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↑