week 7 cardiac output

Question 1

what is cardiac out

Answer 1

= heart rate (beats/min) x stroke volume (ml/beat)

Question 2

how does the parasympathetic nervous system change hate rate

Answer 2

reduces the rate of action potentials in the SA node
- cause hyper polarastion so increases time to reach threshold
PNS dominates in resting potential as it slows it to slower then the SA node automatic speed

Question 3

how does the sympathetic nervous system change hate rate

Answer 3

• increases the rate of the action potential in SA node

- increases heart rate - rapid depolarization

Question 4

what is stroke volume

Answer 4

volume of blood pumped out of the ventricles

- difference between EDV minus ESV

Question 5

what is venous return

Answer 5

volume of blood returning back to the heart each minute

Question 6

what will increasing venous return

Answer 6

increases EDV
cause heart musclesto stretch
as muscles stretch means next contraction will be stronger

Question 7

what are the 5 factors that effect venous return

Answer 7

• cardiac suction -
• skeletal pump
• venous valves
• respiratory pump
• sympathetic nervous system

Question 8

what are is cardiac suction

Answer 8

when the ventricles contract, AV valve drawn downwards increases volume in atria and decrease pressures causes suck of blood from veins in atria
this is the same in ventricles

Question 9

what is the skeletal muscle pump

Answer 9

large veins lie between skeletal muscles so when the muscle contracts it compresses the vein to help push blood

Question 10

what are venous valves

Answer 10

stop back flow in veins

Question 11

what is the respiratory pump

Answer 11

when you breathe in expansion of thactic cavity & decrease pressure

• right atria and venae cavae expand
• which increase pressure between venous system and atria
• which increase venour return

Question 12

what is sympathetic stimulation

Answer 12

• causes vasoconstriction of the veins reduces storage space of blood