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MED310B > cardiac system 4 > Flashcards

cardiac system 4 Flashcards

1
Q

cardiac output

A

the volume of blood ejected by each ventricle each minute

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2
Q

CO through the pulmonary and systemic circulations

A

is equal

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3
Q

what is CO determined by

A

heart rate times stroke volume

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4
Q

how is heart rate varied

A

by altering balance of parasympathetic and sympathetic influence on SA node

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5
Q

parasympathetic stimulation and heart rate

A

slows it
vagus nerve

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6
Q

sympathetic stimulation and heart rate

A

speeds it up
cardiac nerve

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7
Q

where are cardio inhibitory and acceletory centres located

A

in the medulla oblongata

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8
Q

what do cardio inhibitory and acceleratory centres recieve

A

sensory (chemosensory and baroceptors) and higher (cortex and hypothalamys) input

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9
Q

what does the parasympathetic nerve (vagus) release

A

acetylcholine that increases permeability of the SA node to potassium
slows closure of K+ channels
decreases AV nodes excitability, lengthens AV ndoal delay
weakens atrial contraction
little to no efffect on ventricular contraction

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10
Q

what does the sympathetic stimualtion of the heart release

A

norepinephrine has an effect on SA node stimulation
nore decreases time for SA to reach threthold
more frequent AP
speeds spread of AP throughout the cardiac conduction pathways
contractile cells beat more forcefully due to higher ca permeability and enhanced excitation-contraction coupling

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11
Q

effect of parasymp stimulation on SA node

A

decreases the rate of depolarization to threthold, decreases heart rate

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12
Q

effect of sympth stimulation on SA node

A

inc the rate of depolarization to threthold, inc heart rate

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13
Q

parasymth on AV node

A

decreases excitability, inc the AV nodal delay

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14
Q

sympathetic on AV node

A

inc excitability, dec AV nodal delay

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15
Q

parasympth on ventricular conduction pathway

A

no effect

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16
Q

sympth on ventricular conduction pathway

A

inc excitability, hastens conduction thorugh bundle of his and purkinje cells

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17
Q

parasympth on artial muscle

A

dec contractility, weakens contraction

18
Q

sympth on artial muscle

A

inc contractility, strenthens contraction

19
Q

para on ventricular muscle

A

no effect

20
Q

para on adrenal medulla

A

no effect

21
Q

para on veins

A

no effect

22
Q

symp on ventricular muscle

A

inc contractility, strengthens contraction

23
Q

symp on adrenal medulla

A

proote adrenomedullary secretion of epinephrine, augments sympth actions NS actinos of the heart

24
Q

symp on veins

A

increases venous return, inc the strength of cardiac contraction through the frank starling mech

25
Q

stroke volume

A

volume of blood ejected by a cardiac ventricle per beat

26
Q

what influences stroke volume

A

two types of cotnrols

-intrinsic control of stroke volume determined by ectent of venous return (preload)

-extrinsic control of stoke volume determined by sympathetic activity

27
Q

what do the two types of control of stroke volume do

A

increase stroke volume by increasing strength of heart contraction (contractility)

28
Q

preload

A

initial stretching of the cardionmycytes prior to contraction and is related to the sarcomere length at the end of diastole (and therefore EDV)

29
Q

what is the level of filling

A

essentially the workload imposed on the heart before contraction

30
Q

contractility

A

contractility of the heart and realtive effectiveness or strength of the ventricular pump

31
Q

afterload

A

the pressure or load that each ventricle has to work against when pumping blood

32
Q

what are the determinants of stroke volume

A

preload
contractility
afterload

33
Q

inc in ventricular preload effect on outflow resistance and afterload

A

increaes

34
Q

inc in ventricular preload effect on atrail inotropy

A

increase

35
Q

inc in ventricular preload effect on ventricular compliance

A

increase

36
Q

inc in ventricular preload effect on venous pressure

A

increase

37
Q

inc in ventricular preload effect on inflow resistance

A

decrease

38
Q

inc in ventricular preload effect on ventricular inropy

A

decrease

39
Q

inc in ventricular preload effect on heart rate

A

decrease

40
Q

inc in venous complaince effect on venous pressure

A

increase

41
Q

inc in venous blood volume (total blood volmue and venous return) on nevous pressure

A

increase

42
Q

sympathetic stimulation of the heart and the frank starling cruve

A

shifts the curve to the left

MED310B (11 decks)

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