Mass transport in animals

• Cardiovascular diseases:

  If damage occurs to endothelium of artery, WBCs and lipids from blood clump together under lining, forming fatty streaks. They start to build up and harden to form a fibrous plaque known as an atheroma.
• What do atheromas do?

  They partially block lumen of artery which restricts blood flow, increasing blood pressure
• Atheromas can also break off and travel through the circulatory system until they get stuck somewhere else (embolism). This is very dangerous because it cuts off supply of oxygenated blood to vital organs
• Coronary heart disease

  • occurs when coronary arteries have lots of atheromas
  • restricts blood flow to heart muscles which can lead to myocardinal infarcation.
• Aneurysm

  • atheroma plaques damage and weaken arteries which narrows them, increasing blood pressure
  • blood travels through weakened artery at high pressure
  • may push inner layers of artery through outer elastic layer
  • causes balloon-like swelling which may burst, causing a haemorrhage.
• Thrombosis

  • atheroma plaque can rupture endothelium of artery, damaging the artery wall
  • leaves rough surface
  • platelets and fibrin accumulate at sight of damage
  • form blood clots
  • can cause complete blockage or become unlodged and block blood vessel elsewhere
• Myocardinal Infarcation

  • heart muscle supplied with blood by coronary arteries
  • coronary artery blocked
  • area of heart muscles cut off from blood supply
  • no O2 for respiration
  • causes myocardinal infarcation (heart attack)
  • leads to damage and death of heart muscle
  • if large areas of heart affected, can result in heart failure which can be fatal
• Factors that increase risk of cardiovascular diseases

  1. High cholesterol and poor diet
  2. cigarette smoking
  3. high blood pressure
• How does high cholesterol increase risk of CD

  cholesterol is main constituent of fatty deposits that cause atheromas. This causes an increase in blood pressure and blood clots which block flow of blood to coronary arteries, leading to myocardinal infarcation.
• How does a poor diet increase risk of CD

  A diet high in saturated fat is associated with high blood cholesterol

  A diet high in salt increases risk of CD as it increases risk of high blood pressure.
• How does smoking cigarrettes increase risk of CD

  Nicotine increases risk of high blood pressure. CO combines with haemoglobin, reducing the amount of O2 given to tissues. Heart muscles won’t receive enough O2 for respiration, resulting in a heart attack. Furthermore, smoking decreases amount of antioxidants in blood which are important for protecting cells from damage. Fewer of these means damage in coronary artery walls are more likely to result in atheroma formation
• How does high blood pressure increase risk of CD?

  It increases the risk of damage to artery walls which increases risk of atheroma formation, causing further increase in blood pressure. Anything that increases blood pressure, increases risk of CD (e.g., not exercising, being overweight and alcohol consumption)
• How is tissue fluid formed?

  • Ultrafiltration in the capillaries.
  • Higher hydrostatic pressure in arteriole end than in tissue fluid
  • difference in hydrostatic pressure means overall outwards pressure forces small molecules out of capillary
• High blood pressure leads to an accumulation of tissue fluid. Explain how.

  • higher hydrostatic pressure due to high blood pressure
  • increases outwards pressure from arteriole end of capillary
  • more tissue fluid formed
• The water potential of the blood plasma is more negative at the venule end of the capillary than the arteriole end of the capillary. Explain why.

  water forced out of capillary at arteriole end

  leaves plasma proteins at venule end as too large to leave capillary

  lowers water potential due to high concetration of plasma proteins
• what is the function of the coronary arteries?

  Are the hearts own blood supply; supplies blood to heart muscles. Carries oxygen and glucose to heart for respiration.
• What is the role of the renal vein?

  transports blood from kidneys to the heart
• What is the role of the renal artery?

  transports blood from heart to kidneys
• what is the role of the hepatic vein?

  transports blood from liver to the heart
• what is the role of the hepatic artery?

  transports blood from heart to the liver
• what is the role of the hepatic portal vein?

  transports blood from the gut to the liver