BL - Cardiovascular System Flashcards
What are the functions of the cardiovascular system?
Circulates and transports nutrients/O2/CO2/hormones/blood cells, fights disease, stabilises temperature and pH
What is the difference between the pulmonary and systemic circulation?
Pulmonary travels through lungs where blood is oxygenated, systemic forms a loop through the rest of the body to provide oxygenated blood
What is meant by the term “closed cardiovascular system”?
Blood never leaves the network of arteries, veins and capillaries.
How much circulating blood does the average adult have?
5 litres, of which 2 is red cells and 3 is plasma.
Where is our blood situated within the body?
65% in peripheral veins, 20% in heart and lungs, 10% in peripheral arteries, 5% in capillaries.
What is “bridging” of an artery?
The compression of a segment of a coronary artery during systole, resulting in a narrowing that reverses during diastole.
What is an “end artery”?
A terminal artery supplying all/most of the blood to a body part without significant collateral circulation - if occluded, there is insufficient blood supply to the dependant tissue.
Give some examples of functional end arteries.
Coronary arteries, splenic artery, cerebral and renal arteries.
Give an example of an absolute end artery.
The central artery to the retina.
What is “collateral circulation”?
“Back-up” arteries that can take over function if an artery becomes broken/blocked.
Where does the heart beat originate?
The sino-atrial node
Why is there a pause between the contractions of the SAN and the AVN?
To ensure that the ventricles have time to fill up.
What is fibrillation?
Rapid, irregular and unsynchronised contraction of muscle fibres.
Does the pressure in the aorta rise or fall during systole?
It rises due to left ventricle contraction, then falls in diastole.
What are the three layers of arteries and veins?
Tunica intima (next to lumen), tunica media, tunica adventitia
Where is the commonest site to find an aneurysm?
Infrarenal abdominal aorta, due to elastin fibres being less well-distributed here
How many layers of smooth muscle does the tunica media contain?
40 (this is a lot)
What is the name given to arteries that supply blood to capillary beds?
Metarterioles
What do pre-capillary sphincters control?
Flow of blood through the capillary bed
What are pericytes?
Cells that are capable of dividing into muscle cells or fibroblasts
Which veins have a well-defined muscular wall (an exception to the rule that veins have less muscle than arteries)?
Superficial veins of legs, to resist distension caused by gravity
