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101 Cards in this Set
- Front
- Back
circulation
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- pressure driven bulk flow of blood through a system of tubular vessels or passages
- rapid transport of oxygen, carbon dioxide, nitrogenous wastes, hormones, immunoglobulins, heat, nutrients, ions |
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pumps
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- peristaltic pump
- wave of contraction pushes blood |
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muscular heart
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- single chambered
- may have accessory or auxiliary hearts - multichambered |
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open circulation for single chambered
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- blood baths tissue directly
- no clear distinction between blood and extracelluar tissue - fluid = hemolymph - blood exits discrete blood vessels - enters lacunae = small spaces around tissues - enter sinuses = large spaces used as channels for blood flow |
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blood flow through lacunae and sinuses
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- aorta and lateral artery branches end abruptly
- slow rate of blood flow - circulatory system can remain simple because tracheal system - blood flows principally form posterior to anterior in dorsal part of body - anterior to posterior in ventral part of body |
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circulation through body or crayfish or lobster
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closed circulation for single chambered
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vertebrate circulation
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- single loop
- double loop |
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circulatory plan in gill-breathing fish
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- heart pumps blood anteriorly into ventral aorta
- gives afferent branchial vessels to gill arches - blood perfuses gills - blood is collected into efferent branchial vessels which empty into dorsal aorta - blood distributed to systemic tissues by dorsal aorta - great veins return deoxygenated blood from systemic tissues to heart |
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circulatory plan through human
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teleost heart
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- myocardium usually spongy and oxygenated by blood in ventricle
- sinus venosus are great veins that empty into it - ventricle is main propulsive force - bulbus arteriosus acts as an elastic chamber and pressure reservoir |
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amphibians
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- 2 separate atrial chambers
- ventricular trabeculas and spongy myocardium help shunt right atrial blood into pulmonary arteries - conus arteriosus is contractile and has spiral folds which contribute to shunting - double loop circulation |
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truncus arteriosus
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- formed from conus arteriosus
- systemic arch goes to body - pulmocutaneous arch goes to lungs and skin - carotid arch goes to head region |
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crocodiles
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- ventricle incompletely divided by muscular ridges and spongy septa
- 2 systemic aortas: one from right and left ventricle - formen of panizza prevents left systemic arch from carrying deoxygenated blood |
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blood flow in ventricles and atrium of crocodiles
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- cog valve is constricted and dilated by muscle action
- foreman diameter can be actively regulated - when blood flows to lungs - pressure in right ventricle stays too low to push open the flap valve into systemic aorta - lung resistance rises and/or cog valves closes - pressure in right ventricle rises high enough to eject blood into systemic aorta |
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vertebrate heart
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- anterior vena cava = superior vena cava
- posterior vena cava = inferior vena cava |
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chordae tendinae
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- thread-like bands of fibrous tissue
- attach one end to tricuspid and mitral valves and the other end to papillary muscle - serve to anchor the valves |
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papillary muscle
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- originate in ventricule wall
- small muscle within heart - anchor heart valves - attach to tricuspid valve by chordae tendinae |
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heart valves
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- pulmonary valve
- tricuspid valve - aortic valve - mitral valve |
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heart contraction and relaxation
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- systole is period of contraction
- diastole is period of rest/relaxation - atrial and ventricular diastole - atrial systole and ventricular diastole - ventricular systole and atrial diastole |
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human heart
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- oxygenated blood travels to heat in pulmonary veins and enters left atrium
- blood flows through left atrioventricular valve to enter left ventricle - strongly muscular left ventricle pumps oxygenated blood through aortic valve into systemic aorta - slows to entire systemic circuit - after passing through systemic circuit, blood is partly deoxygenated - flows into venae cavae, then into right atrium - blood flows through right atrioventricular valve to enter right ventricle - right ventricle pumps deoxygenated blood through pulmonary valve into pulmonary trunk - flows to lungs in pulmonary circuit |
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heart rate
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- pacemaker generates wave of signals to contract
- signals are delayed at AV node - signals pass to heart apex - signals spread throughout ventricles |
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pacemaker action potential
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- pacemaker cells are special myocardial cells that discharge rhythmically
- have special type of action potential - first part of prepotential is caused by relatively smaller efflux of K+ in phase 4 of action potential - transient type of calcium channel (T) opens - form second part of prepotential - as potential declines, the long lasting calcium channel opens - leads to depolarization - mostly due to Ca2+ with only little influence from Na+ influx - absence of sharp depolarizing spike |
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cardiac action potential
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- sodium enters the cell through fast Na channels
- fast Na channels close - Ca and additional Na enter cell through slow channels - K exits cell and resting membrane potential is reestablished - equilibration of Na and K occurs |
