BI 103 Lecture Notes Chapter 28: Circulation: The Cardiovascular System

  1. Hearts:  Pump blood through vessels

                  1.  2 chambered (fish)

                  2.  3 chambered  (amphibians and most reptiles)

                  3.  4 Chambered, mammals/birds: most efficient, no mixing of oxygenated and                                    deoxygenated blood.

      A. Heart anatomy

                  1. Right/Left atrium (collect blood returning to heart)

                  2. Right/ Left Ventricle (pump blood to body/lungs)

                  3. Vena cavas: return blood from body

                  4. Pulmonary artery: blood to lungs

                  5. Pulmonary veins: blood returns from lungs

                  6. Aorta: Blood to body

                  7. Valves: Atrioventricular (prevent backflow into atria)

                  8. Valves: Semilunar (prevent backflow into ventricles)

      B. Pathway of blood through heart:

                  1. Pulmonary circuit:

                              a) vena cavaà:R atriumà R ventricleà pulmonary arteryà lungsà                                       pulmonary veinsà L atrium

                  2. Systemic circuit:

                              a) L ventricleà aortaà bodyà superior/inferior vena cavaà R. atrium

      C. Heart contraction

                  1. Sinoatrial node (SA Node) contains pacemaker cells that initiate contraction

                              a) Located in upper wall of right atrium

                  2. Atria contract

                  3. Signal delayed at Atrioventricular node (AV node)

                  4. Ventricles contract

                  5. Uncoordinated contractions = fibrillation

      D. Control of heart Rate

                  1. Nervous system

                              a) parasympathetic: normally in control

                              b) sympathetic: in control in exercise, stress (increase heart rate)

                  2. Endocrine system

                              a) Epinephrine = increased heart rate

  1. Blood (average human blood volume = 5-6 L

      A. Components

                  1) Formed elements: all cells produced originally from bone marrow (40-45%)

                              a) Erythrocytes: RBC’s 

                                          1. Carry oxygen with hemoglobin (needs iron)

                                          2. Have A, B, or AB or no (O) proteins for recognition

                                          3. Kidney hormone: Erythropoietin stimulates production of                                            RBC’s in bone marrow.

                              b) Leukocytes WBC’s

                                          1. immune function

                              c) Platelets 

                                          1. Physically start forming clots

                                          2. Stimulate production of enzyme (thrombin) which helps form                                                blood clots

                                          3. Produced from fragmenting megakaryocytes in marrow

                  2) Plasma

                              a) Water (90% of plasma)

                              b) Proteins: regulate osmotic pressure, clotting factors

                              c) Other solutes: nutrients, salts, gases, wastes, hormones

  1. Vessels

      A. Arteries (thick walled, withstand high pressure)

      B. Arterioles (control distribution of blood flow)

      C. Capillaries (thin walls, materials enter & exit via diffusion, slow flow)

      D. Venules (carry blood back to veins)

      E. Veins (return blood to heart- low pressure system)

                  1. One way valves

                  2. Skeletal muscle pumps

  1. Disorders

      A. Hypertension: High blood pressure

      B. Atherosclerosis: Deposits (plaques) collect in vessel walls