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Circulatory System
- Consists: heart , blood vessels, blood
- Hematogly: study of the heart
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Functions of Blood
- Hormones to target organs
- Transportation- nutrients,wastes, heat
- Protection- limit speed of infection, destroy pathogens, platelets secrete stuff inate blood clotting for blood loss
- Regulation-Absorption (give off fluid help stabilize fluid distribution in the body) stabilize pH, Buffering
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Properties of Blood
- 8% body weight
- Temp- 100 degrees F
- pH- 7.35-7.45
- Viscosity- 4.5
- Salinty-0.9%
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Components of Blood
- Liquid CT
- Plasma- clear extracellular fluid
- Formed Elements
- RBC ,WBC ,Platelets
- How substances travel
- Vessels- routing of materials
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Blood Plasma
- Complex mixture
- Water 90% , Proteins 8% , Other solutes 2%
- Enzymes, hormones, wastes, gases
- Serum
- Plasma without clotting protein fibrinogen
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Plasma Proteins
- Albumins- smalles and most abundant 1.Transport carries
- 2.Blood buffers- if change affects blood vol., pressure, and flow
- 3.Contgributions to viscosity and osmolarity Globulins, three categories- transport, clotting, immunity
- 1.Alpha and Beta transport proteins
- 2.Gamma function as antibodies
- Fibrinogen
- 1.Clotting Protein- forms clot, soluble precursor of fibrin, come from plasma cells
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Other Constituents of Plasma
- Electrolytes-sodium ions, contribute to osmotic pressure, major influence on blood volume and pressure
- Nutrients- simple aa, fatty acids, lactic acid, urea, uric acid
- Gases- oxygen, co, nitrogen
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Blood Viscosity and Osmolality
- Viscosity- important for circulatory function
- 1.Resistance of fluid to flow from particle cohesion
- 1.1Whole blood due to RBCs
- 2.1Plasma due to proteins
- Osmolality- cardiovascular function 1.2Molarity of dissolved particles in blood 2.2Sodium ions, protein, erythrocytes 2.2.1Colloid osmotic pressure- contribution of proteins to blood osmotic pressure 2.3Remove waste nourish surrounding cells 2.4Governs rate of reabsorption
- 2.5If increase blood, absorb too much water= high blood pressure vice versa
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Blood Cell production
- Hemopoiesis- production of blood Myeloid Hemopoiesis- made in red bone marrow\
- Lymphoid Hemopoiesis- made in thymus, tonsil, lymph nodes, spleen
- Trace origins to common tube Hemopoiesis stem cell
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Hemopoiesis
- Pluripotent stem cells- hemocyoblast Develop multiple mature cells
- Colony forming unit- committed cells Surface receptor on membrane
- Produce one or another class of elements Precursor Cells
- Mature Cells- requires continual replacement, in plasma
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Formed Elements
- Erythrocytes RBC
- Leukocytes WBC
- Platelets Features: Most are short lived and renewed and replaced
- Come from CT plasma cells and live
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Erythrocytes RBC
- Function- carry O2 and CO2
- Form- Biconcave disc- promotes quick diffusion
- No nucleus or DNA
- No mitochondria- ATP through anaerobic mechanisms, made to deliver oxygen Cytoplasm-red pigment
- Plasma Membrane
- Outer proteins for blood type
- Inner proteins provide durability and resilience
- Glycolipids- blood type, outer surface,
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Hemoglobin Structure
- Globin’s
- 4 polypeptide chains
- 2 alpha chains- 141 chains of aa each
- 2 beta chains – 146 aa long each
- Heme
- Each chain conjugated
- Binds oxygen to ferrous ion
- Carries 4 oxygen atoms
- Has globin moiety
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RBC count and Hb concentration-
- Determine amount of oxygen blood can carry More in girls than boys
- Hematocrit- packed cell vol. PCV
- Larger in women because androgens stimulate RBC product. , menstrual loses, body fat
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Erythrocyte Life Cycle-
- Life Span 120 days
- Erythropoiesis –production of RBC
- 4 major developments: Reduction, lose nucleus, increase in cell #, synthesis of hemoglobin
- Iron metabolism
- RBC homeostasis
- Death and Disposal
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Erythropoiesis
- PPSC
- ECFU –begins
- Receptors for Erythropoietin (EPO) Erythroblast
- Synthesize hemoglobin and discard nucleus Reticulocyte
- Leaves bone marrow into blood
- No nucleus and network of polyribosomes Erythrocyte
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Iron Metabolism
- Dietary Iron-convert Ferris to ferrous ions
- Gastro ferritin- stomach to small intestines
- Transferrin – plasma protein go to bone marrow, live, etc.
