Intro to PNS

Question 1

What do the autonomic and somatic divisions of the PNS provide? What are the divisions of the autonomic nervous system and where do they exit?

Answer 1

Autonomic:
Unconscious and involuntary control for the heart, blood vessels, organs, and glands.
Sympathetic - thoracic-lumbar outflow
Parasympathetic - craniotomy-sacral outflow
Somatic:
Conscious and voluntary control of skeletal muscle

Question 2

What 2 divisions make up the Peripheral Nervous System?

Answer 2

1-Autonomic Nervous System (Involuntary)

2-Somatic Nervous System (Voluntary)

Question 3

Autonomic Nervous System

1. Are preganglionic fibers myelinated?
2. Are there peripheral ganglia?
3. Are postganglionic fibers myelinated?

Answer 3

1. Yes
2. Yes
3. No
   * postganglionic synapses for nerve impulse transmission to peripheral organs

Question 4

What does the Somatic Nervous System control?

Answer 4

Conscious, Voluntary control of the Skeletal Muscle

Question 5

What 2 divisions make up the Autonomic Nervous System?

Answer 5

1-Sympathetic (Thoraco-Lumbar)

2-Parasympathetic (Cranio-Sacral)

Question 6

Most body structures are innervated by both the sympathetic and parasympathetic systems, what are the exceptions and which system innervates these exceptions?

Answer 6

Blood vessels, sweat glands, liver, spleen, and adrenal glands are innervated by the Sympathetic Nervous System ONLY!

Question 7

What structures are innervated by the sympathetic system only?

Answer 7

Blood vessels, sweat glands, liver, spleen, adrenal gland

Question 8

Autonomic Nervous System

1. Are preganglionic fibers myelinated?
2. Are there peripheral ganglia?
3. Are postganglionic fibers myelinated?
4. What are the primary neurotransmitters?

Answer 8

1. Yes
2. Yes
3. No
   * postganglionic synapses for nerve impulse transmission to peripheral organs
4. Acetylcholine and norepinephrine

Question 9

Somatic Nervous System

1. What kind of receptors does it have at NMJ?
2. Are there peripheral ganglia?
3. Are fibers myelinated?

Answer 9

1. Cholinergic nerves with nicotinic receptors at NMJ
2. No - cell bodies and axons extend to the effector muscles
3. Yes - motor axons are myelinated

Question 10

What are the primary neurotransmitters of the ANS and what are they released by?

Answer 10

Acetylcholine (ACh) : released by all preganglionic nerves, all postganglionic PS nerves, and some postganglionic sympathetic nerves (50% sweat glands), all somatic nerves
Norepinephrine (NE) : released by most postganglionic sympathetic nerves
**Dopamine: released by some postganglionic sympathetic nerves in renal vasculature

Question 11

What is the role of a co-transmitter? What are examples of these?

Answer 11

They are packaged with primary transmitters and may elicit faster or slower responses that modulate the action of the primary neurotransmitter
Ex: purines, peptides, nitric oxide

Question 12

Sweat Glands

1. What innervates them?
2. What type of nerves are they?

Answer 12

1. Innervated by sympathetic nerves, but 50% of these release ACh instead of NE
2. Cholinergic sympathetic with muscarinic receptors

Question 13

Adrenal Medulla

1. What is it?
2. What do cholinergic preganglionic fibers release into the adrenal medulla?
3. What do chromaffin cells do?

Answer 13

1. Modified sympathetic ganglion
2. ACh
3. Respond to the ACh that is released into the adrenal medulla and release epinephrine and NE directly into the blood to act as hormones for sympathetic activity
   * *80% epi, 20% NE