Cardiovascular System Flashcards
What does the CV system do? (2)
- Circulates and transports nutrients, O2, CO2, hormones and blood cells to and from cells of body
- Fights disease, stabilises temp, pH and helps maintain homeostasis
What are the essential components of the human CV system?
Heart
Blood
Blood vessels
What is the pulmonary circulation?
“Loop” through the lungs where blood is oxygenated
What is the systemic circulation?
“Loop” through the rest of the body to provide oxygenated blood and receive deoxygenated blood
What is a closed CV system?
Blood never leaves the network of arteries, veins and capillaries
How much blood does an average adult have?
5L of circulating blood, of which 2L is RBCs and 3L is plasma
What % of our blood lies in the peripheral veins?
65%
What % of our blood lies in the heart and lungs?
20%
What % of our blood likes in the peripheral arteries?
10%
What % of our blood lies in capillaries?
5%
What is the name of the mechanism that prevents exsanguination if the closed CV system is breached?
Haemostasis
What is haemostasis?
Balance of pro-coagulant and anti-coagulant systems
What is bridging?
Compression of a segment of a coronary artery during systole, resulting in narrowing that reverses during diastole
What is an end artery?
Terminal artery supplying all or most of the blood to a body part without significant collateral circulation
What are some examples of functional end arteries? (4)
Coronary arteries
Splenic artery
Cerebral arteries
Renal arteries
What is an absolute end artery?
Anatomically true end artery
Give an example of an absolute end artery
Central artery to the retina
Why is there an atrioventricular delay?
To prevent simultaneous contraction of the atria and ventricles
Complete the sentence:
Left ventricle contraction causes the BP in the aorta to rise to approx ____mmHg (systolic pressure).
120
Complete the sentence:
The aortic semilunar valve closes. The walls of the aorta recoil, maintaining pressure on the blood and moving it towards the heart and smaller vessels. Aortic pressure drops to __-__ mmHg (diastolic pressure)
70-80
What are the three layers of the walls of arteries and veins?
Tunica intima-next to lumen Tunica media Tunica adventitia (outer)
What is the commonest site for an aneurysm?
Infrarenal abdominal aorta
How many layers of smooth muscle cells does the tunica media contain?
40
Why do the muscular arteries have many layers of smooth muscle layers?
Propulsion vessels-push blood forward and can contract to allow vasoconstriction
What are metarterioles?
Arteries that supply blood to capillary beds
What is a precapillary sphincter?
Individual muscle cells are spaced apart and each encircles the endothelium of a capillary arising from the metarteriole
Complete the sentence:
When the precapillary sphincter are open, there is _________ blood flow through the capillary bed
Plentiful
Complete the sentence:
When the precapillary sphincters are closed, the blood flow through the capillary bed is greatly _______
Reduced
What are capillaries made of?
Single layer of endothelium and its basement membrane
What are pericytes?
Form branching network on the outer surface of the endothelium. Capable of dividing into muscle cells or fibroblasts during angiogenesis, tumour growth and wound healing
True or false: postcapillary venules are more permeable than capillaries
TRUE
True or false: veins have a larger diameter than arteries and a thinner wall that has more CT and fewer elastic and muscle fibres
TRUE
Define capacitance
Ability of a blood vessel to increase the volume of blood it holds without a large increase in pressure. Inversely proportional to elasticity
What is another term given to veins?
Capacitance vessels
How does venous blood get from the legs back to the heart in a standing human?
Skeletal muscle contraction (calf muscle pump)
Thoracic pump-diaphragm lowers down when breathe in and creates negative pressure in chest cavity and ‘sucking’ effect, attracts blood to right atrium
What does calf muscle pump failure lead to?
Venous hypertension
What is venous pooling?
Too much blood in lower limbs and insufficient blood return to the heart so less brain to the brain, leading to fainting
