تنزيلات

• The human cardiovascular system

  • Ability to divert blood during diving
  • Different pressures in the two circuits
  • Pressure drops at capillaries
• The heart contracts and relaxes rhythmically


  1. Valves open and close

  2. Cardiac cycle consists of two main phases
• Ventricles


  Right and left ventricles have different thickness (muscle mass)
• Heart valves


  • Atrioventricular (AV) valves maintain unidirectional blood flow between atria and ventricles
  • Semilunar (SL) valves ensure one-way flow out of the ventricles to the arterial systems
• LV contracts with a greater force than RV, but both ventricles pump the same volume of blood
• Cardiac output (CO)


  Volume of blood pumped by each ventricle per minute
• Cardiac output


  Depends on heart rate and stroke volume
• SA node


  Generates electrical impulses in atria and sets the rate of heart contractions
• AV node


  Relays signals from SA node to ventricles and triggers ventricular contractions
• An electrocardiogram (ECG/EKG) detects electrical impulses in the heart and can provide data about heart health
• Arteries


  • Transport blood from heart to lung and other tissues
  • Have the thickest wall of all the vessels
  • Outer layer of connective tissue with elastic fibers
  • Layer of smooth muscles controlled by hormones/neurons
• Capillaries


  • Have a single layer of epithelial cells wrapped in ECM
  • Diameter barely permits passage of RBCs
• Veins


  • Transport blood from the lung and other tissues to the heart
  • Have thinner walls than arteries
  • Large veins have valves to ensure blood flow toward the heart
  • Have lower blood velocity and pressure than arteries
• Blood pressure


  The force that blood exerts against the wall of blood vessels
• During systole


  Elastic walls of arteries stretch, resulting in systolic pressure
• During diastole


  Elastic arteries snap back, resulting in diastolic pressure
• Mean arterial pressure


  Cardiac output x Total peripheral resistance
• Blood velocity


  The speed with which blood flows forward through a given segment of the circulatory system
• Blood velocity


  Inversely proportional to the total cross-sectional area of all vessels at any given level of the circulatory system
• Arterioles and precapillary sphincters


  • Regulate the flow of blood into capillaries
• Regulation of blood flow


  • Relaxation of precapillary sphincters in digestive tract after meal
  • Increased blood flow to muscles during exercise
  • Regulation of blood flow to skin to control body temperature
  • Increased blood flow to sites of infection or injury
• Exchange between capillaries and interstitial fluid

  Occurs through diffusion, endocytosis/exocytosis or through pores
• Blood pressure


  Forces fluid and small solutes out of the capillary at the arterial end
• Osmotic pressure


  Draws in fluid at the venous end, because the blood has a higher concentration of solutes than the interstitial fluid
• Edema


  Tissue swelling caused by excessive accumulation of interstitial fluid
• Components of blood


  • Red blood cells
  • White blood cells
  • Plasma
• Anemia


  Abnormally low amounts of hemoglobin or a low number of red blood cells, causing fatigue due to lack of oxygen in tissues
• Erythropoietin (EPO)


  Stimulates the bone marrow to produce more red blood cells
• Blood clotting


  Blood contains self-sealing materials that are activated when blood vessels are injured
• The human cardiovascular system


  • Ability to divert blood during diving
  • Different pressures in the two circuits
  • Pressure drops at capillaries
• The heart contracts and relaxes rhythmically


  1. Valves open and close

  2. Cardiac cycle consists of two main phases
• Ventricles


  Right and left ventricles have different thickness (muscle mass)
• Heart valves


  • Atrioventricular (AV) valves maintain unidirectional blood flow between atria and ventricles
  • Semilunar (SL) valves ensure one-way flow out of the ventricles to the arterial systems
• LV contracts with a greater force than RV, but both ventricles pump the same volume of blood
• Cardiac output (CO)


  Volume of blood pumped by each ventricle per minute
• Cardiac output


  Depends on heart rate and stroke volume
• SA node


  Generates electrical impulses in atria and sets the rate of heart contractions
• AV node


  Relays signals from SA node to ventricles and triggers ventricular contractions
• An electrocardiogram (ECG/EKG) detects electrical impulses in the heart and can provide data about heart health
• Arteries


  • Transport blood from heart to lung and other tissues
  • Have the thickest wall of all the vessels
  • Outer layer of connective tissue with elastic fibers
  • Layer of smooth muscles controlled by hormones/neurons