By H. Armon. Zion Bible Institute.
It extends inferiorly from the level large unpaired structures buy cheap cialis professional 20mg erectile dysfunction diabetes medication, and six are smaller and paired buy 20mg cialis professional amex erectile dysfunction medicine online. The of the hyoid bone to the larynx and opens into the esopha- largest of the unpaired cartilages is the anterior thyroid cartilage. It is at the lower laryngopharynx that the The laryngeal prominence of the thyroid cartilage is commonly respiratory and digestive systems become distinct. Tonsils are lymphoid organs and tend to be- come swollen and inflamed after persistent infections. The removal of the palatine epiglottis is located behind the root of the tongue where it aids tonsils is called a tonsillectomy, whereas the removal of the pharyn- in closing the glottis, or laryngeal opening, during swallowing. The entire larynx elevates during swallowing to close the glot- tis against the epiglottis. This movement can be noted by cup- Larynx ping the fingers lightly over the larynx and then swallowing. In this case, the abdominal thrust ducting division that connects the laryngopharynx with the trachea. Respiratory System © The McGraw−Hill Anatomy, Sixth Edition Body Companies, 2001 Chapter 17 Respiratory System 609 Posterior Base of tongue Vestibular folds Vocal folds Cuneiform Corniculate cartilage cartilage Anterior (a) Posterior Epiglottis Glottis Inner lining of trachea (c) Anterior (b) FIGURE 17. In (a) the vocal folds are taut; in (b) they are relaxed and the glottis is opened. This third unpaired cartilage connects glottis during swallowing and in speech. There are two groups of la- the thyroid cartilage above and the trachea below. The other paired cuneiform cartilages and corniculate pitches are produced as air passes over the altered vocal folds. Mature males Two pairs of strong connective tissue bands are stretched generally have thicker and longer vocal folds than females; therefore, across the upper opening of the larynx from the thyroid cartilage the vocal folds of males vibrate more slowly and produce lower anteriorly to the paired arytenoid cartilages posteriorly. The loudness of vocal sound is determined by the force of the vocal folds (true vocal cords) and the vestibular folds (false the air passed over the vocal folds and the amount of vibration. The vestibular folds support the vocal vocal folds do not vibrate when a person whispers. The vestibular folds are not essary to convert sound into recognizable speech. Vowel sounds, used in sound production, but rather the vocal folds vibrate to for example, are produced by constriction of the walls of the phar- produce sound. The pharynx, paranasal sinuses, and oral and nasal cavities folds, whereas the rest of the larynx is lined with pseudostratified act as resonating chambers. This is an important anatomical complished through movements of the tongue and lips. Respiratory System © The McGraw−Hill Anatomy, Sixth Edition Body Companies, 2001 610 Unit 6 Maintenance of the Body Thyroid cartilage Larynx Cricoid cartilage Tracheal cartilage Trachea Carina Left principal (primary) bronchus Right principal (primary) bronchus Lobar (secondary) bronchus Segmental (tertiary) bronchus FIGURE 17. It is positioned anterior tube into the trachea to permit breathing and to keep the passage- to the esophagus as it extends into the thoracic cavity. A tracheotomy should be performed only by a competent physician as there is a great risk of cutting a recurrent la- of 16 to 20 C-shaped hyaline cartilages form the supporting walls ryngeal nerve or the common carotid artery. These tracheal cartilages ensure that the airway will always remain open. The open part of each of these cartilages faces the esophagus and permits the esophagus to Bronchial Tree expand slightly into the trachea during swallowing. The mucosa (surface lining the lumen) consists of pseudostratified ciliated The bronchial tree is so named because it is composed of a series columnar epithelium containing numerous mucus-secreting gob- of respiratory tubes that branch into progressively narrower tubes let cells (see figs. The trachea bifurcates against dust and other particles as the membrane lining the nasal into right and left principal (primary) bronchi at the level of the cavity and larynx. Medial to the lungs, the trachea splits to form sternal angle behind the manubrium. Because of the more vertical position of the right principal bronchus, foreign particles If the trachea becomes occluded through inflammation, exces- are more likely to lodge here than in the left principal bronchus. A tracheotomy is the procedure of surgi- lobar (secondary) bronchi and segmental (tertiary) bronchi (see cally opening the trachea, and a tracheostomy involves inserting a figs. Respiratory System © The McGraw−Hill Anatomy, Sixth Edition Body Companies, 2001 Chapter 17 Respiratory System 611 Lumen of Tracheal esophagus epithelium Trachealis Tracheal muscle cartilage Lumen of trachea Tracheal epithelium Tracheal Thyroid cartilage gland Tracheal cartilage Adventitia (a) (b) FIGURE 17. There is connect to respiratory bronchioles that lead into alveolar ducts, little cartilage in the bronchioles. The conduction por- encircles their lumina can constrict or dilate these airways.
