Transcript All_the_circulatory_slides

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-)
Blood
Blood - hemopoiesis
• production of blood cells
– erythropoiesis -RBCs
• kidneys produce erthropoietin
when O2 levels drop
• new RBCs produced in
red bone marrow
• negative feedback loop
• 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 erthropoietin
when O2 levels drop
• new RBCs produced in
red bone marrow
• negative feedback loop
• production of blood cells
– leukopoiesis -WBCs
• triggered by infections or other
attacks on the body
• production of platelets
– thrombopoiesis
• megakarocytes
– bone marrow
– lungs
• pinches off pieces of
cytoplasm
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
Blood - erythrocyte disorders
• 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 Types
• 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 to
agglutinogens and link
RBCs together
• cause RBCs to
form “clumps” (agglutination)
Blood Types
ABO blood groups
– type A and type B agglutinogens (antigens)
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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)
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type A blood - antiB agglutinins
type B blood - antiA agglutinins
type AB blood - no agglutinins
type O blood - both agglutinins
Blood Types
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
Rh group
– Rh+
– Rh-
have the Rh agglutinogen
do not have Rh agglutinogen
• will produce antiRh agglutinin if exposed to Rh+ blood
Blood Types - hemolytic disease of the newborn (HDN)
• Rh- Mom exposed to Rh+ blood
of newborn at birth
• no problem during first
pregnancy
Blood Types - hemolytic disease of the newborn (HDN)
• Mom produces antiRh
agglutinins
Blood Types - hemolytic disease of the newborn (HDN)
• Mom’s antiRh agglutinins attack
Rh+ RBCs of fetus in next
pregnancy
• Can be prevented by treating
with RhoGAM
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
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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)
Hemostasis
• The stoppage of bleeding (3 ways)
– 1) Vascular Spasm
– 2) Platelet plug formation
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– 3) Coagulation
• the formation of fibrin
• two pathways
– intrinsic mechanism
– extrinsic mechanism
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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
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
Hemostasis - coagulation pathways
• Fibrin formation
– intrinsic mech. - 3-6 min.
– extrinsic mech. - ~15 sec.
• Clot retraction (30 minutes)
• Healing stimulated by
platelet-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
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Circulatory System
• Basic structure of arteries and veins
Tunica intima
-mostly endothelium
lumen
Tunica media
-mostly smooth muscle
Tunica externa
-mostly connective tissue
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
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
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
Precapillary sphincters
– capillary bed
• very thin walled
- just tunica intima
• site of exchange between
blood and body cells
– nutrients, O2 CO2 , wastes
• 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
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??
Skeletal Muscle Pump
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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?
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
The Circulatory system
• Your body can
control blood flow
to diff. areas by
changing peripheral
resistance.
• Regulation of
peripheral
resistance
– Local control
– Neural control
• baroreflex
• negative
feedback
The Circulatory system
• Your body can
control blood flow
to diff. areas by
changing peripheral
resistance.
• Regulation of
peripheral
resistance
– Local control
– Neural control
• baroreflex
• chemoreflex
Decreased
CO2 levels
chemoreceptors
fire fewer APs
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
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