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Physiology Test Two > cardiac > Flashcards

cardiac Flashcards

1
Q

name the two coverings of the heart?

A

pericardium
epicardium

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2
Q

name the three functions of the pericardium?

A

protect the heart
anchor the heart to surrounding structures
prevent the heart from over filling with blood

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3
Q

describe the epicardium?

A

a thin, slippery membrane that turns inward at the base of the heart and lines the external surface of the heart

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4
Q

what is the pericardial space?

A

The space between the pericardium and epicardium that fills with serous fluid allowing the two layers to glide past one another during normal cardiac functions

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5
Q

Name the three layers of the heart wall from outer to inner?

A

epicardium (outer)
Myocardium (middle layer of muscle tissue)
Endocardium (inner layer)

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6
Q

The endocardium contains a thin layer of ______ _______ that is covered by a thin sheet of __ __ cells that line the chambers and is continuous with blood vessels that enter and leave the heart.

A

connective tissue

squamous epithelial

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7
Q

The heart has how many chambers?

A

4

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8
Q

How many atria and ventricles?

A

2 atria
2 ventricles

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9
Q

Describe the function and structure of the atria?

A

Function: The atria are the receiving chambers for blood returning to the heart from the systemic and pulmonary circulation.
Structure: They are smaller chambers with thin walls that contract generating minimal pressure.

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10
Q

Describe the function and structure of the ventricles?

A

Function: Provide the pressure needed to push blood throughout our entire body.
Structure: they make up the bulk of the heart, meaning they have thicker walls b/c they generate a higher pressure

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11
Q

describe the structure of the pericardium?

A

The out fibrous layer composed of tough dense connective tissues

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12
Q

describe the blood flow through the heart?

A

right atrium-right tricuspid valve-right ventricle-pulmonary valve-pulmonary circulation-left atrium-left bicuspid valve-left ventricle-aortic valve-systemic circulation- then start over back at the right atrium

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13
Q

name the three sources of blood supply that empty into the right atrium?

A

superior vena cava (body regions superior to the diaphragm

inferior vena cava (body regions inferior to the diaphragm,

coronary sinus (blood from the heart)

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14
Q

What is the goal of the heart valves?

A

to maintain unidirectional blood flow throughout the heart.

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15
Q

What are the atrioventricular valves?

A

Valves located between the atria and the ventricles

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16
Q

The AV valves prevent what from happening?

A

keep blood from flowing from the ventricles into the atria, while the ventricles are contracting

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17
Q

The left AV valve is called the ?

A

bicuspid valve

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18
Q

the bicuspid valve has how many cusps? and is also known as the?

A

2 cusp

Mitral Valve

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19
Q

The AV valves are attached to ____ ____ which are attached to _______ muscles.

A

chordae tendineae

papillary muscles

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20
Q

what is the purpose for the AV valves being attached to the chordae tendineae?

A

To provide strength and reinforcement to keep the valves closed when pressure builds up within the ventricles.

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21
Q

Describe the AV valve position as blood flows from the atria to the ventricles and from the ventricles to the systemic circulation

A

The av valves hang limply when blood is flowing through the atria into the ventricles and closed when the ventricles are contracting.

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22
Q

What are the valves located between the ventricles and the large arteries called? and name the two valves?

A

semilunar valves

aortic and pulmonic valve

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23
Q

The right semilunar valve is the _______ valve.

A

pulmonic

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24
Q

the left semilunar valve is the _____ valve.

A

aortic

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25
Q

The semilunar valves are shaped like a?

A

crescent moon

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26
Q

the semilunar valves have how many cusps?

A

three

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27
Q

describe the position o the semilunar valves during ventricular contraction and relaxation?

A

The semilunar valves are open during ventricular contraction and when the ventricles relax blood flows back from the arteries and fills the cusps at the semilunar valves forcing them closed.

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28
Q

How many types of cells are involved in the contraction of the heart? Name them.

