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Exercise 34
Blood
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Composition of Blood
Blood is sticky
 Color varies from scarlet to dark red
 The pH of blood is 7.35–7.45
 Temperature is 38C
 Average volume: 5–6 L for males, and
4–5 L for females

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Composition of Blood
It is composed of liquid plasma and formed
elements
 Formed elements include:

Erythrocytes, or red blood cells (RBCs)
 Leukocytes, or white blood cells (WBCs)
 Platelets

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Blood Plasma - Matrix

Blood plasma contains over 100
solutes, including:
Water – 90%
 Proteins – albumin, globulins, clotting
proteins, and others
 Organic nutrients – glucose,
carbohydrates, amino acids
 Electrolytes – sodium, potassium,
calcium, chloride, bicarbonate
 Respiratory gases – oxygen and
carbon dioxide

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Components of Whole Blood
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Figure 17.1
Erythrocytes (RBCs)
Biconcave discs, anucleate,
essentially no organelles
 Filled with hemoglobin (Hb), a protein
that functions in gas transport
 Red or pink
 4.5million to 5.0 million cells/mm3
 Life span – 100 to 120 days

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Erythrocytes (RBCs)
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Figure 17.3
Components of Whole Blood
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Figure 17.2
Leukocytes (WBCs)
4000-11000 cells/mm3
 Nucleated
 Diapedesis
 Divided into 2 groups:


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Granulocytes and agranulocytes
Granulocytes

Granulocytes – neutrophils,
eosinophils, and basophils
Contain cytoplasmic granules that
stain specifically (acidic, basic, or
both) with Wright’s stain
 Are larger and usually shorter-lived
than RBCs
 Have lobed nuclei

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Neutrophils

Neutrophils have two types of
granules that:
Take up both acidic and basic dyes
 Give the cytoplasm a lilac color

Neutrophils are our first body’s
defense
 Increase in bacterial infections
 40% - 70% of all WBCs
 Nucleus with 3 to 7 lobes
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
Eosinophils

Eosinophils account for 1–4% of WBCs
Have red-staining, bilobed nuclei
connected via a broad band of nuclear
material
 Have red to crimson (acidophilic) large,
coarse, lysosome-like granules
 Lead the body’s counterattack against
parasitic worms. Increased in allergic
patients
 Lessen the severity of allergies by
phagocytizing
immune
complexes
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
Basophils

Account for 0.5% of WBCs and:
Have U- or S-shaped nuclei with two
or three conspicuous constrictions
 Are functionally similar to mast cells
 Have large, purplish-black (basophilic)
granules that contain histamine.
 Mediates inflammatory reactions

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Agranulocytes

Agranulocytes – lymphocytes and
monocytes:
Lack visible cytoplasmic granules
 Are similar structurally, but are
functionally distinct and unrelated cell
types
 Have spherical (lymphocytes) or
kidney-shaped (monocytes) nuclei

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Lymphocytes

Account for 25% or more of WBCs and:
Have large, dark-purple, circular nuclei with a
thin rim of blue cytoplasm
 Responsible for immunologic responses
 Smallest type of leukocytes


There are two types of lymphocytes: T cells
and B cells
T cells function in the immune response
 B cells produce antibodies

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Monocytes

Monocytes account for 4–8% of leukocytes
They are the largest leukocytes
 They have abundant pale-blue cytoplasms
 They have purple-staining, U- or kidneyshaped nuclei
 They leave the circulation, enter tissue, and
differentiate into macrophages
 Increases in chronic infections

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Leukocytes
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Figure 17.10
Platelets




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Platelets are fragments of megakaryocytes
with a blue-purple color
Irregular shape
250,000 - 500,000/mm3
Platelets function in the clotting mechanism
by forming a temporary plug that helps seal
breaks in blood vessels
Hematologic Tests

Total WBCs count
Leukocytosis
 Leukopenia
 Leukemia


Total RBCs count
Polycythemia
 Anemia

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Hematologic Tests
Differential WBCs count
 Hematocrit or packed cell volume (PVC)

Obtained by centrifuging the whole
blood
 Normal male: 47
 Normal female: 42


Hemoglobin concentration
Male normal value: 13-18g/100ml of
blood
 Female normal value: 12-16g/100ml of
20 blood

Hematologic Tests

Sedimentation rate
It is the speed at which RBCs settle to
the bottom of a vertical tube
 Adult normal value: 0 to 6 mm/hr
 It is increased in anemia, infections,
tissue necrosis, pregnancy
 It is decreased in polycythemia

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Hematologic Tests

Bleeding time
Measurement of how long a bleeding
lasts
 It tests the health of the platelets
 Normal rate: 0 to 5 minutes (or 2 to 7)
depending on the method used


Coagulation time
Normal value:2 to 6 minutes
 It tests the coagulation factors

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Hematologic Tests – blood
typing
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
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Blood Groups
The antigens of the ABO and Rh blood
groups cause vigorous transfusion
reactions when they are improperly
transfused
 Other blood groups (M, N, Dufy, Kell, and
Lewis) are mainly used for legalities
 Antibodies are also called agglutinins

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ABO Blood Groups
The ABO blood groups consists of:
 Type A blood:

Has antigens A on the surface of their
RBCs
 Has antibodies anti-B in their plasma


Type B blood:
Has antigens B on the surface of their
RBCs
 Has antibodies anti-A in their plasma

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ABO Blood Groups

Type AB blood:
Has both A and B antigens on the
surface of their RBCs
 Has no antibodies in their plasma


Type O blood:
Has no antigens on the surface of their
RBCs
 Has anti-A and anti-B in their plasma

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ABO Blood Groups
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Table 17.4
Rh Blood Groups
There are eight different Rh agglutinogens,
three of which (C, D, and E) are common
 Presence of the Rh agglutinogens on RBCs is
indicated as Rh+
 Anti-Rh antibodies are not spontaneously
formed 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

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Blood Typing
When serum containing anti-A or anti-B
agglutinins is added to blood,
agglutination will occur between the
agglutinin and the corresponding
agglutinogens
 Positive reactions indicate agglutination

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Blood Typing
Blood type being
tested
RBC agglutinogens
Serum Reaction
Anti-A
Anti-B
AB
A and B
+
+
B
B
–
+
A
A
+
–
O
None
–
–
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