- Ferritin- store complex and release Fe 2+ into circulation
- Other nutrients- vitamin B-12, Folic acid, copper, vitamin
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Erythrocyte Homeostatic
- Neg. feedback loop- RBC count
- Hypoxemia-oxygen deficiency in blood, no oxygen in air, increase in oxygen consumption
- Kidneys releases EPO
- Increase in O2 inhibits
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RBC Death and Disposal
- Hemolysis-
- hemoglobin and PMs (leaves them empty)
- Plasma membranes- Macrophages in liver and spleen
- Hemoglobin
- 1.3Heme- hormones, iron and biliverdin 1.31Bind to albumin in plasma, liver unbinds them and goes to bile, to small intestine convert to urobilinogen
- 2.3Globin- free amino acids
- Many die in spleen
- Membrane foes fragile, no organelles can’t make spectrum
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Erythrocyte Disorders
- Imbalance between rate of Erythropoiesis and RBC destruction
- Primary- cancer, increase RBC circulates system engaged, clots
- Secondary- dehydration, water loss, smoking, air pollution
- Polycythemia – increase blood vol, pressure, and viscosity
- Excess of RBC
- Anemia- cause inadequate hemoglobin synthesis, hemolytic anemia
- Deficiency of RBC or hemoglobin
- Sickle Cell Disease- iron- deficiency anemia, no iron, and pernicious anemia, no B12
- Lead to kidney and heart failure, stroke, paralysis
- Pos feedback loop – hemolysis cause anemia and hypoxemia
- Altered hemoglobin structure
- Alters RBC shape and becomes sticky agglutinate clump together
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Based on large molecules – antigens and antibodies
- Antigens- complex molecules,
- Genetically unique to each indiv., Not identical twins, on surface of cell, ables body to distinguish its own cells
- Detected: immune response activated, plasma cells, antibodies, secrete proteins
- Antibodies- bind to antigens and mark them for destruction
- Agglutination- method of antibody action, antibodies stick antigens together
- Blood types result from reaction between antigens
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ABO
- A, B, AB, O
- Presence and absence of A and B
- Appear in blood for 2-8 months
- O most common
- Universal recipient- AB no antibodies
- Universaldonor- O
- Blood types are fixed
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Rh group
- Antigen D , C, or E present
- Rh + if have any
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Leukocytes-
- white blood cells, live in CT , have organelles Least abundant formed element in blood
- Form- complete cells, rough ER, ribosomes, Golgi, lysosomes
- Function - Defense against pathogens-phagocytosis, and immune response
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Types of Leukocytes-
- All have nonspecific granules
- Granulocytes
- 1.1Neutrophils- defense against pathogens 2.1Eosinophil’s
- 3.1Basophils
- Agranulocytes-lack granules 1.2Lymphocytes
- 2.2Monocytes
- Different in shape of nuclei, presence or absence of granules, and function
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Functions of Granulocytes
- Neutrophils –Most abundant
- 1.1 Bacterial infections
- 1.2Immediate phagocytosis
- 1.3Antimicrobial chemicals
- Eosinophils- increase night and day, seasons, cycles
- 1.2Release anti-histamines
- 1.3Parasitic worms
- Basophils widen blood vessels, helps repair injured tissue
- 1.3Secrete histamine
- 1.4Secrete heparin- inhibits blood clots and attracts other two to infections
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Functions of Agranulocytes
- Lymphocytes- nucleus round and purple 1.1Second most abundant
- 2.1Role in specific immunity
- 3.1Secrete antibodies
- 4.1Coordinate immune cells
- 5.1Immune memory
- Monocytes-largest, increase inflammation 1.2Differentiate into macrophages 2.2Phagocytosis
