cardiovascular and lymphatic systems

• cardiovascular = heart and vessels

  • parts that transport blood
  • anything that enters the body will probably end up in the blood stream (systematic circulation)
• Blood:

  • tissue = connective
  • ECM = plasma
  • cells = RBCs, WBCs and platelets
  • + nutrients, waste, hormones, ions, proteins
• functions of blood:

  • transports O2 to respiring tissues
  • hormones
  • antibodies - immunity
  • temperature control
  • transports nutrients around the body after digestion
• heart:

  • 4 chambered heart - 2x atria and 2x ventricles
• right atrium receives deoxygenated blood from the body and delivers it to the right ventricle, which pumps it into the lungs
• left atrium receives oxygenated blood from the lungs and delivers it to the left ventricle, which pumps it to the rest of the body
• What are the two types of valve in the heart?

  atrioventricular valve and semi-lunar valve
• atrioventricular valves (AV valves)

  • maintain unidirectional blood flow between atria and ventricles
  • tricuspid valve = on the right
  • bicuspid (mitral) valve = on the left
• semi-lunar valves

  • ensure one-way flow out of the ventricles to the vessels
  • pulmonary valve = located at the exit of the right ventricle
  • aortic valve = located at the exit of the left ventricle
• red blood cells = erythrocytes - oxygen binds to Fe in haemoglobin to be transported
• white blood cells = leukocytes
• valves open and close as the heart goes through the cardiac cycle
• diastole - ventricles are relaxed and filling
• systole - ventricles contract and pump
• heart contains self-excitable autorhythmic fibres that act as a pace maker:

  • sinoatrial nodes
  • atrioventricular nodes
• the heart contracts 70-80 times per minute
• blood pressure = the force that the blood exerts on the walls of blood vessels
• pressure in large arteries varies with the heartbeat

  • highest = when ventricles contract
  • lowest = when ventricles are relaxed
• normal blood pressure = 110-120 mmHg systolic and 75-80 mmHg diastolic
• arteries

  • carry oxygenated blood (except one)
  • thick wall to withstand high pressures
• arterioles - same as arteries but smaller
• veins

  • carry deoxygenated blood (except one)
  • valves to prevent backflow
• venules are the same as veins but smaller
• capillaries:

  • one cell thick
  • site of exchange of nutrients and gases between tissues and the blood
• 3 parts of circulation

  • systematic circulation
  • pulmonary circulation
  • portal circulation
• systematic circulation = blood travels from left ventricle round rest of the body and back to the right atrium
• pulmonary circulation - blood travels from right ventricle to lungs and back to left atrium
• portal circulation - blood travels from the gut to the liver
• 60-70% of water and solutes in blood plasma filter through capillary walls due to pressure, and end up in the interstitial space
• fluid that doesn't return to capillaries is returned to circulation by the lymphatic system
• lymph = interstitial fluid once is has entered the lymphatic system
• functions of the lymphatic system:

  • collects excess interstitial fluid and returns it to the blood (3L/day)
  • returns plasma proteins to the blood
  • defends body against diseases by transporting cells of the immune system and filtering pathogens from the blood
  • absorbs lipids and fat-soluble vitamins from intestine and transports them to the blood
• anatomy of the lymphatic system:

  • lymph vessels
  • lymph nodes
  • ducts and trunks
  • spleen
  • thymus gland
• lymph vessels - capillaries and larger vessels, similar to veins in structure
• lymph nodes - lymph gets filtered of bacteria and cellular debris, lymphocytes are added
• ducts and trunks - emptying areas
• spleen - removes foreign bodies and dead RBCs from blood
• thymus gland - site of T-lymphocytes maturation
• lymphatic drainage:

  • lymph vessels from lower part of the body converge to form cisterna chyli in the lumbar region of the abdomen, from this lymph flows along the thoracic duct
  • lymph from all over the body, except the right upper quadrant, drain into the thoracic duct
  • it returns the lymph to the blood circulation at the base of the left subclavian vein
  • lymph from the right upper quadrant is gathered into the right lymphatic duct