Circulation Chapters 32 and 33

Circulation and Circulatory Systems heart atria: receive blood ventricles: pump blood veins vessels that transport blood back to heart all veins carry deoxygenated blood (CO2-rich) , except those leaving the lungs connective tissue  thin layer of smooth muscle  elastin  epithelial tissue contain one-way valves  prevent backflow venules smallest veins in body  leave capillaries  join larger veins arteries vessels that transport blood away from heart all arteries carry oxygenated blood (O2-rich) , except those bringing blood to lungs connective tissue  thick layer of smooth muscle  elastin  epithelial tissue arterioles smallest arteries in body  merge into capillaries capillaries smallest blood vessels in body thin layer of epithelial tissue gas and nutrient exchange capillary beds

blockages can be a problem in all vessels especially arteries Fig. 32.3 Arteries, capillaries, and veins

Page 605 Coronary arteries and plaque

Some Animals Lack a Circulatory System utilize diffusion, osmosis, or cell-to-cell transport Invertebrate Circulatory Systems open circulatory systems blood enters and then leaves the vessels after leaving, blood fills hemocoels (“blood cavities”) saturates body tissues in blood  muscular contractions  blood returns to heart closed circulatory systems more efficient blood remains in vessels blood flows much more rapidly

Fig. 32.2 Open vs. closed circulatory systems

Vertebrate Circulatory Systems all vertebrates have closed systems blood a connective tissue; 0.9% saline formed elements (cell types) – 45% erythrocytes (rbc’s) transport O2 t0 body (hemoglobin) concave shape and no nucleus spleen removes old rbc’s and stores wbc’s leukocytes (wbc’s) many different types  function in the immune system thrombocytes (platelets) cellular fragments that play a major role in blood clotting all derive from hemocytoblasts in red bone marrow plasma (a watery substance) – 55% 92% H2O, 7% proteins, 1% other solids, gases, wastes plasma proteins albumins, globulins, fibrinogen, prothrombin, etc. salts, fats, glucose, amino acids, hormones, vitamins, ions, etc. gases: extra O2, CO2 nitrogenous wastes: urea, uric acid Fig. 31.4 Formed elements

Fig. 32.13 Composition of blood

blood clotting 7-10 steps; about 15 substances involved some substances prevent accidental clotting three major reactions platelets form a “plug” at wound site  release thromboplastin thromboplastin and Ca+ ions convert prothrombin to thrombin thrombin converts fibrinogen to fibrin fibers  seal wound the damaged cells, collagen, and other substances also help seal wound Fig. 32.14 Blood clotting

fish two-chambered heart 1 atrium, 1 ventricle gas exchange across gill capillaries amphibians and most reptiles three-chambered heart 2 atria, 1 ventricle systemic vs. pulmonary circuit pulmonary: blood flow to and from lungs systemic: blood flow to and from rest of body the two are not completely separate deoxygenated vs. oxygenated blood some mixing occurs in the single ventricle birds, crocodilians, mammals, humans four-chambered heart 2 atria, 2 ventricles systemic and pulmonary circuits completely separate normally no mixing of deoxygenated and oxygenated blood

Fig. 32.5 Comparison of circulatory systems in vertebrates

Human Circulatory System path of blood flow through body deoxy. blood in body capillaries  body venules  body veins  superior/inferior vena cavas  right atrium  right AV valve  right ventricle  pulmonary semilunar valve  pulmonary artery  lung arterioles  lung capillaries (gas exchange; blood now oxy.)  lung venules  pulmonary veins  left atrium  left AV valve  left ventricle  aortic semilunar valve  aorta  body arteries  body arterioles  body capillary beds (gas & nutrient exch.; blood now deoxy.)  REPEAT blood makes a complete circuit with every beat

Fig. 32.6 External view of the heart

Fig. 32.7 Internal view of the heart Fig. 32.8 Heart valves

Fig. 32.10 Path of blood

control of heart contractions unique nature of heart (cardiac) muscle branching of muscle fibers extrinsic control external control outside of heart nervous system and hormones (esp., epinephrine) speeds up or slows down heart rate intrinsic control control within heart itself sinoatrial (SA) and atrioventricular (AV) nodes specialized regions of cells that can generate and carry electrical impulses ventricular septum and Purkinje fibers SA node creates impulse  walls of atria  atria contract  signal travels to AV node  signal routed down ventricular septum in two paths  Purkinje fibers  walls of ventricles  ventricles contract SA node initiates heartbeat; AV signals ventricles to contract

Fig. 32.9 Contraction system of the heart

the working heart heart beat and activity 1st sound: right and left AV valves closing 2nd sound: aortic and pulmonary semilunar valves closing all valves prevent backflow of blood can be monitored with an EKG (electrocardiogram) systole vs. diastole stroke volume vs. cardiac volume heart rate (pulse) – average = 72 beats/minute blood pressure sphygmomanometer systolic vs. diastolic pressure (mm Hg) normal measurements (120/80) arterioles vasoconstriction  muscle walls thicken  increases blood pressure vasodilation  muscle walls thin  decreases blood pressure all gas and nutrient exchange takes place across capillaries blood pressure lowest in veins (venous blood) movement assisted by valves and smooth/skeletal muscle contraction

Fig. 32.12 Cross section of a valve in a vein

human circulatory circuits circuit: a major pathway of blood flow and return pulmonary systemic hepatic portal nutrients absorbed by small intestine  travel in hepatic portal vein to liver  liver monitors blood content and stores extra nutrients  blood enters general circulation renal cardiac coronary arteries and veins numerous ones in head and brain

Lymphatic System series of small vessels that parallel circulatory system transports lymph instead of blood colorless, interstitial fluid that is derived from tissues may be in tissue cells or between tissue layers may be blood plasma that seeps into tissues fluid moves in same fashion as venous blood  merges with circ. system four essential functions maintain fluid and ion balances in body transports certain fatty acids part of the immune system and cooperates with it route by which interstitial fluids can return to the circ. system structures lymph capillaries  larger lymph vessels lymph nodes mass of lymphoid tissue located along the course of a lymph vessel highly involved with immune system lymph organs other organs strongly associated with lymph spleen, bone marrow, tonsils, thymus gland, etc.

Fig. 33.1 Lymphatic system

Fig. 33.2 Some lymphoid organs