- 3.2Slow but numerous
- 4.2Great capacity- destroy foreign cells
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Leukocyte Life Cycle
- Leucopoiesis- production of WBC
- 1.1PPSCs heomopoietic stem cells
- CFUs
- Receptor for Colony Stimulating Factors
- Precursor Cells
- 1.2Myoblasts- granulocytes
- 2.2Monoblasts
- 3.2Lymphoblast’s- lymphocytes
- Mature Cells- secrete several types of CSs in response to infections
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Precursor Cell
- Committed Colony Forming Units (CFUs) 1.1 Receptor for specific CSFs
- Myoblasts
- 1.2Granulocytes -Stored in red bone marrow Neutrophils, Eosinophils, Basophils Monoblasts
- 1.3Monocytes- Stored in red bone marrow Lymphoblast’s
- 1.4Lymphocytes
- Begin in red bone marrow
- Some mature in thymus
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WBC disorders
- Below normal range- leukopenia
- Above range- leukocytosis, allergies and infections
- Leukemia- tissue that makes a lot of WBC
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Platelets-
- Not cells and 2nd most abundant
- Form- Pseudopods is how they move Fragments of marrow cells (megakaryocytes)
- Complex internal structure
- 1.2Lysosomes, mitochondria, microtubules
- 1.3Granules contain platelet secretions, Open canalicular system
- 1.4 No nucleus
- Functions
- Secrete vasoconstrictors –reduce blood loss Secrete clotting factors-promote blood clotting
- Platelet plugs-seal breaks in injured blood vessels
- Dissolve blood clots
- Phagocytize and destroy bacteria
- Attract neutrophils and monocytes- to inflammation
- Secrete growth factors
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Platelet Production
- Called Thrombopoiesis
- 1.1PPSCs
- 2.1Megakaryoblasts
- Receptor for thrombopoietin- duplicate DNA
- 3.1Megakaryocytes
- Numerous mitotic divisions with cytokinesis
- 4.1Platelets form when cytoplasm breaks
- 25-40% stored in spleen
- Rest circulate in blood
- Deficiency called thrombocytopenia
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Hemostasis
- Cessation of bleeding
- Hemostatic response
- 1.2Vascular spam
- 2.2Platelet plug formation
- 3.2Blood clotting
- Three mechanisms in microcirculation
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Vascular Spasm-
- Protection against blood loss
- Immediate contraction to contract vessel
- Reduce blood flow
- Triggered by
- Direct injury to vascular SM
- Chemicals from platelets and ECs
- Local pain receptors
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Platelet Plug Formation
- Temporary seal in vessel wall
- 1.1Damaged collagen fibers exposed 2.1Platelet adhesion occurs via pseudopods, which pull broken wall together 3.1Degranulation, which releases factors promoting hemostasis, of platelets Release serotonin, ADP, and thromboxane A2
- Aggregation, degranulation, vasoconstriction
- Initiates positive feedback cycle 1.4Stops minor bleeding
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Coagulation
- Most effective defense against bleeding 1.1Converts fibrinogen to fibrin- stick to walls
- 1.2Different pathways
- Extrinsic-damage blood vessels Clotting factors outside
- Faster (~ 15 sec)
- Intrinsic- in blood itself
- Clotting factors inside
- Slower (3-6 min)
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Clotting Factors
- Procoagulation
- Plasma proteins made by liver 1.1Numbered I to XIII (order of discovery) 2.1Circulate in inactive form
- Procoagulants or coagulation factors 1.2Enhance clotting- produced by liver in plasma
- 2.2 Reaction cascade, activates next enzyme Anticoagulants
- 1.3Inhibit clotting
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Initation of Coagulation
- Extrinsic
- 1.1Thromplastin release
- From vessels or tissues
- Intrinsic
- 1.2Factor XII release , from Platelets 2.2Cascade of events
- Both lead to activation of Factor X!
