2) effective kamagra soft 100mg erectile dysfunction with ms. Itcontainsthenuclearpores citric acid cycle and respiratory-chain (oxida- (BC3) that probably open only temporarily. The karyoplasm of the nucleus contains finely dispersed chromatin granules, which The Golgi complex consists of a number of consist of DNA and proteins. The nucleolus dictyosomes (A–C14), which are stacks of (A–C4), a spongiform area of the nucleus flattened, noncommunicating cisternae. The forming side receives transport vesicles from the endoplasmic reticulum. At the In the cytoplasm, the Nissl bodies appear as margins of the maturing side, Golgi vesicles roughendoplasmicreticulum (A–C5), a lamel- are formed by budding. The Golgi complex lar system of membranes that enclose flat- is mainly involved in the modification (e. To maintain the long axon The numerous lysosomes (A–C17) contain (up to 1m long), it is essential that the cell various enzymes (e. The rough endoplasmic reticulum communicates with the perinuclear space (BC9) and with the marginal cisternae (A10) below the cell sur- face. Marginal cisternae are often found at sites where boutons or glial cell processes are attached. The cytoplasm is crossed by neurofilaments and neurotubules (A–C11) that are arranged into long parallel bundles inside the axon. The transport of substances takes place along neurofilaments and neurotubules (p. Neurofibrils are the light-micro- scopic equivalent of densely packed neu- rotubules. These are enclosed in a double membrane; the inner membrane shows projections (cristae) (C13) into the inner space (matrix). The mitochondria are of various shapes (short and plump in the perikaryon, long and slender in the den- drites and the axon) and move constantly along fixed cytoplasmic paths between the Kahle, Color Atlas of Human Anatomy, Vol. Ultrastructure of the Nerve Cell, Function of Organelles 23 2 18 5 10 1 4 12 14 A Electron-microscopic view of a nerve cell (diagram) 17 14 11 11 6 7 17 1 3 4 5 B Detail of A 9 12 5 16 Protein synthesis 14 15 9 12 1 Oxidation DNA 7 ATP 3 4 13 6 C Function of Acid cell organelles esterases 17 8 11 Kahle, Color Atlas of Human Anatomy, Vol. In type I synapses, the synaptic cleft The axon ends with numerous small knob- is wider and the density of the postsynaptic like swellings, the axon terminals or boutons. In type II synapses, the synaptic the next neuron, the bouton forms the syn- cleft is narrower and the postsynaptic den- apse where excitation is transmitted from sity is about the same as the presynaptic one neuron to another. The synapse consists of the presynaptic com- ponent (bouton) (AB1) with the presynaptic Function (C) membrane (BC2), the synaptic cleft (B3), and There are excitatory and inhibitory synapses. Most of the inhibitory syn- neurotubules but contains mitochondria apses are found at the perikaryon or at the and small, mainly clear vesicles (BC5) which axon hillock, where excitation is generated are clustered near the presynaptic mem- and can be most effectively suppressed. The synaptic cleft con- While synaptic vesicles are usually round, tains filamentous material and communi- some boutons contain oval or elongated cates with the extracellular space. They are characteristic of in- synaptic and postsynaptic membranes ex- hibitory synapses. Asymmetric synapses hibit dense zones of apposition, which re- (type I) are often excitatory, whereas sym- semble those found at various cell junctions metric synapses (type II) are mostly inhibi- (zonulae or maculae adherentes, adherent tory. Synapsescanbeclassifiedaccordingtotheir localization, their structure, and their func- tion, or according to the neurotransmitter substances they contain. Localization (A) The boutons may be apposed to dendrites (AC7) of the receptor neuron (axodendritic synapses) (A8, C), to small projections of the dendritic membrane, spines (axospinoussyn- apses) (A9), to the perikaryon (axosomatic synapses) (A10), or to the initial segment of the axon (axoaxonal synapses) (A11). Structure (B) Depending on the width of the synaptic cleft and the properties of the apposing membranes, two types of synapses, type I Kahle, Color Atlas of Human Anatomy, Vol. Types of Synapses 25 9 7 1 7 8 9 10 A Electron-microscopic view of a dendrite (left) and a nerve cell (right) with synapses (according to Bak) 11 5 1 B Synapses, Gray type I (left) and type II (right) 2 6 3 3 2 4 2 4 12 5 13 7 4 2 C Electron microscopic view of a cross section of a dendrite with surrounding synapses (diagram according to Uchizono) Kahle, Color Atlas of Human Anatomy, Vol. The synaptic con- The catecholamines norepinephrine (NE) tact between parallel axons and dendrites is and dopamine (DA) also act as transmitters, called parallel contact or bouton en passant and so does serotonin (5-HT). Many dendrites have thornlike projec- ropeptides act not only as hormones in the tions (spines) that form a spinous synapse bloodstream but also as transmitters in the (A2) with the bouton. Several axons for transmitter synthesis are produced in and dendrites can join to form glomerulus- the perikaryon, while the transmitter sub- like complexes in which the different synap- stances themselves are synthesized in the tic elements are closely intertwined. The small and clear vesicles are probably affect each other in terms of fine- thought to carry glutamate and ACh, the tuning (modulating) the transmission of elongated vesicles of the inhibitory synapses impulses.
