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Cardiovascular System
Blood
52
Anatomy
Undergraduate 4
03/03/2008

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Term
RBC Life Cycle (1)
1-5
Definition
1. macrophages in spleen, liver, or red bone marrow phagocytize worn RBCs
2. globin and heme split
3. globin broken down into aa- used to synthesize other proteins
4. Iron (Fe3+) removed from heme and associates with transferrin
5. in spleen and liver cells, Fe3+ detaches from transferrin and bind to iron-storage protein, ferritin
Term
RBC Life Cycle (2)
6-10
Definition
6. upon release, it reattaches to transferrin
7. carried to red bone marrow, where RBC precursor cells endocytose it and use it for Hg synthesis (iron needed for 8. heme portion)
8. erythropoiesis in red bone marrow result in RBC production
9. when iron removed from heme, the non-iron portion is converted to biliverdin (green), and then bilirubin (yellow)
10. bilirubin enters blood and is transported to the liver
Term
RBC Life Cycle (3)
11-14
Definition
11. within the liver, bilirubin is released into bile, which passes into the small intestine, then the large intestine
12. in the large intestine, bacteria convert bilirubin into urobilinogen
13. some urobilinogen is reabsorbed by blood, converted to a yellow pigment, urobilin and excreted in urine
14. most urobilinogen is eliminated in feces in the form of stercobilin (brown pigment)
Term
Iron Overload
Definition
free iron ions bind to and damage cells, so transferrin and ferritin act as protective “protein escorts” and as a result only small amounts of iron are available inside cells for synthesis
Term
Common Conseq. Of Iron Overload
Definition
in cases of iron overload, the amount of iron in the body builds up
we have no method for eliminating excess iron
common consequences include diseases of the liver, heart, pancreas and gonads
Term
Erythropoiesis
Definition
Production of RBCs.
occurs in the red bone marrow with precursors called proerythroblast.
Proerythroblasts divide repeatedly producing cells that start synthesizing Hg.
Ultimately, a cell ejects its nucleus (causing the characteristic shape) and becomes a reticulocyte, which maintains some mitochondria, ribosomes, and ER
Term
reticulocyte
Definition
bloodcell which maintains some mitochondria, ribosomes, and ER.
Reticulocytes escape from bone marrow into the blood
In 1-2 days, they mature into RBCs and eject their remaining organelles
Term
If erythropoiesis does not keep up with destruction . . .
Definition
a negative feedback system steps up production- the controlled condition is the amount of oxygen delivered to the tissues
Term
hypoxia
Definition
cellular oxygen deficiency, occurs if too little oxygen enters the blood, and this stimulates the kidneys to increase the release of EPO
Term
anemia
Definition
RBC production falls below RBC destruction
Term
Kidney response to hypoxia
Definition
release erythropoietin
speeds up development of proerythroblasts into reticulocytes
Term
Low count in an anemic person might indicate
Definition
shortage of EPO or an inability of the red bone marrow to respond to EPO
Term
High blood cell count might indicate
Definition
recent blood loss or successful iron therapy, or illegal use of artificial EPO by an athlete
Term
Leukocytes have surface proteins, as do other cells, called
Definition
major histocompatibility antigens (MHC), and are unique for each person (except for identical siblings)
Term
Neutrophil Anatomy
Definition
Polymorphonuclear leukocytes (PMNs or Polys).
Nuclei 2 to 5 lobes connected by thin strands.
young cells called band cells because of horseshoe shaped nucleus (band).
Fine, pale lilac practically invisible granules.
Diameter is 10-12 microns.
60 to 70% of circulating WBCs.
Term
Neutrophils Function
Definition
Fastest response of all WBC to bacteria.
Direct actions against bacteria.
release lysozymes which destroy/digest bacteria.
release defensin proteins that act like antibiotics & poke holes in bacterial cell walls destroying them.
release strong oxidants (bleach-like, strong substances) that destroy bacteria.
Term
Eosinophils Anatomy
Definition
Nucleus with 2 or 3 lobes connected by a thin strand.
Large, uniform-sized granules stain orange-red with acidic dyes.
do not obscure the nucleus.
Diameter is 10 to 12 microns.
2 to 4% of circulating WBCs.
Term
Eosinophils Function
Definition
Leave capillaries to enter tissue fluid.
Combat the effects of histamine by releasing histaminase.
slows down inflammation caused by basophils.
Attack parasitic worms.
Phagocytize antibody-antigen complexes.
Term
Basophils Anatomy
Definition
Large, dark purple, variable-sized granules stain with basic dyes.
Obscure the nucleus.
Irregular, s-shaped, bilobed nuclei.
Diameter is 8 to 10 microns.
Less than 1% of circulating WBCs.
Term
Basophils Function
Definition
Involved in inflammatory and allergy reactions.
