TEST 3: Circulatory System (Ch 13)

plasma

- liquid portion of the blood including the dissolved substances

- 92% water, 8% salt and organic molecules

- top layer after centrifuging

serum

serum = plasma - fibrinogen

- plasma with clotting factors removed

layers after centrifuging

top: plasma (matrix)

bottom: formed elements (55%)

- upper bottom: buffy coat (WBCs and platelets)(<1%)

- lower bottom: RBCs (45%)

hematocrit

percent of blood volume that RBCs make up (usually about 45%)

plasma proteins

- aid in clotting, immune defense, and transport

albumins

- most abundant plasma protein

- good for TRANSPORT

- good at acting as a pH buffer

- produced in the liver

- affect blood osmolarity

blood osmolarity

- concentration of particles that CANNOT pass through the blood vessel walls

- high osmolarity= high H2O; high at VENULE end; response: water removed from the tissues causing volume and pressure to increase at the VENULE end

- low osmolarity= low H2O; low at ARTERIAL end; response: water remains in the tissues causing the volume and pressure to decrease at the ARTERIAL end

globulins

- play a role in transport, immunity, and clotting

fibrinogen

IMPORTANT

- plays a key role in blood clotting

- soluble

- converted into fibrin to produce a clot

viscosity

thickness/stickiness; resistance to flow

formed elements

- WBCs, platelets, and RBCs

= blood - plasma

red blood cells

- erythrocytes

- small, bioconcave disks, no nucleus

-shape: large surface area for fast diffusion

- two functions:

1) transport O2 from the lungs

2) pick up CO2 from the tissues

hemoglobin

- respiratory pigment (red)(bc of iron)

- 4 globin chains (2 alpha, 2 beta)

- each chain contains a heme group (containing 1 molecule of iron each)

heme group

- 1 per globin chain (4 per hemoglobin)

- each contains an iron molecule

- each iron molecule binds to 1 O2 molecule

globin chain

- globin binds CO2

- 4 chains (2 a, 2 b) per hemoglobin molecule

oxyhemoglobin

- oxygenated

- bright red

deoxyhemoglobin

- deoxygenated (hemoglobin not bound to O2)

- maroon

erythropoiesis

- production of RBCs

-originate in hemopoietic stem cells

- erythropoietin: a hormone produced by the kidneys in response to low blood oxygen

Iron (modification during erythropoiesis)

- modified in small intestine/stomach

- transported from the stomach via gastroferritin

- uptake in small intestine

- circulates in the blood; transported by transferrin

- stored in the liver/spleen by ferritin

- when RBCs are destroyed, iron released to plasma and bound to transferrin

gastroferritin

- binds to and transports iron (Fe2+)from the stomach to the small intestine and releases it for absorption

transferrin

- in the blood plasma, Fe2+ binds to ferritin

- in the liver, some transferrin releases iron for storage

- remaining transferrin is distributed to other organs where Fe2+ is used to make hemoglobin, myoglobin, etc

ferritin

- iron binds to apoferritin in the liver to be stored at ferritin

- stores iron

RBC death

- RBCs cannot synthesize new proteins or repair membrane proteins

- membrane eventually becomes fragile and ruptures

- often happens in the liver or spleen (narrow passageways)(iron conserved)

hemolysis

- RBC rupture

- usually in the spleen or liver

- iron conserved

- hemoglobin converted to bilirubin (bile)

Bilirubin

- orange-yellow pigment in bile; formed by the breakdown of hemoglobin when red blood cells are destroyed

- broken down from heme, converted into bile

White Blood Cells (Leukocytes)

- larger than RBCs

- nucleated

- no color (no heme)

- functions (fight infection, destroy toxins etc, recognizing and remembering (infections etc)

- very dispersed; low amount in blood (<1%)

- two categories (granulocytes and agranulocytes)

granulocytes

- 1/2 categories of WBCs

- specific granules

-specific stain

- contain enzymes and chemicals used in defense

- neutrophils, eosinophils, and basophils

agranulocytes

- monocytes and lymphocytes

- lack specific granules --> don't stain (cytoplasm is clear)

platelets (thrombocytes)

- not "cells", but other organelles; fragments of large bone marrow cells

- considered formed elements

- many functions: secrete vasoconstrictors, platelet plugs, clotting factors, clot-dissolving enzymes, and growth factors

blood types

- A, B, AB, O

- based on antigens (and antibodies)

antigens

- complex molecules on the surface of the cell membrane to activate an immune response

- on RBCs

- foreign antigens generate an immune response

-basis for blood typing

- also called agglutinogens

- Ab has both A and B antigens, O has no antigens

antibody

- proteins secreted by WBCs

- bind to antigens for destruction

- immune response to foreign matter

- agglutinins: antibodies in the plasma, bring about transfusion mismatch

agglutination

-antibody molecule binds to antigen, causing the RBCs to clump together

ABO Blood Type

- determined by presence or absence of antigens (agglutinogens) on RBCs

- each antibody can attach to several foreign antigens on several different RBCs at the same time

- blood vessels become blocked, hemolyze, and burst

- "transfusion rxn"

Rh group

- agglutinogens (on surface of RBCs)

- Rh+: have agglutinogen

- Rh-: do not

Anti-D agglutinins (antibodies)

