Fewell - Coronary Blood Flow

Question 1

Hg is _ times as dense as H2O

Answer 1

13.6 times

Question 2

1 cmH20 = _ mmHg

Answer 2

0.73

Question 3

stroke volume

Answer 3

the amount of blood pumped by the ventricle duing one cardiac cycle

Question 4

both right and left heart eject ___

Answer 4

eject the same amount of blood

Question 5

calculating stroke volume

Answer 5

SV = End-diastolic volume - end-systolic volume

ex: 70mL = 120mL - 50mL

Question 6

what is normal stroke volume

Answer 6

70mL

Question 7

normal end-diastolic volule

Answer 7

120mL

Question 8

normal end-systolic volume

Answer 8

50mL

Question 9

Ejection Fraction formula

Answer 9

stroke volume/end-diastolic volume

Question 10

ejection fraction ideal value

Answer 10

over 55% for healthy

>below and you may tire more easily during activity or if very low at rest

Question 11

ejection fraction definition

Answer 11

compares the amount of blood in the heart to the amount of blood pumped out

Question 12

determinants of stroke volume

Answer 12

• preload
• contractility
• afterload

Question 13

preload

Answer 13

Force that stretches the relaxed muscle fiber (end-diastolic volume)
>set sarcomere lenght

Question 14

contractility

Answer 14

cardiac performance at a given preload & afterload
>indicies - rate of pressure development, ejection fraction
>cannot be measured directly so we use parameters

Question 15

afterload

Answer 15

the load the ventricle faces before it begins to contract
>Force again which the contracting muscle must act
>aortic pressure
>force that must be overcome to eject blood

Question 16

Frank-Starling “ Law of the Heart”

Answer 16

that stroke volume of the heart increases in response to an
increase in the volume of blood filling the heart when all other
factors remain constant.

Question 17

why does more blood volume entering the herat improve stroke volume of the heart

Answer 17

more volume means more stretching means sacromeres are closer to their optimal length/postion to contract

Question 18

cardiac muscle is capable of ___ contractions

Answer 18

> graded (contractions that vary in strength)

Question 19

syncytium contract

Answer 19

all cardiac msucle fibers contract at the same time

>by additing more Ca2+

Question 20

cardiac muscle contraction release and uptake of intracellular calcium

Answer 20

figures from slide 12

Question 21

ejection fraction ho to increase

Answer 21

increase contractility increase ejection fraction

Question 22

rate of pressure development

Answer 22

rate of pressure with time (dP/dt)

Question 23

increasing afterload ___ stroke volume

Answer 23

decreases

Question 24

coronary blood flow function

Answer 24

The blood supply to the heart derives from the right and left
coronary arteries

Question 25

where do the coronary arteries originate

Answer 25

at the root of the aorta behind | the cusps of the aortic valves

Question 26

coronary arteries are classified as

Answer 26

Classified as End Arteries – Arteries that do not anastomose (no back up routes), or have a poorly developed collateral circulation

Question 27

coronary arteries move around the heart

Answer 27

>artery bifurcates repeatedly into smaller and smaller arteries running on the epicardium >penetrates myocardium and form tee-like network >reaches capillaries (nont tree-like)

Question 28

arteries in muscle can be ___-

Answer 28

influenced by the contraction of the muscle

Question 29

right vs left coronary blood flow

Answer 29

-coronary flow increases during diastole >bigger increase in the left than the right >left needs to generate more tension to eject blood than the right (higher resistance because radius of blood vessel is collapsing from outside pressures)

Question 30

heart has _ energy requirements

Answer 30

high > needs lots of oxygen and nutrients >ventricular myocardium is packed with mitochondria

Question 31

the heart has a high _ ratio

Answer 31

oxygen extraction >organs usually take 25% of oxygen in blood >heart takes 65-75%

Question 32

mycardial oxygen transport formula

Answer 32

MOT = coronary blood flow x arterial oxygen content

Question 33

increase myocardial oxygen demand by increasing ___

Answer 33

myocardial oxygen transport

Question 34

extravascular compression decreases ____

Answer 34

coronary blood flow during systole