Question

Identify the two major divisions of the peripheral nervous system.

2.            Differentiate between the somatic (motor) nervous system and the sympathetic and parasympathetic branches of the autonomic nervous system in terms of (1) overall anatomic organization (numbers, types of nerves); (2) neurotransmitters made and released by the nerves; and (3) the targets (effectors) of the neurotransmitters’ actions, whether those structures are innervated by one or both branches of the autonomic nervous system, and the effects of activating those structures.
3.            Describe the differences distinguishing the four main subtypes of adrenergic receptors—alpha1, alpha2, beta1, and beta2—in terms of where (on what structures) they are found and the responses their activation causes.
4.            Describe the differences between the two main subtypes of cholinergic receptors—nicotinic (both nicotinicN and nicotinicM) and muscarinic—in terms of where (on what structures) they are found and the responses their activation causes.
5.            Identify the basic processes by which the main autonomic nervous system neurotransmitters are terminated physiologically.

Answer 1

Describe the differences distinguishing the four main subtypes of adrenergic receptors—alpha1, alpha2, beta1, and beta2—in terms of where (on what structures) they are found and the responses their activation causes.

Alpha 1 receptors act on the vascular smooth muscles. It is found in eyes, blood vessels, bladder. It is activated by the sympathetic nervous system and causes vasoconstriction and increased peripheral resistance.

Alpha 2 receptors found on nerve terminals and decrease the peripheral resistance and causes decreased outflow to the heart and blood vessels. Alpha receptors are activated by both epinephrine and norepinephrine.

Beta 1 receptors found in the heart activated by norepinephrine and causes increased heart rate by the contractility of heart muscles.

Beta 2 found in the lungs activated by epinephrine and acts on the smooth muscles results in relaxation of smooth muscles in the lungs.

Describe the differences between the two main subtypes of cholinergic receptors—nicotinic (both nicotinic and nicotinic) and muscarinic—in terms of where (on what structures) they are found and the responses their activation causes.

The two types of cholinergic receptors that bind to acetylcholine are muscarinic and nicotine receptors. Nicotinic receptors have ion channels for the faster transmission of nerve signals. Nicotinic N1 receptor mainly acts on the muscles whereas Nicotonic N2 receptors act on the ganglia of the autonomic and parasympathetic nervous system and in the brain. They found in the sympathetic and parasympathetic nervous system and promotes the release of epinephrine in the brain and nicotine M causes contraction of skeletal muscles. Muscarinic receptors use calcium channel to transmit a signal inside the cells. They use G-protein as the second messenger. They found on the target organs of eyes, heart, blood vessels, GI tract, Bladder and causes contraction of muscles.

Identify the basic processes by which the main autonomic nervous system neurotransmitters are terminated physiologically.

Acetylcholine after disassociated from the receptors, it destroyed by the acetylcholinesterase present in the postjunctional cell. It separates into acetate and choline. The nerve terminals reuptake the choline for reuse. Following this, norepinephrine terminates the transmission and inactivate the monoamine oxidase.