The ANS

Question 1

ANS

Answer 1

Involuntary/visceral

-Motor system that controls visceral organs through nerves to smooth muscles, heart, glands

Question 2

Functions of the ANS

Answer 2

Homeostasis

• metabolic, cardiopulmonary and visceral needs of the body
• metabolic needs for exercise/exertion
• Fight or flight
• aids in reproduction

Question 3

Branches of the ANS

Answer 3

• PNS
• SNS
• ENS

Question 4

Parasympathetic/sympathetic nervous systems

Answer 4

Serve the same visceral organs, but cause opposite effects

Not all organs are dually innervated, but the ones that are, the functional effect of stimulating each division is usually antagonistic

Question 5

Generic Structure of ANS

Answer 5

CNS/Peripheral ganglion/Target cell

Preganglionic neuron and postganglionic neuron

Question 6

Ganglion and neurons in the SNS

Answer 6

Ganglia adjacent to spinal cord

• Cell bodies of neurons are in the spinal cord
• Post ganglionic nerve fibers are much longer

Question 7

Postganglionic neurons

Answer 7

Exit the ganglionic chain via the gray rami, and travel to their target organs along blood vessels or bundled with other nerves
-Cell bodies in para/prevertebral ganglion

Question 8

Preganglionic Neurons

Answer 8

Enter the ganglionic chain from the spinal cord via the white rami. Can synapse up to 10-20 post ganglionic neurons (diffuse pattern of innervation)

Question 9

Sympathetic division- paravertebral ganglion

Answer 9

• cervical ganglia
  1. superior
  2. middle
  3. inferior

Question 10

sympathetic division-preverterbal ganglia

Answer 10

1. celiac
2. superior mesenteric
3. Inferior mesenteric

Question 11

Adrenal Medulla

Answer 11

Special section of SNS

• Important in the stress response
• Releases Epinephrine (90%) NE (10%)

Question 12

Origin of postganglionic neurons

Answer 12

• ganglionic chain

- peripheral sympathetic ganglia

Question 13

Parasympathetic nervous system structure

Answer 13

Longer Preganglionic fibers, ganglia are located in or very near target tissues

Question 14

Cell bodies for preganglionic neurons in PNS are located where?

Answer 14

cranio-sacral

• medulla, pons, midbrain
• S2-S4 levels of spinal cord

Question 15

The vagus nerve (X)

Answer 15

account for ~90% of preganglionic parasympathetic fibers in the body

Question 16

Parasympathetic cranial neurons exit the brain in what four cranial nerves

Answer 16

III (3), VII (7), IX(9), X(10)

Question 17

Parasympathetic sacral outflow

Answer 17

Pelvic/splanchnic nerves
synapse in the intramural ganglion in
-large intestines, 
-bladder,
-reproductive organs (s2, 3, 4 keeps the penis off the floor)

Question 18

Visceral afferents

Answer 18

Provide feedback to ANS

• baroreceptors
• mechanoreceptors
• chemoreceptors
• nociceptors

Question 19

Neurotransmitters of the somatic nervous system

Answer 19

Acetylcholine, acts on nicotinic receptors (N1)

Question 20

Parasympathetic neurotransmitters

Answer 20

Acetylcholine
Acts on Nicotinic (N2) receptors in the ganglion
Acts on Muscarinic receptors at the effector organ

Question 21

Sympathetic neurotransmitters

Answer 21

In ganglion Ach- nicotinic receptors (N2)

At effector organ- NE, E-adrenergic receptors (alpha, beta)

Question 22

Role of the sympathetic nervous system

Answer 22

Response to stress/threat

-promotes physiologic adjustments to exercise

Question 23

Role of the parasympathetic Nervous system

Answer 23

• more active in non-stress situations/rest
• Concerned with keeping the bodies energy consumption as low as possible.
• Directs processes such as digestion and elimination
• directs the enteric nervous system

Question 24

Where are cell bodies of visceral afferents located?

Answer 24

dorsal root ganglia and cranial nerve ganglia

Question 25

VSM contraction by alpha adrenergic receptors

Answer 25

NE-->Calcium released from SR, activates Calmodulin which activates MLCK which leads to muscle contraction

Question 26

VSM relaxation by beta adrenergic receptors

Answer 26

Epi stim beta receptors--> calcium channels close--> cAMP activates PKA which phosphorylates MLCK inactivating it, leading to muscle relaxation

Question 27

Antagonist to alpha 1 receptor

Answer 27

Prazosin- treats high blood pressure by blocking VSM contraction by stimulation of alpha receptors.

Question 28

Beta 1- antagonist

Answer 28

-olol

Question 29

Muscarinic receptor antagonist

Answer 29

Atropine

Question 30

Advantage of basal tone in the ANS

Answer 30

provides the advantage of raising or lowering dominant tone, rather than invoking an antagonistic system.

Question 31

Function of the Myenteric plexus in the ENS

Answer 31

Regulates motility

Question 32

Function of the submucosal plexus in the ENS?

Answer 32

Coordinates secretions

Question 33

ENS can self-regulate but is coordinated by what branch of the ANS?

Answer 33

PNS

Question 34

Parasympathetic reflexes control

Answer 34

Salivation, swallowing, pupil diameter, accommodation, respiration

Question 35

Brainstem center controls

Answer 35

heart rate, BP, respiration

Question 36

Function of the Hypothalamus

Answer 36

``` Temperature Blood volume/Water balance Feeding BP/HR Reproduction Response to stress ```

Question 37

What part of the brain is the main integration center of the ANS?

Answer 37

The hypothalamus

Question 38

Is the hear dually innervated by the SNS/PNS and if so, by what receptors?

Answer 38

Yes, the heart is dually innervated SNS- Beta-1 Parasympathetic-Muscarinic -Atropine antagonizes muscarinic receptors, hence why we give it in symptomatic bradycardias.

Question 39

Blood vessels are primary innervated by which system (PNS or SNS)

Answer 39

The SNS (except the genitalia)

Question 40

What receptors cause contraction/relaxation of blood vessels

Answer 40

Contraction- Alpha 1 | Relaxation- Beta 2

Question 41

Net effect of epinephrine in the heart

Answer 41

increased conduction velocity and contractility | -Beta 1 receptors

Question 42

Net effect of epinephrine on blood vessels

Answer 42

Vasodilation | -Beta 2 receptors predominate over alpha receptors

Question 43

ENS receptors

Answer 43

peptinergic