Unfortunately few specific full D1 agonists have been available for evaluation until recently (see Hagan et al generic cialis professional 20mg online impotence ginseng. Some show promise in both animal models and humans generic 40mg cialis professional erectile dysfunction johns hopkins, although the reported absence of dyskinesias is perhaps surprising in view of the considered role of D1 receptors in their initiation (see above). Never- theless, treatment with specific D1 and D2 agonists in controlled combinations could be useful. The efficacy of DA agonists, even if not total, does show that striatal function can be reinstated to some extent by merely flooding it with the equivalent of DA and that this does not have to be released physiologically. Summary: DA augmentation Clearly there are a number of ways of treating PD based on the concept of augmenting DA but clinical advice is not the object of this text. Views are conditioned by the knowledge that the disorder is progressive, requiring long-term therapy and tempered by the cost of some agonists. Perhaps the consensus now is to start therapy as late as possible, keep it to the minimum and only increase dose or add drugs as is absolutely necessary. Hardly any patient avoids polypharmacy but the order of prescription is probably to augment existing DA with MAOI, then either replenish with levodopa or use DA agonist. There is a developing consensus that since levodopa so frequently causes motor complications (e. In fact a recent multicentre 5-year trial of ropinirole compared with levodopa showed it to have similar efficacy to levodopa but producing fewer dyskinesias. To these approaches must be added adjuncts such as ExCDDIs, antiemetics, antimuscarinics and possibly amantidine. Since the most likely effect is considered to be the release of DA it is not surprising that its value is limited when most DA neurons have been destroyed. Co-transmitters Although CCK is known to co-exist with DA in nigrostriatal nerve terminals its precise role is not yet sufficiently understood to be manipulated to advantage. Since GABA is, of course, widely distributed and its antagonism is primarily proconvulsant manipulating its function specifically in the basal ganglia is not a current option, unless molecular biology establishes a distinct subset of receptors there and drugs can be found to block them. Much the same might be said of the peptides but some recent research requires consideration. There is evidence from some experimental studies that metENK can decrease GABA release in the GPext while dynorphin reduces GLUT release in GPint. The former effect would reduce the inhibition of GPext neurons by the Ind Path (just as DA would in the striatum) leaving them with greater control of the SThN and hence reduced stimulation of GPint. Dynorphin inhibition of glutamate release within GPint would have the same effect (Fig. Since the increased output of this nucleus is believed to cause akinesia these processes could be of benefit in PD. Preliminary data indicate that in the reserpinised rat or MPTP marmoset, the enkephalin agonist (SNC80) reduces PD-like symptoms without causing increased activity, i. Enadoline, a dynorphin-like kappa opioid agonist also has similar effects in the same models. Despite the fact that neither delta nor kappa agonists caused hyperkinetic (dyskinesia-like) activity in the above studies, antagonism of these receptors with naloxone can apparently diminish such activity induced in animals by long-term dosage with levodopa and has been shown to work in preliminary human studies (Henry and Brotchie 1996). Of course, levodopa-produced DA might be expected to inhibit striatal GABA/ENK output to GPext sufficiently to ensure that very little met ENK was actually released to be antagonised, although dynorphin release from the Dir Path could be maintained so that blocking its inhibitory effects on glutamate release would result in decreased output from GPint and a shift away from dyskinesia. Clearly many more data are needed on the release of these peptides and their function in GP before their possible role in PD can be properly evaluated but they illustrate an interesting alternative approach to therapy. Enkephalin released from axon terminals of neurons of the indirect pathway (see Fig. This will free the neurons to inhibit the subthalamic nucleus (SThN) and its drive to GPint and SNr which in turn will have less inhibitory effect on cortico-thalamic traffic and possibly reduce akinesia. Dynorphin released from terminals of neurons of the direct pathway may also reduce glutamate release and excitation in the internal globus pallidus and further depress its inhibition of the cortico-thalamic pathway. High concentrations of these peptides may, however, result in dyskinesias. Currently benzhexol and benztropine are sometimes added to levodopa therapy but peripheral effects such as dry mouth, blurred vision and constipation are unpleasant. They are also often used to counteract neuroleptic-induced extrapyramidal effects. Stratal GABA (ENK) neurons are normally inhibited by both DA, released from nigrostriatal nerve terminals and GABA from their recurrent collaterals. Excitation is mediated by ACh released from intrinsic interneurons and glutamate from cortico-striatal afferents. To compensate for the absence of DA-mediated inhibition in PD the excitation could be reduced by antagonising the actions of ACh (a) at M1 receptors (antimuscarinics), glutamate (NMDA antagonists) (b) or possibly adenosine. Through its A2A receptor adenosine (c) appears to counter D2 receptor activity and increase ACh and reduce GABA release, all of which would increase neuron excitability. Since ACh is excitatory and DA inhibitory on striatal neurons, various schemes have been proposed to balance their antagonistic action but the role of ACh in striatal function (and PD) appears to be relatively minor. DISEASES OF THE BASAL GANGLIA 317 Dopamine inhibits cholinergic neuron firing and ACh release in the striatum predominantly through D2 receptors. Released ACh probably stimulates the GABA/ ENK neurons through M1 receptors opposing the inhibitory action of DA on them.