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conducting system
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- depolarization begins in SA node and spreads outward through atrial muscle
- spreads into AV node is delayed - depolarized atria starts to contract - once AV becomes depolarized, depolarization spreads rapidly into ventricles along conducting system - atrial muscle starts to repolarize - nearly simultaneous depolarization of cells throughout ventricular myocardium leads to forceful ventricular contraction |
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human electrocardiogram
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heart as a pump
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- cardiac output is volume of blood per unit time
- vertebrate cardiac output is volume of blood in left ventricle to systemic circulation - product of heart rates in beats per minute - stroke volume is volume of blood pumped per cardiac cycle |
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anatomy of blood vessels
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- arteries carry blood away from heart
- veins carry blood back to heart - capillaries connect smallest arteries to veins |
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layers of muscular artery
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- tunica intima
- tunica media - tunica externa/adventitia |
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tunica intima
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- simple squamous endothelium
- overly basement membrane - layer of fibrous tissue |
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tunica media
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- usually thickest
- smooth muscle - collagen - some elastic |
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tunica externa/adventitia
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- loose connective tissue with vasa vasorum
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large artery
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- conducting or elastic arteries
- internal elastic lamina - expand during systole and recoil during diastole - collagenous tissue - aorta, common carotid, subclavian, pulmonary trunk, common illeac |
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medium artery
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- muscular or distributing arteries
- brachial, femoral, renal - internal and external elastic lamina |
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arteriole
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- resistance arteries
- smallest of these are arterioles - smooth muscles in walls are responsible for vasomotor control of blood distribution - vasoconstriction and vasodilation |
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arteries
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- become smaller in diameter
- walls become thinner - very little drop in pressure in arterial system - circumferential tension (stretch) developed within walls is directly proportional to tube radius - small artery exposed to same blood pressure as larger one - tension developed in walls is lower in large one because radius is smaller - smaller artery can be less fortified than a larger one and not over-expand |
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microcirculatory bed
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- arteriolar-venular anastomoses are direct connection between arterioles and venules
- when open provide way for blood to bypass capillary bed - precapillary sphincters composed of rings of smooth muscle cells that act as muscular valves - blood enters through arteriole at rate determined by arteriole radius - controlled by smooth muscle cells in arteriole wall - blood leaves through venule |
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sphincters
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- smooth muscles and precapillary sphincters permit highly sensitive temporal and spatial control of blood distribution
- change blood pressure and blood flow |
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fenestrated capillary
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- only endothelium
- filtration holes - contain channels - discontinuous and continuous cells - important in kidneys, endocrine glands, smal intestines, choroid plexus of brain |
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continuous capillary
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- endothelial cells held together by tight junctions
- may have pericytes that contract to regulate blood flow |
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sinusoidal capillary
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- discontinuous capillaries
- irregular blood filled spaces - liver, bone marrow, spleen - blood forming organs - huge sinus - diffusion through cell - thicker epithelium |
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circulatory routes
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- simplest pathway = one capillary bed
- portal system - arteriovenous anastomosis |
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portal system
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- 1 capillary system to next capillary system
- hypothalamus and anterior pituitary - small intestine and liver - kidney |
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arteriovenous anastomosis
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- can pass through capillary bed, around capillary bed, or combination of both
- embryonic - shunt |
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capillary exchange
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- only occurs across capillary walls between blood and surrounding tissues
- 3 routes across endothelial cells - intracellular clefts - fenestrations - cytoplasm or transcytosis |
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diffusion
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- most important mechanism of capillary exchange
- movement of material through OM - high concentration to low concentration - lipid soluble substances = steroid hormones - O2 and CO2 diffuse easily - insoluble substances - glucose and electrolytes must pass through channels, fenestrations, or intracellular clefts - large particles such as proteins are held back |
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transcytosis
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- endothelial cells pick up material on one side of PM by pinocytosis or receptor mediated endocytosis
- transport it through cell to other side where it exits by exocytosis - mediated by endocytosis and exocytosis - enters one cellular face and leaves through another - tissues to blood or blood to tissue - large proteins and small peptides |
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filtration
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- hydrostatic pressure forces fluid through a selectively permeable membrane
- driven by pressure differences - capillaries give off fluid at arteriole end due to higher BP/hydrostatic pressure - hydrostatic and osmotic pressure decrease along length of capillary - create collodial pressure that's greater than outside pressure - collodial osmotic pressure higher at venule end forces fluid back in (reabsorption) - net filtration pressure is difference between outward and inward pressure |
