Pharm 3: Autonomic Nervous System

List the adrenergic receptor subtypes and their ganglionic nerve terminal and effector organ distribution.

Alpha receptors are located postsynaptically at sympathetic neuroeffector junctions of many organs. In general, alpha receptors mediate excitation or increased activity of the effector cells. Vascular smooth muscle is an important site of alpha receptors. SNS activity maintains vascular tone, and thus blood pressure, by maintaining a tone of neurotransmitter on vascular alpha receptors. Beta receptors are also located postsynaptically at sympathetic neuroeffector junctions of many organs. In general, beta receptors mediate relaxation or decreased activity of the effector cells. Thus, blood vessels dilate and uterine smooth muscle relaxes in response to activation of beta receptors. Heart muscle is an important exception to this rule. Activation of beta adrenoceptors in heart increases the automaticity and contractility of all parts of the heart.

Define words containing the suffixes, -ergic, -mimetic, -lytic and -captive.

Ergic - work or activation Mimetic- simulation of specified effects Lytic- destruction Ceptive-taken, seized

Describe homeostasis, fight-or-flight, and rest-and-repair with regard to ANS activity.

Homeostasis: For example, the arterial blood pressure is homeostatically controlled, and measured by sensors in the aorta and carotid arteries. The sensors send messages via sensory nerves to the medulla oblongata of the brain indicating whether the blood pressure has fallen or risen, and by how much. The medulla oblongata then distributes messages along motor or efferent nerves belonging to the autonomic nervous system to a wide variety of effector organs, whose activity is consequently changed to reverse the error in the blood pressure. Another example is the rate of sweating. This is one of the effectors in the homeostatic control of body temperature, and therefore highly variable in rough proportion to the heat load that threatens to destabilize the body's core temperature, for which there is a sensor in the hypothalamus of the brain. Fight or flight: The Adrenergic system stimulates NE and EPI to flood into bloodstream and prepares body to move in response to a recognized threat. Shuts down non-essential digestion and sexual systems and diverts blood to muscles. Rest and Repair: Cholinergic system stimulates secretion of Acetyl cholinesterase that produces saliva, gastric acids, defecation, urination, sweat, and tears. These restorative qualities are classified as the "rest and digest" response.

6. List the cholinergic receptor subtypes and their ganglionic nerve terminal and effector organ distribution.

Muscarinic (M1-M5) M1, M4 and M5 receptors: CNS. These receptors are involved in complex CNS responses such as memory, arousal, attention and analgesia. M1 receptors are also found at gastric parietal cells and autonomic ganglia. M2 receptors: heart. Activation of M2 receptors lowers conduction velocity at sinoatrial and atrioventricular nodes, thus lowering heart rate. M3 receptors: smooth muscle. Activation of M3 receptors at the smooth muscle level produces responses on a variety of organs that include: bronchial tissue, bladder, exocrine glands, among others. Nicotinic N1 or NM receptors: these receptors are located at the neuromuscular junction, acetylcholine receptors of the NM subtype are the only acetylcholine receptors that can be found at the neuromuscular junction. N2 or NN receptors: Nicotinic receptors play a key role in the transmission of cholinergic signals in the autonomic nervous systems. Nicotinic receptors of the NN subtype can be found both at cholinergic and adrenergic ganglia, but not at the target tissues (e.g, heart, bladder, etc). These receptors are also present in the CNS and adrenal medulla.

List the enzymes and transport systems involved in the synthesis, storage, release, degradation and reuptake of norepinephrine and acetylcholine. Focus on the enzymes involved in the degradation of these neurotransmitters.

NOR/EPI: Monoamine Oxidase (MOA) Acetylcholine: Acetyl cholinesterase (AChE)

Characterize the different classes of sympathetic and cholinergic agents and their antagonists.

See in class worksheet

Characterize the different neuromuscular blocking agents.

See in class worksheet

Describe how the central nervous system controls the activity of the ANS.

Sensors send messages via sensory nerves to the medulla oblongata of the brain indicating whether the blood pressure has fallen or risen (for example), and by how much. The medulla oblongata then distributes messages along motor or efferent nerves belonging to the autonomic nervous system.

Describe sympathetic and parasympathetic tone.

Sympathetic/Adrenergic: "Flight or Fight" response, is GENERAL. In emergency, adrenal gland releases Norepinephrine (NE), and Epinephrine (EPI). Prepares body to respond physically to external threat. Parasympathetic/Cholergenic: Rest and Repair or "Rest and Digest" (Digestion, Heart Rate). Response to stimulation is SPECIFIC and FOCUSED. Primary neurotransmitter is acetylcholine (ACh).

Describe the general treatment of anticholinesterase toxicity.

The antidote for anticholinergic toxicity is physostigmine salicylate. Most patients can be safely treated without it, but it is recommended when tachydysrhythmia with subsequent hemodynamic compromise, intractable seizure, severe agitation or psychosis, or some combination thereof is present.

Describe the important physiological functions of the sympathetic and parasympathetic divisions of the Autonomic Nervous System (ANS).

The sympathetic nervous system (SNS) is one of two main divisions of the autonomic nervous system (ANS). Its general action is to mobilize the body's fight-or-flight response. Blood shunts to muscles, senses are more acute, the heart rate and contractility increase. The parasympathetic nervous system is one of the two main divisions of the autonomic nervous system (ANS). Its general function is to control homeostasis and the body's rest-and-digest response.