1. Functions of Blood Blood performs a number of functions:
Substance distribution
Regulation of blood levels of particular substances
Body protection

2. Blood Functions: Distribution
Blood transports:
Oxygen from the lungs and nutrients from the digestive tract
Metabolic wastes from cells to the lungs and kidneys for elimination
Hormones from endocrine glands to target organs

3. Blood Functions: Regulation
Blood maintains:
Appropriate body temperature by absorbing and distributing heat to other parts of the body
Normal pH in body tissues
Adequate fluid volume in the circulatory system

4. Blood Functions: Protection
Blood prevents blood loss by:
Activating plasma proteins and platelets
Initiating clot formation when a vessel is broken
Blood prevents infection by:
Synthesizing and utilizing antibodies
Activating complement proteins & WBCs to defend the body against foreign invaders

5. Physical Characteristics of Blood
Average volume:
5–6 L for males; 4–5 L for females
The pH is 7.35–7.45
Accounts for approximately 8% of body weight

6. Composition of Blood
Blood is the body’s only fluid tissue (a connective tissue)
2 major components
Liquid = plasma (55%)
Formed elements (45%)
Erythrocytes, or red blood cells (RBCs)
Leukocytes, or white blood cells (WBCs)
Platelets – cell fragments

7. Components of Whole Blood
Plasma (55% of whole blood)
Buffy coat: leukocyctes and platelets (<1% of whole blood)
Formed elements
Erythrocytes (45% of whole blood) 1
Withdraw blood and place in tube 2
Centrifuge

8. Blood Plasma Blood plasma components: Water = 90-92% Proteins = 6-8%
Albumins-maintain osmotic pressure of the blood
Globulins-used for transport purposes
Fibrinogen-a clotting protein
Organic nutrients – glucose, carbohydrates, amino acids
Electrolytes – sodium, potassium, calcium, chloride, bicarbonate
Non-protein nitrogenous substances – lactic acid, urea, creatine
Respiratory gases – oxygen and carbon dioxide

9. Formed Elements
Only WBCs are complete cells
RBCs have no nuclei or organelles, and platelets are just cell fragments
Most F.E. survive in the bloodstream for only a few days
Most do not divide but are renewed by cells in bone marrow

10. Erythrocytes (RBCs) Biconcave disc
Folding increases surface area (30% more surface area)
Anucleate, no centrioles, no organelles
End result - no cell division
No mitochondria means they generate ATP anaerobically
Prevents consumption of O2 being transported
Filled with hemoglobin (Hb) - 97% of cell contents
Hb functions in gas transport
Most numerous of the formed elements

11. Erythrocyte Function
Erythrocytes are dedicated to respiratory gas transport
Hemoglobin reversibly binds with oxygen and most oxygen in the blood is bound to hemoglobin
Composition of hemoglobin
A protein called globin
A heme molecule
Each heme group bears an atom of iron, which can bind to one oxygen molecule

12. Production of Erythrocytes
Hematopoiesis – blood cell formation
Occurs in the red bone marrow
Axial skeleton and girdles
Epiphyses of the humerus and femur
Marrow contains immature erythrocytes

13. Erythrocyte Disorders
Anemia – blood has abnormally low oxygen-carrying capacity
Blood oxygen levels cannot support normal metabolism
Signs/symptoms include fatigue, paleness, shortness of breath, and chills
It is a symptom rather than a disease itself

14. Leukocytes (WBCs) Protect the body from infectious microorganisms
Can leave capillaries
Move through tissue spaces
Many are phagocytic
Two major types of leukocytes
Granulocytes: Neutrophils, Eosinophils, Basophils
Agranulocytes: Monocytes, Lymphyocytes
Leukemia - a cancer of WBC

15. Granulocytes
Contain cytoplasmic granules that stain specifically with Wright’s stain
Are larger and usually shorter-lived than RBCs
Have lobed nuclei
Are all phagocytic cells

16. Granulocytes: Neutrophils
Account for 65-75% of total WBC’s
Neutrophils have two types of granules that:
Contain peroxidases, hydrolytic enzymes, and defensins (antibiotic-like proteins)
Neutrophils are our body’s bacteria slayers

17. Granulocytes: Eosinophils
Eosinophils account for 1–4% of WBCs
Function:
Lead the body’s counterattack against parasitic infections
Lessen the severity of allergies by phagocytizing immune complexes (ending allergic reactions)

18. Granulocytes: Basophils
Account for 0.5-1% of all WBCs
Have large, purplish-black granules that contain histamine
Histamine – inflammatory chemical that acts as a vasodilator and attracts other WBCs (antihistamines counter this effect)

19. Agranulocytes: Lymphocytes
Account for 20-25% or more of WBCs and:
Are found mostly enmeshed in lymphoid tissue (some circulate in the blood)
Most important cells of the immune system
Involved in graph rejection, fighting tumors and viruses
There are two types of lymphocytes: T cells and B cells
T cells - attack foreign cells directly
B cells give rise to plasma cells, which produce antibodies

20. Monocytes Account for 3–7% of leukocytes
They are the largest leukocytes
They have purple-staining, U- or kidney-shaped nuclei
They leave the circulation, enter tissue, and differentiate into macrophages
Increase in # during chronic infections.

21. Platelets Platelets are fragments of megakaryocytes
Platelets function in the clotting mechanism by forming a temporary plug that helps seal breaks in blood vessels.
Platelet

22. Human Blood Groups
RBC membranes have glycoprotein antigens on their external surfaces
These antigens are:
Unique to the individual
Recognized as foreign if transfused into another individual
Promoters of agglutination and are referred to as agglutinogens
Presence or absence of these antigens is used to classify blood groups

23. ABO Blood Groups The ABO blood groups consists of:
Two antigens (A and B) on the surface of the RBCs
Two antibodies in the plasma (anti-A and anti-B)
An individual with ABO blood may have various types of antigens and spontaneously preformed antibodies
Agglutinogens (antigens) and their corresponding antibodies cannot be mixed without serious reactions

24. Group A – has only the A antigen on red cells (and B antibody in the plasma)
Group B – has only the B antigen on red cells (and A antibody in the plasma)
Group AB – has both A and B antigens on red cells (but neither A nor B antibody in the plasma)
Group O – has neither A nor B antigens on red cells (but both A and B antibody are in the plasma)
The universal red cell donor has Type O negative blood type.
The universal plasma donor has Type AB positive blood type.

25. Transfusion Reactions
Transfusion reactions occur when mismatched blood is infused
Donor’s cells are attacked by the recipient’s plasma agglutinins causing:
Diminished oxygen-carrying capacity
Clumped cells that impede blood flow
Ruptured RBCs that release free hemoglobin into the bloodstream
Circulating hemoglobin precipitates in the kidneys and causes renal failure

26. Rh Blood Groups
Presence of the Rh agglutinogens on RBCs is indicated as Rh+; 85% of population is +
Lack of antigen indicated as Rh -; 15% of pop.
Anti-Rh antibodies are not spontaneously formed only in Rh– individuals
However, if an Rh– individual receives Rh+ blood, anti-Rh antibodies form
A second exposure to Rh+ blood will result in a typical transfusion reaction