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heart physiology Flashcards

1
Q

T/F the heart needs neural stimulation and neurotransmitters to depolarize

A

false! the heart generates its own ability to depolarize and contract

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2
Q

autorhythmic cells

A

noncontractile cells within contractile cells within muscles of the heart

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3
Q

pacemaker potentials

A

self-regulated action potentials in the heart

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4
Q

how do autorhythmic cells initiate and spread impulse

A

they are leaky-
Na can easily move in, K cannot easily move out

they are connected with desmosomes to neighboring cells- when they depolarize, it quickly spreads

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5
Q

T/F auto rhythmic cells have unstable resting potentials

A

true

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6
Q

autorhythmic cell location

A 
SA node
AV node
Bundle of His
Bundle Branches
Purkinje Fibers
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7
Q

how do we change rate at which heart beats

A

nervous connections

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8
Q

SA Node

A

main controller of electricity in heart

sits atop R atrium; just beneath where coronary sinus empties

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9
Q

“pacemaker of the heart”

A

SA node

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10
Q

AV Node

A

depolarizes; signal transfers from AV node all the way to apex of heart
sits atop inter ventricular septum

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11
Q

bundle of His

A

site of autorhythmic cells

splits to R and L sides of heart (splits higher or lower depending on person)

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12
Q

bundle branches

A

branches of bundle of his; go right or left

contain autorhythmic cells

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13
Q

Purkinje fibers

A

fibers coming off Bundle of His branches

send electrical impulse to muscle cells; end up in papillary muscles

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14
Q

2 clusters of neurons in medulla that send reflexes to heart

A

cardioaccelatory center

cardioinhibitory center

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15
Q

cardioaccelatory center

A

sends sympathetic nervous impulses to heart
sympathetic nerve fibers use norepinephrine as NT –> norepinephrine causes autorhymic cells to depolarize and HR increases

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16
Q

cardioinhibitory center

A

sends parasympathetic nervous impulses to heart

parasympathetic nerve fibers use acetylcholine –> ACh hyper polarizes SA node cells, then slows down and HR decreases

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17
Q

ECG (electrocardiogram)

A

graphic recording of electrical events of the heart

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18
Q

deflection waves

A

what we see in an ECG

includes P wave, QRS complex, and T wave

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19
Q

P Wave

A

represents wave of depolarization in atria

SA node has depolarized and made pacemaker potential that’s spread through atria

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20
Q

QRS Complex

A

represents depolarization of ventricles

2 things happening, only 1 shown (repolarization of atria not shown)

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21
Q

T Wave

A

represents repolarization of ventricles

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22
Q

how can we see if there are problems with the heart’s conduction pathway?

A

looking at timing between intervals in ECG

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23
Q

PR interval

A

time between start of P wave and start of R wave

represents movement of electrical impulse through atria down

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24
Q

heart sound and what is it generated by?

