Autonomic Nervous System

What are the inner and outer rinds of the adrenal glands?

Adrenal Cortex (Outer) Adrenal Medulla (Inner)

What neurotransmitter(s) are released from the parasympathetic postganglions?

All are cholinergic (use ACh as a neurotransmitter).

What neurotransmitters are used in all preganglions of the ANS.

All are cholinergic (use ACh as a neurotransmitter).

What are the two types of adrenergic receptors?

Alpha receptors and beta receptors.

What role does the cerebral cortex play in the ANS?

Even if we usually cannot consciously control the ANS, it is clear that the mind does influence it. Anger raises the blood pressure, fear makes the heart race, thoughts of good food make the stomach rumble, sexual thoughts or images increase blood flow to the genitals, and anxiety inhibits sexual function. The limbic system, an ancient part of the cerebral cortex, is involved in many emotional responses and has extensive connections with the hypothalamus, a site of several nuclei of autonomic control. Thus, the limbic system provides a pathway connecting sensory and mental experiences with the autonomic nervous system.

What is the function of the sympathetic division of the ANS?

It adapts the body in many ways for physical activity—it increases alertness, heart rate, blood pressure, pulmonary airflow, blood glucose concentration, and blood flow to cardiac and skeletal muscle, but at the same time, it reduces blood flow to the skin and digestive tract. Cannon referred to extreme sympathetic responses as the "fight-or-flight" reaction because it comes into play when an animal must attack, defend itself, or flee from danger.

What is the function of the adrenal medulla?

It is essentially a sympathetic ganglion. It consists of modified postganglionic neurons without dendrites or axons. Sympathetic preganglionic fibers penetrate through the cortex and terminate on these cells. When stimulated, it secretes a mixture of hormones into the bloodstream—about 85% epinephrine (adrenaline), 15% norepinephrine (noradrenaline), and a trace of dopamine.

What role does the hypothalamus play in the ANS?

It is the major control and integration center of the ANS. It receives sensory input related to visceral functions, olfaction (smell), and gustation (taste), as well as changes in temperature, osmolarity, and levels of various substances in blood. It also receives input relating to emotions from the limbic system. Output from the hypothalamus influences autonomic centers in both the brain stem (such as the cardiovascular, salivation, swallowing, and vomiting centers) and the spinal cord (such as the defecation and urination reflex centers in the sacral spinal cord).

What is the function of the adrenal cortex?

It secretes several types of hormones.

What neurotransmitter(s) are released from the sympathetic postganglions?

Most are adrenergic (use norepinephrine as a neurotransmitter).

What are the two types of cholinergic receptors?

Nicotinic receptors and muscarinic receptors.

Where are alpha and beta receptors found?

On visceral effectors innervated by most sympathetic postganglionic axons.

What is the function of the autonomic nervous system?

Regulates sensory and motor functions of viscera (smooth muscle, cardiac muscle and glands) usually without conscious perception or effort. The ANS is also responsible for the body's visceral reflexes.

What are the effects of the sympathetic division and parasympathetic division on the bronchial smooth muscles?

Sympathetic Division: - Airways dilate allowing faster movement of air into and out of the lungs. Parasympathetic Division: - Decreases diameter of airways (bronchoconstriction).

What are the effects of the sympathetic division and parasympathetic division on the heart?

Sympathetic Division: - Increases rate and force of heartbeat Parasympathetic Division: - Decreases rate; slows heart

What are the effects of the sympathetic division and parasympathetic division on the digestive and urinary organs?

Sympathetic Division: - Inhibits Voiding - Inhibits digestion - Constricts urethra sphincter - Decreases the activity and glands of digestion - Constricts anal sphincter Parasympathetic Division: - Promotes voiding - Promotes digestion - Relaxes urethra sphincter - Increases motility and secretions of digestion - Relaxes anal sphincter

What are the effects of the sympathetic division and parasympathetic division on the blood vessels in skeletal muscles?

Sympathetic Division: - Mostly dilates the blood vessels for increased blood flow and supply. Parasympathetic Division: - Relaxes blood vessels and slows down blood flow.

What are the effects of the sympathetic division and parasympathetic division on the blood vessels?

Sympathetic Division: - They dilate, increasing blood flow Parasympathetic Division: - No effects

What are the two primary divisions of the ANS?

Sympathetic and parasympathetic.

What is another name for the autonomic nervous system?

The Visceral Motor System

Where are nicotinic receptors found?

These receptors are present in the plasma membrane of dendrites and cell bodies of both sympathetic and parasympathetic postganglionic neurons, the plasma membranes of chromaffin cells of the adrenal medullae, and in the motor end plate at the neuromuscular junction. They are so named because nicotine mimics the action of ACh by binding to these receptors.

Where are muscarinic receptors found?

These receptors are present in the plasma membranes of all effectors (smooth muscle, cardiac muscle, and glands) innervated by parasympathetic postganglionic axons.

What do adrenergic receptors bind to?

These receptors bind to both norepinephrine and epinephrine.

What do cholinergic receptors bind to?

These receptors only bind to ACh.

What do alpha receptors do when binding to norepinephrine or epinephrine?

They make smooth muscles and effectors contract.

What do beta receptors do when binding to norepinephrine or epinephrine?

They make smooth muscles and effectors loosen/widen.

Where are the adrenal glands located?

They rest like hats on the superior poles of the kidneys.

What is the function of the parasympathetic division?

This ANS division provides a calming effect on many body functions. It is associated with reduced energy expenditure and normal bodily maintenance, including such functions as digestion and waste elimination. This can be thought of as the "resting- and-digesting" state. Mostly directed to smooth muscle and glands of the GIT and respiratory tracts.