Transcript Circulation
Transport in Animals • Gastrovascular cavities – flatworms and cnidarians • Nutrients and gases can move by processes such as diffusion and active transport. Figure 42.1 Internal transport in the cnidarian Aurelia Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. No Circulatory System Hydra Sponge Water Gastrovascular cavity Water Nematode Water Osculum (excurrent opening) Water Gastrovascular cavity Incurrent pore Anus Mouth Water Water Gastrovascular cavity a. Open Circulation Grasshopper Closed Circulation Earthworm Heart Heart Lateral hearts Hemolymph b. c. Open Circulatory systems • Insects, other arthropods and most mollusks • No distinction between blood and the interstitial fluid Open Circulatory systems • Hemolymph – name of general body fluid – directly bathes the internal organs • System of sinuses • Heart and body movements cause circulation Open Circulatory systems • Slower circulation • sluggish animals BUT... – Insects are very active Figure 42.2 Open and closed circulatory systems Closed Circulatory Systems – Earthworms, squids, octopuses, and vertebrates • Blood is confined to vessels and is distinct from interstitial fluid • Consists of the heart, blood vessels and blood Blood • Plasma – about 55% of blood volume – 90% water – inorganic salts (electrolytes), metabolites (vitamins, aa, glucose), wastes & hormones – proteins • osmotic balance, viscosity • buffers, transport lipids, antibodies, clotting factors (fibrinogen) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Plasma Plasma (92% water, 55% of whole blood) Red blood cells Platelets and leukocytes (<1%) Formed elements Platelets White blood cells Blood Plasma Red Blood Cells Red blood cells (erythrocytes) (45% of whole blood) Platelets Plasma proteins (7%) Albumin (54%) Globulins (38%) Fibrinogen (7%) All others (1%) 4 million–6 million/ 150,000–300,000 mm3 blood mm3 blood Water (91.5%) Other solutes (1.5%) Neutrophils Electrolytes Nutrients Gases Regulatory substances Waste products Monocytes 3–8% 60–70% Basophils 0.5–1% Eosinophils 2–4% Lymphocytes 20–25% Figure 42.14x Blood smear Blood Cellular Elements: • Red Blood Cells (Erythrocytes) – Most numerous (5-6 million in one cubic ml) – Transport oxygen & carbon dioxide Blood Cellular Elements: • White Blood Cells (Leukocytes) – Function in body’s defense – A cubic ml of blood has about 5,000 – 10,000 – in interstitial fluid or in the lymphatic system – where your body fights pathogens Blood Cellular Elements: Platelets are cell fragments that pinch off from larger cells in the bone marrow -Function in the formation of blood clots Prothrombin Thrombin Fibrinogen Thrombin Fibrin 1. Vessel is damaged, exposing surrounding tissue to blood. 2. Platelets adhere and become sticky, forming a plug. 3. Cascade of enzymatic reactions is triggered by platelets, plasma factors, and damaged tissue. 4. Threads of fibrin trap erythrocytes and form a clot. 5. Once tissue damage is healed, the clot is dissolved. Figure 42.16x Blood clot Heart • one atrium or two atria • one or two ventricles Heart • one atrium or two atria – chambers that receive blood returning to the heart • one or two ventricles – chambers that pump blood out of the heart. Blood vessels • Arteries – branch into arterioles • Capillaries • Veins – venules merge into veins Blood vessels • Arteries – branch into arterioles – carry blood away from heart • Capillaries – materials are exchanged • Veins – venules merge into veins – carry blood back toward heart Blood Vessel Structure • Walls of arteries or veins have three layers: – – – – epithelium smooth muscle with elastic fibers connective tissue Arteries have thicker walls than veins • Capillaries only have the inner epithelium layer Capillary Exchange • Law of Continuity – blood flows slowly in capillaries because larger total cross-section – allows materials to be exchanged Figure 42.10 The interrelationship of blood flow velocity, cross-sectional area of blood vessels, and blood pressure Capillary Exchange • About 85% of the fluid that exits capillaries