Cardiac Output, Venous Return, and Their Regulation

Question 1

cardiac output

Answer 1

quantity of blood pumped into the aorta or into the pulmonary artery every minute by the heart and blood flowing through the circulation

Question 2

venous return

Answer 2

Quantity of blood flowing from the vein to the atrium each minute.

Question 3

t/f cardaic putput = venous return

Answer 3

true

Question 4

Factors affecting cardiac output

Answer 4

Level of metabolism
Age
Size of the body
Exercise level
Cardiac index

Question 5

Control of cardiac output by venous return Frank-Starling mechanism

Answer 5

increased quantity of blood flows into the heart = increased stretch of the walls of heart chambers = increased force of muscle contraction = emptying of the chambers

Question 6

Bainbridge reflex, cardiac output by increasing heart rate, how does it work?

Answer 6

acts on the vasomotor center stimulating SNS and PNS increasing heart rate
this helps to pump blood from the heart

Question 7

Increased amount of blood in the chambers causes stretching o and affects

Answer 7

sinus node in the right atrium affecting the rhythmicity of the heart

Question 8

the venous return to the heart is the sum of

Answer 8

All the local blood flows through all the individual tissue segments of the peripheral circulation.

Question 9

what regulates blood locally in the tissues?

Answer 9

metabolism
O2

Question 10

t/f cardiac output is determineed by the sum of all factors that regulate blood flow

Answer 10

true

Question 11

hyper-effective cardiac function is affected by

Answer 11

Nervous stimulation
hypertrophy
SNS stimulation
PSNS inhibition

Question 12

hypo-effective cardiac function is affected by

Answer 12

Nervous inhibition
disease
valvular heart disease
hypertension (increased AP)
congenital heart disease
myocarditis
cardiac anoxia
myocardial damage due to toxins

Question 13

Hypertrophy of heart occurs due to

Answer 13

Caused by increased workload = increase in mass and increase in contractile strength

Question 14

what happens with AP during exercise?

Answer 14

nervous system increases AP to above normal
brain centers send info toperipheral muscles to increase activity
brain center send impulses to ciculatory syst. to increase heart rate, contractility and venous return to heart

Question 15

Factors that affect venous return

Answer 15

right atrial pressure - backward force on veins to impede flow of blood from veins into atrium
mean systemic filling pressure- forces blood to heart
resistance blood flow- between peripheral vessels and the right atrium

Question 16

Mean circulatory filling pressure (psf)

Answer 16

when there is no blood flow, the pressure everywhere in the circulation become equal. It is the mean pressure forcing blood into the heart.

Question 17

how do youi measure Mean circulatory filling pressure (psf)?

Answer 17

stopping the heart’s pumping ability by shock or other means.

Question 18

2 factors that determine the Mean circulatory filling pressure (psf)

Answer 18

Degree of sympathetic stimulation on the peripheral arteries and veins

Amount of blood in the circulation

Question 19

if the SNS stimulation acts on Mean circulatory filling pressure (psf)

Answer 19

constricts all the systemic blood vessels, larger pulmonary vessels, and chambers of the heart, resulting in increased mean filling pressure

Question 20

for venous return, the greater the system is filled

Answer 20

easier for blood to flow to the heart

Question 21

for venous return, the lesser the system is filled

Answer 21

The more difficult it is for the blood to flow into the heart.

Question 22

when the right atrial pressure = psf

Answer 22

There is not a pressure difference between the peripheral vessels and the right atrium = no longer any blood flow from the periphery to the right atrium

Question 23

Greater the difference between psf and RAP

Answer 23

greater the venous return

Question 24

pressure gradient for venous return is calculated

Answer 24

psf-RAP

Question 25

when resistance in veins increases

Answer 25

venous return decreases

Question 26

when arteriolar and artery resistance increases

Answer 26

blood accumulates in the arteries increasing the pressure, overcomes resistance and venous return goes back to normal

Question 27

Blood tansfusion causes an increase in psf and a decrease in

Answer 27

resistance venous return

Question 28

spinal anesthesia inhibits

Answer 28

SNS blocking transmission of nerve signals through the autonomic ganglia and cardiac output decreases

