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At this point purchase malegra fxt plus 160 mg on line erectile dysfunction vacuum, it is close to the surface the upper medial thigh muscles are supplied with blood from and its pulse can be palpated order malegra fxt plus 160mg fast delivery erectile dysfunction protocol book review. The internal pudendal artery of the in- femoral artery to serve the thigh region. The largest of these, ternal iliac artery serves the musculature of the perineum and the deep femoral artery, passes posteriorly to serve the ham- the external genitalia. The lateral and medial femoral circumflex ar- blood for vascular engorgement of the penis in the male and teries encircle the proximal end of the femur and serve clitoris in the female. Circulatory System © The McGraw−Hill Anatomy, Sixth Edition Body Companies, 2001 Right lung Left lung Diaphragm muscle Heart Inferior vena cava Right kidney Left renal artery Celiac trunk Left kidney Common hepatic Abdominal aorta artery Inferior mesenteric Superior mesenteric artery artery Right common iliac artery Right external iliac artery Right external iliac vein FIGURE 16. Circulatory System © The McGraw−Hill Anatomy, Sixth Edition Body Companies, 2001 570 Unit 6 Maintenance of the Body FIGURE 16. To At the ankle, the anterior tibial artery becomes the dor- prevent a victim from bleeding to death, it is important to know sal pedal artery that serves the ankle and dorsum (superior where to apply pressure to curtail the flow of blood (fig. The pressure points for the appendages are the brachial artery on the portion) of the foot and then contributes to the formation of medial side of the arm and the femoral artery in the groin. Clinically, palpation of the dorsal plied pressure to these regions greatly diminishes the flow of blood to pedal artery can provide information about circulation to the traumatized areas below. A tourniquet may have to be applied if foot; more important, it can provide information about the bleeding is severe enough to endanger life. These vessels traverse the anterior oneal, artery to serve the peroneal muscles of the leg. At the and posterior aspects of the leg, respectively, providing blood to ankle, the posterior tibial bifurcates into the lateral and medial the muscles of these regions and to the foot. Circulatory System © The McGraw−Hill Anatomy, Sixth Edition Body Companies, 2001 Chapter 16 Circulatory System 571 FIGURE 16. The structures within the femoral triangle are shown in (a); the boundaries of the triangle are shown in (b). PRINCIPAL VEINS OF THE BODY Digital arteries arise from the plantar arch to supply the toes After systemic blood has passed through the tissue, this oxy- with blood. Knowledge Check Objective 18 Describe the venous drainage of the head, 17. Describe the clinical significance of the brachial and radial Objective 19 Describe the venous drainage of the thorax, arteries. Describe the arterial pathway from the subclavian artery to Objective 20 Describe the vessels involved in the hepatic the digital arteries. List the arteries that supply blood to the lower abdominal wall, the external genitalia, the hamstring muscles, the In the venous portion of the systemic circulation, blood flows knee joint, and the dorsum of the foot. Circulatory System © The McGraw−Hill Anatomy, Sixth Edition Body Companies, 2001 572 Unit 6 Maintenance of the Body Superficial temporal artery Facial artery Subclavian artery Common carotid artery Brachial Radial artery artery Femoral Popliteal artery artery Dorsal pedal artery FIGURE 16. Veins are more numerous than arteries and are both neck regions is drained by the external jugular veins (fig. Superficial veins generally can be seen just These vessels descend on the lateral sides of the neck, superficial beneath the skin and are clinically important in drawing blood to the sternocleidomastoid muscle and deep to the platysma mus- and giving injections. They empty into the right and left subclavian veins, located ies and are usually similarly named. Circulatory System © The McGraw−Hill Anatomy, Sixth Edition Body Companies, 2001 Chapter 16 Circulatory System 573 FIGURE 16. Superficial veins are depicted in the left extremities and deep veins in the right extremities. Circulatory System © The McGraw−Hill Anatomy, Sixth Edition Body Companies, 2001 574 Unit 6 Maintenance of the Body FIGURE 16. You can voluntarily distend this vein by performing Valsalva’s maneu- ternal jugular veins are larger and deeper than the external jugu- ver. To do this, take a deep breath and hold it while you forcibly con- lar veins. They arise from numerous cranial venous sinuses tract your abdominal muscles as in a forced exhalation. The increased thoracic pressure that results compresses the vena cavae and interferes with the return of blood to the right in turn, receive venous blood from the cerebral, cerebellar, oph- atrium. Thus, Valsalva’s maneuver can be dangerous if performed by thalmic and meningeal veins.

