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Flashcards in The Autonomic Nervous System Deck (27):
1

Overall function of ANS

Homeostasis: Maintaining a stable internal environment within a narrow physiological range amid changing external conditions

2

ANS is?

Involuntary
Diffuse projections
Slow action
Innervates smooth and cardiac muscle, and gland cells
Disynaptic

3

Somatic motor system is?

Voluntary
Specific projections
Rapid action
Innervates skeletal muscle
Monosynaptic

4

The ANS consists of 3 subdivisions

Sympathetic: “Fight/flight”

Parasympathetic: “Rest/digest”

Enteric: Semi-autonomous control of digestion

5

Comparative anatomy- Sympathetic

Preganglionic neurons originate in thoracic and lumbar spinal cord
Ganglia located near spinal cord
1:10 ratio of pre- to post-ganglionic neurons

6

Comparative anatomy- Parasympathetic

Preganglionic neurons originate in brainstem and sacral spinal cord
Ganglia located near target organs
1:3 ratio of pre- to post-ganglionic neurons

7

Ganglion:

cluster of cell bodies in the peripheral nervous system

8

Neurotransmitters and receptor subtypes determine effects and timecourse of ANS innervation
Preganglionic:

Acetylcholine (ACh)


9

Neurotransmitters and receptor subtypes determine effects and timecourse of ANS innervation

Postganglionic:


Sympathetic: Norepinephrine
NE) and epinephrine
Parasympathetic: ACh

10

Neurotransmitters and receptor subtypes determine effects and timecourse of ANS innervation

Receptors:


ACh: nicotinic vs. muscarinic
NE: α- and β-adrenergic

11

Adrenal medulla – functionally, a?

sympathetic ganglion

12

Adrenal medulla fx?

Innervated by preganglionic sympathetic neurons

Releases norepinephrine and epinephrine into bloodstream

Widespread sympathomimetic effects (e.g., increased heart rate)

13

Cardiovascular regulation by the nervous system

Sympathetic and parasympathetic control of heart rate and force of contraction

Baroreceptor reflex

Humoral response to low blood pressure

14

ANS regulation of heart rate and force of contraction
Sympathetic stimulation (via increased NE)

increases blood pressure
Increase in heart rate and contractile force
Constriction of blood vessels

15

ANS regulation of heart rate and force of contraction
Parasympathetic stimulation (via increased ACh)

decreases blood pressure
Decrease in heart rate and contractile force

16

muscarinic (M2) antagonist in heart; increases heart rate

Atropine

*mimic sympathetic activation

17

β-adrenergic (β1 and β2) antagonist in heart; decreases heart rate

Propranolol

*mimic parasympathetic activation

18

If blood pressure falls, such as on orthostatic hypotension or in hypovolaemic shock, firing rate decreases and _________ act to help restore blood pressure by increasing heart rate.

baroreceptor reflexes

19

Humoral response to low blood pressure: controlled by _____-

hypothalamus

20

Hypothalamus controls release of hormones via the _________

pituitary

Posterior pituitary: brain
Anterior pituitary: gland

21

Low blood pressure is detected by __________ Which causes release of vasopressin in posterior pituitary

subfornical organ

22

release of vasopressin in posterior pituitary causes _________

vasoconstriction

Which acts on kidneys to increase water retention

23

vasoconstriction acts on _______ to increase water retention

kidneys

24

Low blood pressure causes _____ to be releases from kidneys

renin

25

Angiotensinogen + renin --> --> Angiotension II that fxs to?


Angiotensin II:

Constricts blood vessels
Acts on kidney to increase water retention
Activates neurons in subfornical organ

26

Opposing effects of ______ divisions enable homeostasis

sympathetic and parasympathetic

27

Hypothalamus coordinates ANS and ________

humoral responses