Flashcards in Vascular and Ischaemic Heart Disease Deck (241)
Where do the right and left coronary arteries arise from?
The base of the aorta
Where does most coronary venous blood drain into?
The coronary sinus and then into the right atrium
What area of the heart becomes deprived of blood supply if the left coronary artery becomes blocked?
Give four special adaptations of coronary circulation?
1. High capillary density
2. High basal blood flow
3. High oxygen extraction (75% compared to 25%)
4. Extra oxygen can only be supplied by increasing coronary blood flow
What does decreased PO2 do to the coronary arteries?
What is an intrinisc mechanism of coronary blood flow, and matches flow to demand?
What is a potent vasodilator for coronary blood flow (intrinsic mechanism)?
Adenosine from ATP
What type of nerves are coronary arterioles supplied by?
Sympathetic vasoconstrictor nerves
What are sympathetic vasoconstrictor nerves in coronary arterioles over-ridden by?
Metabolic hyperaemia as a result of increased heart rate and stroke volume
What does sympathetic stimulation of the heart result in?
Coronary vasodilatation despite direct vasoconstrictor effect
What substances activates beta-2-adrenoceptors, which causes vasodilatation?
What receptors does sympathetic stimulation act on in relation to coronary blood flow?
What do increased metabolites such as K, PCO2 and H+ do to coronary blood flow?
What does an increase in adenosine, do to coronary blood flow?
When does peak left coronary flow occur?
What does shortening diastole (e.g. very fast heart rate) do to coronary flow?
What gives blood supply to the brain?
Internal carotids and vertebral arteries
What is very sensitive to hypoxia in the brain?
What two arteries form the basilar?
Two vertebral arteries
What arteries anastomose to for the circle of Willis?
Basilar and carotid arteries
Where do the major cerebral arteries arise from?
The circle of Willis
What is caused by an interruption/cut-off of blood supply to a region of the brain?
What are the two main types of stroke?
1. Haemorrhagic bleeding
2. Ischaemic stroke
What type of stroke is described - blood leaks out of artery wall which is damaged?
What type of stroke is dewscribed - blood clot forms on atheroma on artery wall or comes from another part of body and gets stuck, blood cannot flow past?
What is autoregulation of cerebral blood flow guard against?
Changes in cerebral blood flow if mean arterial blood pressure changes within a range (60 - 160 mmHg)
In relation to autoregulation of cerebral blood flow: what happens to resistance vessels automatically when MABP rises?
Resistance vessels constrict to limit blood flow
When does autoregulation fail in relation to MABP falling?
What does MABP below 50 mmHg, result in?
Confusion, fainting and brain damage if not quickly corrected