L7 Autonomic nervous system

Question 1

What are the two major efferent pathways of the Autonomic Nervous System (ANS)?

Answer 1

Sympathetic and Parasympathetic pathways

The sympathetic pathway is associated with ‘fight or flight’ responses, while the parasympathetic pathway is related to ‘rest and digest’ functions.

Question 2

What is the main function of the sympathetic pathway?

Answer 2

Fight or flight response

Activated during exercise, excitement, emergency, and embarrassment.

Question 3

What is the main function of the parasympathetic pathway?

Answer 3

Rest and digest

Activated during digestion, defecation, and diuresis.

Question 4

How do sympathetic and parasympathetic pathways generally interact?

Answer 4

They have opposing effects but work synergistically (together)

This allows for rapid, precise control of tissue function.

Question 5

What type of neurons are always cholinergic in the ANS?

Answer 5

Preganglionic neurons

They release acetylcholine (ACh) as their primary neurotransmitter.

Question 6

What are the target tissue receptors for the sympathetic pathway?

Answer 6

α- and β- adrenergic receptors

These receptors are activated by norepinephrine released from postganglionic neurons.

Question 7

What type of neurons does the parasympathetic pathway utilize?

Answer 7

Long, cholinergic preganglionic neurons from brainstem and lumbar spinal cord
Short ,cholnergic postganglionic neurons

The target tissue expresses muscarinic ACh receptors.

Question 8

What is the role of the vagus nerve in the parasympathetic system?

Answer 8

Carries ~80% of total parasympathetic outflow

The vagus nerve is also responsible for conveying visceral afferents.

Question 9

Which areas of the Central Nervous System (CNS) regulate ANS output?

Answer 9

Brainstem nuclei and hypothalamus

The brainstem mediates autonomic reflexes, while the hypothalamus integrates various autonomic functions.

Question 10

True or False: The autonomic nervous system is largely under voluntary control.

Answer 10

False

The ANS operates largely outside of voluntary control.

Question 11

Fill in the blank: The sympathetic pathway is activated by _______.

Answer 11

exercise, excitement, emergency, embarrassment

Question 12

Fill in the blank: The parasympathetic pathway is activated by _______.

Answer 12

digestion, defecation, and diuresis

Question 13

What type of sensory input takes priority over cortical functions in the ANS?

Answer 13

Visceral afferents

For example, bladder distension can override conscious thought.

Question 14

What is the primary neurotransmitter released by cholinergic neurons?

Answer 14

Acetylcholine (ACh)

ACh activates nicotinic ACh receptors on the postsynaptic cell.

Question 15

List the main functions regulated by the hypothalamus in the ANS.

Answer 15

• Feeding
• Thermoregulation
• Circadian Rhythms
• Water Balance
• Sexual drive
• Reproduction

Question 16

How does the sympathetic pathway differ anatomically from the parasympathetic pathway?

Answer 16

Sympathetic: short preganglionic, long postganglionic; Parasympathetic: long preganglionic, short postganglionic

Sympathetic neurons originate from the thoracic and lumbar spinal cord, while parasympathetic neurons originate from the brainstem and sacral spinal cord.

Question 17

What is an exception to the general anatomical organization of the sympathetic pathway?

Answer 17

The adrenal medulla

Chromaffin cells in the adrenal medulla function similarly to postganglionic neurons but release mainly adrenaline (epinephrine).

Question 18

What does ANS stand for?

Answer 18

Autonomic nervous system

Motor part of the Peripheral Nervous System

Question 19

What 5 things does the sympathetic stimulation impact?

Answer 19

Heart, blood vessels, lungs, eyes, liver

Heart rate increases, blood vessels becoome constricted, relaxes airway muscles in lungs (increased oxygen intake), pupils dilate (improve vision), stimulate breakdown of glycogen into glucose in liver to provide energy

Question 20

What is the general organisation of ANS?

Answer 20

Central nervous system (Preganglionic neuron) –> Peripheral ganglion (Postganglionic neuron) —> Target cell

Both sympathetic and parasympathetic pathways have this organisation

Question 21

What do ACh activate on the post synaptic cell?

Answer 21

Nicotinic ACh receptors

Question 22

What type of neurons does the sympathetic pathway utilise?

Answer 22

Short, cholinergic preganglionic neurons from the thoracic and lumbar spinal cord
Long, adrenergic postganglionic neurons

Question 23

What are the target tissue for the parasympathetic system?

Answer 23

Muscarinic ACh receptors

Question 24

Where are the essential central components of the ANS located?

Answer 24

The brianstem nuclei and the spinal cord