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blood plasma volume
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- loses volume in initial segment of blood capillaries
- regain fluid in final segments - lose at arteriole and gain at venous - hydrostatic pressure of blood pushes stuff out - hydrostatic pressure of tissue and collodial osmotic pressure bring stuff in |
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net filtration pressure
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- hydrostatic pressure of blood in capillaries
-minus hydrostatic pressure of tissue fluid outside capillaries - plus collodial osmotic pressure of blood |
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veins
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- lower blood pressure with fluctuation
- thinner walls - less muscular and elastic tissue - expand easily - high capacitance - valves aid skeletal muscles in upward blood flow |
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venous sinuses
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- veins with thin walls
- large lumens - no smooth muscle |
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large vein
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- venae cavae, pulmonary veins, internal jugular, renal veins
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medium vein
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- many have valves
- infoldings of tunica interna - skeletal muscle pump pushes blood through valve toward heart - prevents backflow |
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venule
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- post capillary
- surrounded by pericytes - porous - exchange fluid with surrounding tissue |
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mechanism of venous return
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- pressure gradient
- gravity drains blood from head and neck - skeletal muscle pump in the limbs = pushes blood back - thoracic has negative pressure = draws blood up - cardiac suction of expanding atrial space = sucks blood up |
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venous return
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- valves in veins prevent backflow of blood
- skeletal muscles compress veins - force blood towards heart |
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blood distribution
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- majority in veins
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cross sectional area and capillaries
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- as blood flows from aorta to capillaries
- total cross sectional area increases - average linear velocity decreases - greatest cross sectional area in capillaries - cross sectional area increases, velocity decreases - velocity slowed down due to decreased pressure - pressure decreases from arteries to veins - never return to original velocity - greatest velocity in arteries |
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hematocrit
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- 43% erythrocytes (RBC)
- thin layer of leukocytes called buffy coat between erythrocytes and plasma |
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red blood cells
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- erythrocytes
- 7-7.4 um - biconcave - increased surface area |
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reticulocyte
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- immature RBC
- everyone has certain number - carry almost as much oxygen as normal RBC |
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sickle cell anemia
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- abnormal RBC
- get stuck in capillaries - heterozygous have some sickling - homozygous have a lot of sickling |
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rouleaux
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- RBC done't settle very much
- some disease conditions increase production of fibrinogen and immunoglobulins causing RBC to clump - ERS used to follow progress of certain disease conditions |
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2 classes of leuckocytes
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- granulocytes
- a granulocytes |
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granulocytes
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- have granules
- neutrophils - eosinophils - basophils |
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a granulocytes
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- azurophilic granules
- some granules but very little - lymphocytes - monocytes |
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neutrophils
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- larger than RBC
- one nucleus and variable number of lobes - squeeze out of blood into tissue - diaponeses is process of squeezing into tissue |
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basophils
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- numerous granules cover nucleus
- release histamines - deal with inflammatory response - larger than RBC |
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eosinophils
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- found in high numbers
- allergic reaction and parasitic infection - larger than RBC |
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monocyte
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- large kidney shaped nucleus
- cytoplasm slightly basophilic - located in blood - called macrophage in located outside blood - phagocytic - antigen presenting cell |
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lymphocyte
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- killer cells, B and T cells
- antibody production = B cells - mediated cell response = T cells - specific protein receptors on cell surface |
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platelets
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- derived from megakarocytes in bone marrow
- multi nucleated cells - live in bone marrow - fragments of cell - contain growth factors and clotting factors |
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blood cell production
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- controlled by cytokines
- almost all glycoprotins that act of stem cells |
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3 factors of cytokines affect blood cell production
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- colony stimulating factors (CSF)
- erythropoietin - interleukins |
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colony stimulating factors (CSF)
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- made by endothelial cells and white blood cells
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erythropoietin
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- lack of oxygen or shortage of erythrocytes
- stimulates cells in kidney to synthesize and secrete hormone |
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interleukins
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- made by lymphocytes
- serve as growth factor for B cells - non-lymphocytes blood cells |
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total fluid energy
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- true driving force for blood flow
- potential energy of pressure produced by heart - plus kinetic energy - plus kinetic energy of position in earth's gravitational field |