Leave capillaries & enter connective tissue.
Similar in function as mast cells.
Release heparin, histamine & serotonin in response to allergic reaction.
heighten the inflammatory response and account for hypersensitivity (allergic) reaction.
Term
Lymphocyte Anatomy
Definition
Dark, oval to round nucleus.
Cytoplasm sky blue in color.
amount varies from rim of blue to normal amount.
Small cells 6 - 9 microns in diameter.
Large cells 10 - 14 microns in diameter.
increase in number during viral infections.
20 to 25% of circulating WBCs.
Term
Lymphocyte Function
Definition
B cells -
destroy bacteria and their toxins.
in response to the presence of foreign substances called antigens, differentiate into tissue plasma cells that produce antibodies.
T cells -
attack viruses, fungi, transplanted organs, cancer cells & some bacteria.
Natural killer cells (NK) -
attack many different microbes & some tumor cells.
destroy foreign invaders by direct attack.
Term
Monocyte Anatomy
Definition
-Nucleus is kidney or horse-shoe shaped.
-Largest WBC in circulating blood.
-does not remain in blood long before migrating to the tissues.
-differentiate into macrophages.
-fixed group found in specific tissues.
-alveolar macrophages in lungs.
-kupffer cells in liver.
-wandering group gathers at sites of infection.
-Diameter is 12 - 20 microns.
-Cytoplasm is a foamy blue-gray.
-3 to 8% of circulating WBCs.
Term
Monocyte Function
Definition
Take longer to get to site of infection, but arrive in larger numbers.
Become wandering macrophages once they leave the capillaries.
Destroy microbes and clean up dead tissue following an infection by phagocytosis.
Term
WBC Physiology
Definition
Can live for several months or years, but most for only a few days.
Less numerous than RBCs.
5000 to 10,000 cells/µL.
1 WBC for every 700 RBC.
Term
Leukocytosis
Definition
is a high white blood cell count (↑10,000/µL).
normal response to microbes, strenuous exercise, anesthesia or surgery
Term
Leukopenia
Definition
is low white blood cell count (↓5,000/µL).
radiation, shock or chemotherapy (never good)
Term
Only _____ of total WBC population is in circulating blood at any given time
Definition
Only 2% of total WBC population is in circulating blood at any given time
rest is in lymphatic fluid, skin, lungs, lymph nodes & spleen
Term
Emigration & Phagocytosis in WBCs
Definition
WBCs leave the blood, roll along endothelium, stick to it & squeeze between cells.
adhesion molecules (selectins) help WBCs stick to endothelium.
This is the EC display in response to injury
neutrophils stick to carbohydrates on EC causing them to slow down and roll.
integrins on neutrophils tether them to EC and assist in their transmigration.
Neutrophils & macrophages phagocytize bacteria & debris and these cells chemotax in response to several factors secreted by cells/microbes
Term
Differential WBC Count
Definition
Detection of changes in numbers of circulating WBCs (percentages of each type).
indicates infection, poisoning, leukemia, chemotherapy, parasites or allergy reaction
Term
Normal WBC counts
Definition
neutrophils 60-70% (up if bacterial infection).
lymphocyte 20-25% (up if viral infection).
monocytes 3 -- 8 % (up if fungal/viral infection).
eosinophil 2 -- 4 % (up if parasite or allergy reaction).
basophil <1% (up if allergy reaction or hypothyroid).
Term
How are platelets made?
Definition
Thrombopoietin stimulates myeloid stem cells to develop
into megakaryocyte-colony-forming cells that develop into megakaryoblasts
Megakaryoblasts transform into megakaryocytes which fragment.
Each fragment, enclosed by a piece of cell membrane, is a platelet (thrombocyte).
Platelets break off from megakaryocytes in red bone marrow and then enter the blood circulation
Term
Normal platelet count
Definition
Normal blood contains 150,000 to 400,000 platelets/µL
Term
What do platelets do?
Definition
Platelets help stop blood loss from damaged blood vessels by forming a platelet plug, and their granules also contain substances which aid in clot formation
Term
Platelet Life span
Definition
Platelets have a life span of only 5 to 9 days; aged and dead platelets are removed by fixed macrophages in the spleen and liver.
Term
Complete Blood Count (CBC)
Definition
Screens for anemia and infection
Total RBC, WBC & platelet counts per µL of whole blood; differential WBC; and hematocrit
The amount of hemoglobin in grams per mL is also determined.
Term
Normal hemoglobin range
Definition
infants = 14 to 20 g/100mL of blood adult females = 12 to 16 g/100mL of blood adult males = 13.5 to 18g/100mL of blood
Term
[image]
Definition
Term
Stem cell transplant from bone marrow
Definition
Bone marrow transplant replaces diseased red marrow with healthy red marrow in order to establish normal blood cell counts.
