Circulatory System Flashcards
why do we describe our circulatory system as being a double circulatory system?
Blood flows through the heart twice during each circuit round the body; once on its way to the lungs, and once on its way back round the body.
why are the walls of the ventricles thicker (have more cardiac muscle) than the walls of the atrium?
the ventricles pump blood out of the heart, whereas the atrium receive blood
why is the wall of the left ventricle thicker than the right?
the left ventricle needs to pump the blood further (around the body) whereas the right ventricle only needs to pump he blood to the lungs.
what are the role of the heart valves?
they ensure that blood does not flow backwards and that it flows in one direction.
how does the heart muscle itself receive oxygen and glucose it needs for respiration?
via the coronary arteries
what is unusual about the pulmonary artery and vein?
the pulmonary artery carries de-oxygenated blood
and the pulmonary vein carries oxygenated blood
name the vessel which carries digested food from the small intestine to the liver
the hepatic portal vein.
name the vessel which carries blood rich in urea to the kidneys for excretion.
renal artery
what is the role of the muscle and elastic in the artery walls?
- the muscle helps withstand and maintain the high
pressure - the elastic can stretch and recoil to control blood flow
and cope with pulses of blood
give 4 differences between arteries and veins
- arteries have a thicker wall of elastic and muscle
- arteries have a smaller lumen
- arteries do not have valves
- arteries carry blood rich in oxygen whereas veins carry blood low in oxygen
how is blood backflow prevented in veins?
they have valves
why are capillary walls only one cell thick?
so they are thin enough to be permeable and allow nutrients, gases and wastes to diffuse through them to, and from body cells
what type of solution do red blood cells need to be surrounded in to prevent crenation or lysis?
Isotonic
what type of surrounding solution would cause lysis in red blood cells?
Dilute, hypotonic
how are red blood cells adapted for carrying oxygen? x3
- biconcave disc shape to increase surface area
- no nucleus to allow for more room for oxygen
- contain haemoglobin to transport oxygen
how are white blood cells different to red blood cells? x3
- no haemoglobin
- do contain a nucleus
- they are larger and there are fewer of them
what do platelets do?
help blood to clot by converting fibrinogen to a meshwork of fibres made of fibrin
jobs of plasma? x4
- transport blood cells
- transport glucose and amino acids
- distribute heat around the body
- transports wastes like urea away from cells
what is cardiac output?
the volume of blood pumped out of the heart per minute.
what is pulse rate?
how often a surge or pulse of blood passes round the body
why does heart rate increase during exercise?
the muscles have a greater demand for oxygen and glucose required for increased respiration
what are the two main functions of the circulatory system?
transport
protection
what is a capillary?
a very thin blood vessel through which the exchange of material between blood and cells takes place
what is a vein?
a blood vessel that carries blood back to the heart
