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259 - physiology > lecture 1: Guyton chapter 9 > Flashcards

lecture 1: Guyton chapter 9 Flashcards

1
Q

the heart is approximately the size of your…

A

fist

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2
Q

what is the location of the heart?

A

The superior surface of the diaphragm
Left of the midline
Anterior to the vertebral column, posterior to the sternum

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3
Q

true or false: the left and ride side of the heart are the same

A

false; they are anatomically and functionally separate

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4
Q

what does it mean for the heart to be a dual pump

A

right=lungs

left=systemic

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5
Q

what ensures that the blood from the left and right sides of the heart does not mix.

A

The interventricular septum

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6
Q

true or false: even if the left and right sides are separated, the heart contracts in a coordinated fashion.

explain

A

true

the atria contract together and the ventricles contract together….

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7
Q

the left side of the heart is coupled in…

A

parrallel

blood goes to diff capilaries depending on where its needed

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8
Q

the right side of the heart is coupled in …

A

series

only goes from heart lungs and back top heart

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9
Q

which side is a low pressure system

A

right side (doesn’t have to go as far)

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10
Q

which side is a high pressure system

A

left (pump oxygenated blood to entire body)

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11
Q

why is the left side a high pressure system

A

must overcome systemic pressure

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12
Q

explain the pathway of blood through the body

A

1) O2 deficient blood returns from body via sup and inf vena cava
2) enters right atrium
Tricuspid valve
3) enters right ventricle
4) goes to pulmonary artery
5) goes to lungs

6) blood is oxygenated
=PULMONARY CIRC.

7) blood comes back through pulmonary veins
8) blood goes to left atrium
Bicuspid valve
9) blood goes to left ventricle
10) blood goes to aorta

11) circulates to the body
=systemic circulation

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13
Q

what is the lining that covers the heart

A

pericardium

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14
Q

what is the pericardium

A

a double walled sac around the heart

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15
Q

what are the 2 layers of pericardium

A

1) superficial fibrous pericardium

2) a deep 2 layer serous pericardium

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16
Q

what are the 2 layers of the deep serous pericardium

A

parietal layer and visceral layer

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17
Q

where does the parietal layer line

A

the interal surface of the fibrous pericardium

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18
Q

where does the visceral layer line

A

lines the surface of the heart

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19
Q

what is another name for the visceral layer

A

the epicardium

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20
Q

what are the visceral and parietal layers separated by?

A

fluid filled pericardia cavity

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21
Q

what are the 3 functions of the pericardium

A

Protects and anchors the heart

Prevents overfilling of the heart with blood

Allows for the heart to work in a relatively friction-free environment

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22
Q

what allows for the heart to work in a relatively friction-free environment

A

the pericardial space that is fluid filled

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23
Q

what are the 3 types of cardiac muscle

A 
atrial muscle (the chambers that receive the blood)
ventricle muscle (chambers that eject
special excitatory and conductive muscle fibers
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24
Q

what is the difference between cardiac and skeletal muscle contraction

A

Atrial and ventricular types of muscle contract in much the same way as skeletal muscle
However, the duration of contraction is much longer

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25
Q

why is heart muscle contraction longer than skeletal muscle

A

heart needs time to fill after blood ejection

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26
Q

true or false: cardiac muscle is smooth

A

false its branched and striated

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27
Q

where is the nucleus of cardiac muscle

A

centrally located

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28
Q

what are muscle cells of the heart called

A

myocutes (cardiomyocytes)

or myofibrils

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29
Q

what is the outside membrane of the cardiac muscle called

A

sarcolemma

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30
Q

true or false: Cardiac muscles have the same arrangement of actin and myosin, and the same bands, zones and Z discs as skeletal muscles forming sarcomeres.

