Circulatory system

• Circulatory system:

  • blood transport system that is the link between cells in body and external environment
• Functions of blood:

  1. transports oxygen and nutrience to cell
  2. transports CO2 and other waste away from cell
  3. tranports hormones
  4. maintinance of pH
  5. disributes heat/maintains body temp
  6. maintains water content
  7. protection against disease
  8. clotting when damage
• Components of blood:

  • plasma
  • red blood cells (erythrocytes)
  • white blood cells (leucocytes)
  • platelets (thrombocytes)
• Plasma:

  • mixture of water with disolved substances such as sugar and salts
  • Function: transports componenets of blood - cells, nutrients, waste, hormones, protines, and antibodies throughout body.
• Red Blood Cells (erythrocytes):

  • bioconcave disk, no nucleus
  • contains haemoglobin which carries oxygen
  • produced in bone marrow, destroyed in liver and spleen
  • Function: transport oxygen from lungs to cells in body
• White Blood Cells (leucocytes):

  • neutropils: digest pathogens
  • monocytes: engult pathogens and aged/damaged cells my phagocytosis
  • basophills: responsable for allergic reactions
• platelets (thrombocytes):

  • small, no nucleus
  • formed bone marrow
  • function: adhere to blood vessles when injury occurs
• Heart:

  • cardiac muscle
  • held in pericardial membrane
  • RHS: collects blood from body
  • LHS: recives blood from lungs
• Atrioventricular valve:

  • seperates atria and ventrical preventing backflow
• Semilunar valves:

  • seperates ventricals and arteries
  • right: pulminary artery
  • left: aorta
• order of blood around body:

  lungs -> pulminary vein -> left atria -> atrioventricular valve ->

  left ventrical -> semilunar valve -> aorta -> superior vena cava -> inferior vena cava -> right atria -> atrioventricular valve -> right ventrical -> seilunar valve -> pulminary artery -> lungs
• 3 steps of clotting:

  1. vasoconstriction
  2. platelet plug
  3. coagulation
• vasoconstriction:

  • first step
  • muscles in walls of damaged small arteries constrict to reduce blood flow and therefore bloodloss
• platelet plug:

  • second step
  • platelets stick to rough surface of vessle and attract others
  • platelets relese substance that further acts as vasoconstrictors
• coagulation:

  • step 3
  • only applies to bigger cuts
  • formation of blood clot
  • clotting factors in plasma form clot
  • complex reactions form fibrin threads
• clot retraction

  • fourth step
  • only happens in larger cuts
  • slow proccess after clot formation
  • threads contract and bring endges of damaged vessle together
  • serum, a fluid, then squeezed out
• Why dont RBCs not have nucleus:

  • increases SA got more haemoglobin can be held withing RBC
  • more haemoglobin = more oxygen transport
• why are L and R side of heart seperated:

  • seperation between left and right prevents mixing of oxygenated and deoxygenated blood
  • ensures oxygenated blood goes to cells are deoxygenated to lungs
  • without seperation, less oxygen would be transported to cells and less waste products removed
• how are arteries suited to their function:

  • thick walls: help withstand high pressure of blood flow from heart
  • elastic walls: allows for control of blood flow - vasodialation, vasoconstriction
• how are veins suited to their function:

  • valves: prevents backflow to lower limbs/extremities
  • large lumen diameter: allows greatest amount of blood to move up past valves during each muscular contraction
• explain how blood clotting would be impacted in person didnt make fibrinogen:

  • no mesh produced to trap blood cells, platements and plasma
  • means no clot would form as made of matirials trapped in fibrin thread
  • no scab formation leading to infection
• Role of circulatory system, absorbing nutrience. with examples:

  • capilary networds are within each villi (in SI)

  Nutrients absorbed:

  • glucose - active transport
  • amino acids -active transport
  • water - osmosis