Week 8: Coronary circulation Flashcards

1
Q

What is the mass of the heart?

A

300 g

4% total body weight

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2
Q

What is the flow rate of the coronary circulation?

A

150 ml/min

3%

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3
Q

What is Vo2 (oxygen uptake)

A

30 ml/ min

(250 ml O2 / min)

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4
Q

What is the capillary density of the coronary flow?

A

3000-4000 cap/ mm3

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5
Q

AVDO2 of coronary circulation

A

120 ml/l

arterial: 200 ml/ l
vein: 150 ml/l

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6
Q

What type of organ is the heart

A

obligate aerobic organ

meaning: needs O2 supply at all times

susceptible to O2 limitations

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7
Q

What is the result of the lack of collateral circulation in the coronary circulation?

A
  • abrupt occlusion → ischemia
  • slow occlusion → can develop collaterals
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8
Q

What is the mechanical aspect of coronary circulation?

A

Ohms Law: Q= deltaP/R

R ~ 1/r4

Left ventricle: systole R↑↑↑ ⇒ Q↓↓↓

diastole R↓↓↓ ⇒ Q↑↑↑

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9
Q

What is the systole time

A

.27 s

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10
Q

What is the diastole time?

A

.53 s

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11
Q

How is blood flow in the coronary circulation regulated?

A
  1. Metabolic regulation
  2. Autoregulation
  3. Neurohumoral regulation
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12
Q

What happens in the metabolic regulation of coronary circulation?

A

[O2] ↓

[CO2] ↑

[K+] ↑

[lactate] ↑

pH ↓

adenosine ↑

all lead to dilation

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13
Q

What is the graph displaying autoregulation in coronary circulation?

A
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14
Q

Describe the sympathetic part of the neurohumoral regulation in coronary circulation?

A

NE, E, adrenal

direct: alpha1 = constriction

beta2 = dilator

indirect: HR ↑

contractility ↑

↑↑↑ metabolism

dilation

Q↓

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15
Q

Describe the parasympathetic part of the neurohumoral regulation in coronary circulation?

A

endothelial cells

mACHr → Ca2+ (NO reduction) → dilation → Q↑

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16
Q

What is the weight of the brain?

A

1400g

17
Q

What is rate of the cerebral blood flow?

A

750- 850 ml/min

carotid: 2 x 330 ml/min
vertebral: 2 x 75 ml/min

18
Q

What is the VO2 of the cerebral blood flow?

A

50 ml/min

19
Q

What kind of organ is the brain?

A

obligate aerobic organ for glucose and oxygen

20
Q

What would happen if we closed the arteries?

A

5 seconds = loss of consiousness

3 minutes = reversible

5 minutes = irreversible damage

21
Q

What is the volume of the intracranial compartment of the blood?

A

150 ml

22
Q

What is the volume of the intracranial compartment of the CSF?

A

150 ml

23
Q

What is the volume of the intracranial compartment of the IS?

A

75 ml

24
Q

What is the intracranial pressure?

A

5-13 mmHg

25
Q

What does the CBF depend on?

A
  1. perfussion pressure
  2. resistance
26
Q

What is the perfussion pressure?

A

deltaP = Pa - Pv

deltaP = Pa- ICP

deltaP ≈ 90 mmHg

(ICP ↑ → deltaP → Q↓)

27
Q

What are the 4 components of the resistance in regards to cerebral circulation?

A

A.) Local control

B.) CO2 , O2 in blood

C.) Autoregulation

D.) Neural control

28
Q

Discuss the A. (Local control) component of resistance

A

metabolic: [CO2] → pH ↓

adenosine↑

[K+] ↑

[O2] ↓

local dilation

astrocytes: neural activity ↑

[Ca2+]

dilation

neuron: NO

29
Q

Discuss the D. (Neural Control) component of resistance

A

sympathetic innervation

BP↑ autoregulatory curve shifted to autoregulatory range

30
Q

What is the graph displaying the PCO2 v.s CBF

A
31
Q

What is the graph displaying the PO2 v.s CBF

A
32
Q
A