Lecture 16, Blood Flow

Question 1

cardiac output

Answer 1

amount of blood pumped per minute
factors affecting-
HR
SV

CO=HRxSV
CO=5040ml=5L/minute

Question 2

heart rate

Answer 2

contractions per minute

72/min

Question 3

stroke volume

Answer 3

amount of blood pumped per contraction

70ml/contraction AT REST

Question 4

to control cardiac output you can alter…

Answer 4

heart rate

stroke volume

Question 5

what types of regulation can be used to control cardiac output

Answer 5

extrinsic-usually neuronal or hormonal, regulation from a distance
intrinsic-autoregulation

Question 6

factors influencing heart rate

Answer 6

sympathetic nervous system
parasympathetic nervous system
plasma epinephrine

Question 7

controlling cardiac output by regulating HR using sympathetic nervous system

Answer 7

adrenergic postgang releases norepinephrine
norepinephrine targets the beta 1 adrenergic receptors on the SA node
causes MORE funny channels
which causes MORE Ca++ channels
means more depol
also means hitting threshold MORE often

more threshold=increased HR

Question 8

controlling cardiac output by regulating HR using the parasympathetic nervous system

Answer 8

cholinergic postgang releases acetylcholine
Ach targets muscarinic cholinergic receptors on SA node
Ach causes more K+ channels to open
causes less Ca++ to open
means more hyperpolerization
which means less depolarization
means hitting threshold less often

less threshold=decreased HR

Question 9

plasma epinephrine control of HR when regulating cardiac output

Answer 9

same as sympathetic nervous system control

Question 10

factors influencing stroke volume

Answer 10

ventricular contractility
end diastolic volume
venous return

Question 11

ventricular contractility

Answer 11

force on ventricles per contraction

more force=more volume

Question 12

end diastolic volume

Answer 12

amount of blood in ventricles at the end of diastole

larger edv=larger contractile force

Question 13

why does larger edv=larger contractile force?

Answer 13

because cardiac muscles stretch

REMEMBER-a balloon with more air in it with expel the air with more force when released

Question 14

venous return

Answer 14

the amount of blood returning back to the heart PER MINUTE

can be altered by…
skeletal muscle pump
respiratory muscle pump

Question 15

skeletal muscle pump

Answer 15

one way valves in peripheral veins surrounded by skeletal muscle

when muscles are contracting-
more pressure on veins, squeezing blood through valves, towards the heart
valves prevent back flow

when muscles are relaxed-
less pressure, so blood going into veins

Question 16

respiratory muscle pump

Answer 16

during inspiration (inhalation)...
decreased pressure in thoracic cavity
means increased pressure in abdominal cavity

SO blood would move FROM abdominal cavity TO thoracic
*blood always moves from areas of high to low pressure