🏥 Chapter 6 - Transport in Humans

• Plasma


  • yellowish liquid in blood
  • contains water, nutrients, hormones and excretory products, as well as red and white blood cells
• Red Blood Cells


  • contain haemoglobin that combines reversibly to with oxygen
  • when oxygen concentration is high, haemoglobin binds to oxygen to form oxyhaemoglobin, which releases oxygen when oxygen concentration is low
  • biconcave shape to increase surface area-to-volume ratio, increasing the rate of absorption and release of oxygen
  • flexible to easily flow through blood capillaries
  • no nucleus to store more haemoglobin
• Phagocytes


  • undergoes phagocytosis whereby the phagocyte engulfs and destroys foreign particles
• Lymphocytes


  • recognize foreign particles
  • destroy harmful organisms
  • cause bacteria to clump together for easy ingestion by phagocytes
  • neutralize toxins produced by bacteria
• Platelets (How blood clots)

  • platelets convert soluble fibrinogen to insoluble fibrin threads
  • fibrin entangles blood cells and the whole mass forms a clot
  • clot prevents excessive blood loss and entry of microorganisms
  • blood clot = coagulation/agglutination
• Blood Groups


  Blood Group A:

  • antigen A
  • antibody b

  Blood Group B:

  • antigen B
  • antibody a

  Blood Group AB:

  • antigen A and B
  • no antibodies

  Blood Group O:

  • no antigens
  • antibody a and b
• When different blood groups mix

  • when different blood groups mix, agglutination may occur
  • this may result in tissue rejection

  SPECIAL CASES

  1. AB - universal acceptor, since there are no antibodies
  2. O- universal donor, no antigens
• Heart


  • circulates blood around the body via pumping
• Arteries


  • carry blood away from heart
  • thick muscular wall since blood flows at high pressure
  • carry oxygenated blood (except pulmonary a.)
• Arterioles


  • branched from arteries
• Capillaries


  • partially permeable for diffusion of certain susbtances
  • provides large surface area for exchange of substances between blood and tissue cells
  • cross-sectional area increases, lowering blood pressure, giving more time for exchange of substances
• Venules

  • formed before blood capillaries leave an organ
• Veins


  • carry blood to the heart
  • thinner walls than artery since blood moves at low pressures, slowly and smoothly
  • has valves to prevent backflow
• Tissue fluid


  • colourless liquid transports dissolved substances between tissue cells and blood capillaries
  • dissolved oxygen and food substances diffuse from blood in the blood capillaries into the tissue fluid into the cells
• Atria


  • receive blood from the veins
  • comparatively thin muscular walls, only force blood to ventricles
  • low pressure
• Ventricle


  • comparatively thicker on the left since left ventricle pumps blood to whole body, higher pressure
  • comparatively thinner of the right since blood is only pumped to the lungs
• Median septum


  • divides right and left side of the heart to prevent mixing of deoxygenated and oxygenated blood, resulting in less oxygen carries to the rest of the body
• Cardiac Cycle Structure


  1. During atrial/ventricular diastole/systole, the atrial/ventricular muscles contract/relax,
  2. causing blood pressure in the atrium/ventricle to be higher/lower than that of the ventricle/atrium.
  3. blood flows from _____ to ______ via opened valves

  OR

  3. valves are closed to prevent backflow of blood
• Blood Pressure


  • highest during ventricular systole
  • decreases during ventricular diastole
• Pulse


  • produced after every ventricular contraction
• Pressure Graph


  • acronym "COCO"
  • at point 1, tricuspid valves close
  • at point 2, semi-lunar valves open
  • at point 3, semi-lunar valves close
  • at point 4, tricuspid valves open

  
• What happens during a heart attack?

  • when blood flow to a particular part of the heart may be completely blocked, and due that, the heart receives insufficient oxygen and that region of the heart dies
  • extensive heart damage is often fatal, as heart is no longer able to pump blood around the body
• What happens during Coronary Heart Disease?

  • cholesterol and saturated fats may be deposited on the inner surface of the coronary arteries (atherosclerosis)
  • narrows lumen of these arteries and increases blood pressure
  • artery develops a rough surface
  • risk of blood clot is increased
  • if it occurs in coronary arteries. blood and oxygen to the heart muscles may be completely cut off
  • leads to heart attack
• Risk factors of CHD

  • smoking

  1. Nicotine increases blood pressure and risk of blood clotting

  • Unhealthy diet

  1. high amounts of cholesterol, saturated fat and salt increase risk of high blood pressure, leading to CHD which --> heart attack

  • Genetics
  • Age

  1. As age increases, risk of CHD increases
• How to reduce risk of CHD

  • healthy diet
  • avoid smoking
  • regular exercise to strengthen heart
• common misconceptions

  1. all veins have valves (false, pulmonary vein has no valves, since pressure exerted by the heart is high enough to prevent backflow of blood)
  2. pulmonary artery has valves (false, there is only one semi-lunar valve in the p.a, and it is in the heart)
  3. aorta has valves (false, there is only one semi-lunar valve in the aorta, and it is in the heart)
• yt video on chapter

  https://www.youtube.com/watch?v=_vZ0lefPg_0