A

2

contractile cells

auto-rhythmic cells

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29
Q

The most abundant cell type involved in the contraction of the heart is? they make up about ____% of the heart cells and are primarily involved in contraction

A

myocardial contraction cells

99%

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30
Q

Describe pacemaker or auto-rhythmic cells

A

These cells are involved in the intrinsic electrical conduction system that is mostly responsible for initiating and conducting the action potential responsible for contraction.

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31
Q

does pacemaker or auto-rhythmic cells contract?

A

no, but they are responsible for allowing the contractile cell to continue to function normally.

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32
Q

what are the slow and fast response cells in the heart?

A

slow: autorhythmic cells
fast: contractile cells

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33
Q

describe how cardiac muscle is similar to the skeletal muscle?

A

it contracts by the sliding filament mechanism, which consists of thin filaments (which are polymers of actin, troponin, and tropomyosin) sliding over stationary thick filaments like myosin, thereby shortening the length of the muscle

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34
Q

Cardiac cells are short _____ _____ cells with _____ nuclei.

A

striated branched
one or at most two nuclei

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35
Q

Individual cardiac muscle cells are interconnected and held together at their ends by specialized junctions called?

A

intercalated disc

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36
Q

not only are the plasma membranes interlocked, but president intercalated discs are ______ and ______.

A

desmosomes and gap junctions

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37
Q

describe desmosomes function?

A

mechanically hold cells together

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38
Q

describe gap junctions function?

A

electrically couple adjacent cells, allowing action potentials to spread from 1 cell to adjacent cells.

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39
Q

contractile cells have lots of _______ and use ____ ____ as primary source of energy.

A

mitochondria

Fatty acids

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40
Q

________ from both the extracellular fluid and the sarcoplasmic reticulum , initiate a cascade of events resulting in contraction.

A

Calcium

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41
Q

This coupling of electrical impulse to contraction is called?

A

excitation contraction coupling

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42
Q

Contraction of myocardial contractile cells is triggered by what?

A

A complete reversal in membrane potential and basically an action potential triggers a set of events that results in myocardial contractions.

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43
Q

describe sliding filament theory?

A

Step 1: Once calcium (key) is bound to troponin-C (lock) and the conformational change of tropomyosin (bike Chain) has occurred allowing myosin (person) being capable to bind to actin (bike)

Step 2: ATP can bind to the myosin head allowing the binding to actin filament.

Step 3: The ATP is hydrolyzed into ADP and inorganic phosphate. Following this ADP and inorganic phosphate are released from the myosin head so the power stroke can occur.

Step 4: In this the myosin head pivots and bends, pulling on the actin and moving it, causing muscle contraction.

Step 5: After this occurs a new molecule of ATP binds to the myosin head, causing it to detach from the actin.

Step 6: Following this, the cycle can begin again and further contraction can occur.

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44
Q

name two places calcium comes from in order to cause a cardiac contraction?

A

extracellular fluid and the sarcoplasmic reticulum

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45
Q

The membrane potential of contractile cells remains essentially at about _______ unless there is an input from an outside signal.

A

-90

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46
Q

Contractile cells are stimulate by ____ _____ channels that open allowing a influx of ______ ions which depolarize the cell.

A

fast sodium

sodium

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47
Q

The action potential results in a complete reversal of the membrane potential, so it is going from -90 to ____ millivolts

A

+30

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48
Q

The fast sodium channels are only very briefly and are quickly inactivated by the ______ _____ ____.

A

positive membrane potential

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49
Q

Once the sodium channels close, what channels open and what happens?

A

fast potassium channels open, resulting in an efflux of potassium and slight depolarization as the membrane potential becomes slightly less positive.

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50
Q

following the fast potassium channels opening, what channels open? and what happens?

A

the slow L-type calcium channels are then activated and opened. Then calcium enters the cells from the extracellular fluid and the sarcoplasmic reticulum.

