cardiovascular system

• Red blood cells (Erythrocytes) -Carry oxygen
• White blood cells (Leucocytes) - Part of body’s ‘defence’ system

  Platelets (Thrombocytes)- Helps thicken blood
• Neutrophils are the most common phagocytic white blood cells

  Lymphocytes (15-30%) involved in immune response (T and B cells)

  Monocytes include phagocytic macrophages
• Eosinophils (pink granules) - (1-2%) remove toxins and dispose of histamine

  Basophils (purple granules) are the rarest white blood cells and release histamine at sites of inflammation
• The artery and veins are made up of:

  Endothelium, Elastic tissues, Smooth muscles, Fibrous tissues (collagenous)
• Flow across blood capillary walls causes continuous mixing of fluid between the plasma and the interstitial fluid compartments, and maintains the interstitial environment 20 L of fluid is filtered out per day

  17 L of fluid per day is reabsorbed into the capillaries at the venous end
• atrioventricular valves

  Tricuspid - right

  bicuspid - left
• Semilunar Valves

  Aortic

  pulmonary
• involuntary and striated muscle –

     Also called myocardium

  The outer layer called epicardium

  The inner layer called endocardium

  Short branched cells, unlike normal cells
• Diastole: contraction of the atria, ventricles relax  (‘diastolic phase’)

  Blood flows from atria – ventricles
• Systole: contraction of the ventricles, atria relax (‘systolic phase’)

  Blood flows from ventricles to lungs/body
• pause between diastole and systole Contraction of the different chambers is dictated by an ‘action potential’
• We can record the electrical events taking place during the heart beat by placing electrodes on the chest - ECG
• ECG annotation

  A) P

  B) q

  C) r

  D) s

  E) t

  F) QRS complex

  
• ECG summary

  A) Diastole (atrium contracts)

  B) builds up in atria

  C) QRS wave

  D) P wave

  E) systole (ventricle contracts)

  
• The right side pumps blood to the lungs

  The left side pumps blood to the body
• Pressure required is less on the right side so the right heart has a thinner wall than the left
• Heart rate (‘how quickly’ it pumps) is dictated largely by the autonomic nervous system

  Sympathetic nerves which stimulate heart rate, Parasympathetic nerves which depress heart rate
• Blood flow factors

  Directly related to pressure difference

  Inversely related to resistance

  Resistance depends on viscosity of the blood and the diameter of the blood vessel

  Resistance increases as the tube gets smaller
• blood pressure = systolic / diastolic
• lymphatic system

  A) hydrostatic greater than osmotic, blood leaves capillar

  B) no fluid movement, hydrostatic equal osmotic

  C) fluid renters capillary osmotic higher than hydrostatic

  
• Blood flow veins to heart

  By altering the diameter of the veins

  By muscles compressing the veins

  Vein contain ‘valves’ to ensure no back-flow of blood

  The diaphragm compresses the major veins while breathing