Week 8: Coronary circulation Flashcards
What is the mass of the heart?
300 g
4% total body weight
What is the flow rate of the coronary circulation?
150 ml/min
3%
What is Vo2 (oxygen uptake)
30 ml/ min
(250 ml O2 / min)
What is the capillary density of the coronary flow?
3000-4000 cap/ mm3
AVDO2 of coronary circulation
120 ml/l
arterial: 200 ml/ l
vein: 150 ml/l
What type of organ is the heart
obligate aerobic organ
meaning: needs O2 supply at all times
susceptible to O2 limitations
What is the result of the lack of collateral circulation in the coronary circulation?
- abrupt occlusion → ischemia
- slow occlusion → can develop collaterals
What is the mechanical aspect of coronary circulation?
Ohms Law: Q= deltaP/R
R ~ 1/r4
Left ventricle: systole R↑↑↑ ⇒ Q↓↓↓
diastole R↓↓↓ ⇒ Q↑↑↑
What is the systole time
.27 s
What is the diastole time?
.53 s
How is blood flow in the coronary circulation regulated?
- Metabolic regulation
- Autoregulation
- Neurohumoral regulation
What happens in the metabolic regulation of coronary circulation?
[O2] ↓
[CO2] ↑
[K+] ↑
[lactate] ↑
pH ↓
adenosine ↑
all lead to dilation
What is the graph displaying autoregulation in coronary circulation?

Describe the sympathetic part of the neurohumoral regulation in coronary circulation?
NE, E, adrenal
direct: alpha1 = constriction
beta2 = dilator
indirect: HR ↑
contractility ↑
⇕
↑↑↑ metabolism
dilation
Q↓
Describe the parasympathetic part of the neurohumoral regulation in coronary circulation?
endothelial cells
mACHr → Ca2+ (NO reduction) → dilation → Q↑
What is the weight of the brain?
1400g
What is rate of the cerebral blood flow?
750- 850 ml/min
carotid: 2 x 330 ml/min
vertebral: 2 x 75 ml/min
What is the VO2 of the cerebral blood flow?
50 ml/min
What kind of organ is the brain?
obligate aerobic organ for glucose and oxygen
What would happen if we closed the arteries?
5 seconds = loss of consiousness
3 minutes = reversible
5 minutes = irreversible damage
What is the volume of the intracranial compartment of the blood?
150 ml
What is the volume of the intracranial compartment of the CSF?
150 ml
What is the volume of the intracranial compartment of the IS?
75 ml
What is the intracranial pressure?
5-13 mmHg
What does the CBF depend on?
- perfussion pressure
- resistance
What is the perfussion pressure?
deltaP = Pa - Pv
deltaP = Pa- ICP
deltaP ≈ 90 mmHg
(ICP ↑ → deltaP → Q↓)
What are the 4 components of the resistance in regards to cerebral circulation?
A.) Local control
B.) CO2 , O2 in blood
C.) Autoregulation
D.) Neural control
Discuss the A. (Local control) component of resistance
metabolic: [CO2] → pH ↓
adenosine↑
[K+] ↑
[O2] ↓
local dilation
astrocytes: neural activity ↑
[Ca2+]
dilation
neuron: NO
Discuss the D. (Neural Control) component of resistance
sympathetic innervation
BP↑ autoregulatory curve shifted to autoregulatory range

What is the graph displaying the PCO2 v.s CBF

What is the graph displaying the PO2 v.s CBF