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51
Q

what prolongs the positive membrane potential inside the cell known as the plateau portion of the action potentials?

A

The continued influx of calcium

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52
Q

Why is the potassium channels slowly closing during the plateau portion of the cardiac contractile cell action potential graph?

A

preventing rapid repolarization of the membrane potential

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53
Q

during the down swing on the graph for cardiac contracticle cells depicting rapid depolarization, what is occuring?

A

calcium permeability is reduced by inactivation of calcium channels and the potassium channels are activated promoting a record rapid outward diffusion of potassium ions resulting in the repolarization of the cells and the restoration of the resting membrane potential

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54
Q

How long is the action potential of a cardiac contractile cell?

A

250 milliseconds

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55
Q

what is the absolute refractory period? what causes this?

A

The period known as the action potential (250 milliseconds) when a second action potential cannot be triggered until an excitable membrane has recovered from the action potential.

the sodium channels being incapable of opening so shortly after activation.

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56
Q
A
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57
Q

the absolute refractory period prevents what?

A

subsequent rapid contraction and provides enough time for the ventricles to fill with blood between contractions, and prevents tetanic contraction (which is when a muscle stays in contracted state for too long.

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58
Q

what is the maximum heart rate is _____ beats per second, _____ beats per minute

A

4 beats per second

240 beats per minute

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59
Q

say the acronym for the cardiac contractile cell’s action potential and describe the process

A

Summit- Sodium channels open and allow an influx of sodium ions which depolarizes the cell, resulting in a complete reversal of the membrane potential from -90 to +30. Sodium channels are innactivated by the positive membrane potential

Plummet - Fast potassium channels open, resulting in an efflux of potassium and slight repolarization of the membrane potential

Continue -Slow L-type calcium channels are then activated and open, calcium enters the cells from the extracellular fluid and the sarcoplasmic reticulum. The continued influx of the calcium prolongs the positive membrane potential. Potassium channals slowly closing.

Plummet - Calcium channels are closed and potassium channels open wide and promote a rapid outward diffusion of potassium ions resulting in repolarization of the cells and restoration of the resting membrane potential.

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60
Q

_____ enters the cytoplasm of the cell and binds to the troponin-tropomyosin complex that resides in active polymer of the thin filaments.

which allows ______ to form cross bridges

A

Calcium

myosin

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61
Q
A
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62
Q

During the plateau phase of the cardiac contractile cell’s membrane potential, when cytosolic ______ levels are high and a contraction occurs for the same amount of time the levels are high in the cell.

A

calcium

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63
Q

when calcium channels open after the efflux of potassium following the initation of the action potential, the influx of extracellular calcium triggers what? this process is called what?

A

the opening of a special subset of calcium channels in the membrane of the sarcoplasmic reticulum.

calcium induced calcium release

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64
Q

Calcium induced Calcium Released ensures what?

A

a dramatic increase in cytosolic calcium sufficient to stimulate contraction. Higher levels of calcium stimulates a stronger contraction.

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65
Q

Cardiac autorhythmic cells are also known as?

A

pacemaker cells

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66
Q

Cardiac autorhythmic cells have an unstable resting membrane potential that leads to _____ _____ ______.

A

spontaneous action potentials

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67
Q

Describe the Cardiac Autorhythmic Cells Action Potential Cycle

A
  1. Pacemaker potential - The membrane potential slowly depolarizes (less negative than the resting potential), caused by a slow leak of sodium through voltage gated sodium channels, allowing sodium ions to enter the cell. The potassium channels are closed reducing the efflux of calcium. The potassium piling up in the cell and sodium coming into the cell increases the positive membrane potential until it reaches threshold.
  2. Once the depolarization reaches a critical level known as threshold (which occurs at -55 to -50mV), and explosive depolarization or action potential can take place. Meaning the action potential spreads throughout the heart, triggering the myocardial contractile cells to contract. This occurs, because at threshold voltage gated calcium channels (L-Type Calcium channels ) open allowing the influx of calcium producing the exposive positive membrane potential.
  3. Once the positive membrane potential of 0 mV is reached the calcium channels close and the potassium channels open, and potassium flows out of the celll causing the membrane potential to repolarize.
  4. Once repolarization has occured (-60 mV) potassium channels clos and depolarization to threshold begins again.
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68
Q

action potential for the pacemaker cells is from what mV to what mV?

