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Flashcards in The ANS Deck (43):
1

ANS

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

2

Functions of the ANS

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

3

Branches of the ANS

-PNS
-SNS
-ENS

4

Parasympathetic/sympathetic nervous systems

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**

5

Generic Structure of ANS

CNS/Peripheral ganglion/Target cell
Preganglionic neuron and postganglionic neuron

6

Ganglion and neurons in the SNS

Ganglia adjacent to spinal cord
-Cell bodies of neurons are in the spinal cord
-Post ganglionic nerve fibers are much longer

7

Postganglionic neurons

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

8

Preganglionic Neurons

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)

9

Sympathetic division- paravertebral ganglion

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

10

sympathetic division-preverterbal ganglia

1. celiac
2. superior mesenteric
3. Inferior mesenteric

11

Adrenal Medulla

Special section of SNS
-Important in the stress response
-Releases Epinephrine (90%) NE (10%)

12

Origin of postganglionic neurons

-ganglionic chain
-peripheral sympathetic ganglia

13

Parasympathetic nervous system structure

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

14

Cell bodies for preganglionic neurons in PNS are located where?

cranio-sacral
-medulla, pons, midbrain
-S2-S4 levels of spinal cord

15

The vagus nerve (X)

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

16

Parasympathetic cranial neurons exit the brain in what four cranial nerves

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

17

Parasympathetic sacral outflow

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

18

Visceral afferents

Provide feedback to ANS
-baroreceptors
-mechanoreceptors
-chemoreceptors
-nociceptors

19

Neurotransmitters of the somatic nervous system

Acetylcholine, acts on nicotinic receptors (N1)

20

Parasympathetic neurotransmitters

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

21

Sympathetic neurotransmitters

In ganglion Ach- nicotinic receptors (N2)
At effector organ- NE, E-adrenergic receptors (alpha, beta)

22

Role of the sympathetic nervous system

Response to stress/threat
-promotes physiologic adjustments to exercise

23

Role of the parasympathetic Nervous system

-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

24

Where are cell bodies of visceral afferents located?

dorsal root ganglia and cranial nerve ganglia

25

VSM contraction by alpha adrenergic receptors

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

26

VSM relaxation by beta adrenergic receptors

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

27

Antagonist to alpha 1 receptor

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

28

Beta 1- antagonist

-olol

29

Muscarinic receptor antagonist

Atropine

30

Advantage of basal tone in the ANS

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

31

Function of the Myenteric plexus in the ENS

Regulates motility

32

Function of the submucosal plexus in the ENS?

Coordinates secretions

33

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

PNS

34

Parasympathetic reflexes control

Salivation, swallowing, pupil diameter, accommodation, respiration

35

Brainstem center controls

heart rate, BP, respiration

36

Function of the Hypothalamus

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

37

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

The hypothalamus

38

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

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

39

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

The SNS (except the genitalia)

40

What receptors cause contraction/relaxation of blood vessels

Contraction- Alpha 1
Relaxation- Beta 2

41

Net effect of epinephrine in the heart

increased conduction velocity and contractility
-Beta 1 receptors

42

Net effect of epinephrine on blood vessels

Vasodilation
-Beta 2 receptors predominate over alpha receptors

43

ENS receptors

peptinergic