Diversity among neuronal nicotinic receptors is generated by having nine more different a subunits (a2±a10) and three further b subunits (b2±b4) generic 160mg malegra fxt plus visa do herbal erectile dysfunction pills work. These receptors are activated by nicotine and blocked by the antagonists hexamethonium buy 160 mg malegra fxt plus fast delivery impotence in the sun also rises, mecamylamine and trimetaphan, and the erythrina alkaloid dihydro-b-erythroidine. The neuronal nicotinic receptors are found in autonomic ganglia and in the brain may be either heteromeric (e. The a7 receptor is likely to be the source of the a-bungarotoxin binding sites in the brain observed in autoradiograms of 123I-a- bungarotoxin binding to brain sections (Clarke 1992) and a-bungarotoxin sensitive nicotinic receptors have been shown in a number of studies to stimulate transmitter release from nerve terminals such as dopaminergic terminals in the striatum and glutamatergic terminals in the cortex. Its main functional role may therefore be as a presynaptic receptor regulating transmitter release. It has a high affinity for nicotine and so may mediate some of the central effects of nicotine. Notice that a homomeric receptor has implications for the interpretation of functional studies since the number NEUROTRANSMITTER RECEPTORS 65 of agonist (and antagonist) binding sites on the receptor must equal the number of subunits. In the case of a7 receptors, Hill coefficients (see Appendix) of around 1. GLYCINE RECEPTORS Inhibitory glycine receptors with high affinity for the antagonist strychnine are predominantly found in the spinal cord and brainstem. Three different a subunits have been cloned (a1±a3) and a single b subunit (b1). Interestingly, the foetal-type of glycine receptor which is a homomer (the adult stoichiometry is likely to be a3b2) has Hill coefficients nearer 3. GABA RECEPTORS The GABA receptor subunits are one of the most diverse groups of ion channel receptor subunits in the brain. Six different a subunits (a1±a6), four b subunits (b1±b4), four g subunits (g1±g4), an e subunit, a p subunit, and three r subunits (r1±r3) have been found. This diversity of subunits is reflected in the complicated pharmacology of the GABA receptors. Functional GABA receptors can be formed by co-expression of any a subunit with any b subunit probably in the stoichiometry a2b3. However, these receptors, although activated by GABA and muscimol, potentiated by barbiturates and neurosteroids, and blocked by bicu- culline and picrotoxin, lack classical benzodiazepine sensitivity which can be restored to the molecule by co-expressing a g subunit with a and b. These are activated by the weak agonist CACA, relatively insensitive to bicuculline, not sensitive to barbiturates or neuro- steroids, and blocked by TPMPA. They have been described in the retina (where r1is expressed) but relatively little is known of their function in the brain although they are widely expressed (Bormann 2000). For example, all three r subunits are found in cerebellar Purkinje cells. Native GABAC receptors may be homomeric pentamers of a single r subunit or heteromeric pentamers of more than one of the r subunits. GABAC receptor dose±response curves have Hill slopes around 3 or greater, unlike GABAA receptor dose±response curves where the Hill slope is usually around 2. When expressed alone, 5-HT3-A subunits form functional homomeric receptors but these have a much smaller single channel conductance (less than 1. Native 5-HT3 receptors are likely to be pentameric heteromers of 5-HT3-A and 5-HT3-B subunits. Synaptic transmission mediated by 5-HT3 receptors has been 66 NEUROTRANSMITTERS, DRUGS AND BRAIN FUNCTION described in only a few places in the brain, such as in the locus coeruleus and it has been suggested that most 5-HT3 receptors are located presynaptically on nerve terminals where their calcium permeability may be important in potentiating transmitter release. GLUTAMATE RECEPTORS Glutamate receptors mediate fast synaptic transmission throughout the nervous system. They have been classified pharmacologically as three main types according to their sensitivity to three specific agonists: kainate, AMPA and NMDA. The NMDA receptors are unique among the ion channel receptors in requiring the binding of two separate agonists, glutamate and glycine in order to activate the receptor. Selective antagonists for both the glutamate binding site (AP5) and the glycine binding site (7-chloro- kynurenate) have been developed.

