1. Human Anatomy and Physiology
Blood
Chapter 17

2. Blood Composition Overview
a fluid connective tissue
5–6 L for males, and 4–5 L for females
Plasma
2. Formed elements
Erythrocytes (red blood cells, or RBCs)
Leukocytes (white blood cells, or WBCs)
Platelets

3. • Least dense component • Leukocytes and platelets
Blood Composition 1
Withdraw
blood and place
in tube. 2
Centrifuge the
blood sample.
Plasma
• 55% of whole blood
• Least dense component
Buffy coat
• Leukocytes and platelets
• <1% of whole blood
Erythrocytes
• 45% of whole blood
• Most dense
component
Formed
elements

4. Functions of Blood Distribution Functions
Delivers O2 and nutrients to body cells
Removes metabolic wastes to the lungs and kidneys for elimination
Transports hormones from endocrine organs to target organs

5. Functions of Blood Regulatory Functions
Maintains body temperature by absorbing and distributing heat
Maintains normal blood pH using buffers
Maintains adequate fluid volume in the circulatory system

6. Functions of Blood Protective Functions Hemostasis Prevents Infections
Protects against blood loss
Plasma proteins and platelets initiate clot formation
Prevents Infections
Antibodies
Complement proteins
WBCs defend against foreign invaders

7. • Least dense component
Blood Plasma
Straw colored, viscous
90% water
10% solutes
nutrients, gases,
salts, hormones,
proteins
Plasma
• 55% of whole blood
• Least dense component

8. • Least dense component • Leukocytes and platelets
Formed Elements
Most blood cells originate in bone marrow and do not divide
Most formed elements survive in the bloodstream for only a few days
Three classes
Erythrocytes
Leukocytes
Platelets
Plasma
• 55% of whole blood
• Least dense component
Buffy coat
• Leukocytes and platelets
• <1% of whole blood
Erythrocytes
• 45% of whole blood
• Most dense
component
Formed
elements

9. Erythrocytes Red Blood Cells Characteristics Anucleate Hemoglobin (Hb)
Side view (cut)
Top view
Red Blood Cells
Characteristics
Biconcave discs
Anucleate
Hemoglobin (Hb)

10. Erythrocyte Function RBCs are dedicated to respiratory gas transport
Hemoglobin binds reversibly with oxygen
Heme
group
(a) Hemoglobin consists of globin (two
alpha and two beta polypeptide
chains) and four heme groups.
(b) Iron-containing heme pigment.
a Globin chains
b Globin chains

11. Hematopoiesis Blood Cell Formation Hemocytoblasts
Occurs in red bone marrow of axial skeleton, girdles and proximal epiphyses of humerus and femur
Hemocytoblasts
Hematopoietic stem cells
Give rise to all formed elements
Hormones and growth factors push the cell toward a specific pathway of blood cell development

12. Fate and Destruction of Erythrocytes
Life span: 100–120 days
Old RBCs become fragile, and Hb begins to degenerate
Macrophages engulf dying RBCs in the spleen and liver

13. Leukocytes White blood cells (WBCs)
Make up <1% of total blood volume
Can leave capillaries via diapedesis
Move through tissue spaces by ameboid motion and positive chemotaxis
Two classes of leukocytes
1. Granulocytes
2. Agranulocytes
Diapedesis image- neutrophil

14. Differential WBC count (All total 4800 – 10,800/l) Formed elements
Platelets
Leukocytes
Erythrocytes
Differential
WBC count
(All total 4800 –
10,800/l)
Neutrophils (50 – 70%)
Lymphocytes (25 – 45%)
Eosinophils (2 – 4%)
Basophils (0.5 – 1%)
Monocytes (3 – 8%)
Agranulocytes
Granulocytes

15. Granulocytes Characteristics Three types 1. Neutrophils 2. Basophils
Cytoplasmic granules
stain specifically with Wright’s stain
Larger and shorter-lived than RBCs
Lobed nuclei
Phagocytic
Three types
1. Neutrophils
2. Basophils
3. Eosinophils

16. Neutrophils Most numerous WBCs Multi-lobed nuclei
Granules contain hydrolytic enzymes or defensins
Very phagocytic—“bacteria slayers”

