Pressure Graph

Question 1

Pulmonary Circulation

Answer 1

• Pressure increase in pulmonary arteries = ventricular systole/ contraction of right ventricle
• Lower pressure than systemic = shorter distance to lungs and right ventricle thin-walled
• Pressure decrease in pulmonary arteries = diastole/ ventricle relaxation
• Pressure in capillaries lower than systemic to prevent tissue fluid form forming in lungs
• Reduces damage to alveoli

Question 2

Systemic circulation (arteries/ aorta)

Answer 2

• Blood pressure increase in aorta/ arteries = ventricular systole/ contraction of left ventricle
• High pressure needed to pump blood round the body = long distance
• Pressure decrease in aorta/ arteries = ventricular diastole/ relaxation
• High pressure maintained due to elastic recoil of artery walls and closure of semi-lunar valves

Question 3

Systemic circulation (capillaries and veins)

Answer 3

• Pressure decrease in arterioles/ capillaries = frictional resistance with vessel walls as narrower lumen
  
  • Blood flowing through greater total cross-sectional area
  • Blood vessels distant/ further from heart
• Pressure decrease in capillaries = tissue fluid formation
• Low pressure in capillaries necessary for diffusion = slow flow rate for exchange
• Blood flow in veins due to massaging effect/ contraction of skeletal muscles

Question 4

Why does pressure in aorta not fall to 0 but ventricle does?

Answer 4

• Closing of aortic/ semi-lunar valve

- Prevents backflow of blood into the ventricle

Question 5

Advantage of lower pressure in lung capillary

Answer 5

• Reduced flow rate
• Allows more time for gas exchange
• Less tissue fluid produced

Question 6

Pressure in ventricles and atria

Answer 6

• Muscles thickness affects pressure
• Atrium pushes blood to ventricles (close) and thin muscle wall (low pressure)
• Ventricles have to push blood around the entire body
• Right ventricle has to push blood to lungs which needs lower pressure than left ventricle