Download THE PHYSIOLOGY OF BLOOD

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THE PHYSIOLOGY
OF BLOOD
Objectives
1. ERYTHROCYTES
2. ERYTHROCYTE AGGLUTINOGENES,
3. PLASMA AGGLUTININS
4. TRANSFUSION
5. Practical tasks
ERYTHROCYTE COUNT
BLOOD GROUPING
RH FACTOR
CROSSMATCHING TEST
BLOOD
COMPOSITION:
PLASMA
BLOOD CORPUSCULES:
• RED BLOOD CELLS – ERYTHROCYTES
• WHITE BLOOD CELLS –LEUKOCYTES
• PLATELLETS – THROMBOCYTES
FUNCTION:
TRANSPORT – NUTRIENTS, WARMTH, GASSES
PROTECTION- BLOOD LOSS, ILLNESS,
ERYTHROCYTES - RBC
Function: transport of oxygen in the blood.
Shape: biconcaved discs.
(This shape increases the surface area-to-volume ratio of the cell,
thus increasing the efficiency of diffusion of oxygen and carbon dioxide)
Fexible plasma membrane
(This feature allows erythrocytes to squeeze
through capillaries)
No nucleus, no other organelles
in the mature Erythrocyte
(to have more room for hemoglobin – carries oxygen)
Limited life span of about 120 days.
The removal of old and dying erythrocytes is
carried out by the spleen.
NORMOCYTE
ERYTHROPOESIS
The process of Ery formation
(tibia, femur…ribs, sternum, vertebra)
The kidney monitors the
level of oxygen in the blood.
Erythropoetin is secreted in decreased
oxygenation.
(90% kidneys, 10% liver)
All cells are exposed to erythropoetin,
but only red bone marrow cells,
respond to the hormone.
Erythropoetin stimulates the production of erythrocytes in the bone marrow.
Erythropoetin induces the differentiation of the erythropoetic cells
As the erythrocyte population increases, The oxygen carrying capacity of the
blood increases, kidney responds by slowing the secretion of erythropoetin.
This negative feedback loop ensures that the size of the erythrocyte
population remains relatively constant and that the oxygen carrying capacity
of the blood is always sufficient to meet the needs of the body.
ERYTHROPOESIS
STEM CELL
1% in blood
Takes 1-2 days
To mature
NORMOCYTE
Most of the erythrocytes are of normal size and shape:
Diameter: 7.5 micrometers
Width: 1.9 micrometers
Volume: 83 cubic micrometers
Those are called NORMOCYTES
Erythrocytes having in diameter less than 7 micrometers are called MICROCYTES
Erythrocytes having in diameter more than 8.5 micrometers are called MACROCYTES
In normal blood there is a distribution of erythrocytes of different size some 10 % of
them are less than 6, some 5 % are more than 8.5
WE CALL THIS DISTRIBUTION
PHYSIOLOGICAL ANISOCYTOSIS
Normal erythrocyte count:
For women: 4,2 .10 12 per Liter of blood (+ - 0.3 .10 12 per Liter)
For men: 5,2 .10 12 per Liter of blood (+- 0.3. 10 12 per Liter)
ANEMIA, POLYCYTEMIA
ANEMIA
Causes of Anemia
characterized by either low hemoglobin, low hematocrit, or both.
The causes of anemia include:
Dietary deficiencies of iron, vitamin B12 or folic acid.
Hemorrhage
Hemolysis
Bone marrow failure
Kidney disease
Dietary deficiencies
Iron is required for the production and function of hemoglobin.
In the absence of adequate iron, hemoglobin production slows down.
Low hemoglobin can lower the hematocrit.
Vitamin B12 and Folic Acid are required for DNA synthesis prior to cell division.
In the absence of these nutrients production of erythrocytes is reduced.
The hematocrit is low and many erythrocytes are huge, fragile cells called macroblasts.
B12 deficiency can be caused by a lack of intrinsic factor, this
is called pernicious anemia. Intrinsic factor, which is produced in the stomach,
is required for efficient absorption of B12 out of the small intestine and into the blood.
SYMPTOMS OF ANEMIA
Fatigue - particularly with exercise.
Oxygen is required to metabolize fuel molecules (sugars, fats and proteins)
to obtain energy. A person with a low hematocrit cannot carry enough oxygen
in the blood to meet their energy demands.
Increased heart rate. The body increases heart rate to compensate for the low
oxygen carrying capacity of the blood.
If more blood is moved faster through the tissue then tissues
get more oxygen per unit time – hyperkinetic circulation.
Shortness of breath – faster breathing - tachypnea
This is a compensation for the poor delivery
of oxygen to the tissues.
Low blood pressure. The viscosity of the blood drops as the hematocrit decreases.
A decrease in blood viscosity directly lowers total peripheral resistance (TPA)
to the flow of blood, thus lowering mean arterial blood pressure (MAP).
Pale Skin. Hemoglobin is bright red when oxygenated and less red when deoxygenated.
Because the redness of skin is due to the redness of blood,
the skin of an anemic person is less red than the average person.
BLOOD TYPING
Blood groups – A,B,AB,O
(according of the presence of antigens)
Antigens - agglutinogens
Antibodies / agglutinins
FENOTYPE vs GENOTYPE
BLOOD TYPE DISTRIBUTION
According to race: in percentage
A
B
O
AB
WHITE 41
10
45
4
Yellow
28
23
36
13
Red
3
Black
28
97
20
47
5
BLOOD TYPING
COMPATIBLE BLOOD
NO AGGLUTINATION
INCOMPATIBLE BLOOD
AGGLUTINATION
AND
HEMOLYSIS
(IMMUNOLOGICAL
HEMOLYSIS)
Erythroblastosis fetalis in Rh
incompatibility
1st pregnancy – Rh+ Ery of a child pass to
mother´s blood. Mother develops antibodies
2nd pregnancy – mother´s antibodies
Hemolyse the child´s Rh+ Ery
Causing anemia that leads to
Fetal erythroblastosis – production of
unmatured Ery
HEMOLYTIC NEWBORN
DISEASE
1. Anemia
2. Fetal erythroblastosis