Blood is composed of plasma and formed elements including red blood cells, white blood cells, and platelets. Red blood cells carry oxygen and carbon dioxide throughout the body. White blood cells help protect the body from infection and disease. Platelets are cell fragments that help form blood clots to stop bleeding. Careful matching of blood types is important for safe transfusions, as incompatible blood can cause a dangerous immune response.

1. Blood
Chapter 18

2. Blood Composition and Function
Components
• Blood is the only fluid tissue in the
body
• Has both cellular and liquid
components
• Blood cells, or formed elements, are
suspended in a nonliving fluid matrix
called plasma

3. What is in a blood sample?
• Erythrocytes – red blood cells (about 45% of
blood)
• Buffy coat – thin, white layer present at
erythrocyte-plasma junction
• Leukocytes – white blood cells that protect
body (less than 1% of blood)
• Platelets – cell fragments (less than 1% of
blood)
• Plasma – fluid portion of blood (remaining
55% of blood)

4. Physical Characteristics and
Volume
• Blood is sticky and has a metallic
(salty) taste.
• Blood is scarlet with large oxygen
content and dark red/violet with poor
oxygen content.
• Blood accounts for 8% of body weight.
– Healthy males have 5-6 L
– Healthy females have 4-5 L

5. Blood Functions

6. Distribution
1. Delivering oxygen from the lungs and
nutrients from the digestive tract.
2. Transporting metabolic waste
products from cells to elimination
sites.
3. Transporting hormones from the
endocrine organs to their target
organs.

7. Regulation
1. Maintaining appropriate body
temperature.
2. Maintaining normal pH in body
tissues.
3. Maintaining adequate fluid volume in
the circulatory system.

8. Protection
1. Preventing blood loss
2. Preventing infection

9. Blood Plasma
• Yellow, sticky fluid
• Made mostly from water
• Contains over 100 different dissolved
solutes
• Contains many proteins
– Albumin is the protein with greatest
volume
• Carries certain molecules through circulation
• Blood buffer

10. Blood Plasma (con’t)
• Content continuously changes by
adding/removing substances
• Also distributes heat throughout the
body

11. Formed ElementsElements

12. 3 Unusual Features of Formed
Elements:
1. Only one cell is a true cell
(leukocytes)
2. More formed elements only survive
for a few days
3. Blood cells do not divide

13. AKA
Red Blood Cells

14. Red Blood Cells
(RBC’s)
• Small, flattened discs with depressed
centers
• Basically, little “bags” or hemoglobin
(Hb – the RBC protein that aids in gas
transport)
• Pick up oxygen in the capillary bed of
the lungs and releases it to tissue cells
across the capillaries throughout the
body.
• Transport ~20% of the carbon dioxide
by tissue cells back to the lungs.

15. RBC’s (con’t)
• Spectrin, RBC protein, allows the RBC
to bend and change shape to move
through blood vessels and capillaries.
• Women typically have a lower RBC
count than men.
• Thickness of the blood is affected by
the # of RBC’s. (thicker = more RBC’s)

16. RBC’s (con’t)
• Hemoglobin serves as the molecule for
gas transport.
– 1 hemoglobin molecule can transport 4
oxygen molecules at a time.
• Blood cells are made by hematopoiesis
in the red blood marrow.

18. Anemia
A condition in which the blood
has an abnormally low oxygen-
carry capacity.
It is not a disease, but a
symptom of a disease.

19. Causes of anemia:
1. An insufficient # of RBC’s
• Hemorrhagic anemias result from rapid
blood loss. Usually treated with
transfusion.
• Hemolytic anemias result from RBC’s
that rupture prematurely. It is caused by
hemoglobin abnormalities, bad blood
transfusion, or infection.
• Aplastic anemia results from destruction
or inhibition of the red marrow by
bacterial toxins, drugs, or radiation.

20. Causes (con’t)
2. Decreased hemoglobin content
• Iron-deficiency anemia is generally a secondary
result of hemorrhagic anemias, but it can be
from an inadequate intake of iron-rich foods.
• Athlete’s anemia occurs when athletes exercise
vigorously, expanding their blood volume by as
much as 15%, diluting the blood. Converts back
within a day or so.
• Pernicious anemia is caused by a deficiency of
vitamin B12, which is provided by meats,
poultry and fish.

21. Causes (con’t)
3. Abnormal hemoglobin
• Thalassemias are typically seen in people of the
Mediterranean ancestry (Italians and Greeks).
RBC’s are thin, delicate, and deficient in
hemoglobin.
• Sickle-cell anemia is caused by an abnormal
hemoglobin molecule which causes the RBC’s
to become crescent shaped. The standard
treatment is blood transfusion. Occurs chiefly
in black people who live in the malaria belt of
Africa and among their descendants.

22. Polycythemia
• Abnormal excess of erythrocytes that
increase blood thickness
• Treated by blood dilution
• “Blood Doping”
– Artificially induced polycythemia
– Practice of drawing off RBC’s and
reinserting them later.
– Used by athlete’s to increase blood’s
oxygen-carrying capacity

23. AKA
White Blood Cells

24. White Blood Cells
(WBC’s)
• Only formed element that is a true cell
• Critical to our defense system
• Protects the body from bacteria,
viruses, parasites, toxins, and tumor
cells
• Slip in and out of capillaries through a
process called diapedesis.
– WBC’s follow a signal
– Go to the area of damage and infection to
destroy foreign substances or dead cells

25. WBC’s (con’t)
• When mobilized, body speeds up WBC
production, doubling the # in the blood.
– When WBC count goes over 11,000 cells
per mL, this is called leukocytosis.

