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Physiology > Cardiovascular Physiology Excitation and Conduction Part 1 > Flashcards

Cardiovascular Physiology Excitation and Conduction Part 1 Flashcards

1
Q

what are the 3 principle components of the circulatory system

A

-the heart
- the blood vessels
-the blood

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2
Q

what is the number one cause of death worldwide

A

cardiovascular disease

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3
Q

what are the most common forms of cardiovascular disease

A

atherosclerosis and hypertension

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4
Q

what is the function of systemic circulation

A

-supply O2 and nutrients to tissues
-remove waste

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5
Q

what is the function of the pulmonary circulation

A

-add O2
-remove CO2

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6
Q

do the right and left side of the heart pump the same amount of blood into each circulation

A

yes

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7
Q

what chamber of the heart are the pulmonary veins attached to

A

LA

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8
Q

what chamber of the heart are the pulmonary arteries attached to

A

RV

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9
Q

what chamber of the heart is the aorta attached to

A

LV

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10
Q

what chamber of the heart is the vena cava attached to

A

RA

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11
Q

what are the functions of the heart valves

A

keep blood flowing in one direction/prevent back flow

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12
Q

what do heart valves open and close due to

A

changes in pressure

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13
Q

when do the AV valves open? close?

A

open: pressure in atria > pressure in ventricles
close: pressure in ventricles > pressure in atria

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14
Q

what chambers does the tricuspid valve separate

A

RA/RV

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15
Q

what chambers does the bicuspid valve separate

A

LA/LV

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16
Q

when do semilunar valves open? close?

A

open: pressure in ventricles > pressure in arteries
close: pressure in arteries > pressure in ventricles

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17
Q

where does exchange between plasma and interstitial fluid occur

A

at capillaries

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18
Q

what are capillaries arranged in when supplying

A

parallel

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19
Q

how does the distribution of systemic cardiac output change from at rest to strenuous exercise

A

more blood is distributed to skeletal muscle, skin, heart and brain. less blood is distributed to organs

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20
Q

what are the types of arteries and where are they located

A

-elastic arteries - heart
- muscular arteries- distribution
- arterioles- capillaries

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21
Q

what is the function of arteries

A

-carry blood to tissue capillaries from heart
- regulate blood pressure

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22
Q

what are the types of veins and where are they located

A

-large veins - heart
- medium sized vein -collection
- venules - capillaries

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23
Q

what is the function of veins

A

-carry blood from heart to tissue capillaries (venous return)
- reservoir of blood (peripheral venous pool)

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24
Q

what are the types of capillaries

A

-continuous
-fenestrated
-sinusoid

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25
Q

what is the function of capillaries

A

site of exchange

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26
Q

what is pressure

A

the force exerted by a fluid in a tube

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27
Q

what is flow

A

the volume of fluid moved in a given amount of time

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28
Q

what is resistance

A

how difficult it is for blood to flow between two points at any given pressure difference
-measure of friction that impedes flow

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29
Q

what is Ohm’s law

A

F= Change in pressure/resistance

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30
Q

what does F stand for in Ohm’s law

A

volume of blood moved in a unit of time

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31
Q

what is change in pressure calculated by

A

P1-P2 where P1 = pressure generated by heart beat and P2 = drop in pressure as move further from heart due to friction

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32
Q

what is R controlled by in Ohm’s law

A

factors defined by Poiseuille’s law

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33
Q

what is poiseuilles law

A

R = 8nl/pi(r^4)

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34
Q

what 3 factors contribute to cardiovascular resistance

A

-blood viscosity (n)
- total blood vessel length (l)
-blood vessel radius (r)

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35
Q

what is blood viscosity affected by

A

blood volume and number of RBC

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36
Q

what do vasodilated vessels do to r and R

A

increase r
decrease R

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37
Q

what is the main contributor to minute-to-minute control of resistance in the vascular system