A

Lub-Dup; generated by valves closing

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25
"Lub" is caused by what
AV valve closure
26
"Dup" is caused by what
SL Valve closure
27
murmur
extraneous or abnormal heart sound
28
pathological murmur
murmur related to malfunctioning of heart valves | valves may not be closing all the way
29
cardiac cycle
systole and diastole of both atria plus systole and diastole of both ventricles
30
systole
phase of contraction
31
diastole
phase of relaxation
32
blood pressure
pressure that blood exerts on arteries as it leaves the heart generated by pressure difference
33
why is bp higher on left side?
left wall much more muscular and thick because it has to push blood to entire body
34
why is bp lower on right side
so lung tissue won't be damaged | so blood flows slow enough for adequate gas exchange
35
cardiac output
amount of blood that leaves ventricles per minute produce of stroke volume and heart rate
36
stroke volume
amount of blood that leaves heart per beat difference between amount of blood in ventricles before and after systole end diast. volume - end syst. volume
37
cardiac reserve
difference between max CO and normal CO
38
how high can max CO go
20-25 mL/min
39
avg SV for healthy people my age
70 mL/b
40
avg HR for healthy people my age
75 bpm
41
how do we increase the amount of blood pumping through the heart
cardiac reserve
42
end diastolic volume
when ventricles are most relaxed and full; just before contraction
43
end systolic volume
blood that's left behind in ventricle after it contracts
44
factors affecting stroke volume
stretch of cardiac muscle (starling law of heart) contraction strength NOT due to stretch arterial pressure
45
how does stretch of cardiac muscle affect stroke volume
when cardiac muscle tissue is stretched (by blood), it contracts with increased force greater blood in ventricle (preload) means greater force of contraction
46
preload
amount of blood in ventricles before they contract | directly proportionate with contraction strength
47
how does contraction strength not due to stretch affect stroke volume
norepinephrine changes rate of contraction and amount of calcium allowed into muscle cell increases force of contraction
48
how does arterial pressure affect stroke volume
blood moves in response to pressure differences | higher pressure of arteries causes pressure difference to not be as high, so decreases blood out
49
afterload phenomenon
higher pressure of arteries causes pressure difference to not be as high, so decreases blood out
50
factors that affect HR
``` sympathetic nervous system parasympathetic nervous system adrenal medulla production of epinephrine thyroid production of thyroxine BP changes (baroreceptors) ionic imbalances age sex exercise temperature ```
51
how does norepinephrine affect HR
speeds up HR
52
how does acetylcholine affect HR
slows down HR
53
how does adrenal medulla production of epinephrine affect HR
speeds up HR suddenly
54
how does thyroid production of thyroxine affect HR
speeds up HR gradually/sustained
55
how does bp change (baroreceptors) affect HR
changes speed at which heart contracts when bp incr, change in pressure is detected by baroreceptors --> send signal to heart to beat faster
56
how does ionic imbalance affect HR
ion imbalance can incr or decr HR based on what is imbalanced depolarization of tissues requires ion movement
57
how does age affect HR
HR decreases as you age
58
how does gender affect HR
female HR > male HR
59
how does exercise affect HR (short and long term)
short term- HR increases when exercising because muscles need more O2 delivered long term- resting HR decreases with continued long term exercise
60
how does temperature affect HR
HR is higher when you have a fever
61
vagal tone
reduction in heart's rate of contraction due to stimulation from vagus nerve
62
if we were able to disconnect heart from all nerves, what would HR be? what is it actually?
100 bpm; 75 bpm
63
how does vagal tone make the heart slow down?
parasympathetic nervous impulses from cardioinhibitory center travel from medulla oblongata and cause hyper polarization of SA node
64
where do parasympathetic fibers that slow down the heart run?
along cranial nerve 10 (vagus nerve)
65
why do we have vagal tone?
so we can increase HR even more in case of emergency
66
tachycardia
abnormally high resting HR | >100 bpm
67
bradycardia
abnormally low resting HR <60 bpm
68
congestive heart failute
dangerously low cardiac output
69
factors that could cause CHF
coronary atherosclerosis high BP myocardial infarction dilated cardiomyopathy
70
coronary atherosclerosis
blockages within coronary artery | decreases diameter of vessels, which decreases CO (heart doesnt have enough energy to pump strongly)
71
how does high blood pressure cause CHF
high blood pressure in aorta reduces "ejection fraction" coming from heart
72
high blood pressure
diastolic over 90
73
how does myocardial infarction cause CHF
as blood supply is decreased to heart muscle, myocardium loses its ability to contact
74
dilated cardiomyopathy is usually due to:
valve failure
75
dilated cardiomyopathy
eventually, if we have high bp or low HR and blood is allowed to continue to pool in ventricles, ventricles stretch too much ventricles so stretched that they don't respond with increased contraction --> they just get loose and weak
76
the heart is developed from which embryonic structure?
mesoderm
77
heart development
1. originates as 2 endothelial tubes 2. tubes fuse into single chambered "heart" by day 23 3. early chambers formed by day 25 4. D-looping and structural changes divide heart into separate chambers and change orientation by day 46
78
D-looping of heart
heart makes rightward circle until it is upside down during development
79
foramen ovale
connection of 2 atria through interatrial septum | right up until birth, 2 atria are connected by this
80
why are atria connected in utero?
fetus doesn't have to do gas exchange until it is born bc it gets all oxygenated blood from mom
81
ductus arteriosus
connection between pulmonary trunk and aorta that seals at birth
82
ductus arterioles becomes ______
ligamentum arteriousum
83
T/F no blood goes to lungs before birth
false- some blood goes to lungs to supply them with blood (but no oxygenation is taking place there)
84
age related changes of heart
valve sclerosis decreased cardiac reserve fibrosis of myocardium atherosclerosis
85
valve sclerosis
cusps of heart valves accumulate deposits --> so cusps do not close right --> leakage --> decreased CO
86
how to decrease risk of valve sclerosis
eat lipids and Calcium
87
decreased cardiac reserve due to aging
as you age, you get sedentary, and cardiac reserve decreases
88
fibrosis of myocardium
as you age you get sedentary, so unused heart muscle converts to fibrous CT (cannot contract)

Anatomy II (17 decks)

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