Phys 20

Front 1

Cardiac output

Back 1

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

Front 2

What are some main factors that affect CO

Back 2

1) basic body metabolism 2) whether person is exercising 3) age 4) size of body

Front 3

resting CO for young healthy male and female

Back 3

5.6 L/min and 4.9 L/min

Front 4

cardiac index

Back 4

CO per square meter of body surface area

Front 5

normal average cardiac index

Back 5

3L/min/m^2; with 70 kg person, SA 1.7 m^2, CO 5 L/min

Front 6

primary controller of CO

Back 6

venous return

Front 7

Frank-starling law of the heart

Back 7

heart pumps automatically the amount of blood that flows into the right atrium

Front 8

what effect does stretching of the heart have on contractions

Back 8

causes heart to pump faster; stretching SA node has effect on rhymicity to increase 10-15%

Front 9

Bainbridge reflex

Back 9

stretching R atrium initiates a nervous reflex passing to vasomotor center of brain back to heart via sympathetics and vagi to increase heart rate

Front 10

when does the heart become the limiting factor in CO

Back 10

returning blood becomes more than heart can pump

Front 11

long term CO level varies reciprically with

Back 11

changes in total peripheral resistance

Front 12

equation for CO

Back 12

(arterial P)/(total peripheral resistance)

Front 13

what can CO increase to without special stimulation

Back 13

2.5 times normal

Front 14

what can cause a hypereffective heart

Back 14

1) nervous stimulation 2) hypertrophy of heart muscle

Front 15

dinitrophenol

Back 15

increases metabolism of virtually all tissues of the body 4-fold

Front 16

what occurs with dinitrophenol administration with and without nervous stimulation

Back 16

with-CO increased, no change in arterial P; without-CO same, arterial P falls

Front 17

what can cause high CO

Back 17

1) beriberi 2) AV shunt 3) hyperthyroidism 4) anemia

Front 18

what is the source of high CO in all these causes

Back 18

chronically reduced total peripheral resistance

Front 19

beriberi

Back 19

insufficient vit B

Front 20

how does anemia cause increased CO

Back 20

reduced viscosity of blood, diminished O2 delivery

Front 21

two categories that cause CO to be decreased

Back 21

1) pumping effectiveness of heart to fall to low 2) venous return is too low

Front 22

cardiac shock

Back 22

CO falls so low that tissues throughout body begin to suffer nutritional deficiency

Front 23

non-heart causes for low CO

Back 23

1) decreased blood V 2) acute venous dilation 3) obstruction of large veins 4) decreased tissue mass

Front 24

what can cause acute venous dilation

Back 24

sympathetic system suddenly becomes inactive (fainting)

Front 25

normal external P outside the heart

Back 25

equal to normal intrapleural P = -4 mmHg

Front 26

what direction does a rise in intrapleural P cause the CO curve to shift

Back 26

to the right; extra P must be exerted to overcome

Front 27

What can alter external P on the heart

Back 27

1) cyclical changes during respiration (+/-2 mmHg normal breathing and +/-50 mmHg strenuous breathing) 2) breathing against neg P 3) positive P breathing 4) opening thoracic cage 5) cardiac tamponade

Front 28

3 factors that affect venous return to the heart from systemic circulation

Back 28

1) right atrial P 2) mean systemic filling P 3) resistance to blood flow

Front 29

mean systemic filling P

Back 29

P measured everywhere in the systemic circulation when all flow of blood is stopped; generally ~7 mmHg

Front 30

why does venous filling stop at negative Ps

Back 30

collapse of veins entering chest (sucks walls of veins together)

Front 31

what occurs to mean systemic filling P with extra blood V

Back 31

increases due to stretch of walls of vasculature

Front 32

how does sympathetic nervous stimulation affect mean systemic filling P

Back 32

increases it; constricts vessels making lower capacity of vasculature

Front 33

mean circulatory fillng P

Back 33

excludes lung when calculating P, otherwise same as mean systemic filling P

Front 34

pulmonary circulation vs systemic circulation

Back 34

less than 1/8 capacitance and 1/10 the amount of blood as systemic

Front 35

pressure gradiant for venous return

Back 35

difference btwn R atrial P and mean systemic filling P

Front 36

what occurs when resistance in veins increases

Back 36

blood begins to be damned up mainly in the veins, but little change in P since veins highly distensible

Front 37

formula for caculating venous return

Back 37

equals (Psf-PRA)/RVR; Psf is mean systemic fillng P, PRA is right atrial P, RVR is resistance to venous return

Front 38

values for calculating venous return in healthy adult

Back 38

Psf= 7 mmHg, RVR = 1.4 mmHg, PRA= 0 mmHg

Front 39

highest level R atrial P can rise and still have venous blood flow

Back 39

mean systemic filling P

Front 40

how does homeostatis occur after infusing extra V of blood

Back 40

1) increased CO increases capillary P causing fluid to go into tissues 2) veins distend (stres-relaxation) 3) autoregulatory increase in peripheral resistance increasing resistance to venous return

Front 41

how does sympathetic stimulation affect CO

Back 41

1) makes heart stronger pump 2) increases mean systemic filling P-peripheral vessel contration, increased resistance to venous return

Front 42

how can sympathetic nervous system be blocked

Back 42

total spinal anesthesia, hexamethonium (block transmission through autonomic ganglia)

Front 43

what occurs to CO during total synpathetic inhibition

Back 43

1) mean systemic filling P falls to 4 mmHg 2) heart pumping effectiveness decreases 80% 3) CO falls about 60%

Front 44

what occurs immediately after opening of large AV fistula

Back 44

1) large decrease in resistance to venous return 2) slight increase in CO curve

Front 45

Fick principle eqn for CO

Back 45

(O2 absorbed per minute by lungs)/(arteriovenous O2 difference)

Front 46

what artery and vein are used in fick principle

Back 46

brachial vein through system and intopulmonary artery; any systemic artery