Circulatory and respiratory system

• Circulation


  The movement of materials within a cell or between part of an organism
• Circulatory system in simple organisms

  • Diffusion
  • Active transport
  • Cytoplasmic streaming
• Circulatory system in large and complex organisms


  • Many cells are far from external environment
• Components of a circulatory system

  • Fluid in which transported material is dissolved
  • Network of tubes or body spaces through which the fluid flows
  • A means of driving the fluid through the tubes or spaces
• Closed circulatory system in humans and other vertebrates

  • Fluid: blood
  • Network of tubes: blood vessels (arteries, veins and capillaries)
  • Means of driving fluid: heart

  
• Blood


  Unique tissue that is made up of cells (formed elements) suspended in liquid

  
• Functions of blood


  • Transporting respiratory gases, nutrients, cellular wastes and regulatory substances (enzymes, hormones)
  • Maintaining and regulating the chemical state, pH and water content of cells and body fluids
  • Regulating body temperature
  • Protecting the body from disease-causing microorganisms
  • Ability to clot to protect the circulatory system from collapse
• The average human body contains about 5.5 L of blood
• Composition of blood


  • 55% plasma
  • 45% cells (red blood cells, white blood cells, platelets)

  
• Plasma


  Clear, straw-colour liquid. 90% water + 7% dissolved proteins + salts + glucose + amino acids + fatty acids + vitamins + hormones + cellular wastes
• Plasma proteins


  • Albumin
  • Globulins
  • Fibrinogen
• Red blood cells (erythrocytes)

  Transport O2 from lungs to the tissues and CO2 from tissues to lungs

  
• Iron-containing pigment hemoglobin gives blood its red colour and functions in the transport of O2 and CO2
• During early embryo; liver, spleen and lymph nodes, after birth; bone marrow produce red blood cells
• Red blood cells do not have nucleus and live about 120 days
• Anemia


  Condition caused by lack of red blood cells or hemoglobin
• White blood cells (leukocytes)


  Protect the body against infection by bacteria and other microorganisms
• Functions of white blood cells

  • Phagocytosis
  • Production of antibodies
• Leukemia


  Cancer of the white blood cells
• Platelets


  Small, round or oval fragments formed in bone marrow that trigger the blood clotting process
• Arteries


  • Distribute blood from heart to organs and tissues
  • Walls are thick and elastic
  • Contain connective tissue, muscle tissue and epithelial tissue
  • Become smaller and smaller (arterioles)

  
• Veins


  • Drain blood from body tissues to the heart
  • Walls are thin and slightly elastic
  • Smallest are venules
  • Contain valves that allow blood to flow in one direction only

  
• Capillaries


  • Microscopic vessels that connect arterioles and venules
  • Walls consist of a single layer of epithelial cells
• Heart


  • Composed of cardiac muscle
  • Cardiac muscle cells form a branching, interlocking network that enables them to contract with great force
• Pericardium


  • Tough protective sac of connective tissue surrounding the heart
  • Filled with water

  
• Layers of the heart wall

  • Epicardium (outermost layer)
  • Myocardium (middle layer)
  • Endocardium (innermost layer)

  
• Heart chambers


  • Two upper, thin-walled atria
  • Two lower, thick-walled ventricles
  • Left and right sides separated by a septum
• Heart valves


  • Semilunar valves (blood from ventricles to pulmonary artery and aorta)
  • Atrioventricular (A-V) valves (blood from atria to ventricles)

  
• Heart murmurs


  Abnormal sounds caused by turbulent blood flow through the heart

  
• Functions of the heart

  • Generating blood pressure
  • Routing blood
  • Ensuring one-way blood flow
  • Regulating blood supply

  
• In 1628, William Harvey proposed the correct pathway of human circulation, which was proven in 1660 with the discovery of capillaries
• Specialized circulatory pathways


  • Hepatic-portal circulation (blood from digestive tract to liver)
  • Coronary circulation (supplies blood to the muscle of the heart)
  • Renal circulation (blood to and from kidneys)

  
• Lymphatic system


  Returns excess fluid and proteins from the intercellular spaces to the blood

  
• Functions of the lymphatic system


  • Filters foreign matter (cancer cells, bacteria etc.) and produces white blood cells to defend against diseases
• Requirements for an efficient respiratory surface

  • It must be thin-walled so that diffusion occurs rapidly
  • It must be moist because O2 and CO2 must be in solution
  • It must be in contact with an environmental source of O2
  • In multicellular organisms, it must be in close contact with the system that transports dissolved materials to and from the cells
• Glucose + Oxygen -> Carbondioxide + water + energy
• Respiratory system in protists and very small multicellular organisms


  • Respiratory surface is directly between the cells and the environment
• Respiratory system in larger animals

  • Respiratory surfaces are in special organs and systems
• Components of the human respiratory system

  • Lungs
  • Air tubes (nose, pharynx, trachea, bronchi, bronchial tubes, bronchioles and alveoli)
• Air tubes


  • Have long hairs at the openings
  • Walls of mucous membrane with ciliated epithelial cells
  • Secrete mucus to trap particles and moisten the air
  • Have capillaries below to warm the air