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PPoS > Intro to CVS (#2) > Flashcards

Intro to CVS (#2) Flashcards

1
Q

List 3 ways cardiac output is regulated

A
  1. Preload
  2. Afterload
  3. ANS
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2
Q

What is preload?

A

degree of stretch at end of diastole just before vent begin to pump

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3
Q

How does preload affect CO?

A
  • inc CVP stretches RV which responds by beating more forcefully + pumping more blood into the lungs
  • this inc pul vascular P + therefore P in LV which stretches + beats more forcefully
  • inc CO as pushing heart to work harder
  • also works with EDP (amount of blood in vent just before contraction) as more blood in vent make them more stretched
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4
Q

How do venous P differ between R + L side of heart?

A
  • CVP on R side

- pul venous P on L side

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5
Q

What is afterload + what is it determined by?

A
  • load against which heart works to eject blood

- determined by aortic P

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6
Q

How does afterload affect CO?

A
  • inc afterload works against heart which caused dec ejection of blood
  • dec CO
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7
Q

What causes inc afterload?

A
  • if mean BP v.high

- aortic stiffness - gets stiffer with age - causes inc P within it which inc afterload

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8
Q

How does ANS affect CO?

A
  • SNS inc HR, cardiac contractility (strength of contraction) through beta 1 receptors + SV which inc CO
  • PNS dec HR through muscarinic receptors which dec CO
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9
Q

What happens to ESV at end of systole?

A
  • dec as heart pumped out more blood
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10
Q

What does the Frank-Starling curve show?

A

relationship between SV + EDP

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11
Q

How does F-S curves affected by inc afterload + inc SNS activity?

A
  • inc afterload: inc EDP means less inc in SV so curve shifts down showing that for any given EDP, SV dec - less blood ejected
  • inc activity of cardiac symp nerve fibres: dec EDP means greater in SV so shifts curve up showing that for any given EDP, SV inc - more blood ejected
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12
Q

What is rel low arterial P gen by + why is it sufficient to drive blood through pul circ?

A
  • gen by RV (~ 16mmHg)

- bc pul vascular R v. low

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13
Q

What is Poiseuille’s law?

A

R prop to r to power of 4 of vessel

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14
Q

What is r + R of pul arteries + why?

A
  • shorter + so have larger radius which dec R

- also cap network supplying alveoli with blood forms v.dense mesh lowers R

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15
Q

What is sig of cap network surrounding alveoli?

A

massive SA for gas exchange of O2 + CO2 between blood + alveoli due to small diffusion distance between them

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16
Q

Why must R of lungs be low?

A
  • receiving same vol of blood as rest of body

- R must be low to accomm high CO from R side

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17
Q

What is pO2, Hb O2 binding site sat, O2 content of blood in systemic vascular system?

A
  • pO2: ~ 100mmHg (higher due to gas exchange in lungs)
  • Hb O2 binding site sat: >/= 97%
  • O2 content: ~ 200ml/l
18
Q

What is pCO2 + CO2 content of blood in systemic vascular system?

A
  • pCO2: ~ 40mmHg

- CO2 content: ~ 480ml/l (dec as its diffused into alveoli)

19
Q

What is P in aorta in systemic circ?

A
  • 120 (diastolic)/80 (systolic)mmHg

- oscillating P

20
Q

How does diastolic + systolic P change with age?

A
  • diastolic inc until middle age + then dec

- systolic P inc through life so chances of high BP is 50% by 50 which continues to inc

21
Q

What is blood velocity during systole + why?

A
  • ~ 70cm/sec

- blood has lots of momentum as just been pumped out of L vent + quicker than velocity going into heart

22
Q

Describe passage of blood flow from heart to body

A
  1. Blood pumped from LV into aorta
  2. Blood vessels branch out aorta to main organs: heart, brain, muscle, GIT, liver
  3. Blood then flows into microcirc
  4. Blood returned to RA
  5. Enters RV then pumped to lungs
  6. Blood returns to LA
23
Q

What is function of arterial system + its P?

A
  • high P
  • regulates distribution of blood to diff regions of body mainly by small arteries + arterioles
  • does this by changing R through contraction + P of arteries in diff organs
24
Q

What is R of arterial system also known as + why?

A
  • peripheral R
  • systemic peripheral R
  • systemic vascular R
  • TPR
  • biggest contributor to reg of BP +, vas R etc
25
Q

How does liver get arterial supply + why does it need it?

A
  • hepatic artery

- venous blood from GIT goes to liver but not getting enough O2

26
Q

What is portal system and why is it needed?

A
  • blood moves sequentially through 2 cap beds in series connected by a larger vessel
  • in liver, kidneys + part of brain
  • process ingested toxins from GIT before it gets to rest of body
27
Q

What is org of microcirc?

A

large arteries —> muscular arteries —> arterioles —> cap —> venules —> small veins —> large veins

28
Q

What is function of venous system?

A

collects blood from tissues + returns it to the heart

29
Q

How much blood do the veins contain?

A

70% - acts as blood reservoir

30
Q

What does contraction of veins cause?

A

redis blood to arteries, maintaining BP

31
Q

What is arterial BP like?

A
  • pulsatile

- osc between 80 + 120mmHg

32
Q

How do you calc MABP?

A

diastolic + (systolic - diastolic)/3 or 1/3 pulse P

33
Q

What is the pulse P?

A

diff between systolic + diastolic P

34
Q

Why is MAP not av of sys + dia?

A

Heart spends more time in diastole so MABP closer to diastolic P bc its longer than systolic

35
Q

What is incisura/notch due to?

A

closure of aortic valve

36
Q

What is the P wave that occurs during diastole?

A
  • aorta + arteries already full of blood so need to expand for blood to eject from heart
  • causes P wave where blood that’s entered pushes against blood already there
  • propagated v. fast along aorta into large arteries which expand so can accept more blood
37
Q

What causes a large pulse P?

A

large arteries bring blood to vas beds

38
Q

Where is 75% of ejection fraction stored?

A
  • transiently in aorta + large arteries where energy stored in elastic walls
  • already blood in aorta so expands to take on extra blood entering
39
Q

What causes inc P in aorta?

A
  • vent pump distends aorta

- aortic valve shuts at end of so blood can only go forwards

40
Q

What happens to 25% of blood in aorta?

A

pushed forward out of other end of aorta into small arteries + rest of body in stuttering motion with each heartbeat

PPoS (11 decks)

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