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Completion of Coagulation
- Factor X activated, combine with factor 3 and IIV
- Prothombin activator, produced
- Thrombin formed
- Fibrin formed
- Fibrinogen and Thrombin
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Fate of Blood Clots
- Clot Retraction
- 1.1Platelet induced process
- 2.1Pseudopods adhere to fibrin and contract
- 3.1Compacts blood clot
- Repair
- 3.2Platelet-derived growth factor (PDGF) 3.3Stimulates fibroblasts and smooth muscle cells, which help strengthen and seal vessels
- Fibrinolysis- Kallikrein- converts plasmin and breaks up the clot
- 4.1Dissolution of clot
- 4.2Cascade of events
- 4.3Plasmin produced
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Homeostatic Mechanisms
- Prevention of inappropriate clotting 1.1Platelet repulsion
- Prostacyclin-coated endothelium 2.1Dilution
- Blood flow limits accumulation of thrombin
- 3.1Anticoagulants
- Inhibitors of thrombin
- Antithrombin from liver
- Heparin, from Basophils, mast cells
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Blood Vessels
- Arteries- Carry blood away (efferent)
- Veins- Carry blood towards (afferent)Capillaries- Microscopic connections
- Differ in histological structure of their walls
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Anatomy of Blood Vessels
- With endothelium of heart
- Tunica Interna- Intima
- Endothelium is selective permeable, secretes chemicals, repels blood cells and platelets, which repair it when damaged
- Lines inside of vessels exposed to the blood, loose CT, simple squamous Tunica Media
- Middle layer, thickest, smooth muscle, strengthens vessel, prevents blood pressures, vasomation changes the diameter of blood vessels
- Tunica Externa –outermost layer
- Loose CT, anchors vessels, passage for small nerves, 3 layers Adventitia
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Tunica Interna
- Platelets repair it when damage
- Composition
- 1.1Endothelium
- Continuous layer of cells throughout system
- Simple squamous epithelium
- Layer in contact with the blood Functions:
- 1.2Selectively permeable barrier
- 2.2Secretion of chemicals
- 3.2Repels blood cells and platelets 4.2Inflammation
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Tunica Media
- -middle layers and thickest
- Composition
- Smooth muscle, elastic tissue, collagen
- Amount of SM varies
- Functions:
- 1.2Strengthen vessels/prevent rupture 1.3Vasomotion!!
- Vasoconstriction and Vasodilation
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Tunica Externa
- -outermost
- Composition- Loose connective tissue
- Functions:
- 1.2 Protects and anchors vessel
- 2.2Passage for nerves, lymphatic vessels 3.2Vaso Vasorum- Supplies blood to outer wall of larger vessels
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Arteries
- Withstand pressure when heart beats retain shape, resistance vessels
- Designed to withstand surges of pressure
- More smooth muscle
- 3 categories
- Conducting arteries- Elastic, large
- Distributing arteries- Muscular, medium
- Resistance arteries- Arterioles, small
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Conducting Arteries
- Largest diameter 40-70 layers
- 1.1Elastic tunica media
- 2.1Examples- Aorta, pulmonary trunk, common carotid, subclavian, common iliac
- 3.1Internal elastic Lamina is the border between interna, and media
- 4.1External elastic lamina- between media and externa
- Functions:
- 1.2Reduce effects of BP surges
- Expand during systole
- Recoil during diastole
- Maintains blood flow
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Distributing Arteries
- Thickest smooth muscle- small branches, “exit ramps to highway”
- 1.1Examples- Brachial, femoral, renal, splenic
- Functions:
- 1.2Blood to specific organs
- 2.2Adjust flow based on demand
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Resistance Arteries
- 25 layers, thick tunica media, smallest of this type (arterioles)
- SM layers variable
- Little elastic tissue
- Arterioles
- 1.4Smallest resistance vessels
- Lead into capillary bed Connected by metarterioles
- Function
- 1.5Primary control of blood flow
- 2.5Most responsible for PR
- 3.5 Significantly affects BP
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Matartioles
- Link arteries and caps
- Muscle cells form precapp sphincter
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Arterial Sense Organs
- Above heart, monitor heartbeat, transfer info to brainstem
- 3 kinds
- 2.1Carotid sinuses- baroreceptors
- Pressure sensors
- Respond to changes in blood pressure
- Wall of internal carotid artery, thin tunica media
- 2.2Carotid Bodies- chemoreceptors
- Near carotid arties
- Monitor change in blood composition, signals to brainstem
- 2.3Aortic Bodies- chemoreceptor
- Like carotid bodies
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Capillaries
- Exchange vessels
- Smallest blood vessels
- 1.1Single layer of ECs
- 2.1Small lumen
- Function:
- 1.2Exchange of materials
- 2.2Close proximity to cells
- Types
- 1.3Continuous
- 2.3Fenestrated
- 3.3Sinusoid
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Continuous Capillaries
- Present in most tissues
- 1.1Skeletal muscle
- Tight junctions- form tubes separated by intercellular clefts
- 2.1 Hold ECs together
- Intracellular clefts
- 1.3Small molecules pass thru- Glucose 2.3Large molecules held back- Plasma proteins, Formed elements
- Pericytes- Contractile proteins
- 1.4Wrap around capillaries and regulate blood flow through cap.
