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Physiology of the Blood I.

Fluid compartments and the plasma

Prof. Szabolcs Kéri

University of Szeged, Faculty of Medicine, Department of Physiology

2019

Ferenc Domoki

Introductory case vignette

• Young male patient

• Pale skin

• Fatigue, dizziness, shortness of breath

• Poor attention and concentration

• Recurrent infections, fever

• Sensitive gingiva (bleeding)

• Small suffusions under the skin

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Blood sample

Increased number of undifferentiated white blood cells

(accelerated division, poor differentiation – lymphoblasts)

Lymphoblasts destroy the bone marrow:

- Red blood cell ↓ → pale skin, fatigue

- Mature white blood cells ↓ → infections

- Platelets ↓ → bleeding

Diagnosis: acute leukaemia

Petechia and purpura due to low platelet number

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Severe or chronic inflammation in the oral cavity (e.g., ginigva):A potential sign of disturbed leukocyte function or number

• Blood and the fluid compartments of the body

• Functions of the blood in general

• Components of the blood: plasma and cells

• Anorganic and organic components of the

plasma

• Special emphasis: proteins of the plasma

Topics to be discussed:

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Intracellular Extracellular

Cell membrane Capillary

wall

Interstitial fulid P

las

ma

Principles of:

- Isotonicty- Isovolemia

EDEMA: fluid movement and accumulation through the cell membrane

and/or capillary wall

Inside the cell

Organization of the fluid spaces: the three compartment model

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Blood and the fluid compartments of the body

Total water: 0.6 x body weight (kg)

1. INTRACELLULAR COMPARTMENT: 0.4 x body weight

2. EXTRACELLULAR COMPARTMENT: 0.2 x body weight

2.1. Interstitial (0.75 x extracellular)

2.2. Intravasal = BLOOD PLASMA (0.25 x extracellular)

2.3. Transcellular (liquor, eye, inner ear, pleura)

Volume = amount of indicator / concentration after equilibrium

- Intravasal (plasma): Evans-blue or 131I bound to albumin

- Extracellular: inulin

- Total: tritiated water, antipyrine

- Intracellular = Total – extracellular

- Blood volume = Intravasal / 1- Hematocrit

When the continuity of fluid compartments is disrupted:thrombosis

Thrombus in the blood vessel

Ahead the thrombus: insufficient/ceased flowBeyond the thrombus: congestion andedema

Ultrasound diagnosis of deep vein thrombosis

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Excessive fluid in the chest: hydrothorax

Chest X-ray:pleural effusion (accumulation of fluid around the lungs)

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Blood components after centrifugation

PLASMA (55%)

WHITE BLOOD CELLS AND PLATELETS (<1%) (buffy coat)

RED BLOOD CELLS (45%)

HEMATOCRIT: the proportion of cells in

the blood

(~ 0.44-0.46 male, 0.41-0.43 female)

Serum = plasma without fibrinogen and

clotting

factors (after blood coagulation)~ 5 liters

Components of the plasma1. ANORGANIC

ELECTROLITES: sodium,

potassium, calcium, magnesium,

chloride, bicarbonate,

phosphate

2. ORGANIC SUBSTANCES:

- proteins

- glucose

- amino acids

- urea (blood urea nitrogen

[BUN]), creatinine, uric acid

- lipids (triglyceride, cholesterol)

- organic acid (lactate, pyruvate,

citrate, bilirubin)

NORMAL VALUES !!!

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Proteins of the plasma

- synthesis: liver, gut, white blood cells, endothelium (60-80 g/l)

- function: oncotic pressure, transport, acid-base buffer, inhibition of

renal filter and receptor effect

1. Albumin (35-45 g/l): oncotic pressure, bilirubin transport, binding of drugs

2. α1-globulin: thyroxine, cortisol, vitamin D transport

3. α2-globulin: ceruloplasmin (copper), haptoglobin

4. β-globulin: transferrin (iron)

5. γ-globulin: antibodies

6. Fibrinogen: blood coagulation

Normal Liver cirrhosis

Nephrosis Multiple myeloma

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Lipoproteins of the plasma

Hydrophobic core: triglycerides (T), cholesterol (C)

Hydrophilic periphery: phospholipids, apolipoproteins (Apo)

Chylomicron, VLDL (Very Low Density Lipoprotein), IDL (intermediary),

LDL (low), HDL (high): increased density and protein content in this

order

Chylo: absorbed from gut

HDL („good” cholesterol): synthesis in liver, taking up cholesterol in

vessels

Peroxisome proliferator- activated receptors(PPARs): nuclear receptors, Apo-expression

Ligand: e.g. fatty acids