Cardio 4

Question 1

What two factors determine the amount of force generated by cardiac muscle?

Answer 1

• contractibility of the heart

- length of muscle fibres at beginning of contraction

Question 2

inotropic agent

Answer 2

any chemical that affects contractibility

Question 3

positive inotropic effect

Answer 3

chemicals increasing contractibility

Question 4

negative inotropic effect

Answer 4

chemicals decreasing contractibility

Question 5

Catecholamines

Answer 5

norepinephrine and epinephrine; positive inotropic effect

Question 6

preload

Answer 6

degree of myocardial stretch prior to contraction

Question 7

stretch

Answer 7

indicated by ventricular end-diastolic volume

Question 8

frank starling law

Answer 8

stroke volume increases with increasing end-diastolic volume

Question 9

skeletal muscle pump

Answer 9

Skeletal muscle activity compresses veins in the extremities pushing blood back to the heart

Question 10

respiratory pump

Answer 10

during inspiration the chest expands and diaphragm moves down creating a subatmospheric pressure in the thoracic cavity, this draws blood into the vena cava that exist within this cavity

Question 11

sympathetic constriction of veins

Answer 11

decreases their volume squeezing blood back towards that heart.

Question 12

afterload

Answer 12

end load against which the heart contracts to eject blood

Question 13

ejection fraction (EF) =

Answer 13

SV/EDV

Question 14

progressive branching of vessels

Answer 14

Aorta>Arteries> arterioles> capillaries> venules > Veins>vena cava

Question 15

arteries

Answer 15

all; mostly elastic tissue and smooth muscle

Question 16

arteriole

Answer 16

endothelium and smooth muscle

Question 17

capillary

Answer 17

endothelium

Question 18

venule

Answer 18

endothelium and fibrous tissue

Question 19

vein

Answer 19

all