- Carbohydrate layer- thin protein
- 1.5Basal lamina, separate CT from enod.
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Fenestrated Capillaries
- ECs with filtration pores
- 1.1Greater permeability
- 2.1Rapid passage of small molecules
- 3.1No formed elements
- Examples- Kidneys, Endocrine glands, Small intestine, Choroid plexus
- 1.2Organs that have rapid absorption
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Sinusoids
- EC separated by wide gaps with no basal lamina and have microphages
- Discontinuous capillaries
- Irregular, blood-filled spaces
- ECs with large fenestrations
- 1.4Formed elements pass
- Examples- Liver, Bone marrow, Spleen
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Capillary Beds
- Network of capillaries
- 1.1Exchange of materials
- Not all perfused
- Thoroughfare channel- leads to venule 1.3Metarteriole to venule
- 2.3Precapillary sphincters
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Venules
- Post capillary venules
- 1.1Smallest veins
- 2.1Tunica intima
- 3.1Often have pericytes
- 4.1Extremely porous
- Muscular venules- exchanging with surrounding tissue
- 1.2Thin tunica media
- 2.2Thin tunica externa
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Medium Veins
- Have all 3 tunics
- 1.1Thin tunica media
- 2.1Thick tunica externa
- 3.1Large lumen
- 4.1Tunica intima
- 5.1Endothelium
- 6.1Valves
- Relatively thin wall vessel
- 1.2BP much lower
- 2.2Collapse when empty
- Blood reservoirs
- 1.3Large percentage of total blood supply Flow of blood depend on massaging action of skeletal muscles
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Venous Valves
- Abundant where upward flow opposed by gravity
- Not present in: ex- coronary sinus
- 1.2Small or large veins
- 2.2Abdominal and thoracic cavities
- 3.2Brain
- Thin walls, no smooth muscles, large lumens
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Large Veins
- Very thin tunica intima
- Very thick tunica externa
- No veins
- Examples: Venae cavae, Pulmonary, Internal jugular, Renal
- Smooth muscle in all tunics
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Circulatory Routes
- Simple Pathway
- Portal System
- 1.2Kidneys
- 2.2Hypothalamus and Anterior Pituitary Arteriovenous anastomosis- Shunt, blood flow from arteries to veins,
- 1.3In fingernails, palms, and toes
- 2.3Reduce heat loss
- Venous anastomose- Alternative drainage
- Arterial anastomoses- Collateral supply
- Anastomosis-where blood vessels merge
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Flow, Perfusion, and Pressure
- Flow- Volume of blood through organ, tissue, or vessel in a given time
- Expressed in ml/min
- Perfusion- Flow per given volume or mass of tissue
- Expressed in ml/min/g
- Pressure- Force of blood exerted on vessel wall
- Expressed in mmHg
- Large organ=great flow and less perfusion
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Hemodynamics
- Study of physical principles of blood flow
- Based on pressure and resistance
- F ≈ ΔP /R
- F = blood flow, ΔP = difference in pressure, R = resistance to flow
- Great R less F, Great change in O Greater F
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Blood Pressure
- Varies throughout system
- 1.1Highest pressure immediately after systole
- 2.1Highest pressure proximal to heart 3.1Arteries à Capillaries à Veins Influenced by:
- 1.2Elasticity of arteries
- Recoil maintains pressure and facilitates flow
- Volume of blood forced
- Kinetic energy of blood stretching the aorta
- Force blood exerts on vessel wall - catheter
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Measures of Arterial BP
- Systolic
- Diastolic
- Pulse pressure (PP)- Measure of pressures surges
- 1.3PP = SBP – DBP
- 2.3Max stress generated by heart
- Mean Arterial Pressure (MAP)-Average of pressures
- 1.4MAP = DBP + 1/3 (PP)
- 2.4Influences syncope (fainting)
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BP increase with age – hypertensions 140/90 or higher
- Depends on coordinated function
- 1.2Brain
- Heart
- Blood Vessels
- Kidneys
- 2.2Main variables
- Cardiac output
- Blood volume- regulated by kidneys
- Resistance to flow
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Resistance
- Arterioles- proximal sides of caps, regulate flow into caps, more
- Measure of friction encountered by blood through vessels
- 1.2Opposition to flow