A

blood vessel radius

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38
Q

why do small changes in r lead to big changes in R

A

because r is to the fourth power

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39
Q

what do Poiseuilles law and Ohms law calculate

A

flow

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40
Q

which impacts resistance more: diameter or length

A

diameter

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41
Q

what is the formula for velocity of blood flow and define variables

A

V = Q/A where Q = blood flow and A = cross sectional area

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42
Q

where is velocity of blood flow slowest and why

A

the capillaries because there’s more surface area and it allows for exchange and increased O2 delivery to tissues

43
Q

where are chordae tendinae and papillary muscles located

A

in AV valves

44
Q

what is the function of chordae tendinae and papillary muscles

A

prevent backflow of blood by preventing valve from prolapsing

45
Q

are all valves open at any given time

A

no

46
Q

what are the types of cardiac myocytes and what percentage of each

A

-conductive muscle fibers- 1%
- contractile muscle fibers- 99%

47
Q

what are examples of conductive muscle fibers

A

autorhythmic AR cells, Pacemaker cells

48
Q

what do conductive muscle fibers do

A

spontaneously generate AP that lead to heart beat

49
Q

do conductive muscle fibers contract

A

very weakly

50
Q

where are conductive muscle fibers located

A

in conduction system of heart

51
Q

what do contractile muscle fibers do

A

contract and generate heart beat

52
Q

what are the types of contractile muscle fibers

A

-atrial myocytes
- ventricular myocytes

53
Q

describe cardiocytes

A

striated cells bc functional unit is sarcomeres

54
Q

anatomy and function of cardiac muscular is similar to ____

A

skeletal muscle

55
Q

what are cardiocytes connected by

A

intercalated discs

56
Q

what are intercalated discs composed of

A

-interlocking plasma membrane
-gap junctions
-desmosomes

57
Q

how are cardiac muscle cells linked

A

mechanically, chemically, and electrically

58
Q

how do cardiac cells work together

A

in a syncytium

59
Q

what are the two syncytiums in the heart

A

atrial and ventricular

60
Q

what are the arteries that supply the myocardium

A

the coronary arteries

61
Q

what is the path of the coronary arteries

A

they exit from behind the aortic valve cusps and lead to a branching network of small arteries, arterioles, capillaries, venules and veins similar to those in other organs

62
Q

what do most of the cardiac veins drain into

A

the coronary sinus which empties into the right atrium

63
Q

what is systole

A

contraction

64
Q

what is diastole

A

relaxation

65
Q

what are the events in the cardiac cycle

A

-atrial systole
-ventricular systole/atrial diastole
- ventricular diastole

66
Q

what must the heart do before systole can occur

A

depolarize

67
Q

what must the heart do before diastole can occur

A

repolarize

68
Q

what is the pathway of excitation of the heart

A

SA node -> internodal pathways -> AV node -> bundle of his (AV bundle) -> down bundle branches -> up purkinje fibers

69
Q

what controls the heart rate

A

the area that makes AP at the highest rate which is the SA node

70
Q

how long is AV delay

A

0.1 sec

71
Q

what do purkinje fibers supply and what does it do

A

papillary muscles - contract during ventricular contraction to tighten chordae tendinae and prevent AV valves from prolapsing into the atria

72
Q

what do pacemaker cells do

A

generate AP leading to contractile cell contraction

73
Q

what is the order of activation sequence in the heart

A

SA node -> AV node -> AV bundle -> right/left bundle branches -> purkinje fibers

74
Q

why is the conduction velocity in the AV node so low

A

because of AV delay

75
Q

why is atrial repolarization not seen on an EKG

A

because ventricular depolarization is much larger and takes over and they happen at the same time

