The Autonomic Nervous System Flashcards

1
Q

Overall function of ANS

A

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

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2
Q

ANS is?

A
Involuntary
Diffuse projections
Slow action
Innervates smooth and cardiac muscle, and gland cells
Disynaptic
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3
Q

Somatic motor system is?

A
Voluntary
Specific projections
Rapid action
Innervates skeletal muscle
Monosynaptic
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4
Q

The ANS consists of 3 subdivisions

A

Sympathetic: “Fight/flight”

Parasympathetic: “Rest/digest”

Enteric: Semi-autonomous control of digestion

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5
Q

Comparative anatomy- Sympathetic

A

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

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6
Q

Comparative anatomy- Parasympathetic

A

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

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7
Q

Ganglion:

A

cluster of cell bodies in the peripheral nervous system

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8
Q

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

A

Acetylcholine (ACh)

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9
Q

Neurotransmitters and receptor subtypes determine effects and timecourse of ANS innervation

Postganglionic:

A

Sympathetic: Norepinephrine
NE) and epinephrine
Parasympathetic: ACh

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10
Q

Neurotransmitters and receptor subtypes determine effects and timecourse of ANS innervation

Receptors:

A

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

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11
Q

Adrenal medulla – functionally, a?

A

sympathetic ganglion

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12
Q

Adrenal medulla fx?

A

Innervated by preganglionic sympathetic neurons

Releases norepinephrine and epinephrine into bloodstream

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

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13
Q

Cardiovascular regulation by the nervous system

A

Sympathetic and parasympathetic control of heart rate and force of contraction

Baroreceptor reflex

Humoral response to low blood pressure

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14
Q
ANS regulation of heart rate and force of contraction
Sympathetic stimulation (via increased NE)
A

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

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15
Q
ANS regulation of heart rate and force of contraction
Parasympathetic stimulation (via increased ACh)
A

decreases blood pressure

Decrease in heart rate and contractile force

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16
Q

muscarinic (M2) antagonist in heart; increases heart rate

A

Atropine

*mimic sympathetic activation

17
Q

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

A

Propranolol

*mimic parasympathetic activation

18
Q

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.

A

baroreceptor reflexes

19
Q

Humoral response to low blood pressure: controlled by _____-

A

hypothalamus

20
Q

Hypothalamus controls release of hormones via the _________

A

pituitary

Posterior pituitary: brain
Anterior pituitary: gland

21
Q

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

A

subfornical organ

22
Q

release of vasopressin in posterior pituitary causes _________

A

vasoconstriction

Which acts on kidneys to increase water retention

23
Q

vasoconstriction acts on _______ to increase water retention

A

kidneys

24
Q

Low blood pressure causes _____ to be releases from kidneys

A

renin

25
Q

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

A

Angiotensin II:

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

26
Q

Opposing effects of ______ divisions enable homeostasis

A

sympathetic and parasympathetic

27
Q

Hypothalamus coordinates ANS and ________

A

humoral responses