- Peripheral resistance
- 1.3Generally from smaller vessels and arterioles
- Sources:
- 1.4Blood viscosity- don’t change
- 2.4Blood vessel length- don’t change
- 3.4Blood vessel diameter
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Blood Viscosity
- Defined as “thickness” of blood, Results from RBC and albumin
- 1.1Deficiency reduces viscosity and increases flow
- Directly proportional to resistance
- Inversely proportional to flow
- 1.3 Increase viscosity, decrease flow
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Blood Vessel Length
- Distance blood must travel
- 1.1Longer distance = more friction
- Directly proportional to resistance
- 1.2Longer vessel = greater resistance Inversely proportional to flow
- 1.3Longer vessel = lower flow
- P+F goes down with distance
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Diameter changes
- 1.1Vasoconstriction- narrowing of vessels 2.1Vasodilation – widening of vessels 3.1Constantly alters peripheral resistance Laminar vs. turbulent
- 1.2Laminar flows in layers
- 2.2Turbulent0 affects blood velocity
- 3.2F= R^4
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Poiseuille’s Law
- Flow = ΔBP * π * r4 /8 * (viscosity * length)
- Resistance = 8 * viscosity * length/ pie * r4
- Resistance: greatestimpact on flow because of arterioles
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Regulation of Pressure and Flow
- Local Control
- Neural Control
- Hormonal Control
- Control of vasomotion
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Autoregulation
- 1.1Ability of tissue to regulate own flow
- Myogenic control
- Metabolic control-stimulate vasomotion
- 1.3CO2, H+, K+, lactic acid
- 2.3Vasoactive chemicals- Histamine, prostaglandins, bradykinin Angiogenesis
- Reactive hyperemia- increase above normal level of flow
- Growth of new blood vessels
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Neural Control
- Vasomotor center in medulla
- 1.1Sympathetic impulses to smooth muscle
- Constrict most vessels
- Dilate vessels of skeletal and cardiac muscle
- Regulated by autonomic reflexes 1.2Baroreflex
- 2.2Chemoreflex
- 3.2Medullary ischemic reflex
- Blood vessels under control by central and ANS
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Baroreflex
- Autonomic, negative feedback mechanism in response to blood pressure
- Baroreceptors
- Inhibits SNS signaling rate increase 1.3Cardiac center
- 2.3Vasomotor center
- Excites vagal fiber
- Effects
- 1.5Reduce HR
- 2.5Reduce CO
- 3.5Dilates vessel
- 4.5Reduces BP
- Good for adapting to changes in posture
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Chemoreflex
- Autonomic response to chemical changes
- 1.1Chemoreceptors
- 2.1↓pH, ↓O2, ↑CO2
- Primary role
- 1.2Adjust respiration
- Secondary role
- 1.3Vasomotor
- Vasoconstriction
- Increases perfusion
- Increase BP
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Medullary Ischemic Reflex
- Autonomic response to drop in brain perfusion
- 1.1Cardiac and Vasomotor Centers
- Increase HR and contraction
- Widespread vasoconstriction
- 1.2Input from higher brain center
- Stress, arousal, anger
- Medulla monitors its own blood supply
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Chemical Control
- Hormones act on vascular smooth muscle 1.1Angiotensin II increase BP
- vasoconstriction
- 2.1Aldosterone increase Blood vol. And pressure
- Sodium retention by kidneys
- 1.3 Atrial natriuretic peptide decrease Blood volume and pressure
- Increases sodium excretion 1.4Antidiuretic hormone vasoconstrictor increase BP
- Water retention
- 1.5Epinephrine and norepinephrine increase blood flow
- Vasoconstriction in most vessels
- Vasodilation in coronary and skeletal muscle blood vessels
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Vasomotion
- Increase or decrease BP
- 1.1Needs centralized control
- 2.1Widespread vasocontriction
- Modifying perfusion of certain organ
- Reroute blood from region to another 1.3Central or local control
- 2.3 Exercise
- 3.3Constricts on blood route and blood doesn’t go to route more resistance
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Redirection of Blood Flow
- Localized vasoconstriction of artery
- 1.1Pressure downstream decreases
- 2.1Pressure upstream increases
- 3.1Blood takes the path of least resistance
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Capillary Exchange
