Autonomic Nervous System

Question 1

Sympathetic Nervous System - Circuitry

Answer 1

Pre-ganglionic neurons originate in thoracic and lumbar spinal cord and synapse onto ganglia located near the spinal cord; pre-ganglionic axons release ACh onto nicotinic cholinergic receptors on the postganglionic neuron, causing depolarization; the postganglionic neuron releases NE onto sweat glands, peripheral blood vessels, GI tract, etc.

Question 2

Adrenal medulla

Answer 2

Functionally, a sympathetic ganglion

Innervated by pre-ganglionic sympathetic neurons; post-ganglionic neurons release epinephrine (80%) and norepinephrine (20%)

Question 3

Receptor sub-types for NE (4)

Answer 3

Alpha 1 adrenergic
Alpha 2 adrenergic
Beta 1 adrenergic
Beta 2 adrenergic

Question 4

Parasympathetic Nervous System - Circuitry

Answer 4

Pre-ganglionic neurons originate in the brainstem and sacral spinal cord, exit the brainstem with CN III, VII, IX, and X, and release ACh onto postganglionic neurons located in ganglia near the effector organs; postganglionic neurons release ACh

Question 5

Receptor types for ACh (2)

Answer 5

Nicotinic - ligand gated, non-selective cation channel

Muscarinic - G-protein coupled (Gi)

Question 6

Role of the hypothalamus in regulating CV system

Answer 6

Hypothalamus is the “head ganglion” of the ANS; it stimulates release of ADH from the posterior pituitary into the blood, where it travels to the kidney causing vasoconstriciton and water retention