A

true that what make it striated

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31
Q

which has less sarcoplasmic reticulum: cardiac or skeletal

A

cardiac

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32
Q

where does cardiac muscle get its calcium from and why

A

from extracellular flued for contraction (they have large t tubyles)

beacuse lsss sarcoplasmic retulum

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33
Q

which has larger T tubule diamters: cardiac or sckeletal

A

cardiac (5 times greater diameter0

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34
Q

what does it mean for cardiac muscle to act as a syncytium

A

cardiomytocites are electrically connected to the next cell

coordinated contraction of muscles along their entire length

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35
Q

true or false: Cardiac muscle fibers are made up of many individual cells connected in series

A

false

in series AND and in parallel with one another

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36
Q

explain intercalated disks

A

cell membranes separating and anchoring individual muscle cells from one another
At each intercalated disc, the cell membranes have fused

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37
Q

at the intercalated disks, the cell mebranes are smoothe>

A

false

they are rough which allows for increased surface area

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38
Q

where is one cardiac cell connected to the other>

A

at the intercalated disk

39
Q

what are the fucntions of gap junctions

A

Gap junctions allow almost free diffusion of ions

Action potentials travel easily from one cardiac muscle cell to the next

40
Q

what helps speed the conduction of AP in heart muscle

A

the syncitum of main heart muscles

41
Q

true or false: there is an atrial and ventricle syncytium?

A

true

42
Q

explain atrial and ventricular syncytium

A

the atrial syncytium means that the conduction only occurs and diffuses through atrial cells

simular to ventricular

43
Q

true or false, the atrium and ventricle are separated

A

true by a fibrous tissue

44
Q

why is it importance that there is a dual syncytium for atrium and ventricles

A

allows atrium to contract a bit before ventricles (ventricles will be relaxed while blood flows from contracted atrium) to bill the heart with as much as possible)

45
Q

what does This division of the muscle of the heart into two functional syncytium allows

A

allows the atria to contract a short time ahead of ventricular contraction

46
Q

what does the myocardium consist of

A

interlacing bundles of cardiac muscle fibers arranged spirally around the circumference of the heart.

47
Q

what is the advantage of the bundles being spiral

A

the cardiac muscle contracts & shortens, a twisting effect is produced, efficiently pushing blood upwards towards the exit of the major arteries of the heart.

48
Q

what is the AP in ventricular muscle fiber

A

-85 mV

49
Q

after initial spike, the membrane remains depolarized for 0.2 s, what does that cause?

A

plateau

50
Q

what does the presence of this plateau in the AP cause in terms of ventricular contraction>

A

ventricular contraction to last as much as 15 times as long in cardiac muscle as in skeletal muscle

51
Q

what are the 5 phases of action potenial in cardiac muscles

A

phase 0: membrane is depolarixe by fast NA channels and slow CA channel

phase 1: K+ cahnnels open once the mebrane is positive
=begining to repolarize

phase 2: platuea occurs because efflux of K+=influx of ca+

phase 3: K+ channels open alow and membrane repolaises

phase 4: resiting membrane potential

52
Q

the cardiac cycle consists of

A

diastole and systole

53
Q

what is diastole

A

of a period of relaxation (diastole) during which the heart fills with blood and the cardiomyocytes re-establish the Na+/K+/Ca2+ gradient

54
Q

what is systole

A

contraction

ejects blood

55
Q

what is each cardiac cycle initiated by

A

initiated by a spontaneous generation of an action potential in the sinus node
=special excitatory cells depolarize by themsevles

56
Q

the AP is conducted where

A

in the atria, the AV bundles and the venetcles

57
Q

true or false: there is A delay of more than 0.1 sec during passage of the cardiac impulse from the atria to contract ahead of ventricular contraction

A

yes and that causes

Thus atria pump more blood into the ventricles prior to ejection

58
Q

true or false: blood does not flow continually from vena cava to atria

A

false, blood flows continually

59
Q

what percentage of blood flows directly through the atrai into ventricels even before contraction

