Cardio 2

Question 1

Late diastole (Phase 1 of cardiac cycle)

Answer 1

• atria are relaxed and fill with blood from veins
• ventricles begin to relax and AV vales open when pressure in atria> ventricular pressure
• ventricles fill passively with blood

Question 2

Atrial systole (phase 2 of cardiac cycle)

Answer 2

Completion of ventricular filling:

-80% of blood fills ventricles passively and the 20% comes from atria contracting

Question 3

Isovolumetric ventricular contraction (phase 3 of cardiac cycle)

Answer 3

• ventricles begin to contract
• pressure builds in ventricles and causes AV vaes to close (lub)
• both valves are closed and ventricles are still contracting so pressure builds up

Question 4

Ventricular ejection (phase 4 of cardiac cycle)

Answer 4

Heart pumps:
- ventricles contract since pressure is higher than outflow arteries which causes semi lunar valves to open and blood flow out

Question 5

Isovolumetric ventricular relaxation (phase 5 of cardiac cycle)

Answer 5

Ventricular relaxation
- ventricles begin to relax and pressure is greater in outflow artery which causes the SL valves to close “dub” so blood doesnt flow back into ventricle

Question 6

end diastolic volume

Answer 6

amount of blood at the end of venticular diastole

Question 7

end systolic volume

Answer 7

volume of blood after ventricular systole

Question 8

stroke volume

Answer 8

amount of blood ejected during a single ventricular contraction. approx 70mL

SV=EDV-ESV

Question 9

ejection fraction

Answer 9

the percentage of EDV that is ejected from the heart

EF=SV/EDV

Question 10

total blood flow (cardiac output)

Answer 10

heart rate x stroke volume

blood flow delivered from one ventricle in a given period of time

Question 11

factors that determine amount of force by cardiac muscle which would increase SV and CO

Answer 11

• contractility - due to amount of Ca2+ entering the cell (increases as Ca2+ increases)
• length of muscle fibers at the beginning of contraction

Question 12

preload (determinant of SV)

Answer 12

amount of ventricular muscle stretch caused by EDV

the greater the EDV, the more the muscle stretches, increasing preload

contract more forcefully while returning to same ESV

affected by venous return and ventricular filling time

Question 13

contracility (determinant of SV)

Answer 13

force of contraction at any EDV

contractility lowers ESV

Question 14

afterload (determinant of SV)

Answer 14

end load against which the heart contracts to eject blood
- determined by the combination of EDV and pressure in aorta or pulmonary artery

increased afterload reduces stroke volume

Question 15

venous return

Answer 15

the rate of blood entering the heart

increase venous return, increase EDV, increase stroke volume

Question 16

Factors affecting HR

Answer 16

• increased sympathetic
  ~increases HR by acting on pacemaker cells
• increased parasympathetic
  ~decreased HR

should be mroe detail in muscle 3?

Question 17

factors affecting venous return

Answer 17

1. skeletal muscle pump
   - movement of extremeties squeezes them
2. respiratory pump
   - when you belly breathe you compress veins in your stomach
3. sympathetic constriction of veins
   - decrease their volume squeezing blood back toward that heart

Question 18

capillaries

Answer 18

• where exchange between blood and interstitial space occur
• gases diffuse across the endothelial cells
• surrounded by pericytes

Question 19

types of capillaries

Answer 19

1. continuous
   - thicker endothelial cells that only allow passage of water and small ions through intercellular junctions
2. fenestrated
   - thin endothelial cells with fenestrations (select what does through)
3. discontinuous (sinusoidal) capillary
   - no bassal membrane; large open fenestrations and gaps between endothelial cells

Question 20

methods of transport

Answer 20

transcellular
paracellular
transcytosis

Question 21

veins

Answer 21

volume reservior bc of larger volume and thinner walls and less muscle tissue