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pressure change
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- important driving force
- around 100 - affects rate of blood flow - above heart = arterial pressure decreases - below heart = arterial pressure increases |
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flow rate
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- dependent on differences in blood pressure and vascular resistance
- poiseuille equation - proportional to pressure difference - proportional to fourth power of radius - inversely proportional to resistance - inversely proportional to viscosity - inversely proportional to length |
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principles of blood flow
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- blood flow is amount of blood flowing through a tissue in given time
- perfusion is rate of blood flow per given mass of tissue - blood flow and perfusion important for delivery nutrients and oxygen, and removal of waste - hemodynamics are physical principles of blood flow based on pressure and resistance |
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change in radius
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- muscles in walls of blood vessels change radius of vessel by contracting or relaxing
- exert profound control over flow rate |
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heat
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- pressure and flow turn to heat during circulation
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velocity profile of laminar flow
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- velocity immediately next to tube wall are zero
- steady and non-turbulent flow, liquid moves in series of concentric layers that differ in linear velocity - layers closer to center move faster |
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frictional force
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- concentric layers encounter as they flow over each other
- total magnitude of internal friction depends in part on diameter and length - viscosity also contributes to internal frictional force - lack of intrinsic slipperiness between liquid layers moving at different velocities |
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radius affects velocity
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- large radius = high average velocity
- small radius = slower average velocity - slowed down by friction against vessel wall |
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energy to heat
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- results in degradation of kinetic energy into heat
- pressure provided at entry end of heart is potential energy - converted to kinetic energy - kinetic energy converted to heat energy - pressure converted to heat |
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blood pressure
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- dependent on elasticity of arteries
- expansion and recoil maintain steady flow of blood throughout cardiac cycle - smoothes out pressure fluctuations and decrease stress on small arteries - rises with age because arteries less distensible (elastic) - produce fewer elastic fibers as you age |
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blood pressure determinants
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- cardiac output = volume of blood pumped by heart
- blood volume - peripheral resistance = mean arterial pressure minus venous pressure divided by cardiac output |
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mean arterial pressure
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- diastole last longer than systole
- equals diastolic plus (systolic - diastolic) |
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cardiac output
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starling's law
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- energy of contraction is proportional to initial length of cardiac fiber
- length of cardiac fiber is increased with increased filling - when cardiac muscle is stretched it contracts more forcefully - optimum overlap creates greatest contraction |
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skeletal vs heart muscle
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- both have developed forces rise to peak at optimal length then then fall off at very long lengths
- declining portion in both is due to diminishing overlap between actin and myosin - at lengths less than optimal, force declines because myosin collision with z line and Ca release from SR declines with short lengths - resting force higher in cardiac and significant at lengths less than optimal - intact heart can respond to increase of filling by improving contraction |
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total peripheral resistance
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regulation of BP and flow
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- local control
- neural control - hormonal control |
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local control
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- ability of tissue to regulate its own blood supply
- when tissue inadequately perfused = becomes hypoxic and metabolites accumulate - metabolites are CO2, H+, K+, lactic acid, adenosine - factors stimulate vasodilation - short term stimulate by vasoactive chemicals like histamine and nitric acid - derived from platelets, endothelial cells, perivascular tissue - long term achieved by growth of new vessels |
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neural control
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- control in vasomotor control center of medulla
- integrate baroreflexes, chemoreflexes, and medullary ischemic reflex - change in blood pressure - chemoreflexes monitor pH, O2, and CO2 levels - issue signals to blood vessels through sympathetic nerve fibers - medullary ischemic reflex responds to drop in perfusion by increasing heart rate and contraction force |
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hormonal control
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- regulated by various hormones like
- angiotensin 2 = vasoconstrictor - aldosterone = promotes Na+, water retention by kidney that increases BP - atrial natiuretic peptide = increases Na+ excretion by kidney that lowers BP - ADH = promotes water retention - epinephrine and norepinephrine = bind to smooth muscle of blood vessels causing vasoconstriction |
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vasomotion
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- generalized raising or lowering of BP
- selectively modifying perfusion of particular organ - rate of oxygen delivery = cardiac output x ([arterial O2] - [venous O2]) |
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exercise
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- cardiac output increased by both heart rate and stroke volume
- cardiac rate result of vagus nerve inhibition and sympathetic nerve stimulation - coordinated by cardiac centers in medulla - arterial blood pressure doesn't rise because vascular resistance reduced by vasodilation - arterioles shift blood flow with changing priorities - increase perfusion of lungs, myocardium, and skeletal muscles - decreases perfusion of kidneys and digestive tract |