A

80%

60
Q

atrial contraction causes an additional BLANK to fill the ventricles

A

20% filling of blood

61
Q

what is the a wave caused by

A

pressure change in atria caused by atrial contraction

62
Q

what is the c wave occur

A

occurs when ventricles begin to contact

pulls a bit on the atrium as well since they are attached so affects pressure

63
Q

when does v wave occur

A

towards the end of ventricular contraction

because as it relaxes, sicne it is attached to the atrium, it causes the pressure oin the atrium to change

64
Q

true or false: walls of the atria are thicker than walls of the ventricles and why

A

false, ventricles are thicker because they are ejecting blood

65
Q

which wall is thicker: left or right ventricle

A

left is thicker because it is a high pressure system

66
Q

when does aortic pressure start to increase

A

during systole after the aortic valve opens

67
Q

when does aortic pressure decrease

A

towards end of ejection pahse

68
Q

what is the relationship between aortic pressure and ventricular volume

A

as aortic pressure increases, ventricular volume decreases

69
Q

after the aortic valve closes, what develops and why

A

incisura develops due to a sudden back-flow towards the left ventricle
(pulse wave gets bounced off by systemic resistance

70
Q

what does the insura supply

A

the back flow supplies the heart

71
Q

Why does aortic pressure start to decrease during diastole?

A

elasticity of the aorta

72
Q

why is it important to always have some blood in the ventricles

A

1) makes it easier to refill for next cardiac cycle

2) w/o blood, ventricle could colapse

73
Q

explain why as volume is increase in the ventricle, pressure isn’t increase in ventricle

A

heart is expanding

74
Q

what is the end diastolic volume

A

when the heart is filled with blood

=preload

75
Q

at a given volume, after the heart filled, what happens

A

isovolumic contraction (ie./ ventricle contracts, pressure is building,

76
Q

during the period of ejection, is pressure constant ?

A

Almost constant but not really because the heart needs to contract against a lesser and lesser amount of blood

77
Q

what is the end systolic volume

A

after load (all the blood has been ejected)

78
Q

what happens after all the blood has been ejected

A

isovolumic relaxation, ventricles relax so pressure decreases

79
Q

what is ejection volume (stroke volume)

A

end diastole-end systolic

80
Q

what is the ejection fraction

A

stroke volume/diastolic

81
Q

what are normal ejection fraction values

A

50 - 60% at rest; > 80% during exercise and < 40% during disease

82
Q

what is the frank starling mechanism

A

An intrinsic ability of the heart to adjust and adapt the volume change of blood

83
Q

explain the frank starling mechanism

A

Within physiological limits the heart pumps all the blood that returns without excessive damming in the veins.

Extra stretch on cardiac myocytes makes actin and myosin filaments find a more optimal degree for force generation.

=ribber band effect forces blood out and not contractility

84
Q

true or false: the heart only contract s sympathetic nerves

A

false, it has parasympathetic nerves (mostly valgus nerve)

85
Q

where is the parasympathetic nerves located

A

around the atrium

86
Q

explain the function of the parasympathtic nerves

A

relaxes the heart rate (since contraction happens in atrium)

87
Q

explain the sympathetic nerves

A

effects hr and contractility (how forceful)

88
Q

excitation of the heart happens by what nerves

A

sympathetic nerves

89
Q

what can the excitation of the heart do to the heart rate

A

go from 70 to 180-200

90
Q

true or false: sympathetic nerves only affect the HR

A

false, Sympathetic stimulation also increases the force of heart contraction to as much as double, thereby increasing the volume of blood pumped.

91
Q

Under normal conditions, sympathetic nerve fibers to the heart discharge BLANK at a slow rate which causes…

A

continuously

This maintains pumping at about 30% above ‘normal’ heart rate with no sympathetic stimulation

92
Q

true ro false: Strong parasympathetic stimulation (PS) can stop the heart for a few seconds

A

true

93
Q

at rest, what is responsible for beating rest

A

parasympthetic

94
Q

where are the vagal fibers mainly distributed

A

to the atria and not much to the ventricles (where power of contraction occurs

259 - physiology (21 decks)

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