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Circulation Chapter 38 General Function 1. Transports nutrients (from digestion), wastes (to respiratory and urinary), hormone (endocrine) and gases (to and from respiratory) throughout the body 2. Helps fight infection 3. Helps regulate body temperature and pH Functional Connections food, water intake oxygen intake DIGESTIVE SYSTEM nutrients, water, salts RESPIRATORY SYSTEM oxygen elimination of carbon dioxide carbon dioxide CIRCULATORY SYSTEM URINARY SYSTEM water, solutes elimination of food residues rapid transport to and from all living cells elimination of excess water, salts, wastes Figure 38.2 Page 665 Circulatory Systems Open System •Arthropods and most mollusks Closed System •Vertebrates and anelids pump pump spaces or cavities in body tissues aorta heart Figure 38.3 Page 666 Circulation of higher animals- Heartpump to move fluids-usually one way with a valve Closed circulatory system- one that has vessels (veins and arteries) to move the blood Open circulatory system- lacking vesselsallowing the blood to move in large sinuses Open circulatory systems: Insect circulatory system (picture) Closed circulatory systems: Earthworm Anterior end--10 hearts (aortic arches) (5 on each side) Vertebrate Circulatory Arteries- take blood away from the heart Veins- take blood to the heart Capillaries- connect arteries and veins (exchanges materials) Fish 1 circuit , 2 chambered heart Amphibians 2 circuits (to lungs and body), 3 chambered heart (blood mixes) 3. Reptiles- 3 chambered heart; 2 atria, 1 ventricle but the ventricle is partial divided allowing very little mixing of blood Birds and mammals – 2 circuits (to lungs and body), 4 chambered heart (blood doesn’t mix) Functions of Blood • Transports oxygen and nutrients to cells • Carries carbon dioxide and wastes away from cells • Helps stabilize internal pH • Carries infection-fighting cells • Helps equalize temperature Components of Blood See figure 38.7, page 669 also Blood 6-8% of body weight Plasma portion (50-60% of total volume) • Water • Proteins • Ions, sugars, lipids, amino acids, hormones, vitamins, dissolved gases Cellular portion (40-50% of total volume) • White blood cells (leukocytes) – involved in immune response Neutrophils-fast acting phagocytes, nonspecific Lymphocytes-B & T cells, specific Monocytes-call up immune response, slow, nonspecific Eosinophils-fast, secrete enzymes, nonspecific Basophils-fast, inflammatory response, nonspecific • Red blood cells (erythrocytes) – carry oxygen • Platelets – involved in clotting Figure 38.5 Page 668 Erythrocytes (Red Cells) • Most numerous cells in the blood • Transport oxygen and carbon dioxide • Colored red by oxygen-binding pigment (hemoglobin) • Have no nucleus when mature • Develop from stem cells in bone marrow • Good for about 120 days, ongoing replacement Biconcave disc Leukocytes (White Cells) • Function in housekeeping and defense • Cell types Basophils Eosinophils B lymphocytes Neutrophils T lymphocytes Macrophages NK cells Dendritic cells Mast cells Leukocytes (White Cells) Platelets (thrombocytes) • Membrane-bound cell fragments • Derived from megakaryocytes, which arise from stem cells • Release substances that initiate blood clotting Blood Cell Development • Stem cells in bone marrow are unspecialized cells that retain the capacity to divide • Some daughter cells of stem cells differentiate to form blood cells • Body must continually replace blood cells natural killer cells mast cells neutrophils eosinophils basophils forerunners of the white blood cells (leukocytes) committed cell stem cells that (proerythroblast) ? multiply and differentiate in bone marrow T lymphocytes (mature in thymus) B lymphocytes (mature in bone marrow) monocytes (immature phagocytes) red blood cells (ertyrocytes) dendritic cells megakaryocytes mature macrophages platelets Fig. 38-5, p.661 Blood Disorders • Red blood cell disorders – Anemia – to few red-blood cells, oxygen blood levels cannot be kept high enough • Many different kinds, from many causes – Polycythemias – too many red-blood cells, makes blood flow sluggish • White blood cell disorders – Infectious mononucleosis – too many monocytes and lymphocytes – Leukemias – cancer suppresses or impairs white blood cell formation in bone marrow Blood Type in Transfusions • Require that donor and recipient have same blood type • If bloods of incompatible types are mixed, recipient’s immune