Download - Blood
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Blood• Blood can actually be considered one of your body’s tissues.
– Formed elements
• all the blood cells
– red blood cells (RBCs) (erythrocytes)
» transport O2
– white blood cells (WBCs) (leukocytes)
» immune response
• and the platelets
– membrane sacs that help seal broken blood vessels
– Plasma
• proteins used for blood clotting and osmotic pressure
• Serum
» nutrients (glc, aas, fats)
» waste (mostly urea)
» dissolved gases (O2, CO2, N2)
» electrolytes (Na+, K+, Cl-)
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Blood
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Blood - hemopoiesis• production of blood cells
– erythropoiesis -RBCs
• kidneys produce erthropoietinwhen O2 levels drop
• new RBCs produced inred bone marrow
• negative feedback loop• production of blood cells
– leukopoiesis -WBCs
• triggered by infections or other attacks on the body
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• production of blood cells
– leukopoiesis -WBCs
• triggered by infections or other attacks on the body
Blood - hemopoiesis• production of blood cells
– erythropoiesis -RBCs
• kidneys produce erthropoietinwhen O2 levels drop
• new RBCs produced inred bone marrow
• negative feedback loop
• production of platelets
– thrombopoiesis
• megakarocytes
– bone marrow
– lungs
• pinches off pieces of cytoplasm
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Blood - erythrocytes• Red blood cells transport O2
(and some CO2)
– hemoglobin
• 4 protein chains (globins)
– 2 alpha chains
– 2 beta chains
• 4 heme groups
– site where O2 molecules bind
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• Polycythemia
– too many red blood cells
• increase blood volume
• increase blood viscosity
• increase blood pressure
– heart over worked
– can lead to embolism, stroke, heart failure
• Anemia
– too few blood cells carrying O2
– hemorrhagic anemia - excessive blood loss
– hemolytic anemia - destruction of RBCs or too little erythropoiesis
– sickle-cell anemia and thalassemia
• both caused by abnormal hemoglobin
Blood - erythrocyte disorders
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• All cells have membrane proteins that label the cell as “friend” or “foe” to the immune system
– antigens
– allow your immune system can differentiate your body cells from foreign or infected cells
• Antigens on RBCs called agglutinogens
– react with antibodies in blood called agglutinins– mismatched transfusions cause agglutination (transfusion reaction)
• agglutinins bind toagglutinogens and linkRBCs together
• cause RBCs toform “clumps” (agglutination)
Blood Types
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• ABO blood groups
– type A and type B agglutinogens (antigens)• just A type agglutinogens - type A blood
• just B type agglutinogens - type B blood
• both agglutinogens - type AB blood
• no agglutinogens - type O blood
– transfusion rxns can occur because you also have agglutinins (antibodies)
• type A blood - antiB agglutinins
• type B blood - antiA agglutinins
• type AB blood - no agglutinins
• type O blood - both agglutinins
Blood Types
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• ABO blood groups
– type AB blood• no agglutinins - sometimes called universal recipient
• what about agglutinins in donor’s blood?
– type O blood - both agglutinins• no agglutinogens - universal donor?
• But has both types of agglutinins
Blood Types
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• Rh group
– Rh+ have the Rh agglutinogen– Rh- do not have Rh agglutinogen
• will produce antiRh agglutinin if exposed to Rh+ blood
Blood Types
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• Rh- Mom exposed to Rh+ blood of newborn at birth
• no problem during first pregnancy
Blood Types - hemolytic disease of the newborn (HDN)
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• Mom produces antiRh agglutinins
Blood Types - hemolytic disease of the newborn (HDN)
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• Mom’s antiRh agglutinins attack Rh+ RBCs of fetus in next pregnancy
Blood Types - hemolytic disease of the newborn (HDN)
• Can be prevented by treating with RhoGAM
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Hemostasis• The stoppage of bleeding (3 ways)
– 1) Vascular Spasm• constriction of the injured blood vessel via:
– pain receptors
– smooth muscle damage
– serotonin (released from platelets)
– 2) Platelet plug formation• platelets react with collagen
• adhere to inner surface of blood vessel
• contract and draw the vessel walls together
• release chemicals (degranulation)– serotonin (vasoconstrictor)
– ADP (platelet aggregation)
– thromboxane A2 (both of the above)
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2
1
Hemostasis• The stoppage of bleeding (3 ways)
– 1) Vascular Spasm
– 2) Platelet plug formation
– 3) Coagulation• the formation of fibrin
• two pathways– intrinsic mechanism
– extrinsic mechanism
3
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Hemostasis - coagulation pathways• Intrinsic mechanism
– platelet degranulation releases fact. XII
– triggers a cascade of rxns
– fact. X activated
– becomes prothrombin activator
– converts prothrombin to thrombin
– converts fibrinogen to fibrin
– becomes fibrin polymer
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Hemostasis - coagulation pathways• Extrinsic mechanism
– damaged tissues release thromboplastin
– fact. VII activated
– results in fact. X activation– becomes
prothrombin activator
– converts prothrombin to thrombin
– converts fibrinogen to fibrin
– becomes fibrin polymer
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Hemostasis - coagulation pathways• Fibrin formation
– intrinsic mech. - 3-6 min.
