chapter 20( Cardiac output, venous return and their regulation)

Question 1

cardiac output

Answer 1

quantity of blood pumped into arota each minute by the heart each minute

Question 2

venus return

Answer 2

quantitiy of blood flowing from the veins into the right atrium each minute.

Question 3

factors that affect cardiac output

Answer 3

metabolism, whether someone excersizes, age, size of body.

Question 4

frank starling law of the heart

Answer 4

increased blood flow to heart stretches the walls of the heart chamber which causes them to contract harder

Question 5

heart peripheral resistance

Answer 5

more resistance= less output. Less resistance= more output

Question 6

cardiac output

Answer 6

arterial pressure/ total peripheral resistance

Question 7

hypereffective heart

Answer 7

pumps better than normal

Question 8

name 2 factors that help the heart pump better than normal

Answer 8

1. nervous stimulation which increases the strength of contraction
2. hypertrophy which allows the heart to have a huge output

Question 9

hypoeffective heart and what causes it.

Answer 9

pumps less than normal. Hypertension, inhibition of nervous excitation of heart, abnormal heart rhythms, coronary artery blockage, valvular disease, congenital heart disease

Question 10

name some cases where you have a high cardiac output caused by low peripheral resistance

Answer 10

beriberi, arteriovenous fistula, hyperthyroidism, anemia

Question 11

Beriberi

Answer 11

caused by insufficient quantity of Thiamine ( B1) in diet. This diminishes the ability of tissues to use some cellular nutrients and the local tissue blood flow mechanisms in turn cause marked compensatory peripheral vasodilation

Question 12

Arteriovenous fistula

Answer 12

when a major artery shunts with a vein. This decreases the peripheral resistance

Question 13

hyperthyroidism

Answer 13

oxygen usage increases and vasodilator products are released from tissue which lowers the peripheral resistance

Question 14

anemia

Answer 14

blood is not as viscous due to less RBC’s and resistance decreases

Question 15

what are the two categories of low cardiac output?

Answer 15

abnormalities that cause pumping effectiveness, and those that lower the venous return

Question 16

what causes abnormalities that cause pumping effectiveness?

Answer 16

anything that affects the heart. Cardiac shock- nutrientes are not getting to tissues

Question 17

what causes abnormalities that lower venous return?

Answer 17

anything that interferes with venous return. Decreased blood volume, acute venous dilation, abstruction of large veins, decreased tissue mass, decreased metabolic rate of tissues

Question 18

normal venous return

Answer 18

will decrease to zero when RA pressure rises to +mmHg

Question 19

mean systemic filling pressure (psf)

Answer 19

systemic pressure when all flowing stops

Question 20

mean circulatory filling pressure

Answer 20

when no flow is occurring the pressures everywhere in the circulation become equal

Question 21

nervous systems role

Answer 21

strong sympathetic stimulation constricts all the systemic blood vessels, inhibition of these relax and dilate the systemic vessels

Question 22

effect of mean systemic filling pressure

Answer 22

the greater it is , the more venous return curve shifts upward and to the right

Question 23

resistance to venous return

Answer 23

most of it comes from veins and some arterioles and small arteries. Veins are distensible so when they are full, they don’t really affect the pressure which would affect the resistance. But with slight accumulation of blood in the arteries the pressure can raise greatly as much as 30 times as much as the veins

Question 24

effect of resistance to venous retunr on the venous return curve

Answer 24

a decrease in this resistance to ½ normal allows twice as much flow of blood and therefore rotates the curve upward to twice as great a slope. An increase in resistance to twice the normal rotates the curve rotates the curve downward to one half as great a slope.

Question 25

blood volume increase on pressure

Answer 25

an increase in volume increases the pressure

Question 26

compensatory effects returning blood to normal levels

Answer 26

increased cardiac output which increases the capillary pressure so the fluid flows out into the tissue, increased pressure in the veins causes them to distend gradually as well as the blood reservoirs like the spleen and liver which reduces venous volume, excess flow through the peripheral tissues causes autoregularoty increase in peripheral vascular resistance which increases the resistance to venous return.

Question 27

what does sympathetic stimulation do on cardiac output

Answer 27

makes the heart a stronger pump, increases the mean systemic filling pressure in the systemic circulation due to contraction of peripheral vessels

Question 28

oxygen fick method for measureing cardiac output

Answer 28

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Question 29

indicator dilution method for measuring cardiac output

Answer 29

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