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Wrongful birth claims may entitle the parents to both economic and noneconomic damages discount 160 mg malegra fxt plus fast delivery best erectile dysfunction drug review. As an offset buy malegra fxt plus 160 mg on line impotence guide, the physician 142 Schneider defendant can claim economic and noneconomic benefits such as love and happiness provided to the parents. Wrongful life litigation typi- cally arises from negligent preconception care or from early preg- nancy genetic counseling. On the one hand, the obstetrician has responsibility for both the mother and the fetus. However, the mother has the right and authority of ascribing patient status to her unborn under the doctrine of autonomy. Assuming a competent parent, the physician may only take those actions for the baby consented to by the mother/parent. All aspects of informed refusal should be thoroughly documented in the medical record, particularly the potential risks imparted to the unborn by the decision of the parent. It is best to avoid making the mother feel accused of potentially harm- ing her baby. The majority of malpractice claims in gynecology arise from the issues surrounding reproductive function. Both medical and surgical management of pelvic diseases may impair fertility and reproduction. When assisted reproduction is at issue, the learned Ob/Gyn specialist defers and refers to experts in the subspecialty of reproductive biology and endocrinology. For those physicians specializing in infertility, the majority of suits evolve from failure to meet implied outcome expec- tations. The patient has the right to receive informed consent, which includes outcome statistics comparing potential results from other infertility centers available to the patient. The more common Ob/Gyn clinical issues leading to litigation include those inherent in all specialties, such as the following: • Failure to provide informed consent. There are a number of issues specific to obstetrics and gynecology that are frequently the subject of litigation. Antibiotic prophylaxis is recommended to prevent vaginal cuff infection in all hysterectomies (3) and to prevent group B streptococcus (GBS) sepsis in the newborn (4,5). The drug of choice for patients who have hysterectomies is a cephalosporin administered intravenously approx 30 minutes before Chapter 11 / Obstetrics and Gynecology 143 transvaginal incision. For GBS prophylaxis, intravenous penicillin G is preferred over ampicillin for two reasons. A single loading dose of penicillin is likely as effective as two doses of ampicillin given 4 hours apart. In addition, the second most frequent cause of neonatal meningitis after GBS is Escherichia coli, 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.