A

-55/-50 to 0

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69
Q

what type of calcium channels open during the pacemaker action potential?

A

L-type Calcium channels, L for long lasting

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70
Q

what is the mV threshold for pacemaker cells?

A

-55 to -50

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71
Q

what is the range for slow depolarization for pacemaker cells?

A

-60 to -55/-50

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72
Q

The pacemaker cells of the heart are located at specialized sites in the heart, which are?

A

SA node

AV node

AV bundle

Right and Left Bundle branches

Purkinjie fibers

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73
Q

where are the purkinje fibers located?

A

in the ventricular walls

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74
Q

depolarization waves spread from one pacemaker cells to another via ____ ______ through a specialized conduction system.

A

gap junctions

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75
Q

The depolarization of the heart from pacemaker cells follows what route through the heart?

A

SA node-AV node-Bundle of HIS- Right and Left Bundle Branches- purkinje fibers

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76
Q

the SA nodes typically generates ____ depolarizations or heart beats per minute ____ to ____.

A

75 depolarizations

60-100 beats per minute

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77
Q

The sinoatrial node is a ____ shaped region. Located where?

A

crescent shaped region

right atria wall near opening of SVC

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78
Q

The SA node set of cells act as the pacemaker cells because why?

A

Because they generate the highest frequency of impulses

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79
Q

From the SA node the depolarization moves through the atria to the _____ ______.

A

AV node

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80
Q

The AV node is a small bundle of cells located at the base of the _____ _____ near the septum above the _____ _____.

A

right artium

tricuspid valve

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81
Q

There is less than ____ second delay at the AV node. Why?

A

0.1 second

Allowing atria to complete their contraction before the impulse travels into the ventricles.

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82
Q

The 0.1 second delay at the AV node occurs due to what?

A

fewer gap junctions in this section of tissue, slowing the conduction

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83
Q

The impulse spreads from the AV node to the?

A

Bundle of HIS (AV Bundle)

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84
Q

The AV bundle is located in the upper ______ _______.

A

intraventricular septum

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85
Q

The AV Bundle separates into the right and left _____ _____ and travels down the septum toward the apex.

A

bundle branches

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86
Q

The right and left bundle branches lead into the _____ _____ at the apex.

A

purkinje fibers

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87
Q

The purkinje fibers project into the _______ ________ like twigs of a small branch

A

ventricular myocardium

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88
Q

In a normal heart the total time between the firing of the SA node and ventricular depolarization is how many milliseconds?

A

220 mS

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89
Q

The AV node depolarizes how many times per minute?

A

50 times per minute

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90
Q

AV Bundle and Purkinje Fibers depolarized how many times per minute?

A

30 times per minute

91
Q

The AV Node, AV Bundle and Purkinje Fibers are back up systems meaning what?

A

meaning they will maintain the heart rate in the event that the faster pacemaker become dysfunctional.

92
Q

Ventricular contraction occurs how soon after depolarization?

A

almost immediately

93
Q

Because depolarizaiton moves down the intraventricular septum then to the apex then moves along free ventricular walls toward the atria, this causes the heart to contract from the _____ to the _____, meaning blood is ejected superiorly into what?

A

apex to the base

large arteries leaving the ventricles

94
Q

The cardiac cycle begins and ends with what phase?

A

ventricular diastole

95
Q

Blood flow through the heart is controlled by ____ _____ and blood flows down a pressure gradient through any available opening.