- Two way movement of materials and fluids
- 1.1Delivery
- Blood->capillary->interstitial space->tissue
- Oxygen, Glucose, AA, lipids, minerals, hormones
- Velocity of blood slows into capillary bed
- Increase in cross sectional area of bed
- Increases time for exchange 1.2Removal
- Tissue->interstitial space ->capillary-> blood
- CO2, ammonia, other wastes
- Chemicals pass 3 routes
- Endothelial cell of cytoplasm, intercellular clefts, and filtration pores
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Modes of Capillary Exchange
- Diffusion
- Vesicular Transport
- 1.2Transcytosis
- Pinocytosis
- Exocytosis
- Bulk Flow
- 1.3Filtration
- 2.3Reabsorption
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Diffusion
- Simple diffusion- Through plasma membrane
- 1.1Requires concentration gradient
- 2.1Lipid – soluble materials
- Water – soluble substances insoluble in lipids
- 1.2Fenestrations -Pores in capillary cell 2.2Intercellular clefts- Gaps in tight junctions between cells
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Vesicular Transport
- Transcytosis
- 1.1Vesicles pick up fluid by pinocytosis 2.1Transport across cell
- 3.1Discharge on other side (exocytosis) Small percent of exchange
- 1.2 Fatty acids
- 2.2Albumin
- 3.2Hormones (insulin)
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Bulk Flow
- Balance of filtration and osmotic forces 1.1Filtration at arterial end of capillary 2.1Reabsorption at venous end of capillary 3.1Fluid from interstitial space to capillary
- Two forces involved
- 1.2Hydrostatic-physical force by liquid on surface of capillary
- 2.2Osmotic
- 3.2Net Filtration Pressure (NFP)
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Exchange-Related Pressures
- Colloid Osmotic Pressures – due to proteins
- Blood (BCOP)
- Interstitial Fluid (ICOP)
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Net Filtration Pressure
- Arterial end of capillary (error in IHP)
- Net Hydrostatic Pressure
- 2.1NHP = BHP – IHP
- NHP = 30 – (3) = 27 mmHg
- Net Colloid Osmotic Pressure
- NCOP = BCOP – ICOP
- NCOP = 28 – 8 = 20 mmHg
- Net Filtration Pressure
- NFP = NHP – NCOP
- NFP = 27 – 20 = 7 mmHg
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Net Reabsorption Pressure
- Venous end of capillary (error in IHP)
- NHP = BHP - IHP
- 1.2NHP = 10 – (3) = 7mmHg
- NCOP = BCOP –ICOP
- 1.4NCOP = 28 – 8 = 20mmHg
- NFP = NHP – NCOP
- 1.5NFP = 7 – 20 = -13mmHg
- Prevailing force inward overrides filtration pressure
- Edema- accumulation of excess fluid in tissue
- 1.7Fluid is filtered faster than reabsorbed
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Mechanisms of Venous Return
- Pressure gradient
- 1.1Central venous pressure
- Gravity- flow downhill
- Skeletal muscle pump
- 1.4Contraction squeezes or “milks” veins- thoracic expands
- Respiratory pump
- 1.5Thoracic pressure
- Cardiac suction
- Venous Return – flow of blood back to heart
- Suction draw blood into atria
- 1.8Increase cap. Filtration
- 2.8Decrease cap reabsorption
- 3.8Obstructed lymph drainage
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Mechanisms of Venous Return
- Exercise increases it
- 1.1faster heartbeat, and harder, increase cardiac output and blood pressure
- blood vessels, and skeletal muscles, increase the flow
- venous poding
- 1.3blood accumulates in limbs
- 2.3person still
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Circulatory shock
A state in which cardiac output is insufficient to body’s needs
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Lymphattic System
- Network of Vessels
- Collection of tissues and organs that produce immune cells
- Functions:
- 1.1Fluiud recovery- filters from blood cells to tissues
- 2.1immunity- picks up foreign cells
- 3.Lipid absoprtion- small intestine
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Components of Lymph system
- Lymph tissues- Lymphocytes
- Lymph organs- Ct capsules
- Lymph vessels-transpoert lymph cells
- 1.3lymph- originate in tissue fluid
- 2.3 clear fluid, similar to blood
- Lymph capp.
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Lymph Cap.
- Absorb interstitial fluid
- assoicated with blood cap
- 1.2higly permeable ECS- no tight junctions, anchored by filaments, Ec opening during swelling
- closed at one end not like blood vessel
- Specialized capp.