If no compen- thetic nerve activity to the ventricular myocardium shifts satory mechanisms existed kamagra soft 100 mg amex impotence drugs, this would significantly reduce the ventricle to a new function curve and buy 100mg kamagra soft fast delivery erectile dysfunction and alcohol, despite the low- cardiac end-diastolic volume and cause a more than 60% ered ventricular filling, stroke volume is decreased to only decrease in stroke volume, cardiac output, and blood pres- 50 to 60% of the recumbent value. In the absence of the sure; the resulting fall in cerebral blood flow would proba- compensatory increase in sympathetic nerve activity, bly cause a loss of consciousness. These cardiac adjust- ues to stand quietly for 30 minutes, 20% of plasma volume ments maintain cardiac output at 60 to 80% of the recum- is lost by net filtration through the capillary walls of the bent value. Therefore, quiet standing for half an hour without arteriolar constriction and increased SVR. The effect of compensation is the hemodynamic equivalent of losing a these compensatory changes in heart rate, ventricular con- CLINICAL FOCUS BOX 18. However, in the presence of certain multiple causative factors are involved. As a practical definition, hypotension exists proach is not possible, other adjunctive measures may be when symptoms are caused by low blood pressure and, in necessary, especially when the symptoms are disabling. Neurogenic causes include autonomic dys- drugs, large meals), volume expansion (using salt supple- function or failure, which can occur in association with other ments and/or medications with salt-retaining/volume-ex- central nervous system abnormalities, such as Parkinson’s panding properties), and mechanical measures (including disease, or may be secondary to systemic diseases that can tight-fitting elastic compression stockings or pantyhose to damage the autonomic nerves, such as diabetes or amyloi- prevent the blood from pooling in the veins of the legs dosis; vasovagal hyperactivity; hypersensitivity of the upon standing). Unfortunately, even when these measures carotid sinus; and drugs with sympathetic stimulating or are employed, some patients continue to have severe, de- blocking properties. Nonneurogenic causes of hypotension bilitating effects from hypotension. A more powerful activation of the barorecep- In fact, mean arterial pressure may be increased slightly tor reflex, as occurs during severe hemorrhage is required to above the recumbent value. However, two other How is increased sympathetic nerve activity maintained if mechanisms return blood from the legs to the central blood the mean arterial pressure reaches a value near or above that volume. If the leg muscles periodically contract sympathetic nerve activity return to recumbent levels if the while an individual is standing, venous return is increased. There Muscles swell as they shorten, and this compresses adjacent are two reasons. Because of the venous valves in the limbs, the blood turns to the same level (or even higher), pulse pressure re- in the compressed veins can flow only toward the heart. As indicated earlier, the fir- provides an effective pump that transiently increases ve- ing rate of the baroreceptors depends on both mean arterial nous return relative to cardiac output. Reduced pulse pressure means the shifts blood volume from the legs to the central blood vol- baroreceptor firing rate is reduced even if the mean arterial ume, and end-diastolic volume is increased. Second, although mean arterial ercise, such as walking, returns the central blood volume pressure is returned to the recumbent value, central blood and stroke volume to recumbent values (Fig. Consequently, the cardiopulmonary re- The respiratory pump is the other mechanism that acts ceptors continue to discharge at a lower rate, leading to in- to enhance venous return and restore central blood volume creased sympathetic activity. Quiet standing for 5 to 10 minutes invariably the decreased stretch of the cardiopulmonary receptors that leads to sighing. This exaggerated respiratory movement provides the primary steady state afferent information for the lowers intrathoracic pressure more than usually occurs with reflex cardiovascular response to standing. The fall in intrathoracic pressure raises the The heart and brain do not participate in the arteriolar transmural pressure of the intrathoracic vessels, causing constriction caused by increased sympathetic nerve activity these vessels to expand. Contraction of the diaphragm si- during standing; therefore, the blood flow and supply of oxy- multaneously raises intraabdominal pressure, which com- gen and nutrients to these two vital organs are maintained. Because the venous valves pre- vent the backflow of blood into the legs, the raised intraabdominal pressure forces blood toward the intratho- Muscle and Respiratory Pumps Help racic vessels (which are expanding because of the lowered Maintain Central Blood Volume intrathoracic pressure). The seesaw action of the respiratory Although standing would appear to be a perfect situation pump tends to displace extrathoracic blood volume toward for increased venoconstriction (which could return some of the chest and raise right atrial pressure and stroke volume. During Just after contraction contraction Just before contraction 90 mm Hg added hydrostatic pressure Artery Vein Arterial pressure Venous pressure 90 + 93 mm Hg 90 + 10 mm Hg 90 + 93 mm Hg 20 + 10 mm Hg FIGURE 18. This mechanism increases ve- static column of blood, lowering venous (and capillary) hydro- nous return and decreases venous volume. Inspiration leads to an (mL) increase in venous return and stroke volume. The decline in arterial pres- sure is caused by a steady loss of plasma volume, as fluid fil- ters out of capillaries of the legs. The center section shows the effects of a shift from the prone to the upright position with quiet standing.
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