Blood physiology I.
Blood
• Specialized liquid mesenchymal tissue
• Contains dissolved blood elements in
liquid matrix
Functions of blood
1. transport of dissolved particles/substances
•
•
•
•
gases – e.g. O2 from lungs to tissues
nutritients – from GIT, liver, ...
hormones – from endocrinne glands to
tissues
degradation products – from cells to kidneys
2. regulation of pH and ions
●
hydrogencarbonate, phosphate, heamoglobine, protein
3. prevents liquid/volume to be lost when
injured – coagulation
Functions of blood
4. defence against the toxins and microbes
5. termogenesis
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heat expense through skin, when hot
heat collection and distribution to vital organs
Blood characteristics
• Overall weight – 7 – 8% of body weight
• Overall volume – 4,5 – 6 l
– volemia (normo-, hypo-, hyper-)
• amount of liquids
– hydremia (normo-, hypo-, hyper-)
• amount of water
• pH 7,36–7,44
Composition
Whole blood
elements
plasma
water
proteins
other
eryhtrocytes
leukocytes
thrombocytes
Blood
Plasma
Very similar to
intersticial
fluid!!!
Blood
• Serum
– liquid part of blood, when fibrinogen is
changed to fibrin !!!
Blood collection
• Human
– Veins
• Vena..... ???
• Full blood count (FBC), biochemistry
– Capillaries
• fast glycaemia, AB balance, hematocrite - Hct
– Arteries
• AB balance, biochemistry
Blood collection
• Laboratory animals
– rat, mouse, rabbit
• veins
–
–
–
–
popliteal
suborbital plexus
tail
cannula
• heart
• decapitation
• ixodes ricinus
Blood collection
• Serum or plasma???
• plasma: EDTA, heparin, citrates,
silicons
Practicals
• Hematocrite value
• Erythrocyte sedimentation rate
• Osmotic resistance of erythrocytes
and blood hemolysis
• Determination of blood and plasma
density
Hematocrite - Hct
Whole blood
erythrocytes
Hematocrite
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•
•
•
•
Men: 44 ± 5 %
Women: 39 ± 4%
Newborn: 55%
Gravidity: lower Hct
High altitude: higher Hct
Hematocrite
• anemia (lower number of red blood
cells),
• polycytemia (higher number of red blood
cells),
• Response to the treatment of anemia or
polycytemia – 1 blood transfusion =
increase in Hct by 3%
• dehydratation
• To or not to give transfusion decision
– if else healthy, transfusion is administered
when Hb is lower than 80g/l and Hct lower
than 24%
Erythrocyte sedimentation rate ESR
• ESR determination is a simple laboratory test
• The test measures the distance that erythrocytes
have fallen after one hour in a vertical column of
anticoagulated blood under the influence of gravity.
• Serum proteins play a crucial role in determining
ESR value
• An elevated value remains a nonspecific finding.
• The most satisfactory method of performing the test
was introduced by Westergren in 1921
Gravitational force
ESR - principle
Factors That May Influence ESR
Factors that
increase ESR
Factors that
decrease ESR
Old age
Female
Pregnancy
Anemia
Red blood cell
abnormalities
Macrycytosis
Technical factors
Dilutional problem
Increased temperature
of specimen
Tilted ESR tube
Elevated fibrinogen
level
Infection
Inflammation
Malignancy
Extreme leukocytosis
Polycythemia
Red blood cell
abnormalities
Spherocytosis
Acanthocytosis
Microcytosis
Technical factors
Dilutional problem
Inadequate mixing
Clotting of blood
sample
Short ESR tube
Vibration during testing
Protein abnormalities
Hypofibrinogenemia
Hypogammaglobulinemia
Dysproteinemia with
hyperviscosity state
Reference Ranges for the ESR
Factors with no
in Healthy Adults
clinically
significant effect or
Upper limit of
questionable effect
Obesity
Body temperature
Recent meal
Aspirin
NSAIDs
Adults
reference range
(mm/hr)
Age < 50 years
Men
Women
0 to 15
0 to 20
Age > 50 years
Men
Women
0 to 20
0 to 30
ESR = erythrocyte sedimentation rate.
Information from Bottiger LE, Svedberg CA.
Normal erythrocyte sedimentation rate and
age. Br Med J 1967;2:85-7.
Age (years) + 10 (if women)
NSAIDs = nonsteroidal anti-inflammatory drugs;
ESR [mm/hrs]=
2
Osmotic resistance
• The ability of the RBC to resist the osmotic
power before the cell will lyse
• The practical demonstrates the hemolysis,
which in real can be:
– physical: vibrations, radiation, etc.
– biological: toxins, bacterias, parasites, etc.
– chemical: HCl, H2O, etc.