Association fibers are confined to a given cerebral hemi- sphere and conduct impulses between neurons within that corpus striatum: L buy discount cialis professional 20mg line impotence 20 years old. Nervous Tissue and the © The McGraw−Hill Anatomy discount cialis professional 40mg on line erectile dysfunction caused by jelqing, Sixth Edition Coordination Central Nervous System Companies, 2001 Chapter 11 Nervous Tissue and the Central Nervous System 369 (a) (b) FIGURE 11. It is a thin layer of gray matter, Knowledge of the brain regions involved in language has been lying just deep to the cerebral cortex of the insula. The globus pallidus regulates the muscle tone necessary left inferior gyrus of the frontal lobe. Neural diseases or motor speech area causes selective stimulation of motor im- physical trauma to the basal nuclei generally cause a variety of pulses in motor centers elsewhere in the frontal lobe, which in motor movement dysfunctions, including rigidity, tremor, and turn causes coordinated skeletal muscle movement in the phar- rapid and aimless movements. Nervous Tissue and the © The McGraw−Hill Anatomy, Sixth Edition Coordination Central Nervous System Companies, 2001 370 Unit 5 Integration and Coordination Corpus callosum Intermediate commissure Septum pellucidum Genu of corpus Choroid plexus of third ventricle callosum Splenium of corpus callosum Posterior commissure Anterior commissure Pineal gland Thalamus Corpora Hypothalamus quadrigemina Optic chiasma Pituitary stalk Cortex of Pituitary gland cerebellum Mammillary body Arbor vitae of Pons cerebellum Medulla oblongata FIGURE 11. Motor cerebral cortex Thalamus Claustrum Putamen Basal nuclei Lentiform nucleus Globus Corpus pallidus striatum Caudate nucleus Cerebellum Spinal cord FIGURE 11. The thalamus is a relay center be- tween the motor cerebral cortex and the other brain areas. The combined muscular stimulation translates a sentence but cannot read it, presumably because of damage to thought patterns into speech. Some recovery usually occurs after damage to the motor Language comprehension has been destroyed in people with speech area, but damage to Wernicke’s area produces more severe Wernicke’s aphasia; they cannot understand either spoken or and permanent aphasias. It appears that the concept of words to be spoken origi- Knowledge Check nates in Wernicke’s area and is then communicated to the motor speech area through the arcuate fasciculus. Diagram a lateral view of the cerebrum and label the four ate fasciculus produces conduction aphasia, which is fluent but superficial lobes and the fissures that separate them. How are these patterns The angular gyrus, located at the junction of the parietal, monitored clinically? Describe the arrangement of the fiber tracts within the integration of auditory, visual, and somatesthetic information. Describe the aphasias that result from damage to the motor damage to the left angular gyrus can speak and understand spo- speech area and Wernicke’s area from damage to the arcuate fasciculus and from damage to the angular gyrus. Wernicke’s area: from Karl Wernicke, German neurologist, 1848–1905 Van De Graaff: Human V. Nervous Tissue and the © The McGraw−Hill Anatomy, Sixth Edition Coordination Central Nervous System Companies, 2001 372 Unit 5 Integration and Coordination Pituitary stalk FIGURE 11. DIENCEPHALON The cerebral cortex discriminates pain and other tactile stimuli, The diencephalon is a major autonomic region of the brain that but the thalamus responds to general sensory stimuli and pro- consists of such vital structures as the thalamus, hypothalamus, vides crude awareness. The thalamus probably plays a role in the epithalamus, and pituitary gland. Objective 17 Describe the location and structure of the pituitary gland. It forms the floor and part of the lateral walls of the bral hemispheres of the telencephalon. Despite its small size, the hypothalamus performs mus, hypothalamus, epithalamus, and pituitary gland. Thalamus The hypothalamus acts as an autonomic nervous center in accelerating or decelerating certain body functions. These hormones and their functions are discussed in chap- organ, with each portion positioned immediately below ter 14. The principal autonomic and limbic (emotional) the lateral ventricle of its respective cerebral hemisphere (see functions of the hypothalamus are as follows: figs. The principal function of the thalamus is to act as a relay center for all sensory impulses, except smell, to the cere- 1. Specialized masses of nuclei relay the incoming impulses nate pattern of contraction, impulses from the hypothala- to precise locations within the cerebral lobes for interpretation. Impulses from the posterior hypothalamus pro- duce a rise in arterial blood pressure and an increase of the thalamus: L. Nervous Tissue and the © The McGraw−Hill Anatomy, Sixth Edition Coordination Central Nervous System Companies, 2001 Chapter 11 Nervous Tissue and the Central Nervous System 373 posite effect. Rather than traveling directly to the heart, Epithalamus impulses from these regions pass first to the cardiovascular centers of the medulla oblongata. The epithalamus is the posterior portion of the diencephalon that forms a thin roof over the third ventricle. Specialized nuclei within the of the roof consists of a vascular choroid plexus, where cere- anterior portion of the hypothalamus are sensitive to changes brospinal fluid is produced (see fig. It is thought to have a neuroendocrine through sweating and vasodilation of cutaneous vessels of the function.
