Nervous system, autonomic

Data are sparse that conclusively establish that altered drug effects result from impaired ANS function/ perhaps due to the difficulty in ascribing a particular drug effect to a particular ANS function. However/ increased orthostatic hypotension seen at baseline/ in addition to drugs that cause sympathetic blockade/ such as typical neuroleptics and tricyclic antidepressants/ is likely to be a contributing factor to the increased incidence of hip fracture noted in patients receiving these drugs (41). Similarly the 

The age-related changes in cardiovascular function that relate to drug responses are usefully separated into changes in cardiac and changes in peripheral vascular function. But this separation must be made with the understanding that the pharmacodynamic responses seen are generally an integrated function of ANS/ cardiaC/ and peripheral vascular function. 

The response of older individuals to calcium channel antagonists is a combination of changes in direct drug effects and age-related alterations in reflex responses to drug effect. Hypotensive responses are maintained because direct arterial vasodilatation remains intact/ even though there is the age-related impairment in reflex sympathetic stimulation/ as previously noted (55). For verapamil and diltiazeni/ atrioventricular nodal conduction delay is less in older than 

Treatment with angiotensin-converting enzyme inhibitors is also more likely to be associated with hyperkalemia in older individuals (69). Impaired angiotensin II formation limits this potent stimulus for aldosterone secretion, and this is superimposed on the already age-related decrease in activity of the renin-angiotensin-aldosterone axis. The same drug-induced hyporeninemic hypoaldosteronism is predicted for the angiotensin receptor blockers. However, to date this has not been documented clincally. 

Thiazide diuretic-induced hyponatremia is much more common in older than in younger patients, probably due to thiazide-mediated impairment in renal diluting capacity superimposed on the already present age-related decrease in capacity to dilute urine. Older studies indicated this was an extremely common cause 

The sympathetic nerves (left.----) leave ihe thoracolumbar region 

All the preganglionic nerve fibres (sympalhctic and para.sympaih- 

A small proportion of autonomic nerves do not release either acetylcholine or norepinephrine. For example, the cavernous nerves release nitric oxide (NO) in the penis. Tliis relaxes the smooth mascle of the corpora cavernosa (via cyclic guanosine-3,5-monophosphate (cGMPj. Chapter 16) allowing expansion of the lacunar spaces juid erection.. Sildenafil, u.sed in mate sexual dysfunction, inhibits phos-phtHliesterasc type 5 and. by increasing the concentration of cGMP, facilitates erection. 

Epinephrine iatirenaliiie) mimics most sympathetic effects, i.e. it is a sympatlumtimetic agetti (Chapter D). Elliot suggested in 1904 that adrenaline was the sympathetic transmitter substance, hut Dale pointed 

These are most easily remembered by thinking of what changes in the body are appropriate in the fright or flight n ciction . Note which of the following effects arc excitatory and which are inhibitory. 

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A special feature of the iris is its autonomic innervation. Sympathetic activation widens the aperture of the iris whereas impulses from the parasympa thetic nervous system decrease the aperture size. Therefore adrenergic agonists and anticholinergic compounds both increase the aperture of the iris, i.e., cause mydriasis, and antiadrenergic and cholinergic agonists decrease it, i.e., cause miosis. The iris can thus be considered an excellent mirror reflecting the balance of the autonomic nervous system in the body. " ... 

Autonomic nervous system. The portion of the nervous system outside of the brain and spinal cord that is responsible for monitoring and controlling the digestive system, cardiovascular system, and other organs that are not under direct conscious control. 

Parasympathetic nervous system. That portion of the autonomic nervous system that utilizes acetylcholine as the neurotransmitter at the neuro-effector junctions. 

The baroreceptor reflex is a central reflex mechanism, which reduces heart rate following an increase in blood pressure. Each change in blood pressure is sensed by baroreceptors in the carotid arteries, which activate the autonomic nervous system to alter heart rate and thereby readjust blood pressure. 

Local anaesthetics are drugs that reversibly interrupt impulse propagation in peripheral nerves thus leading to autonomic nervous system blockade, analgesia, anaesthesia and motor blockade in a desired area of the organism. 

The locus cemleus is important for the regulation of attentional states and autonomic nervous system activity. It has also been implicated in the autonomic and stress-like effects of opiate withdrawal. A noradrenergic pathway originating from the locus cemleus which descends into the spinal cord is part of the descending inhibitory control system, which has an inhibitory effect on nociceptive transmission in the dorsal horn. 

It is well established that the autonomic nervous system shows marked plasticity. The expression of cotransmitters and receptors shows dramatic changes during development and ageing, in nerves that remain... 

Autoimmune Disease Autonomic Nervous System Autophagy... 

The PNS is further divided into the somatic nervous system and the autonomic nervous system. The somatic branch of the PNS is concerned witii sensation and voluntary movement. The sensory part of the somatic nervous system sends messages to the brain concerning die internal and external environment, such as sensations of heat, pain, cold, and pressure The voluntary part of die somatic nervous system is concerned witii die voluntary movement of skeletal muscles, such as walking, chewing food, or writing a letter. 

The autonomic branch of die PNS is concerned witii functions essential to the survival of the organism. Functional activity of the autonomic nervous system... 

TABLE 22-1 Action of the Autonomic Nervous System on Body Organs and Structures... 

The PNS is a part of the autonomic nervous system (see Chap. 22). It helps conserve body energy and is partly responsible for activities such as slowing the heart rate, digesting food, and eliminating body wastes. 

Smooth muscle cell activity is in general under neural control. Thus, the many transmitters of the autonomic nervous system are paired with receptors on the smooth muscle cell membrane. One of the current questions about smooth muscle function is What intracellular processes are the different transmitters modulating in the smooth muscle cells, in addition to their effects on the contractile state ... 

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