1. PHB

• Circulatory System


  Composed of the heart (pump), blood vessels (tubes), and blood (fluid) in a one-way circuit that distributes gases, nutrients, signal molecules, and wastes throughout the body

  
• Components of the Circulatory System

  • Heart
  • Blood vessels
  • Blood

  
• Blood


  • Carries oxygen, nutrients, and wastes
  • Flows in a one-way circuit

  
• Composition of Blood


  • Plasma
  • Formed elements (erythrocytes, leukocytes, platelets)

  
• Plasma


  Aqueous solution (90% water) that contains salts, electrolytes, proteins, nutrients, respiratory gases, hormones, and waste products
• Serum


  Fluid remaining after clotting, containing no cells, fibrinogen, clotting factors or other proteins involved in coagulation
• Serum protein separation by electrophoresis

  1. Apply current across paper

  2. Proteins migrate towards positive electrode based on charge

  3. Proteins appear as bands after staining
• Erythrocytes (red blood cells)

  • Lack mitochondria, contain haemoglobin, lifespan of 120 days
  • Transport oxygen and carbon dioxide, maintain acid-base homeostasis

  
• Haemoglobin content


  Adult male: 14-18 g/dl, Adult female: 12-16 g/dl
• Anaemia


  Deficiency in haemoglobin in the blood
• Polycythaemia


  Excess red blood cells in the blood

  
• Types of Leukocytes (white blood cells)

  • Agranulocytes
  • Granulocytes

  
• Platelets


  • Fragments of megakaryocytes, lifespan of 10 days, important in haemostasis and blood clotting

  
• Blood Haemostasis


  1. Platelet plug formation

  2. Coagulation (extrinsic and intrinsic cascades)

  
• Haemophilia


  Occurs due to lack of factor 8 in the coagulation cascade
• Blood Cell Production


  1. Pluripotent hematopoietic stem cell differentiates into various blood cell lineages

  2. Stimulated by growth inducers and differentiation inducers

  
• Erythropoietin


  Regulates red blood cell production in response to low oxygen supply

  
• Circulatory System Structures


  • Pulmonary circulation
  • Systemic circulation
  • Portal circulation
• Blood Vessel Types


  • Arteries
  • Veins
  • Capillaries
• Arteries


  • Carry oxygenated blood away from the heart at high speed and pressure, have thick, strong walls

  
• Veins


  • Carry deoxygenated blood towards the heart at slower speed and lower pressure, have thin walls with valves to prevent backflow

  
• Capillaries


  • Allow diffusion of nutrients, oxygen and carbon dioxide between blood and tissues, have very thin walls
• Blood flow


  Rapid in arteries, slower in veins, slowest in capillaries
• Blood pressure


  Highest in arteries, lowest in veins, low in capillaries

  
• Blood oxygenation


  Oxygenated in arteries (except pulmonary artery), deoxygenated in veins (except pulmonary vein), both in capillaries

  
• Pressure gradient


  Drives blood flow in the cardiovascular system

  
• Blood flow


  Directly proportional to pressure gradient, inversely proportional to resistance

  
• Resistance


  Determined by the radius of the blood vessel

  
• Blood pressure


  Systolic pressure from heart contraction, diastolic pressure from elastic recoil of arteries

  
• Blood Pressure Categories


  • Normal
  • Elevated
  • Stage 1
  • Stage 2
  • Hypertensive crisis

  
• Lifestyle changes are advocated before/in addition to medication for hypertension
• Atherosclerosis


  • Hardening and narrowing of arteries due to fatty deposits, major risk factors include hypertension, hypercholesterolemia, diabetes, smoking, family history, sedentary lifestyle, obesity
• Anaemia


  Condition with lower than normal amount of healthy red blood cells and haemoglobin, leading to fatigue, weakness, and lack of oxygen
• Causes of Anaemia


  • Less production (vitamin B12 deficiency, folic acid deficiency, iron deficiency, anaemia of chronic disease, pernicious anaemia)
  • Increased breakdown (haemolytic anaemia, menstruation)
• Leukaemia


  Cancer of the blood and bone marrow caused by rapid production of abnormal white blood cells

  
• Types of Leukaemia


  • Acute (faster, in younger age groups)
  • Chronic (slower, in older age groups)
• Multiple Myeloma


  • Bone marrow cancer affecting plasma cells
• Passage of Blood


  1. Oxygenated blood from lungs enters left atrium

  2. Flows through bicuspid valve to left ventricle

  3. Pumped out through aorta to systemic circulation

  4. Deoxygenated blood from body enters right atrium

  5. Flows through tricuspid valve to right ventricle

  6. Pumped out through pulmonary artery to lungs

  
• Cardiac Cycle


  Cardiac output, peripheral resistance, total peripheral resistance, pulmonary vascular resistance, mean arterial blood pressure, heart rate

  
• Contraction starts from the apex