– extrinsic mech. - ~15 sec.
• Clot retraction (30 minutes)
• Healing stimulated byplatelet-derived growth factor(PDGF)
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Hemostasis - coagulation pathways• Classical hemophilia
– lack of fact. VIII
• hemophilia B– lack of fact. IX
• clotting fact. can be produced by transgenic bacteria
3
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Circulatory System
• Basic structure of arteries and veins
lumen
Tunica intima -mostly endothelium
Tunica media -mostly smooth muscle
Tunica externa -mostly connective tissue
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The structure of blood vessels• Blood flows from heart
– into arteries• conducting
– large– very elastic
• distributing– feed specific organs– very muscular
• resistance– arterioles– deliver blood to capillary bed
• metarterioles– control blood flow within capillary bed
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The structure of blood vessels
– capillary bed• very thin walled
- just tunica intima
• site of exchange between blood and body cells
– nutrients, O2 CO2 , wastes
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The structure of blood vessels
– veins• deliver blood back to heart
– metavenules
– venules
– veins
• much less smooth muscle than arteries
• more fragile than arteries– varicose veins are just veins
that have broken open and leak blood
• contain valves to prevent blood flowing backwards
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Precapillary sphincters
• Blood flows from arteriole
• to metarteriole– precapillary sphincters open or close
and determine if blood flows into capillary bed,
– or is shunted straight thru thoroughfare channel (metavenule).
– constantly adjusted (homeostasis again) - depends on activity of the body
– capillary bed• very thin walled
- just tunica intima
• site of exchange between blood and body cells
– nutrients, O2 CO2 , wastes
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Blood Pressure• BP is not constant
throughout circulatory system
• when heart contracts (systole)BP goes up
– systolic pressure
• when heart relaxes (diastole) BP goes down
– diastolic pressure
• as blood flows further from the heart
– BP also decreases
• By the time blood reaches the veins, hardly any pressure is provided by the heart
– So where does pressure come from that moves blood out of your legs and toward your heart??
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Skeletal Muscle Pump
• Veins often run in the middle of skeletal muscle
• as muscles contract, veins get squeezed
• blood is pushed through vein
• venous valves - prevent blood from flowing backward
• blood is squeezed toward heart
• What happens if you stand motionless for 60 minutes or so?
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The Circulatory system
• Your body can control blood flow to diff. areas by changing peripheral resistance.
• Regulation of peripheral resistance
– Local control
• accumulation of metabolic by products
• CO2, H+, lactic acid (+ others)
• trigger vasodilation (decrease peripheral resistance)
• increased blood flow carries by products away
• blood vessels constrict back to normal size
• homeostasis
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• Your body can control blood flow to diff. areas by changing peripheral resistance.
• Regulation of peripheral resistance
– Local control
The Circulatory system
– Neural control
• baroreflex
• negative feedback
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• Your body can control blood flow to diff. areas by changing peripheral resistance.
• Regulation of peripheral resistance
– Local control
The Circulatory system
– Neural control
• baroreflex
• chemoreflex
DecreasedCO2 levels
chemoreceptorsfire fewer APs
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The Circulatory system
• Your body can control blood flow to diff. areas by changing peripheral resistance.
• Remember autonomic nervous system?
– sympathetic division• fight and flight
• diverts blood flow to prepare for stressful activity
– parasympathetic division• rest and digest
• diverts blood flow to GI tract
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The Circulatory system• So the circulatory system transports nutrients and wastes to
and from the cells…
• How do things move between the blood in the capillaries and the cells outside?
• Three routes of capillary exchange
– diffusion
• most important
– transcytosis
• least important
– filtration and reabsorption