In addition purchase cialis professional 20mg causes of erectile dysfunction in 40s, the second most frequent cause of neonatal meningitis after GBS is Escherichia coli purchase 40 mg cialis professional visa impotence mental block, which is often resistant to ampicillin. Delayed diagnosis of cancer is another major issue for this spe- cialty. The Ob/Gyn has a responsibility to inform, educate, and thus empower his or her patients about the importance of appropriate screen- ing evaluations including mammography and Pap smears. The patient’s history, including family history, is an important part of the assess- ment of risk. Trust the patient when she notes a change in status and listen to the history she relates. The responsible physician best serves the patient when he or she obtains the history in the patient’s “own words” rather than the secondhand interpretation of staff’s documen- tation. A family history of breast cancer, particularly under age 45 years, imparts increased risk to the patient. All suspicious masses should be biopsied, regardless of the mammogram interpretation. The diagnosis of cervical cancer is an important consideration in the evaluation of intravaginal bleeding. Pelvic sonography in the postmeno- pausal patient may be done to assess the thickness of the endometrium. Again, the patient’s history is often telling and may lead to a diagnosis of cancer when the appropriate evaluations are performed. The other major area of liability for this specialty is prenatal care and delivery. Prenatal diagnostic ultrasonographic evaluation of the fetus is an increasing area of litigation. It is essential that the respon- sible Ob/Gyn clarify for the patient what fetal anatomy can or cannot be seen and what diagnoses can or cannot be made. Limitations of equipment, the impact of fetal position and number, and maternal size should be emphasized. For example, only one-third of major fetal anatomic abnormalities are defined at second-trimester scans. Even when a consultant provides the interpretation of the study, the primary Ob/Gyn should review the implications of the findings with the patient and family. Additionally, genetic counseling is now so complex that only a certified counselor should do it. Fetal death imparts a responsibility on the part of the delivering phy- sician for documentation of the gross anatomy of the baby, the umbilical cord, and the placenta. Such descriptors are far more meaningful than those following examination by the pathologist hours to days later. The bulk of suits for wrongful fetal death arise when the death is unexplained, although up to 75% of fetal deaths can be under- stood after thorough gross, microscopic, and genetic analyses (6). The obstetric department should define a protocol to assess all fetal deaths. Much potential litigation can be prevented by the responsible Ob/Gyn discussing all findings with the patient and her family. This review should take place prior to discharge from the hospital and again at the postpartum visit. Under no circumstances should the patient be left with unanswered questions or concerns as these only drive attempts to get explanations from an attorney. Complications of induction of labor, although not very common, do occur and have associated risks to mother and, more commonly, baby. Informed consent should be obtained according to ACOG Practice Bulletin regarding induction of labor (7). Elements of the consent include the indication for the induction, the agents and methods of labor stimulation, the risks attendant to the use of these agents, meth- ods and alternatives (typically expectant management or Cesarean section [C-section]), and the associated risk for mother and baby. It is noteworthy that the bulletin states, “A physician capable of perform- ing a Cesarean delivery should be readily available. It is rec- ommended that all patients undergoing labor induction have electronic fetal heart rhythm and uterine contraction monitoring although its utility is problematic except in the high-risk pregnancy. Electronic fetal heart rate (FHR) monitoring is a classic example of a procedure becoming codified as the standard of care without proof of effectiveness. In fact, the prevalence of cerebral palsy has not been altered by this modality (8). The physician must be certain that he or she and the nurses are using the same terminology in describing the FHR tracing.
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