A

pressure changes

96
Q

The pressure changes in the cardiac cycle reflect the alternating ______ and _____ of the myocardium and direct heart valves to open or close, which maintains what?

A

contraction and relaxation

the unidirectional blood flow through the heart.

97
Q

The term systole and diastole refer to the activity of the ______.

A

ventricles

98
Q

How many phases in the cardiac cycle?

A

three

99
Q

Phase one of the cardiac cycle is what?

A

ventricular filling which is mid to late diastole for the ventricles, and involves the atria contracting.

100
Q

during phase 1 the aortic and pumonary valves are ______.

A

closed

101
Q

during ealy ventricular diastole (phase 3) what is happening?

A

the blood is passively flowing from the venous system through the atria and open AV valves into the ventricles. Both the atria and the ventricles are relaxed and the volume in the ventricles is slowly filling

102
Q

during phase three (early diastole of the ventricles) how much ventricular filling occurs?

A

80%

103
Q

In Phase 1 the ventricles continue to fill until the pressure build causing what?

A

AV Valves to close

104
Q

during the late phase of ventricular diastole (Phase 1) the SA node membrane potential reaches the threshold and what occurs?

A

fires an action potential atrial depolarization triggers atrial contraction which forces more blood into the ventricles

105
Q

how much blood is pushed into the ventricles witht he atria kick?

A

20%

106
Q

What is the EDV?

A

the end diastolic volume, the volume of blood in the ventricle at the end of diastole

107
Q

are the atria contraction in phase 2 or phase 3?

A

no

108
Q

during what phase is the atria contracting?

A

phase 1

109
Q

Phase two of the cardiac cycle is known as what?

A

ventricular systole

110
Q

describe what happens in phase two of the cardiac cycle?

A

at this point the action potential has spread into the ventricles and they begin contracting, the pressure inside the ventricles rises sharply and rapidly closing the AV valves. The pressure continues to rise and exceeds the semilunar valves causing them to open, and blood is ejected from the ventricles inot the aorta and the pulmonary artery. The ventricles pressure peaks during this phase

111
Q

for an instant in phase 2 of the cardiac cycle knonw are ventricular systole, the ventricles are completely closed chambers which is called?

A

isovolumetric contraction phase

112
Q

When blood is ejected from the ventricles into the aorta and the pulmonary arteries, this is known as?

A

Bentricular ejection.

113
Q

ventricular pressure peaks during which phase?

A

phase II

114
Q

Phase three of the cardiac cycle is known as what?

A

isovolumetric relaxation phase

115
Q

Describe what happens in phase three of the cardiac cycle?

A

The ventricles begin to relax and for a brief moment, ventricular pressure drops and blood pressure in the aorta and PA force the semilunar valves closed, creating isovolumetric relaxation b/c the AV valves are still closed as well.

116
Q

What is ESV? describe it?

A

End systolic Volume, the amount of blood in the ventricles at the end of systole

117
Q

What is Isovolumetric relaxation? It occurs during which phase?

A

During phase III, when the ventricles relax and blood pressure in the aorta and PA force the semilunar valves closed and the AV valves are still closed.

118
Q

All during ventricular systole the atria have been in _____ and blood has been?

A

diastole, and blood has been flowing into them and the pressure has been rising.

119
Q

once the pressure in the atria has exceeded the pressure inside the ventricles, what happens?

A

the AV valves are forced open, beginning ventricular filling again.

120
Q

the length of the cardiac cycle is less than ____ seconds?

A

1 second

121
Q

what is cardiac output?

A

the volume of blood pumped by the ventricle per minute

122
Q

The cardiac output of each ventricle must be what?

A

the same

123
Q

Cardiac output is determine by what?

A

the heart rate x stroke volume

124
Q

The stroke volume is what?

A

the volume of blood the heart pumps per beat or per stroke

125
Q

The average heart rate is?

A

75 bpm

126
Q

the average stroke volume is ?

A

70 mL/beat

127
Q

The average cardiac output is?