system will attack, clump up and destroy donor cells • This is an agglutination reaction ABO Blood Type • Type A red cells have one type of marker at surface (can accept type A or O) • Type B red cells have a different type of marker (can accept type B or O) • Type AB cells have both markers (tolerate any donor) • Type O cells have neither marker (can only accept type O donor) Blood Type Compatibility Blood type of donor O A B AB O Blood type of recipient A B AB Figure 38.8 Page 670 Rh Blood Type • Based on presence or absence of Rh marker on red cells – Rh+ has marker, Rh- doesn’t have marker • Can cause problems during pregnancy – If mother is Rh negative, – has previously carried Rh positive child, – is carrying fetus that is Rh positive – Mother’s antibodies can attack fetal cells Vessels •Blood flows from heart into arteries (large vessels that lead away from the heart) •Then into arterioles (smaller vessels that lead away from the heart) •Then into capillaries (smallest diameter, with thin walls that allow for diffusion of materials into and out of blood) •Then into venules (small vessels that lead back toward the heart) •And finally into veins (large diameter vessels that return blood to heart) Blood Vessels • Arteries: main transporters of oxygenated blood, thick elastic walls to withstand high pressure Figure 38.15 Page 676 Blood Vessels • Arteries: main transporters of oxygenated blood • Arterioles: diameter is adjusted to regulate blood flow • Capillaries: diffusion occurs across thin walls Figure 38.1 Blood Vessels Human Heart Is a Double Pump • Partition separates heart into left and right sides • Each pumps blood through a different circuit Pulmonary Circuit right pulmonary artery Short loop that oxygenates blood, pumps blood to and from lungs. capillary bed of right lung left pulmonary artery capillary bed of left lung pulmonary trunk (from systemic circuit) pulmonary veins heart Figure 38.10 Page 672 (to systemic circuit) lungs Systemic Circuit Longer loop that carries blood to and from body tissues capillary beds of head and upper extremities (to pulmonary circuit) aorta (from pulmonary circuit) heart capillary beds of other organs in thoracic cavity capillary bed of liver capillary beds of intestines Figure 38.10 Page 672 Hepatic Portal System • Carries blood from capillaries in digestive organs to capillaries in the liver • Allows liver to detoxify substances from digestive tract before they are carried to the body Major Vessels carotid arteries jugular veins ascending aorta superior vena cava pulmonary veins hepatic portal vein renal vein inferior vena cava iliac veins femoral vein pulmonary arteries coronary arteries brachial artery renal artery abdominal aorta iliac arteries femoral artery Figure 38.11 Page 673 Location of the Heart right lung left lung Figure 38.12 Page 674 rib cage diaphragm Pericardium – double sac of tough connective tissue that protects and anchors the heart to nearby structures Figure 38.12 Page 674 Four Chambers • Each side has two chambers – Upper atrium – Lower ventricle • Valves between atria and ventricles (AV valves) • Valves between each ventrical and artery (semilunar) • Contraction of the ventricles is the driving force for blood circulation. Figure 38.12 Page 674 arch of aorta superior vena cava trunk of pulmonary arteries left semilunar valve Heart Anatomy right semilunar valve left pulmonary veins left atrium right pulmonary veins right atrium left AV valve right AV valve right ventricle left ventricle endothelium and connective tissue inferior vena cava inner layer of pericardium septum myocardium heart’s apex Figure 38.12 Page 674 Blood Path • • • • • From body in vena cava To right atrium To right ventricle To lungs (in pulmonary artery – deoxygenated) To left atrium from lungs (in pulmonary vein – oxygenated) • To left ventricle • To body in aorta Cardiac Muscle •Cardiac muscle is striated, like skeletal muscles. •Sliding filament model like skeletal muscles. •But cardiac muscle cells are branching, short and connected at their endings •Lots of gap junctions are present allowing quick spread of action potentials. •Also, 1% of cardiac muscles do not contract, they function in the cardiac conduction system (make the heart pump by rhythmic waves of excitation). one sarco mere mitochon drion intercalated disk Intercalated disk, a region of Fig. 38-15a,b, p.667 c Gap junction. These communicati on junctions occur on the sides of cardiacFig. 