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The Na K GHK equation then predicts a value of À70 mV for Erest if the permeability of the membrane to Na‡ ions is about 4% of that to K‡ ions (P =P ˆ 0:04) buy malegra fxt plus 160mg with mastercard fast facts erectile dysfunction. However order 160mg malegra fxt plus overnight delivery erectile dysfunction doctors raleigh nc, it Na K CONTROL OFNEURONAL ACTIVITY 35 should be noted that, at this potential, although the fluxes of total cations in and out of the cell are equal, the cell will gradually accumulate Na‡ and lose K‡, which will have to be corrected by the Na/K exchange pump; since this involves energy expenditure, it is not a true equilibrium state. The GHK equation can be expanded to include terms for other ions, such as Cl7 ions, which can have a profound effect on the membrane potential under certain circumstances (e. Passive diffusion occurs entirely through ion channels Ð pore-forming membrane proteins. The resting potential may then be generated either by two sets of channels, one set permeant to K‡ and the other to Na‡ (or some other ion with a more positive equilibrium potential), with the former in the majority or opening more often; or a set of channels primarily permeant to K‡ but with some weak permeability to Na‡. Another class of K‡ channels that can contribute to the resting potential of neurons are inwardly- rectifying K‡ channels (Kir channels) Ð so-called because they conduct K‡ ions more readily into the cell than outwards. Both TASK and Kir can be inhibited by certain neurotransmitters which act on receptors that couple to phospholipase C-activating G-proteins, such as acetylcholine, substance P and TRH. As a result, these transmitters can induce a sustained depolarisation of the receptive neurons (e. Several transmitters, acting on receptors coupled to other G-proteins of the Gi/Go family, are capable of activating another class of Kir channels (G-protein-gated inward rectifiers or GIRK channels, also known as Kir3), thereby hyperpolarising the neuron (and inhibiting it). Other ion channels are closed at rest, but may be opened by a change in membrane potential, by intracellular messengers such as Ca2‡ ions, or by neurotransmitters. These are responsible for the active signalling properties of nerve cells and are discussed below (see Hille 1992, for a comprehensive account). This chapter concerns function, rather than structure, and hence does not systematically follow the structural classification. It is a transient electrical signal generated by the opening of voltage-gated Na‡ channels. These are normally shut at rest (or largely so), but are opened when the nerve cell membrane is depolarised by (e. Since the entry of Na‡ ions further depolarises the membrane, so opening more Na‡ channels, the process becomes regenerative once the threshold potential is exceeded: this is the potential at which the rate of Na‡ entry exceeds the rate of K‡ efflux (and/or Cl7 entry). Repolarisation results (in the first instance) from the inactivation of the Na‡ channels Ð that is, as the depolarisation is maintained, the channels close again (though at a slower rate than that at which they open). Recovery then requires that they progress back from the inactivated state to the resting closed state: this takes a little time, so the action potential becomes smaller and eventually fails during high frequency stimulation or during sustained depolarisation Ð a process of accommodation. Local anaesthetics and some anti-epileptic drugs such as phenytoin and carbemaze- pine act by blocking Na‡ channels. Many of these have a higher affinity for the inactivated state of the Na‡ channel than for the resting or open states. This provides a rationale for the use of phenytoin and carbemazepine in controlling epileptic discharges. In unmyelinated fibres (including the squid axon, where the ionic currents responsible for the action potential were first elucidated, see Fig. These may be sustained or transient (inactivating) in kinetic behaviour. However, K‡ channels are normally absent from nodes of Ranvier and action potential repolarisation in myelinated fibres results solely from Na‡ channel inactivation. Thus, blocking K‡ channels with drugs such as tetraethyl- ammonium or 4-aminopyridine (Fig. They can also improve conduction in myelinated fibres following demyelination (e. Cooling the nerve has a similar effect to blocking K‡ channels: hence MS patients are very sensitive to temperature. CALCIUM CHANNELS: TRANSMITTER RELEASE When an action potential arrives at the axon terminal, it induces the release of a chemical transmitter. Transmitter release is a Ca2‡-dependent process (see Chapter 4) and requires a charge of Ca2‡. This is provided through the action potential-induced 38 NEUROTRANSMITTERS, DRUGS AND BRAIN FUNCTION Table 2. A variety of Ca2‡ channels have been described, characterised by their kinetics, single-channel properties, pharmacology (especially sensitivity to different toxins) and molecular structure (Table 2. Those primarily responsible for transmitter release belong to the N (a1B), P/Q (a1A) and R classes (a1E). So far, no pharmacological agents capable of uniquely modifying Ca2‡ channels involved in transmitter release have been described (other than polypeptide toxins).