A

75 bpm x 70 mL/beat = 5.25 L/minute

128
Q

cardiac output can dramatically increase during exercise up to ___ to ____ liters per minute

A

20 to 25 liters per minute

129
Q

What is the cardiac reserve?

A

The difference between the cardiac output at rest and the maximum cardiac output

130
Q

The reason the cardiac output can vary dramatically is because?

A

the heart rate and stroke volume can vary greatly.

131
Q

heart rate is primarily controlled by what?

A

the pacemaker cells of the SA node

132
Q

The heart rate is innervated by the ____ and _____.

A

SNS and PSNS

both divisions of the ANS innervate the SA and AV nodes

133
Q

PSNS will ____ the heart rate.

A

decrease

134
Q

What is released by the Vagus nerve fiber?

A

Acetylcholine

135
Q

The vagus nerve is a part of the _____ nervous system.

A

parasympathetic

136
Q

Acetylcholine binds to _____ receptors.

A

muscarinic receptors

137
Q

when acetylcholine binds to muscarinic receptor adn is coupled to ____ ______, which reduces what?

A

inhibitory G-Protein Coupled Receptors

reduces adenylate cyclase activity and reduce cAMP production

138
Q

how does acetylcholine slow the heart rate?

A

by increasing potassium permeability of the pacemaker cells of the SA. and AV node, meaning potassium leaves the cell, making the membrane potential more negative which makes the membrane potential is even further away from the threshold and decreases the rate of spontaneous depolarization.

The time required to drift to threshold is increased which decreases the heart rate.

139
Q

Muscarinic receptor is coupled directly to a _____ channel.

A

potassium channel

140
Q

SNS will ____ the heart rate.

A

increase

141
Q

Norepinephrine binds with _____ adrenergic receptors to increase the heart rate.

A

Beta 1

142
Q

Beta 1 receptor are coupled to a ________ _______.

A

stimulatory GPCr

143
Q

The Beta 1 receptor coupled w/ a stimulatory GPCr does what?

A

increases the activity of adenylate cyclase and increase cAMP production in the SA and AV Nodes, as well the pacemaker cells located in the ventricles.

144
Q

In the pacemaker cells, the SNS increases the heart rate by?

A

increased permeability of Na and Calcium increasing the slope of the membrane potential so the cells reach the threshold potential more quickly, the inside of the cell is more positive, depolarizing the membrane potential.

Increases the speed of contraction, by allowing a greater influx of CA through L-type of Calcium channels, and enhances the removal of Calcium ions from the cytosol so that relaxation occurs more rapidly following the contraction.

145
Q

AT rest the _____ nervous system dominates our heart rate

A

PSNS

146
Q

The stroke volume is the difference between what?

A

EDV-ESV.

147
Q

on average the EDV is

A

120 mL

148
Q

on average the ESV is around?

A

50 mL

149
Q

The ventricles pump approximately __% of blood in its chambers?

A

60%

150
Q

Stroke volume is primarily influenced by three factors which are?

A

preload

contractility

afterload

151
Q

The heart and blood vessels are controlled to provide the cardiac output and arterial pressure needed to supply?

A

adequate tissue blood flow

transport nutrients to tissues

Transport waste away

Transport hormones

152
Q

circulation system is divided into two systems which are?

A

systemic and pulmonary circulation

153
Q

the systemic circulation does what?

A

moves blood between the heart and the rest of the body

154
Q

the pulmonary circulation does what?

A

moves blood between the heart and the lungs

155
Q

what is the function of the arteries?

A

transport blood under high pressure to the tissues

156
Q

why does arteries have strong vascular walls?

A

the arteries are under high pressure and high velocity

157
Q

What is the function of the arterioles?

A

They act as control conduits through which blood is released into our capillaries,

158
Q

arterioles have strong muscular walls which can do what?

A

close the arterioles completely or by relaxing can dilate the vessels several fold, meaning they can vastly alter blood flow in each tissue in response to its needs.