26. Leukocytes are grouped into 2
categories:
1. Granulocytes
- Contain specialized membrane-bound
cytoplasmic granules
2. Agranulocytes
- Lack obvious granules

27. Granulocytes
•Spherical in shape
•Phagocytes

28. Neutrophils
• Most numerous of the WBC’s - ~ ½ of
the population
• Chemically attracted to inflammation
• Phagocytize bacteria and fungi
• The body’s “bacteria slayers”;
numbers increase during bacterial
infections

29. Eosinophils
• Filled with digestive enzymes
• Lead the attack against parasitic
worms
• Found in intestinal or respiratory
mucosae
• Tend to “hang out” where parasitic
worms may enter

30. Basophils
• Rarest WBC
• Cytoplasm contains histamine-
containing granules
– Histamine is an inflammatory chemical
that acts as a vasodilator and attracts
other WBC’s.

31. Agranulocytes
•Lack visible granules

32. Lymphocytes
• 2nd
most numerous leukocyte
• Large amounts in body; however, small
amounts in blood
• Found in lymphoid tissue (lymph nodes,
spleen, etc.)
• T lymphocytes (T cells) act against virus-
infected cells and tumor cells.
• B lymphocytes (B cells) make plasma cells,
producing antibodies that are released into
the blood.

33. Monocytes
• Largest leukocytes
• Phagocytic and increase in numbers
when active
• Defend against viruses and parasites

34. Leukocyte Disorders

35. Leukemia
• Group of cancerous conditions involving
blood cells
• Without treatment, all are fatal
• Immature WBC’s flood into bloodstream
• Bone marrow becomes totally occupied by
cancerous leukocytes
• Because healthy blood cells are crowded out,
anemia and bleeding disorders occur.

36. Leukemia (con’t)
• Symptoms include fever, weight loss,
and bone pain.
• Most common causes of death are
internal bleeding and infections.
• Treatments include radiation and
antileukemic drugs to destroy cancer
cells.
• Bone marrow transplants are used in
selected patients.

37. Mononucleosis
• Called the “kissing disease”
• Highly contagious viral disease seen in
children and young adults
• Caused by the Epstein-Barr virus
• Symptoms include feeling tired and
achy, sore throat, and a low-grade
fever.
• No cure  must run its course!!

38. Platelets
Are not cells, only fragments,
sometimes called
thrombocytes.

39. Platelets
• Essential for clotting when blood
vessels are injured
• Stick to the damaged site, forming a
temporary plug to seal break
• Quickly degenerate because they have
no nucleus

40. Hemostasis
• Stopping of bleeding
• “Plug the Hole” defensive reaction
• Three main phases…

41. Phases of Hemostasis
1. Vascular Spasms
• Immediate response  constrict blood vessel
• Chemicals released cause vasoconstriction
2. Platelet Plug Formation
• Temporary plug formed to seal break
• Positive feedback mechanism increases the
numbers of platelets to the site to build the plug
3. Coagulation
• Blood turns from liquid to gel
• Multistep process that requires 30 different
substances

42. Bleeding Disorders
Anything that interferes with
the clotting mechanism can
result in abnormal bleeding.

43. Thrombocytopenia
• A condition in which the # platelets is
deficient
• Causes spontaneous bleeding from blood
vessels all over the body
• Even normal movement can cause
hemorrhages (petechiae = small purple
blotches)
• Arises from any condition that suppresses or
destroys the bone marrow
• Blood transfusions give temporary relief

44. Impaired Liver Function
• Several different hereditary bleeding
disorders
• Sex-linked genetic disorder
• Primarily in males
• Lack clotting mechanisms in the blood
• Causes prolonged bleeding with even
minor cuts
• Must receive transfusion or injections
of clotting factors.

45. Transfusions of Whole Blood
• The human cardiovascular system is
designed to minimize the effects of
blood loss by:
1. reducing the volume of affected blood
vessels, which helps to maintain normal
circulation, and
2. stepping up the production of RBC’s.

46. Transfusions (con’t)
• A loss of 15-30% of blood causes pallor
and weakness
• More than 30% results in severe shock,
which can be fatal
• Whole blood transfusions are routine
when blood loss is substantial.

47. Human Blood Groups
• People have different blood types and
transfusion of incompatible blood can be
fatal.
• RBC’s membranes have specific antigens on
their external surfaces.
• One person’s RBC proteins may be
recognized as foreign if transfused into
someone with a different RBC types
• The presence or absence of antigens allows
a person’s blood cells to be classified in
several blood types.

48. ABO Blood Groups
• ABO blood groups are based on the
presence or absence of two agglutinogens,
type A and type B
• Depending on a person’s inheritance, his or
her ABO blood group will be one of the
following:
– A
– B
– AB
– O

49. Blood Groups (con’t)
• The O blood group, which had neither
agglutinogens, is most common.
• AB is the least prevalent of the blood
types.
• Presence of either the A or the B
agglutinogen results in group A or B,
respectively.

50. Rh Blood Groups
• There are at least 8 different types of Rh
agglutinogens, called an Rh factor.
• Most people are Rh+, RBC’s carry the Rh antigen.
• If a person receives Rh+ blood, the immune system
becomes sensitized and begins producing anti-Rh
antibodies against the foreign antigen soon after the
transfusion.
• No problems (hemolysis) occurs the 1st
time.
• 2nd
time, however, and every time thereafter will
result in attack and rupture of the donor RBC’s.

51. Rh (con’t)
• An important problem related to the Rh factor
occurs in pregnant Rh- women who are
carrying Rh+ babies.
• 1st
pregnancy will be successful, and will
result in a healthy baby.
• 2nd
pregnancy will result in hemolytic disease
of the newborn. The mother’s anti-Rh
antibodies built up from the 1st
pregnancy will
attack the baby’s RBC’s.
• RhoGAM, a serum containing anti-Rh
agglutinins, is administered.