re-enters at the venule end. Return of Blood to Heart • Pressure too low in veins • contraction of skeletal muscles move blood • one-way valves in veins prevent backflow Variation in Vertebrate Circulation FISH • Two chambered heart and a single circuit of blood flow Vertebrate Circulatory Systems Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Systemic capillaries Atrium Respiratory capillaries Gills Body Sinus venosus Ventricle Conus arteriosus Variation in Vertebrate Circulation AMPHIBIAN • Three chambered heart (two atria and one ventricle) and double circulation (two circuits of flow) Amphibian Circulation Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Truncus arteriosus Carotid artery Systemic artery Lungs Aorta Pulmonary capillaries Pulmocutaneous artery Right atrium Conus arteriosus Left atrium Right atrium Conus arteriosus Ventricle Pulmonary vein Sinus venosus Left atrium Ventricle Posterior vena cava Systemic capillaries Body a. b. Variation in Vertebrate Circulation AMPHIBIAN • Pulmonary circuit – blood is pumped to the lungs, where it is oxygenated and carried back to the left atrium • Systemic circuit – blood is pumped to the rest of the body, where it gives up oxygen and is carried back to the right atrium Variation in Vertebrate Circulation AMPHIBIAN • Double circulation assures a vigorous flow of blood to the vital organs • single ventricle --some mixing of oxygenrich and oxygen-poor blood. Variation in Vertebrate Circulation MAMMALS & BIRDS • Have a four chambered heart and double circulation • The left side of the heart handles oxygenrich blood and the right side handles only oxygen-poor blood. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Head Systemic capillaries Aorta Superior vena cava Lungs Pulmonary artery Pulmonary veins Left atrium Pulmonary semilunar valve Bicuspid mitral valve Right atrium Tricuspid valve Respiratory capillaries Pulmonary artery Superior vena cava Pulmonary vein Aorta Inferior vena cava Artery Left ventricle Right ventricle Body Inferior vena cava Systemic capillaries a. b. Mammalian or Bird Heart • Valves prevent backflow of blood when the ventricles contract – Between each ventricle and atrium is an atrioventricular (AV) valve • tricuspid and bicuspid (mitral) – At the exits of the heart are the semilunar valves Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Head Systemic capillaries Aorta Superior vena cava Lungs Pulmonary artery Pulmonary veins Left atrium Pulmonary semilunar valve Bicuspid mitral valve Right atrium Tricuspid valve Respiratory capillaries Pulmonary artery Superior vena cava Pulmonary vein Aorta Inferior vena cava Artery Left ventricle Right ventricle Body Inferior vena cava Systemic capillaries a. b. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Right atrium Left atrium SA node (pacemaker) AV node Internodal pathway AV Interventricular septum AV bundle AV bundle Purkinje fibers Left and right bundle branches Purkinje fibers 2. The impulse is delayed at the AV node. It then travels to the AV bundle. 1. The impulse begins at the SA node and travels to the AV node. AV bundle Interventricular septum 3. From the AV bundle, the impulse travels down the interventricular septum. Left and right bundle branches 4. The impulse spreads to branches from the interventricular septum. Purkinje fibers 5. Finally reaching the Purkinje fibers, the impulse is distributed throughout the ventricles. R The control of heart rhythm Millivolts +1 P wave T wave 0 Q S 1 sec -1 Seconds Cardiac Cycle • a complete sequence of the heart contracting to pump blood, relaxing to fill with blood. • total length is about 0.8 s – The contraction phase is called systole – The relaxation phase is called diastole Figure 42.6 The cardiac cycle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Blood pressure gauge 100 150 50 200 0 250 100 150 50 200 0 250 100 150 200 50 0 250 Cuff Stethoscope 1. Cuff pressure: 150 mm Hg No sound: Artery closed 2. Cuff pressure: 120 mm Hg Pulse sound: Systolic pressure 3. Cuff pressure: 75 mm Hg Sound stops: Diastolic pressure