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Cardiovasular System > ANS control > Flashcards

ANS control Flashcards

1
Q

what does the ANS exert control over

A

smooth muscle, exocrine secretion and rate and force of contraction in the heart

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2
Q

what are the 2 divisions of the ANS

A

sympathetic and parasympathetic

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3
Q

where do the preganglionic nerve in the sympathetic originate from

A

thoracic and lumbar regions of the spinal cord

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4
Q

where do the preganglionic nerve in the parasympathetic originate from

A

medulla region and sacrel outflow

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5
Q

what increases sympathetic activity

A

stress

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6
Q

what increases parasympathetic activity

A

basal conditions

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7
Q

where are alpha 1 receptors found

A

pupil of the eye, sweat glands and smooth muscle

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8
Q

where are beta 2 receptors found

A

airways and lungs

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9
Q

where are beta 1 receptors found

A

HEART

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10
Q

where are M2 receptors found

A

heart

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11
Q

where are M3 receptors found

A

pupil, airways, lungs

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12
Q

true or false: sympathetic activity to the heart can only be increased if other systems are also activated

A

false

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13
Q

true or false: the ANS initiates electrical activity of the heart

A

false - it only increases speed and force

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14
Q

by which subsystem of the ANS is the heart predominantly controlled by

A

parasympathetic

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15
Q

which nerve supplies the parasympathetic input to the heart

A

vagus nerve

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16
Q

where are the post ganglionic cells on the heart for parasympathetic input

A

SA - for decreased heart rate

AVN - decreased conduction velocity

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17
Q

what does a negative chronotropic effect mean

A

decreased heart rate

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18
Q

what is released from postganglionic neurones in the parasympathetic NS

A

ACh

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19
Q

what nerve produces the sympathetic input to the heart

A

sympathetic trunk

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20
Q

where are the post ganglionic cells on the heart for sympathetic input

A

SAN - increase heart rate
AVN
Myocardium - increase force of contraction

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21
Q

what does a positive ionotropic effect mean

A

increase in force of contraction

22
Q

what type of receptors are acted on in the heart by the sympathetic NS

A

beta 1

23
Q

true or false: there are only beta 1 receptors found on the heart

A

false - there are also beta 2 and beta 3

24
Q

where are baroreceptors found

A

carotid sinus

arch of the aorta

25
Q

where in the brain controls the ANS output of the heart

A

cardiovascular centre in the medulla oblongata

26
Q

how does the sympathetic NS change the action potentials of the SAN myocytes

A

increases the depolarising slope speeding up action potentials

27
Q

how does the parasympathetic NS change the action potentials of the SAN myocytes

A

decreases the depolarising slope, slowing down action potentials

28
Q

what does activation of the beta 1 receptors in the heart do

A
  • increase cAMP which can cause a direct effect on the HCN
  • also activates PKA which phosphorylates Ca channels increasing Ca entry during plateau
  • increase uptake of Ca in stores
  • increased sensitivity of contractile machinery to Ca
  • increases force of contraction
29
Q

what does activation of the M2 receptors in the heart do

A
  • increase potassium conductance through the beta gamma subunit
  • decrease cAMP
30
Q

what receptors are found in most arteries and veins

A

alpha 1 adrenoreceptors (although skeletal and coronary muscle have beta 2)

31
Q

what is vasomotor tone

A

the amount of tension in the smooth muscle of vessel walls

32
Q

what increases vasomotor tone of arteries

A

increased sympathetic output

33
Q

what decreases vasomotor tone of arteries

A

decreased sympathetic output

34
Q

true or false: alpha 1 receptors are the only receptors found in the blood vessels

A

false - beta 2 receptors are as well

35
Q

which receptor in smooth muscle of blood vessels has a higher affinity for circulating adrenaline

A

beta 2

36
Q

what do activated beta 2 receptors in smooth muscle of blood vessels cause

A
  • increase in cAMP
  • activation of PKA which phosphorylates and inactivates MLCK
  • opening of potassium channels
  • relaxation of smooth muscle (vasodilation)
37
Q

what do activated alpha 1 receptors in smooth muscle of blood vessels cause

A
  • stimulates IP3 production
  • increases Ca release from store
  • increase of Ca causes contraction of smooth muscle
38
Q

true or false: activated beta 2 receptors are the main method of vasodilation

A

false - its the increase in metabolites (adenosine, potassium, hydrogen ions and CO2) from active tissues in coronary and skeletal muscle

39
Q

how does high pressure change baroreceptors

A

it causes them to stretch which increases the firing of action potentials

40
Q

which nerve endings are found in the carotid sinus

A

glossopharyngeal nerve

41
Q

which nerve ending are found in the arch of the aorta

A

vagus nerve

42
Q

what happens to baroreceptors if there is maintained high blood pressure

A

they re-set to higher levels so will only respond to changes of BP at higher values

43
Q

what are sympathomimetics

A

alpha and beta agonists

44
Q

what are uses of sympathomimetics

A
  • adrenaline causes vasoconstriction on alpha 1 go restore function in cardiac arrest and is also administered for anaphylactic shock
  • beta 1 agonists e.g. dobutamine is given in cardiogenic shock and salbutamol for asthma
45
Q

what are alpha antagonists used for

A

anti-hypertension agent as it inhibits NA to cause vasodilation

46
Q

give an example of an alpha antagonists

A

prazosin

47
Q

give an example of a selective beta antagonist

A

atenolol

48
Q

give an example of a nonselective beta antagonist

A

propranolol - this slows heart rate and reduces force of contraction but also causes bronchoconstriction

49
Q

give an example of a muscarinic agonist

A

pilocarpine - used to treat glaucoma

50
Q

give an example of a muscarinic antagonist

A

atropine - increases heart rate and bronchial dilation. also dilates eyes

Cardiovasular System (16 decks)

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