1. Circulatory System Chapter 42

2. What you need to know! The circulatory vessels, heart chambers, and route of mammalian circulation. How red blood cells demonstrate the relationship of structure to function. The pathway a molecule of oxygen takes from the air until it is picked up by the hemoglobin of a red blood cell.

3. Cardiovascular System System combining both the circulatory system and the respiratory system Organs of exchange  body cells (lungs, gills)

4. Circulatory System Components: 1.Heart 2.Blood 3.Vessels

5. Variation of Circulatory Systems Open circulatory system (CS) in arthropods and mollusks: Heart, and some main vessels filled with hemolymph (not blood) bath organs Closed CS in vertebrates: Blood remains in heart and vessels at all times

6. Types of Blood Vessels 1.Arteries 2.Capillaries 3.Veins Pathway (in closed CS): Heart  arteries   arterioles  arterial capillaries  venous capillaries  venules  veins  back to heart

7. Arteries Always carry blood away from the heart High pressure Thick walls Branch into smaller arterioles in organs Once deep in the tissue they become…

8. Capillaries Microscopic blood vessels in the tissue Deliver blood to every cell Thin walls facilitate diffusion and osmosis Exchange of gas, nutrients, and waste Converge into…

9. Veins Always carry blood back to the heart Venules are small veins (much like arterioles are small arteries) Venules converge into larger veins Low pressure Thin walls Valves prevent blood from flowing back into the tissue Supported by surrounding smooth muscles Superficial

10. The Heart Hollow, muscular organ Pumps blood Chambers: Atria: entrance chambers Ventricles: main chambers Cardiac muscle surrounds the chambers Muscle contracts  constricts chamber  pumps blood out Valves prevent back flow

11. Birds and Mammals 4 chambers 2 atria 2 ventricles Separated pulmonary circuit High oxygen demands for endotherms and large brains

12. Reptiles and Amphibians 3 chambers 2 atria, 1 ventricle Oxygen rich and oxygen poor blood mix together in the ventricle

13. Fish 2 chambers 1 atrium 1 ventricle Lower oxygen demand (exothermic) Single pathway heart  gills  body  back to heart Muscle movement helps pump blood Gills and arteries use counter-current exchange for maximum diffusion of O 2 and CO 2

14. Heart Rhythm Cycles: Systole: contractions of chambers (pumping) Diastole: relaxation of chambers (filling) Atrial systole and ventricular diastole are simultaneous Atrial diastole and ventricular systole are simultaneous Regulation: muscle cells contractions are orchestrated by: 1.Sinoatrial node (pacemaker) and 2.Atrioventricular nodes (delayed) They are situated in the cardiac muscle and give off electrical impulses Independent from the brain (involuntary) Hearts can continue to beat after brain-dead (vegetable)

15. Blood A tissue Contains: Cells Red blood cells (RBC) and White blood cells (WBC) Plasma, and Cell fragments Platelets

16. Red Blood Cell (Erythrocytes) Shaped like disks Produced by bone marrow in hollow bones Loose nuclei during maturing (in humans) Lifespan 120 days Aged cells (3-4 months) are reabsorbed by the spleen and liver Blood type antigens Contains hemoglobin (protein with iron) for gas transport and exchange O 2 : bound loosely by hemoglobin in the lung, and is released as blood travels through the body CO 2 : 70% reacts with H 2 O (carbonic acid), 30% reacts with empty hemoglobin

17. RBC Blood Types A, B, AB, O encoded on genome inherited from parents Determined by a surface antigen on erythrocytes Rhesus Factors of antigen (D): Presence of antigen D = Rh + Absence of antigen D = Rh – Blood work at the beginning of a pregnancy is important to help prevent Rh- mothers from producing antibodies against an Rh+ child

18. White Blood Cells (leucocytes/lymphocytes) White blood cells are the largest portion of your immune response 9 different types of WBCs (i.e. macrophages, b cells, t cells, etc.) Have nucleus (unlike RBCs) 1% of the blood They identify and attack foreign substances and microorganisms (i.e. viruses, bacteria, and transplanted organs) Also found in the lymphatic system

19. Plasma Straw colored liquid Contains: H 2 O – 90% Salts (isotonic to cell cytoplasm) Proteins Antibodies (as a result of inheritance as well as previous infections and vaccinations)

20. Platelets Pinched off from bone marrow cells They release sticky networks of protein fibers (fibrin) when stimulated by air Stops blood flow

21. Lymphatic System Plasma and protein can leak into tissue from the capillary beds The lymphatic system returns this fluid (lymph) to the vena cava Before returning the fluid it is filtered through lymph nodes (WBC filters) to remove viruses and bacteria Consists of: Tonsils, thymus gland, spleen, and lymphatic vessels