1. Chapter 17 – Blood

2. Functions of blood Transportation/distribution Regulation/homeostasis
Oxygen, carbon dioxide, nutrients, waste products, hormones
Regulation/homeostasis
Body temperature, pH, fluid volume
Protection
Clotting
Fights infection

3. Blood Classified as connective tissue Color pH Volume
Large extracellular matrix (plasma) approx 55%
Formed elements approx 45%
Color
Due to hemoglobin in red blood cells
Bright red = oxygen-rich; dark brick red = oxygen-poor pH
Slightly alkaline 7.35 – 7.45
Volume
Approx 8% of body weight
Males – 5-6 L
Females – 4-5 L

4. Whole blood composition

5. Formed elements
Are created in red bone marrow (hematopoiesis or hemopoiesis) from stem cells
Erythrocytes (red blood cells)
Leukocytes (white blood cells)
Only type that are true cells
Thrombocytes (platelets)

6. Erythrocyte structure
Biconcave discs
Allows for rapid gas diffusion
Anucleate and no organelles
Packed with hemoglobin

7. Hemoglobin structure 4 polypeptide chains (2 alpha and 2 beta chains)
Each chain has an associated heme group
Each heme group has a central iron atom
Serves as the binding site for oxygen molecule

8. Gas exchange In lungs In body tissues
Oxygen diffuses from air sacs in lungs into blood and binds with iron in hemoglobin
Oxyhemoglobin – bright red
In body tissues
Oxygen detaches from iron to diffuse out of bloodstream
Deoxyhemoglobin – dark red
Hemoglobin also carries about 20% of carbon dioxide
Carbaminohemoglobin
CO2 binds to amino acids of globin chains

9. Erythrocyte production
Red bone marrow
Large capillaries (blood sinusoids)
Cells
Immature blood cells
Marcophages – consume debris/foreign cells
Hemocytoblast
Ability to become any bloodcell type
Once ‘committed’ it can not change pathway
Pathway
Color of cell changes from blue to pink as hemoglobin accumulates
Reticulocytes
Speckled appearance due to clumped ribosomes
In circulation approx 2 days before forming mature RBC
1 – 2% of RBC count; indicates rate of RBC production

10. Regulation of RBC production
Erythropoietin (EPO)
Hormone produced by (mainly) kidneys and liver
Stimulates RBC production in response to low blood oxygen levels
Also in response to testosterone
Commerically available for kidney failure patients
EPO increases hematocrit (measure of % of RBCs in whole blood)
Has been abused by athletes

11. Blood Typing Antigens or agglutinogens Antibodies or agglutinins
Glycoproteins on the surface of RBCs that serve as identification
Antibodies or agglutinins
Will attack foreign antigens
Causes agglutination, or clumping
Small vessels can become blocked
Leads to cell destruction
Free hemoglobin in kidneys can result in acute renal failure
ABO and Rh can cause severe reactions if mismatched during a blood transfusion

12. ABO blood types

13. Rh factor + has the Rh antigen; - does not
Rh – individuals do not have preformed antibodies against the Rh factor
Must have an exposure to the antigen in order to form antibodies against it
Rh- woman
Risk of erythroblastosis fetalis
Given Rogam during pregnancy

14. Erythroblastosis fetalis

15. Leukocytes Involved with immunity
Diapedesis – WBCs can leave bloodstream and enter the lymphatic system and loose connective tissue
Amoeboid movement
Types
Granulocytes – cytoplasm contains obvious granules
Neutrophil
Eosinophil
Basophil
Angranulocytes – cytoplasm does not contain granules
Monocyte
Lymphocyte

16. Granulocytes Neutrophil Eosinophil Basophil Nucleus is multilobed
Also called polymorphonuclear leukocytes (PMNs)
Phagocytize bacteria
Eosinophil
Fight parasites that are too large for phagocytosis
Release enzymes that digest parasite
Basophil
Histamine – allergic reactions
Vasodilator; attracts other WBCs
Heparin – antocoagulant

17. Agranulocytes Monocytes Lymphocytes
Enters tissues to become macrophages
Fight viral infections, chronic infections, bacterial-infected cells
Lymphocytes
Most are located within the lymphatic system
T cells
Destroy infected cells and tumor cells
B cells
Plasma cells produce antibodies
Fight ‘free’ infectious agents (haven’t entered a cell yet)

18. Leukocyte production Relative amount of WBCS
“Never Let Mom Eat Beans”
Lifespan = less than 10 days
Stem cell lines
Hemocytoblast differentiates into either:
Lymphoid stem cell line
Develops into lymphocytes
Myeloid stem cell line
Develops into all formed elements of blood except lymphocytes

19. Thrombocyte (platelet) production
Stimulated by thrombopoietin (produced by kidneys)
Megakaryocyte is formed by mitosis without cytokinesis
Megakaryocyte presses against sinusoid wall and extends cytoplasmic branches through walls into bloodstream
Break off to form platelets

20. Hemostasis Hemostasis – stopping of bleeding 3 stages Clot retraction
Vascular
Vascular spasm
Endothelial damage exposes underlying collagen
Smooth muscle contraction; endothelium becomes sticky
Platelet
Platelets adhere to endothelium and each other to form a plug
Coagulation
Clotting cascade ultimately forms fibers
Clot retraction
Platelets contract – brings damaged regions closer together for repair

22. Fibrinolysis Clot dissolution Plasminogen converts to plasmin
Plasminogen trapped in clot
Slow conversion
Digests fibrin strands

23. Abnormal values Red blood cells White blood cells Platelets
Anemia - low
Iron insufficiency, blood loss, kidney disease, bone marrow disorder
Polycythemia – elevated
Bone marrow disorder, dehydration
White blood cells
Leukopenia – low
Bone marrow disorder
Leukocytosis – elevated
Infection, inflammation, bone marrow disorder
Platelets
Thrombocytopenia – low
Excessive destruction or inadequate production
Thrombocytosis – elevated
Infection, inflammation, cancer