- not normally present in any blood (+ or -)

- forms in Rh- exposed to Rh+ blood

- happens in pregnancy (2nd pregnancy)

- hemolytic disease of the newborn (HDN) mother forms antibodies after first pregnancy

- anti-D antibodies cross the placenta and attack the fetus

RhoGAM

- given to Rh- women during second pregnancy to prevent hemolytic disease of the newborn

- binds to fetal RBCs to prevent the attack

hemostasis

- clotting pathway

- cessation of bleeding

-stops fatal leaks

- 3 mechanisms

hemmorhage

excessive bleeding

step 1 of homeostastis (clotting pathway)

1) vascular spasm

vascular spasm

-reduces blood loss by triggering vasoconstriction

- spasm caused by pain receptors

- platelets then release serotonin (a vasoconstrictor)

- effects: prompt constriction of broken vessel

**-provides time for other 2 clotting pathways

step 2 of homeostasis (clotting pathway)

2) platelet plug

platelet plug

- intact vessels are coated with PROSTACYCLIN (platelet repellent that keeps platelets from binding to walls of blood vessels)

- broken vessel exposes collagen, platelets stick to the collagen

- platelets degranulate (activate) and release ADP (attracts more platelets) and Thromboxane (A2) (promotes platelet aggregation, degranulation, and vasoconstriction)

-POSITIVE FEEDBACK cycle

step 3 of homeostasis (clotting pathway)

3) coagulation (clotting)

coagulation

- most effective defense

-procoagulants produced by liver (present in plasma)

- goal: convert fibrinogen to sticky fibrin

- fibrin adheres to wall of vessel and platelets stick to it

- resultant clot formed, made up of fibrin, platelets, and RBCs

procoagulants

- proteins secreted by the liver

- inactive form always present in plasma

- activation of one causes an activation cascade

- promote fibrin formation by interacting with clotting factors

intrinsic (clotting) pathway

- clotting factors intrinsic to blood begin the cascade

- platelets release factor 12 and activates the cascade of reactions

- ends with factor 8

extrinsic pathway of coagulation

- clotting factors extrinsic to the blood (from damaged tissue)

- factor 3 (thromboplastin)

common pathway

- completes clotting process

- both intrinsic and extrinsic pathways end, factor 10 is activated

- factor 10 activates factor 2, which produces prothrombin, later concerted to thrombin

- thrombin converts fibrinogen to fibrin to form the clot

Common Pathway Summary

Factor X → prothrombin activator;

Prothrombin activator + prothrombin (factor 2)= thrombin;

Thrombin + fibrinogen= fibrin;

Fibrin: sticky mesh, traps platelets, forms clots

factor 10

- activates prothrombin activator (factor 2)

- converted into thrombin by factor 9

thrombin

- produced in common pathway

- converts fibrinogen into fibrin

- forms the clot (fibrin is sticky and traps the platelets)

- positive feedback

fibrin

- the sticky mesh that traps platelets to form a clot

- insoluble (unlike soluble fibrinogen, which it is produced from)

fibrinogen

- plasma protein that is converted to fibrin in the clotting process

- produced by the liver

coagulation vs agglutination

BOTH: blood cell or platelet aggregation

coagulation: platelets stuck together by fibrin

agglutination: RBCs stuck together by antibody molecules

significance of blood viscosity and osmolarity:

- viscosity: controls blood flow resistance

-osmolarity: controls blood concentrations of protein, Na+, RBCs, and water; important for cell nourishment and waste excretion; causes changes in blood volume, which affects blood pressure and flow

structure and function of erythrocytes:

- large surface area for quick diffusion

- carries O2 from lungs to tissues

-picks up CO2 at the tissues and takes to the lungs

structure and function of hemoglobin

- 4 globin chains (2 alpha, 2 beta); globin molecules binds CO2 in the tissues and carry back to the lungs

- 1 heme group per chain, contains 1 iron molecule each; iron molecule binds 1 molecule of O2 in the lungs and carries to the tissues, where it is released

explain what determines a person's ABO and Rh blood types, and how this relates to transfusion compatibility:

- ABO blood type based on antigens on the surface of RBCs

- Rh+/- based on presence or absence of Rh factor (antigen/agglutinogen) on RBC surface

- transfusion compatibility: based on antigens and Rh factor; Rh+ blood can receive either positive or negative blood (neg blood has no Rh factor), Rh- can only receive neg blood; type O blood can only receive O blood (no antigens present), and type AB blood can receive any blood type

describe the body's mechanisms for controlling bleeding

- homeostasis:

1) vascular spasm

2) platelet plug

3) clotting

- clotting pathway: extrinsic or intrinsic, followed by the common pathway which results in fibrin formation and forms a clot with platelets that stick to it in the vessels

what happens to blood clots when they are no longer needed:

clot dissolution:

- platelet-derived growth factor secreted from the platelets

- stimulates damaged tissue replacement

- platelets initiate a reaction chain

- ends with plasmin, which is an enzyme that digests the fibrin and dissolves the old clot

clotting factor deficiencies

- can shut down coagulation cascade if one is missing

- hemophilia: hereditary lack of single protein in cascade that results in the inability to clot (most lack factor 9)

Plasmin

an enzyme that digests fibrin and dissolves blood clots