159
Q

what is the function of the capillaries?

A

to exchange fluid, nutrients, electrolytes, hormones, and other substances between the blood and interstitial fluid

160
Q

The capillary walls are _____ and have numerous minute ____ ____ that are permeable to water and other small molecular substances.

A

thin

capillary pores

161
Q

what is the function of the venules?

A

function as conduits to transport of blood from the venules back to the heart

162
Q

What is the function of the vein?

A

serve as a major reservoir of extra blood

163
Q

why is the venous walls thin?

A

because the pressure in the venous system

164
Q

even though the veins have thin walls, they are muscular enough to contract or expand to serve as a ?

A

controllable reservoir for the extra blood, either a small or large amount depending on the needs of our circulation.

165
Q

Demands are not met by the heart alone but along with _____ and _____ ___.

A

microvessels and nervous system

166
Q

Blood flow to most tissues is controlled according to the ______ needs.

A

tissues

167
Q

Cardiac output is the sum of all the?

A

local tissue flows

168
Q

when tissues are active, they need increased supply of nutrients and therefore more ______.

A

blood flow

169
Q

blood pressure is dependent on what three factors?

A

blood viscosity

vessel length

vessel diameter

170
Q

blood circulation is dependent on three factors which are?

A

blood flow

blood pressure

and resistance

171
Q

blood flow is what?

A

the volume of blood flowing through vessel in a given time period.

172
Q

blood flow is measured in?

A

mL/min

173
Q

blood pressure what?

A

the force of blood exerted on the vessel wall

174
Q

blood pressure is measured in?

A

mmHg

175
Q

Resistance is what?

A

the opposition of blood flow as it moves through a vessel

176
Q

The most occurs at the level of the __________ in the peripheral circulation.

A

arterials

177
Q

The resistance at the level of the arterials is known as?

A

total peripheral resistance

178
Q

the three factors that influence resistance are (3)?

A

blood viscosity

vessel length

vessel diameter

179
Q

what is the blood viscosity?

A

the internal friction that exists in all fluid as the molecules slide over each other during the flow of fluid

180
Q

The greater the viscosity the ____ the resistance to flow.

A

greater

181
Q

blood viscosity is primarily determined by?

A

the number of circulating red blood cells.

182
Q

when red blood cell count increases the viscosity and resistance is ___________.

A

increased

183
Q

The longer vessel length results in ________resistance.

A

greater

184
Q

Obese individuals have a ___________ in their vessel length.

A

increase, thus their resistance is increased, and they increased number of smooth muscle cells surrounding the vasculature decreasing the vessel diameter and increasing their resistance.

185
Q

Viscosity and vessel length remain relatively _________.

A

constant

186
Q

the major determinant of resistance is?

A

vessel diameter

187
Q

fluid passes through a ____ vessel more eaily than a _____ vessel. (vessel diameter)

A

larger

smaller

188
Q

In a small radius vessel, more of a given volume of blood comes into contact with much more of the surface area than in a larger radius vessel, resulting in a ______ friction and resistance

A

greater

189
Q

radius is directly proportional to _____ of the resistance

A

1/4

190
Q

doubling the radius reduces the resistance to _____ its orginial value and increases the flow through the vessel ____fold

A

1/16th

16 fold.

191
Q

Blood flow through a blood vessel is determined by which two factors?

A

pressure difference

resistance

192
Q

pressure difference is also known as?

A

pressure gradiant

193
Q

What is pressure difference?

A

P1-P2=pressure difference

P1= the pressure at the origin of the vessel

P2= pressure at the end of our vessel

194
Q

Resistance occurs as a result of what?

A

friction between the flowing blood and the intravascular endothelial all along the inside of the vessel

195
Q

Blood flow is inversely proportional to?

A

peripheral resistance

196
Q

as you have an increase in the pressure difference, you are going to have a _____ in blood flow?