Patient’s diseased marrow is destroyed by high doses of chemotherapy or full body radiation just before the transplant.
Healthy marrow is supplied by a donor or the patient when the disease is inactive Marrow is removed from the iliac crest with a syringe, and injected into the recipient’s vein. The injected marrow migrates to the recipient’s red bone marrow cavities, the stem cells in the marrow multiple and the recipient’s diseased marrow is replaced entirely with health marrow
Term
Bone Marrow Problems
Definition
patient’s WBC are destroyed and he is now susceptible to infection
donor marrow may produce T cells that attack recipient’s tissue (graft-versus-host disease)
if any of the recipient’s cells survived chemo/radiation, they can attack the donor marrow recipient must take immunosuppressive drugs for life, which increase the risk of infection, and have bad side effects
Term
Cord blood transplant
Definition
Stem cells are taken from the umbilical cord shortly after birth and frozen
Term
Hemostatis
Definition
a sequence of responses that stops bleeding
quick response and carefully controlled
three mechanism reduce blood loss:
vascular spasm
platelet plug formation
coagulation (blood clotting)
prevents hemorrhage, the loss of a large amount of blood from the vessels.
Term
Vascular Spasm
Definition
Damage to blood vessel produces contraction of SMC.
Can reduce blood loss for several hours until other mechanisms can take over
Probably caused by damage to the SMC, by substances released from activated platelets, and by reflexes initiated by pain receptors
Only for small blood vessel or arteriole
Term
Platelet Plug Formation
Definition
Platelets store a lot of substances in granules needed for platelet plug formation: clotting factors, platelet-derived growth factor (cause proliferation of vascular EC, SM fibers & fibroblasts to repair damaged vessels), and ADP, ATP, Ca2+, serotonin, fibrin-stabilizing factor, & enzymes that produce thromboxane (TBX) A2, lysosomes, and glycogen.

Steps in the process
(1) platelet adhesion
(2) platelet release reaction
(3) platelet aggregation
initially the platelet plug is loose, but then tightens when reinforced by fibrin threads formed during clotting.
Term
Step 1 in Platelet Plug Formation:
Platelet Adhesion
Definition
Platelets stick to parts of a damaged bv, such as collagen fibers of connective tissue underlying the damaged EC
Term
Step 2 in Platelet Plug Formation:
Platelet Release Reaction
Definition
Platelets activated by adhesion.
Extend projections to make contact with each other and begin to release the contents of their vesicles.
Liberated thromboxane A2 & ADP activate nearby platelets.
Serotonin & thromboxane A2 are vasoconstrictors, which decrease blood flow through the injured vessel.
Term
Step 3 in Platelet Plug Formation:
Platelet Aggregation
Definition
Activated platelets stick together and activate new platelets to form a mass called a platelet plug.
Plug reinforced by fibrin threads formed during clotting process
Term
Blood Clotting
Definition
Blood remains liquid as long as it is contained in vessels, but if it is drawn from the body it will form a gel.
Eventually the gel (clot) separates from the straw-colored liquid (serum).
A clot consists of a network of insoluble protein fibers (fibrin) in which formed elements of blood are trapped.
Clotting or coagulation is a series of chemical reactions that culminates in formation of fibrin threads.
If blood clots too easily, the result is thrombosis (clotting in an undamaged vessel); if blood takes too long to clot, hemorrhage can occur
Term
Substances involved in Clotting
Definition
The substances involved in clotting are known as coagulation (clotting) factors, and include Ca2+, enzymes, and platelet-associated molecules
Term
Clotting Stages
Definition
Clotting can be divided into three
1. formation of prothrombinase (prothrombin activator)
2. conversion of prothrombin into thrombin
3. conversion of soluble fibrinogen into insoluble fibrin
Term
Extrinsic Pathway of Blood Clotting
Definition
Occurs rapidly- within seconds.
Damaged tissues leak tissue factor (TF; thromboplastin) into bloodstream.
Prothrombinase forms in seconds.
TF is a mixture of lipoproteins and phospholipids released from the surface of damaged cells
In the presence of Ca+2, TF begins a sequence that activates clotting factor X, which when activated, combines with factor V to form prothrombinase
Term
Intrinsic Pathway Blood Clotting
Definition
Occurs more slowly- requiring several minutes
Activation occurs when:
-endothelium is damaged & platelets come in contact with collagen of blood vessel wall
-trauma to EC cause platelet damage & release of phospholipids
Contact with collagen fibers (or glass of collecting tube) activates factor XII, which begins a series of reactions and eventually activates factor X
Platelet phospholipid and Ca+2 can also participate in activation of factor X
Active factor X combines with factor V to form prothrombinase
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