Question 29

measuring cardiac output in animals

Answer 29

electromagentic or ultrasonic flowmeter

Question 30

measuring cardiac output in humans (indirect method)

Answer 30

The oxygen Fick method Indicator dilution method

Question 31

During excercise, what 2 factors are important

Answer 31

Local tissue autoregulation SNS enhancement

Question 32

t/f during exercise all capillaries are open

Answer 32

true

Question 33

the opening of dormant capillaries during excercise increases

Answer 33

surface area for nutrient and O2 exchange

Question 34

control of blood flow through skeletal muscle is done

Answer 34

locally, chemical effects causing vasodilation of arterioles

Question 35

local increase in muscle blood flow is caused by 2 factors

Answer 35

Reduction in oxygen to the muscle release of vasodilator substances

Question 36

vasodilator substances include

Answer 36

Adenosine potassium ions adenosine triphosphate (ATP) lactic acid CO2

Question 37

arterial walls cannot maintain contraction during the absence of

Answer 37

O2

Question 38

muscle blood flow control is don by the

Answer 38

SNS, vasoconstrictor and vasodilators

Question 39

during excercise the SNS stimulates nerve endings and the adrenal medulla to secrete

Answer 39

nor- epi and epi

Question 40

nor - epi attaches to what receptors and causes what effect

Answer 40

alfa receptors vasoconstriction

Question 41

epi attaches to what receptors and causes what effect

Answer 41

beta receptors vasodilation

Question 42

What are the 3 circulatory adjustments that occur during exercise

Answer 42

SNS stimulation Increase in the arterial pressure Increase in cardiac output

Question 43

during excercise, the SNS exchange occurs in two ways

Answer 43

barin - muscle muscle control center of brain - vasomotor control center

Question 44

SNS discharge during exercise is expressed in 4 ways

Answer 44

heart stimulation = increase heart reate and streght contraction and loss of PNS inhibition arterioles of peripheral circulation are contracted arterioles in muscle exerting activity are vasodilated muscle walls of veins contracted increasing systemic filling pressure venous return to heart increasing cardiac output

Question 45

Increase in AP during excercise occurs due to

Answer 45

vasoconstriction of arterioles not directly on the muscle increased pumping activity of heart increase in mean systemic filling pressure caused by venous contraction

Question 46

t/f CO only increases to level of venous return during excercise

Answer 46

true

Question 47

SNS contract veins during

Answer 47

exercise

Question 48

t/f venous return is not dependent on mean systemic filling pressure during exercise

Answer 48

false

Question 49

left coronary arteries supply

Answer 49

anterior and left lateral portions of the left ventricle.

Question 50

Right coronary artery supplies

Answer 50

most of the right ventricle and the posterior part of the left ventricle.

Question 51

Venous blood from the left ventricle retuns

Answer 51

to the right side of the heart by the coronary sinus

Question 52

Venous blood from the right ventricle returns

Answer 52

to the heart via the anterior cardiac veins

Question 53

Capillary blood flow falls to a low value during

Answer 53

systole due to the compression of the left ventricular muscle

Question 54

Capillary blood flow rapidly during

Answer 54

Diastole, cardiac muscle relaxes and no longer obstructs blood flow

Question 55

Control of coronary blood flow is regulated by

Answer 55

local arterial and arteriolar vasodilation in response to cardiac muscle’s need for nutrition.

Question 56

A decrease in O2 concentration in the heart causes

Answer 56

vasodilator substances to be released from the muscle which dilates the arterioles

Question 57

direct nervous control of coronary vessels is through

Answer 57

neurotransmitters released from the nerve terminals PSNS - ACETYLCHOLINE - BETA - VASODILATION SNS - NOR-EPI AND EPI - ALPHA - VASOCONSTRICTIO

Question 58

INDIRECT NERVOUS CONTROL OF CORONARY VESSELS

Answer 58

secondary changes in coronary blood flow by increased or decreased activity of the heart

Question 59

Under resting conditions, cardiac muscle uses what for energy?

Answer 59

fatty acids

Question 60

Under anaerobic conditions or ischemia, the cardiac muscle uses

Answer 60

anaerobic glycolysis