A

increase

pressure difference and blood flow are directly proportional

197
Q

as you have an an increase in resistance, you are going to have a _____ in blood flow

A

decrease

198
Q

blood flow is opposed by _____.

A
199
Q

systemic resistance is the highest in the _____ and decreases to nearly _____ as it approaches the right atrium.

A

aorta

0

200
Q

blood moves along a ______ _____ meaning from an area of higher pressure ot lower pressure area.

A

pressure gradiant

201
Q

what is the diastolic pressure measuring?

A

the lowest aortic pressure, which is after the aortic valve closes, the elastic aorta recoils maintaining sufficient pressure to keep blood flowing florward in the distal vesslels and the aortic pressure drops to the lowest.

202
Q

blood pressure is influenced by how elastic the arteries near the heart and the volume of blood ____ and _____ the artery

A

entering and leaving

203
Q

The pulse pressure is what?

A

SBP-DBP= pulse pressure

204
Q

as blood moves further away from the heart the pulse pressure _____.

A

narrows

205
Q

is MAP or SBP a better indicator of perfusion to the vital organs?

A

MAP

206
Q

what is the equation for MAP?

A

1/3 SBP + 2/3DBP=MAP

207
Q

The three major blood pressure regulators are?

A

cardiac output

peripheral resistance

blood volume

208
Q

the mechanisms that regulate blood pressure are separated into two categories known as?

A

short term and long term neural mechanisms

209
Q

short term or faster controls of blood pressure, control blood pressure by altering ____ and ____.

A

PVR and CO

210
Q

Short term mechanisms (neural control) control blood pressure by altering PVR and CO, but this is achieved two ways which are?

A

Vasoconstriction

heart rate

211
Q

Neural controls of the vasomotor center recieve input from three places which are?

A

baroreceptors, chemoreceptors,and higher brain center

212
Q

what is the vasomotor center, where is it located, and what does it do?

A

a cluster of nerves located in the medulla oblongata of the brainstem and they transmit signals along the sympathetic efferent nerves regulating blood pressure through vasoconstriction

213
Q

Where are the baroreceptors located in the body?

A

in the aortic arch and in the walls of nearly every major artery in the neck and thorax.

214
Q

if the baroreceptors are stretched they send signals to the _____ _____ to do what?

A

the vasomotor center

to vasodilate and reduce the PVR and subsequently decrease BP

215
Q

A decrease in blood pressure causes the baroreceptor to send signals to the ________ _____ to do what?

A

vasomotor center

vasoconstric and increase CO to increase BP back to normal

216
Q

chemoreceptors are located where and do what?

A

located in the aortic arch and the large arteries of the neck and measure oxygen and pH of the blood

217
Q

given an example of a higher brain center that affects the vasomotor center?

A

hypothalamus

218
Q

long-term mechanisms use the _____ system to control blood pressure.

A

renal

219
Q

long-term mechanisms using the renal system control blood pressure by controlling _____ _____.

A

blood volume

220
Q

blood volume is a major determinant of cardiac output through its influence on what three things?

A

venous return

end-diastolic volume

stroke volume

221
Q

the kidneys control blood pressure by releasing _____.

A

renin

222
Q

renin release triggered by low blood pressure, causes a cascade of events that produce?

A

angiotensin II

223
Q

low blood pressure stimulates the RAAS system, describe it

A

kidneys-renin

liver-angiotensinogen

renin+angiotensinogen=angiotensin I

angiotensin I goes to the lungs and the ACE converts it to angiotensin II

angiotensin II is a potent vasoconstrictor, stimulates the adrenal cortex to produce aldosterone (which causes renal absorption of sodium), stimulates the posterior pituitary gland to produce ADH (which causes the kidneys to promote water reabsorption).

Thus, the net results the two hormones promote sodium and water reabsorption to increase blood volume and blood pressure.

224
Q
A

Physiology Test Two (3 decks)

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