CVS 8 (Special circulations) Flashcards
State the normal pressures in the pulmonary arteries, capillaries and veins:
Arteries: 12-15 mmHg
Capillaries: 9-12 mmHg
Veins: 5 mmHg
State the normal pressures in the systemic arteries, capillaries and veins:
Arteries: 70-105 mmHg
Capillaries: 30 mmHg
Veins: 5 mmHg
What is the optimal V/Q ratio?
0.8
Explain hypoxic pulmonary vasoconstriction:
Constriction of pulmonary blood vessels which supply hypoxic alveoli, maintains optimal V/Q ratio (ventilation perfusion matching)
Why does chronic hypoxia cause right ventricular heart failure?
Chronic hypoxia leads to chronic pulmonary hypertension
= Increased afterload = stretches right ventricle
What is the usual treatment of pulmonary oedema?
O2
Loop diuretics ie Furosemide
How does metabolic hyperaemia affect blood vessels?
Causes vasodilation
What is the main consequence of partial (~70%) occlusion of a coronary artery?
Angina = chest pain on exertion
What is the main consequence of partial (~90%) occlusion of a coronary artery?
Unstable angina = unprovoked/prolonged chest pain
What are the possible consequences of partial occlusion of a coronary artery?
- Angina
- Unstable angina
- Myocardial infarction
List the factors which maintain blood flow through the brain:
- Many anastamoses (between basilar and int. carotid arteries)
- High capillary density
- x10 basal flow rate compared to rest of body
- Myogenic regulation
- Metabolic regulation
- Cushing’s reflex
- Blood-brain barrier
What is Cushing’s Triad?
- Hypertension
- Bradycardia
- Apnea
Signs of increased intracranial pressure
List the factors which influence blood flow through skeletal muscle:
- Varied capillary density (higher in postural muscles)
- Precapillary sphincters
- Varied SNS innervation (highest in arterioles)
- Metabolic regulation
Name the 2 types of skin blood vessels:
1) Supply capillary beds
2) Arteriovenous anastamoses
Where are arteriovenous anastamoses mostly located?
Apical/acral skin:
Palms, Soles, Ears, Nose, Lips