38-15c, p.667 Conduction and Contraction •Systole – contraction • SA node in right atrium is pacemaker • Electrical signals cause contraction of atria • Signal flows to AV node and down septum to ventricles, causing the ventricals to contract. • The nervous can only adjust the rate and strength of contractions. Figure 38.14 Page 675 •Diastole - relaxation SA node AV node Blood Pressure • Highest in arteries, lowest in veins • Systolic pressure is peak pressure (ventricular contraction) • Diastolic pressure is the lowest Greatest pressure drop is in arteriolesFigure 38.1 Controlling Blood Pressure • Cardiac output is adjusted by controls over rate and strength of heartbeat (nervous system) • Total resistance in vessels changes due to diameter changes (vasoconstriction and vasodilation) which is controlled by the nervous and endocrine system. • Baroreceptor response is main short-term control of blood pressure – By triggering the sympathetic or parasympathetic nerves that control the blood vessels and heart • Kidneys are the main long-term control of blood pressure – By regulating the volume and composition of the blood Velocity of Flow Varies • Volume of blood flowing through vessels always has to equal heart’s output • Flow velocity is highest in large-diameter transport vessels • Flow velocity is slowest in capillary beds; blood spreads out into many vessels with greater total cross-sectional area Diffusion Zone • Capillary beds are the site of exchange between blood and interstitial fluid • Capillary is a single sheet of epithelial cells • Flow is slow; allows gasses to diffuse across membranes of blood cells and across endothelium Movement in and out Capillaries • Capillary beds are the site of exchange between blood and interstitial fluid • Capillary is a single sheet of epithelial cells (very thin walls), some clefts between them, flow is slow • allows gasses to diffuse across membranes of blood cells and across endothelium • Some proteins leave and enter by endo and exocytosis • Some ions leave at the clefts between the cells • Bulk flow (in response to fluid pressure) also occurs – Ultrafiltration out and reabsorption in Bulk Flow in Capillary Bed blood to venule blood from arteriole outward-directed inward-directed bulk flow osmotic movem cells of tissue Figure 38. Net Bulk Flow • Normally, ultrafiltration only slightly exceeds reabsorption • Fluid enters interstitial fluid and is eventually returned to blood by way of the lymphatic system • High blood pressure causes excessive ultrafiltration and results in edema The Venous System • Blood flows from capillaries into venules, then on to veins • Veins are large-diameter vessels with some smooth muscle in wall • Valves in some veins prevent blood from flowing backward Figure 3 Bicarbonate Formation CO2 + H2O H2CO3 carbonic acid HCO3– + H+ bicarbonate • Most carbon dioxide is transported as bicarbonate • Some binds to hemoglobin • Small amount dissolves in blood Cardiovascular Disorder •Hypertension High Blood pressure (above 140/90) Atherosclerosis • Arteries thicken, lose elasticity, and fill up with cholesterol and lipids Arrhythmias • Irregular heartbeat Risk factors • Smoking, Gender (maleness), Genetic factors, Old age, High cholesterol, Obesity, Lack of exercise, Diabetes mellitus Hemostasis – stops bloodloss • Blood vessel spasm (contracts, slows bloodflow), platelet plug formation, blood coagulation (clotting) • Clotting mechanism – Prothrombin is converted to thrombin – Fibrinogen is converted to fibrin – Fibrin forms net that entangles cells and platelets Fig. 38-23, p.672 Lymphatic System • Collects and returns fluid to the bloodstream – The circulatory system is leaky – Some fluid is forced out of the smallest vessels and into the interstitial fluid – Vessels of the lymphatic system pick up this fluid, filter it, and return it to the circulatory system • Defends against infection Main Parts- See figure page 683 • Lymph nodes – organ acts as a filter for lymph, packed with lymphocytes for immune response • Lymph vessels – tubes that collect and deliver leaky fluid back to vein in lower neck • Lymph – the fluid • Lymphoid organs – central to body’s defense – Tonsils, Thymus, Spleen Lymph Nodes • Located at intervals along lymph vessels • Act as a filter for lymph • Contain lymphocytes that can recognize a foreign invader Figure 38.2 Lymphoid Organs • Central to the body’s defense • Tonsils • Spleen • Thymus gland Figure 38.2