- 1.3Lacteals -absorb and transport dietary lipids
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Lymph Vessels
- Collecting vessel- lymph capp. converge
- Similar to veins
- 1.2 thinner walls and more vavles
- tunica interna- endothelium and vavles
- tunica media-elastic fibers and smooth muscle
- tunica externa-thing
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Lymphatic Trunks
- Drains major portion of body
- Names for location
- 1.lumbar
- 2.Intercostal
- 3.Brachiomediastinal
- 4.Subclavian
- 5.Jugular
- Form collecting ducts
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Collecting Ducts
- Large structrures in thoracic region
- 1.1. right Lymph- to right subclavian
- 2.1 left lymph to thoracic and to left subclavian
- Thoracic duct- larger and longer and below diaphragm
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Flow of Lymph
- Slow speed under low pressure and aided by valves
- Flow promoted by
- 1.skeletal muscles
- 2.smooth muscles contraction in vessels
- 3. breathing
- 4.Pushing of arteries - common ct tissue
- Valves prevent the fluid from flowing backward
- Rhythemic contractions
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Lymph Cells
- All in respiratorym digestive, urinary, reproductive tracts
- 1.Natural killler cells - host cells, destroy bacteria
- 2.T Lymphocytes- mature in thymus
- 3.B lymphocytes- secrete anitbodies
- 4.Macrophages- phagocytize tissue debris
- 5. Dendritic Cells-alert immune system
- Reticular Cells
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Lymph Tissues
- Aggregation of lymph in CT
- 1.1 diffuse Lymph tissue - Mucosa-associated Lymph tissue-MALT
- In the respiratory, digestive, urinary, reproductive tracts
- Lymph scattered
- 2.1Lymphatic nodules (follicles)
- dense Lymphocytes and macrophages
- lymph nodes, tonsils, appendix(in ilieum), peyer's patches
- invade tissues and act aspathogens so the immune system answers
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Lymph organs
- Well defind anatomical sites with CT capsules seperating lymphatitic tissues
- 1.1Primary lymphativ organs
- Immunocompetency of T and B lymphocytes (red bone marrow and thymus)
- 2.1 secondary lymphatic organs
- contain immunocompetent cells
- lymph nodes, tonsils, spleen
- after mature in primary lymph organs
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Red Bone marrow
- Axial skeleton, promixial head of humerous and femur in adulrs
- multiple tissues
- soft loose and high vascular material
- produce AV classes of elements of blood
- Function:
- 1.2 Hemopoeisis
- 2.2 Reticular cells
- colony stimulating factors for WBCs
- immunity
- in meduallry
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Thymus
- houses developing lymph
- secretes hormones that regulate their activity
- bilobed organ and is between sternum and aortic arch
- Endocrine and lymph functions- immune system
- 2 lobes
- 1.2 divivded into lubules
- 2.2 cortex- dense lymphocytes T cells go to medulla
- 3.2 medulla- few lymphocytes
- 4.2Reticular epithelial cells- thymosin, and thymopoieitn
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Blood thymus barrier
- seals off cortex from medualla and surround blood vessels and lymph clusters in cortex
- isolated developing lymph
- produce signaling molecules
- if no thymus then it will never develop immunity
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Lymph Nodes
- Functions: Filter lymph and activiate B and T cells
- Occur in regions
- Coretx
- 1.3lymph nodules have a germinal center and B cell differntiate
- when fighting pathogens they aquire germinal centers and B cell multiply
- Medulla
- 1.4 Medullay cords- lymphocytes, plasma cells, macrophages, reticular cells
- numerous lymph organs
- elongated structure
- has several afferent lymph vessels leading to it
- in cervical and axillary, thoracic, abdominal and intestinal, inguinal, and popliteal
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Tonsils
- Lymp tissue at Pharynx entrance
- FunctionsL guard ingested and inhaled pathogens
- Tonsiliar crypts- deep pits in epithelium, trap bacteria- move into lymph tissue and destroyed
- Food debris
- many sets: Pharyngeal T, Paratine T largest and Lingual T
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Spleen
- Largest lymph organ
- Parenchyma
- White pulp- lymphocytes/macrophages, quick immune repsonse
- Red pulp- erythrocytes engorged and RBC graveyard
- Help stabilize blood volume
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