Circulatory System -Blood o Composed of plasma and formed elements o Functions: transportation, regulation, protection -Blood Plasma o 92% water o solutes: nutrients, wastes, hormonesions (Na+, Cl-, HCO3, CA2+, Mg2+, Cu2+, K+, Nz2+ o proteins albumin, alpha and beta globulins fibrinogen -Formed Elements o 5 million per microliter of blood o Hematocrit is fraction of blood volume occupied by red blood cells o Mature mammalian erythrocytes lack nuclei o RBCs of vertebrates contain hemoglobin Binds and transports oxygen o White blood cells (leukocytes) >1% blood cellslarger and have a nucleican migrate into tissue fluid -granular leukocytes: neutrophils, eosinophils, and basophils -agranular leukocytes: monocytes and lymphocytes o platelets cell fragments that pinch off from larger cells in bone marrow function in formation of blood clots o develop from stem cells in bone marrowslymphoid stem  lymphocytes myeloid stem  all the other blood cells -Invertebrate Circulatory Systems o Sponges, cnidarians, and nematodes lack separate circulatory system o Sponges circulate water through incurrent and excurrent pores o Hydra circulate water through gastrovascular cavity (also digestion)o Nematodes are thin enough that tract can be used as circulatory system o Multicellular circulatory system relates to size, complexity, and lifestyle of organismo No circulatory systemSponges and cnidarians utilize water from environment for circulatory fluid Nematodes use body cavity fluids o Larger animals require separate system for nutrient and waste transport Open system: no distinction between fluidsClose system: distinct and closed in blood vessels and transported focused around heart-Vertebrate Circulatory System o Fish Evolved chamber pump heart with two layers -Sinus venosus and atrium-Ventricle and conus arterioususPumped through gills to rest of bodyo Amphibians Lungs required a second pumping circuit or double concentration Pulmonary circulation moves between heart and lungs Systematic circulation between heart and body 3 chambered with 2 atria and 1 ventricle separation of pulmonary and systemic circulations isn’t completeobtain additional oxygen through diffusion reptiles have septum partially subdividing ventricle, reducing mixing of blood in hearto Mammals, Birds, and Crocodilians 4 chambered heartright atrium receives deoxygenated blood from body and delivers to right ventricle which pumps to the lungs left atrium receive oxygenated blood from lungs to left ventricle to body -Cardiac Cycle o Two pairs of valves Atrioventricular -Unidirectional flow between atria and ventricles-Tricuspid valve on right-Bicuspid on left Semilunar valves -One way flow out of ventricles to arteries -Pulmonary valve at exit of right ventricle-Aortic at exit of left ventricle Valves open and closeVentricles relaxing and filling (diastole)Ventricles contracted and pumping (systole)Lub (AV valves closing) Dub (semilunar valves closing) o Heart has self-excitable autorhythmic fibers SA node in right wall of atrium-Pacemaker to modulate rate -SA depolarization to left atrium and right atrium and AV nodeAV node is only pathway for conduction to ventricles-Spreads through AV bundle to purkinje fibers to stimulate myocardial cells of ventricles to contract Electrical activity can be recorded on an EKG-First peak (P) produced by depolarization of atria (atrial systole) -Second peak (QRS) produced by ventricular depolarization (ventricle systole)-Last peak (T) produced by repolarization of ventricles (ventricular diastole) Right and left arteries deliver oxygen depleted blood from right ventricle to lungs Pulmonary veins return oxygenated blood from lungs to left atrium Aorta and branches are systemic arteries carrying oxygenated blood from left ventricle to body -Coronary arteries supply oxygenated blood to heart Blood from body drains to right atrium -Superior vena cava drains upper-Inferior drains lower Arterial blood pressure can be measured with a sphygmomanometer Systolic pressure is peak when ventricles contracting Diastolic pressure is minimum pressure between heartbeats (ventricles relaxed) Blood pressure is a ratio of systolic over diastolic pressure -Characteristics of Blood Vessels o Blood leaves through arteries o Arterioles are most microscopic branches of arterial tree o Blood from arterioles enter capillaries o Blood collected into venules, leads to larger veins o Veins carry blood back to heart o Arteries and veins are composed of 4 layers Endothelium, elastic fibers, smooth muscles, and connective tissuesWalls too thick for materials across wall o Capillaries composed of only 1 layer of endothelial cells Rapid exchange of gases and metabolites between blood and body cells o Arteries and arterioles Larger arteries containing more elastic fivers in walls than other vesselsContraction of smooth muscle layer results in vasoconstriction -Increases resistance and decreases flow-Chronic vasoconstriction can result in hypertension Relaxation of smooth layer results in vasodilation -Decreasing resistance and increasing blood flow to an organ -Important means of regulating body heat o CapillariesVery narrow but many exist so they have the largest area of any type ofvessel Slows blood flow to allow for gas exchange o Veins and venules Thinner layer of smooth muscles than arteries Venous pump helps return blood to heart-The Lymphatic System o Water and solutes in blood plasma filter through walls of capillaries to form interstitial fluid o Most fluid leaves arteriole end of capillary and returns at venule end o Fluid doesn’t return to capillaries is returned to circulation by lymphatic system o Lymphatic capillaries, lymphatic vessels, lymph nodes, and lymphatic organs (spleen and thymus) o Excess fluid drains into lymph capillaries o Lymph passes into progressively larger vessels with one way valves o Eventually drains into subclavian veins -Cardiovascular Diseases o Atherosclerosis Fatty material in arteries impede blood flow o Arteriosclerosis Arterial hardening due to calcium depositiono Heart attacks (myocardial infarctions)Main cause of cardiovascular deaths Insufficient supply of blood to the heart o Angina pectoris (chest pain)Warning sign that blood supply to heart is inadequate o Stroke Interference with blood supply