3: EXCHANGE SYSTEMS AND MASS TRANSPORT - THE HEART + THE CIRCULATORY SYSTEM Flashcards
What side of the heart pumps deoxygenated blood to the lungs?
the right side
What side of the heart pumps oxygenated blood to the rest of the body?
the left side
Name the vessel that carries blood from the aorta to the heart muscle
coronary arteries
Name the vessel that carries blood from the lungs to the left atrium
pulmonary vein
Name the vessel that carries blood from the left ventricle to the body
aorta
Name the vessel that carries blood from the body to the right atrium
vena cava
Name the vessel that carries blood from the right ventricle to the lungs
pulmonary artery
Name the vessel that carries blood from the body (aorta) to the kidneys
renal artery
Name the vessel that carries blood from the kidneys to the vena cava
renal vein
Do the ventricle/the atria have thicker walls and why?
- ventricles have thicker walls
- have to pump blood out of the heart whereas atria only have to pump blood a short distance to the ventricles
Which ventricle has thicker, more muscular walls and why?
- the left ventricle
- has to pump blood to the rest of the body whereas the right ventricle only has to pump blood to the lungs
What is the name of the valves between the atria and ventricles?
the atrioventricular (AV) valves
What is the function of the atrioventricular (AV) valves?
stop blood flowing back into the atria when the ventricles contract
What is the name of the valves between the ventricles and the pulmonary artery/aorta?
the semi-lunar (SL) valves
What is the function of the semi-lunar (SL) valves?
stop blood flowing back into the heart after the ventricles contract
When do valves open?
when there’s a higher pressure behind the valve
What are the 3 stages of the cardiac cycle?
- atrial systole
- ventricular systole
- diastole
What happens in atrial systole?
- the ventricles relax, and the atria contract
- the volume of the atria decreases
- the atrial pressure increases
- the AV valves open and SL valves remain closed
- blood flows into the ventricles
- slight increase in ventricular pressure and volume as they receive the ejected blood from the atria
What happens in ventricular systole?
- the ventricles contract, and the atria relax
- the volume of the ventricles decreases
- the ventricular pressure increases
- the SL valves open, and the AV valves close
- blood flows into the arteries
What happens in diastole?
- the ventricles and atria relax
- volume of both atria and ventricles increases
- pressure of both atria and ventricles decreases
- the SL valves close and AV valves open
- blood flows passively into the atria
What is cardiac output?
the volume of blood pumped by the heart per min
What is the equation for cardiac output?
cardiac output (cm^3 min^-1) = stroke volume (cm^3) x heart rate (bpm)
What is the function of arteries?
carry blood away from the heart
What is the function of veins?
carry blood back to the heart
What are the adaptations of arteries?
- narrow lumen (maintains high pressure)
- thicker layer of elastic tissue (stretch and recoil to maintain high pressure)
- thicker layer of smooth muscle (constrict and dilate to maintain high pressure)
- thicker layer of collagen (withstand high pressure)
- folded endothelium (stretch to maintain high pressure)
- single layer of flattened endothelium cells (reduce friction to allow blood to flow freely)
What are the adaptations of veins?
- wide lumen (reduces resistance so blood flows more easily)
- thinner layer of elastic tissue and smooth muscle (don’t need to maintain high pressure)
- thinner layer of collagen (withstands pressure (doesn’t need to be thick due to low pressure))
- valves (prevent backflow)
- single layer of smooth flattened endothelium cells (reduce friction to allow blood to flow freely)
- surrounded by muscles (maintain blood flowing through veins in 1 direction)
What is the function of capillaries?
deliver nutrients and O2 to cells throughout the body as well as removing CO2 and other waste from cells
What are the adaptations of capillaries?
- narrow lumen (RBCs squeeze through lumen to decrease rate of flow, provides short diffusion pathway)
- single layer of flattened endothelial cells (short diffusion pathway)
- pores in endothelium (increase permeability)
- capillary bed (increases SA)
- close to cells (short diffusion pathway)
What is the function of venules?
carry blood from capillaries to veins
What is the function of arterioles?
carry blood from arteries to capillaries
What is hydrostatic pressure?
pressure caused by fluid pushing on the walls of the vessel which is carrying it
Which end of the capillary bed has a higher hydrostatic pressure?
the arteriole end
Which end of the capillary bed has a lower hydrostatic pressure?
the venule end
Explain how tissue fluid is formed and how it may be returned to the circulatory system (5 marks)
- hydrostatic pressure of blood high at arterial end
- fluid / water / soluble molecules pass out (reject plasma)
- proteins / large molecules remain
- this lowers the water potential / water potential becomes more negative
- water moves back into venous end of capillary (reject tissue fluid) by osmosis / diffusion
- lymph system collects any excess tissue fluid which returns to blood / circulatory system / link with vena cava / returns tissue fluid to vein