76
Q

what does the P wave represent

A

atrial depolarization

77
Q

what does the QRS complex represent

A

ventricular depolarization/atrial repolarization

78
Q

what does the T wave represent

A

ventricular repolarization

79
Q

describe pacemaker potential

A

AR cells do not have a steady resting membrane potential

80
Q

what are the channels of pacemaker potential

A

-F type channels - VG Na+ channels
-Ca2+ (T) - transient VG Ca2+ channel

81
Q

what is pacemaker potential due to

A

F type channels and Ca2+ T channel

82
Q

what are the channels of AP

A

Ca2+ (L) - long lasting VG Ca2+ channel
K+ channel - VG K+ channel

83
Q

what is depolarization of AR cells due to

A

calcium entering the cell

84
Q

what NT is released in autonomic NS control of AR cells and what is the receptor

A

NE and EPI - beta 1 adrenergic receptors

85
Q

what does NE/EPI do to AR cells

A

-increase probability of F and Ca2+ (T) channels are open
-decreases time to threshold
-increases HR
-positive chronotropic agent

86
Q

what is a positive chronotropic agent

A

agents that increase HR

87
Q

what is the NT released in parasympathetic stimulation of the AR cells and what receptor

A

AcH- muscarinic

88
Q

what does AcH do to AR cells

A

-decreases probability of F channel open
- increases probability of K+ channel opne
- hyperpolarizes Vm
- increases time to threshold
- decreases HR
- negative chronotropic agent

89
Q

what is the SA node spontaneous rate

A

about 100 bpm

90
Q

at rest what control is the heart under

A

parasympathetic

91
Q

what depolarizes contractile cells

A

signal from AR cells

92
Q

what are the phases of the action potential in contractile cells and what happens in each

A
  • phase 4 - resting Vm
    -phase 0 - depolarization spike, fast voltage gated Na+ channel open (both gates)
  • phase 1 - partial repolarization- fast VG Na+ channels close
    -phase 2- plateau, transient K+ channels close, L- type Ca2+ channels open
    -phase 3 - repolarization, L-type Ca2+ channels close, slow K+ channels open
93
Q

what ion depolarizes contractile cells

A

Na+

94
Q

Describe the steps of ECC in cardiocytes

A

-AP enters from adjacent cell
-VG Ca2+ channels open. Ca2+ enters the cell
-Ca2+ induces Ca2+ release through ryanodine receptor channels
-local release causes Ca2+ spark
-summed Ca2+ sparks create a Ca2+ signal
-Ca2+ ions bind to troponin to initiate contraction
-relaxation occurs when Ca2+ unbinds from troponin
- Ca2+ is pumped back into the sarcoplasmic reticulum for storage OR
-Ca2+ is exchanged with Na+
-Na+ gradient is maintained by the Na+ K+ ATPase

95
Q

how is contraction in skeletal muscle different than cardiac muscle

A

calcium in cardiac muscle can be pumped out of the cell or stored back in the SR. in skeletal muscle calcium can only be pumped out

96
Q

what is the difference between the AP and muscle tension in skeletal muscle and cardiac muscle

A
  • in skeletal muscle the AP ends before the contraction begins
  • in cardiac muscle the action potential lasts as long as the muscle contraction
97
Q

why is it important that the AP in cardiac muscle lasts as long as the contraction

A

it prevents summation and tetanus which we dont want in the heart

98
Q

describe cardiac muscle contractions

A

they are graded

99
Q

in the resting state when calcium is released from AP in cardiac cells do troponin sites get saturated

A

no

100
Q

what does the strength of contraction in cardiac cells depend on

A

calcium concentration

101
Q

what are inotropic agents

A

substances that alter the force of contraction of cardiocytes by changing caclium concentration in the cytosol

102
Q

what is the pathway of sympathetic control of contractile cells

A

-EPI and NE bind to B1 receptors
-B1 receptors activate cAMP second messenger system
-resulting in phosphorylation of VG Ca2+ channels and phospholamban
- resulting in more forceful contraction and shorter duration of action

103
Q

what does the cardiac cycle include

A

all the events involved with blood flow through the heart during one heart beat

Physiology (41 decks)

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