17. Eosinophils Red-staining, bilobed nuclei
Red to crimson (acidophilic) coarse, lysosome-like granules
Digest parasitic worms that are too large to be phagocytized

18. Basophils Rarest WBCs (~1 in 100)
Large, purplish-black (basophilic) granules contain histamine
- an inflammatory chemical that acts as a vasodilator and attracts other WBCs to inflamed sites

19. Agranulocytes Lymphocytes and Monocytes
Lack visible cytoplasmic granules
Have spherical or kidney-shaped nuclei

20. Lymphocytes
Large, dark-purple, circular nuclei with a thin rim of blue cytoplasm
Mostly in lymphoid tissue; few circulate in the blood
Crucial to immunity
Two types
B cells
T cells

21. Monocytes The largest leukocytes Kidney-shaped nuclei
Leave circulation, enter tissues, and differentiate into macrophages
Active phagocytic cells
crucial against viruses, intracellular bacterial parasites, and chronic infections
Activate lymphocytes to mount an immune response (APCs)

22. Leukopoiesis Production of WBCs
All leukocytes originate from hemocytoblasts

23. Hemocytoblast
Myeloid stem cell
Lymphoid stem cell
Myeloblast
Monoblast
Lymphoblast
Stem cells
Committed
cells
Promyelocyte
Promonocyte
Prolymphocyte
Eosinophilic
myelocyte
Neutrophilic
Basophilic
band cells
Developmental
pathway
Eosinophils
Neutrophils
Basophils
Granular leukocytes
(a)
(b)
(c)
(d)
(e)
Monocytes
Lymphocytes
Agranular leukocytes
Some become
Some
become

24. Platelets Also called Thrombocytes Small fragments of megakaryocytes
Required for blood clotting

25. Developmental pathway
Thrombopoiesis
Platelet formation
Formation is regulated by thrombopoietin
Stem cell
Developmental pathway
Hemocyto-
blast
Megakaryoblast
Promegakaryocyte
Megakaryocyte
Platelets

27. • Smooth muscle contracts, causing vasoconstriction.
Collagen
fibers
Platelets
Fibrin
Step Vascular spasm
• Smooth muscle contracts,
causing vasoconstriction.
Step Platelet plug
formation
• Injury to lining of vessel
exposes collagen fibers;
platelets adhere.
• Platelets release chemicals
that make nearby platelets
sticky; platelet plug forms.
Step Coagulation
• Fibrin forms a mesh that traps
red blood cells and platelets,
forming the clot. 1 2 3

29. Human Blood Groups
RBC membranes bear 30 types of glycoprotein antigens
Unique to each individual
Perceived as foreign if blood transfusion is mismatched
Presence or absence of each antigen is used to classify blood cells into different groups

30. ABO Blood Groups Types: A, B, AB, and O
Based on the presence or absence of two antigens (A and B) on the surface of the RBCs
Blood may contain anti-A or anti-B antibodies (agglutinins) that act against transfused RBCs with ABO antigens not normally present
Anti-A or anti-B form in the blood at about 2 months of age

31. Rh – and +
Rh – has antibodies and cannot take Rh + blood
Rh + has NO antibodies and can take Rh + or -

33. Transfusion Reactions
Occur if mismatched blood is infused
Donor’s cells are attacked by the recipient’s plasma antibodies
Agglutinate and clog small vessels
Rupture and release free hemoglobin into the bloodstream
Results
Diminished oxygen-carrying capacity
Hemoglobin in kidney tubules and renal failure

34. Erythrocyte Disorders
Anemia: blood has abnormally low O2- carrying capacity
A sign rather than a disease itself
Blood O2 levels cannot support normal metabolism
Accompanied by fatigue, paleness, shortness of breath, and chills

35. Causes of Anemia Abnormal hemoglobin Sickle-cell anemia
Defective gene codes for abnormal hemoglobin (HbS)
Causes RBCs to become sickle shaped in low-oxygen situations

36. Sickle-cell anemia (a) Normal erythrocyte has normal
hemoglobin amino acid sequence
in the beta chain. 1 2 3 4 5 6 7
146
(b) Sickled erythrocyte results from
a single amino acid change in the
beta chain of hemoglobin. 1 2 3 4 5 6 7
146