Blood physiology I

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Blood physiology I

• Andres Soosaarhttp//biomedicum.ut.ee/andress
• September 2004

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Body water

• Adult person contains 60 of water, i.e. 70 kg
  weighting person 42 l
• 2/3 (28 l) of body water is intracellular fluid
  ja 1/3 (14 l) extracellular fluid
• 4/5 of extracellular fluid (11 l) is
  interstitial fluid and 1/5 (3 l) the blood
  plasma
• Extracellular fluid also contains transcellular
  fluids cerebrospinal fluid (CSF), secretions of
  exocrine glands, etc
• Additional information http//www.uhmc.sunysb.edu
  /internalmed/nephro/webpages/Part_C.htm

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Body fluids

• Glandular secretions, filtrates or composites of
  several simultaneously running processes
• Body fluids usually contain many components
• Body fluids have several functions based on their
  component properties.

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Transfer of substances between different fluid
compartments

• Inside of the compartment concentration or
  pressure gradient
• Between compartments
• Extracellular space cells ordinary and
  osmotic diffusion
• Blood plasma interstitial space diffusion ja
  filtration (see the Starling equation by
  microcirculation or ultrafiltration in kidneys)

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Estimation of the fluid compartment volume

• The most popular way to estimate those volumes is
  the dilution method, which takes into account a
  decrease of indicator substantce content in a
  new common volume.
• D2O as an indicator is good to measure total body
  water
• Inulin is good to measure volume of extracellular
  fluid compartmet, because it can penetrate
  capillaries but not cell membranes.
• Evans blue or radioactive 131I are good to
  measure blood plasma volume, because they well in
  circulation.

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Ionic composition of extracellular and
intracellular fluids (mmol/liter)
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Daily water balance
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Blood

• lt kr haima
• Hematolology and many other special terms
• lt ld sanguis
• Sanguinity
• Blood has a holy reputation, other body fluids do
  not serve so good attitudes

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Blood, general features

• Fluid connective tissue, amount 7-8 of body
  weight, 5 L
• 55 of blood volume is plasma and 45 cells
• Blood is a temporary home for its constituents,
  they have different ways and mechanisms to appear
  and leave blood.

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Main functions of blood

• A giant transportation system
• Milieu or homeostatic funtion. Organism tries to
  keep blood composition stable and it help to hold
  interstitial environment stability
• Defense
• 3.1. Defense against blood loss or bleeding
  hemostasis, blood coagulation.
• 3.2. Defense against foreign biological material
  or immunological defense
• NB! To realise those functions blood has to be
  permanently circulating

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Physical and chemical properties of blood

• Total blood density 1050-1060 g/l
• Plasma density 1024-1030 g/l
• Density of blood cells 1089-1097 g/l
• Osmotic pressure 7,4-7,6 atm
• Colloidosmotic or oncotic pressure 25-30 mmHg
  0,002 atm
• Freezing temperature -0,55 C
• Surface tension 67-77 mN/m
• Total relative viscosity 4,0-5,0
• Plasma relative viscosity 1,8

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Hematocrit

• The ratio of blood cells to total blood volume,
  normally 0.4-0.51 (men) and 0,37-0.46 (women)

http//users.rcn.com/jkimball.ma.ultranet/BiologyP
ages/B/Blood.html
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http//cwx.prenhall.com/bookbind/pubbooks/silverth
orn2/
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Blood plasma

• 90-92 water
• 6-8 plasma proteins
• 1-2 heterogenic group of low molecular weight
  substances

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Plasma proteins

• Albumins (60), globuliins fibrinogen (40)
• Electrophoresis is classical method to separate
  proteins
• See biochemistry course

http//users.rcn.com/jkimball.ma.ultranet/BiologyP
ages/B/Blood.html
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Albumins

• A homogeneous group of proteins produced by
  hepatocytes
• Molekular weight 70 000 D
• Functions nonspecific transport vehicle (also
  endogenous regulatory substances and drugs), main
  part of the colloidosmotic or oncotic pressure
  (25 mmHg), nutritional function

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Globulins

• A heterogeneous group of proteins, produce by
  hepatocytes and plasma cells (antibodies)
• a-, ß- ja ?-globulins
• Functions transport (e.g. metals, lipids etc),
  clotting factors, antibodies agains antigenes.

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The synthesis of plasma proteins

• 17 g albumins and 5 g globulins per day.
• The half life time of albumins is 10-15 days and
  globulins 5 days

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The heterogeneous group of low molecular weight
substances (I)

• Members of this group have different structure,
  metabolisam and funtions, but their blood
  contents are relatively
• The initial, intermediate and final products of
  cell metabolism.
• Initial products glucose, amino acids, lipids,
  O2
• Intermediate products lactate
• Final products CO2, urea, uric acid, H2O

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The heterogeneous group of low molecular weight
substances (II)

• Ions
• Cations Na, K, Ca2 etc
• Anions Cl-, HCO3-
• Protons (H) , pH7,35-7,40
• Their contents have held very constant which is
  important for body homeostasis
• Bioregulators hormones, transmitters etc
• Vitamines

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Blood cells
http//cwx.prenhall.com/bookbind/pubbooks/silverth
orn2/
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Red blood cells or erythrocytes

• Number is 4-5X1012 per liter
• Without nuclei, 1/3 of mass is hemoglobin
• Main function is to carry oxygen
• Clinically important are blood groups ABO and
  Rh systems

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Erythrocytes
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Hemoglobin

• Content in men 130-160 g/l, in women 120-160 g/l
• The Hb molecul contains 4 subunits, everyone
  with heme and globin

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White blood cells or leucocytes

• Normal amount is 4-10 x 109 WBCs in 1 L blood.
• Main function immunological defense
• Heterogenous group of cells and exceptionally big
  number of WBCs are outside of circulation

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Leucocyte formula

• Granulocytes
• Neutrophilic granulocytes 50-70
• Eosinophilic granulocytes 2-4
• Basophilic granulocytes 0,5-1
• B. Agranulocytes
• Lymphocytes 25-40 (T- and B-lymphocytes)
• Monocytes 4-8

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Classification of immunological defense mechanisms

• Unspecific mechanisms
• - humoral mechanisms the complement system -
  cellular mechanisms phagocytosis, very potent
  phagocytotic potential have neutrophils and
  monocytes
• Specific mechanisms - humoral mechanisms
  antibodies from plasma cells, antigene-antibody
  reaction - cellular mechanisms cytotoxic
  effect of T-lymphocytes