Blood — Laboratorium

Laboratorium

Five stations — from test tube to blood types.

Keys: Q W E R T — stations Esc stops animations

Whole blood — mixed

Plasma — what floats in it?

Water — the solvent and “delivery medium”≈ 90–92%
Proteins: albumins (≈ 55–60% of proteins), globulins including antibodies (≈ 35–38%), fibrinogen (≈ 4–7%)≈ 7%
Mineral salts (Na⁺, Cl⁻, HCO₃⁻, K⁺, Ca²⁺), glucose, fats, hormones, urea, dissolved CO₂ and O₂≈ 1–2%

Plasma without fibrinogen and the other clotting factors is serum — what is left after blood clots in a tube.

Centrifuge

Sample

Speed (time sped up)0 rpm

Acceleration in the tube0 g

Your hematocrit reading—

Measured hematocrit?

Press Spin. Blood cells are denser than plasma, so in the centrifuge they sink to the bottom.

Layers after spinning

Plasma

—

Buffy coat: white cells and platelets

—

Red cells (hematocrit)

—

Typical hematocrit: men ≈ 40–54%, women ≈ 36–48% (ranges differ between labs).

How much blood do you have?

Body mass70 kg

Blood volume (≈ 70 mL per kg)4.9 liters

of which plasma2.7 L

of which red cells2.2 L

Adults typically have 65–75 mL/kg (women usually a bit less). Plasma and red cells are computed for a hematocrit of 45% or the measured one.

Venous blood is dark red — never blue. Veins look bluish because skin scatters and absorbs red and blue light differently. More on the pump: Heart, on gas exchange: Lungs.

Hemoglobin

pO₂ around the molecule40 mmHg

Four subunits (2 α and 2 β), each with a heme holding an iron ion Fe²⁺. Each heme binds one O₂ molecule. Binding the first makes binding the next ones easier — this is cooperativity, hence the S-shaped curve.

Tissue conditions

Tissue pO₂40 mmHg

pCO₂40 mmHg

pH7.40

Temperature37.0 °C

2,3-BPG in the red cell5.0 mmol/L

Changing pCO₂ also changes pH (CO₂ plus water makes carbonic acid) — the pH slider moves by itself.

P50 (half saturation)26.8 mmHg

Curve shiftnone

Saturation in the lungs (≈ 100 mmHg)97 %

Saturation in the tissue75 %

stays in the blood: 75%given to the tissue: 22%

≈ 45 mL of O₂ from every liter of blood (at hemoglobin 150 g/L).

Carbon monoxide (CO)

CO in the air0 ppm

Hemoglobin taken up by CO after many hours:0%

CO binds to hemoglobin about 200–250 times more strongly than oxygen, so even a small amount in the air blocks some of the hemes. Carbon monoxide has no smell and is invisible. It forms during incomplete combustion — in gas water heaters, stoves and fireplaces with a poor draft. A CO detector, good ventilation and regular inspections protect you. Headache, dizziness, nausea and drowsiness in a room with a gas heater are a signal to get to fresh air and call 112 (the European emergency number; 911 in the US).

Patient: A Rh+

Inheritance of blood types

Child — blood type probability

Alleles A and B are codominant, 0 is recessive; D (Rh+) is dominant over d. The ABO genes (chromosome 9) and RhD (chromosome 1) are inherited independently. We skip rare exceptions such as the Bombay phenotype.

Transfusion

Error-free streak0 / 5

Successful0

Failed0

Drag a bag onto the patient's blood (or press a bag). Check whether the antibodies will attack the red cells.

Red cell compatibility: donor → recipient

Rows: recipient, columns: donor. Universal red cell donor: 0 Rh−, universal recipient: AB Rh+. In practice blood of the same type is transfused, and a crossmatch checks compatibility before every transfusion.

Antigens and antibodies

Type	On red cells	In plasma
A	antigen A	anti-B
B	antigen B	anti-A
AB	A and B	none
0	no A or B	anti-A and anti-B
Rh+	antigen D	—
Rh−	no D	anti-D only after sensitization

Blood types in Poland

Approximate, based on data published by blood donation centers. About 15% of Poles are Rh−.

From history

Karl Landsteiner described the first blood types in 1901 (A, B and 0; type AB was described a year later by his co-workers). He received the Nobel Prize in 1930. In 1940, with Alexander Wiener, he described the Rh factor.

Ludwik Hirszfeld, a Polish physician and microbiologist, showed with Emil von Dungern around 1910 that blood types are inherited according to Mendel's laws. They also proposed the labels A, B, AB and 0, which were adopted worldwide. (The exact three-allele mechanism was described in 1924 by Felix Bernstein.)

Hemolytic disease of the newborn (Rh disease): when an Rh− mother carries an Rh+ baby, she may produce anti-D antibodies, usually dangerous for a later pregnancy. Today this is prevented by giving the mother anti-D immunoglobulin.

Voluntary blood donation

Blood can't be made in a factory.

One donation, several patients

Donated blood is separated into components: red cell concentrate, plasma and platelets. That way one donation can help several people — after accidents, during surgery, and in the treatment of cancers and blood diseases.

The body replaces plasma within 1–2 days and red cells within a few weeks. That's why at least 8 weeks must pass between whole-blood donations. Whether you can donate is always decided by the doctor at the blood donation center (in Poland, the regional RCKiK).

For a person weighing 70 kg, a donation is about 9% of their blood volume.

One whole-blood donation: ≈ 450 mL
Donor age: 18–65 years
Body mass: ≥ 50 kg
Max per year: 6 / 4 times (M / F)

Challenges

They complete on their own. Completed: 0 / 5

Spin the blood and read the hematocrit
Spin a sample, set the marker at the boundary between red cells and plasma, and check the reading — accuracy ±2 percentage points.
To do
Find a lymphocyte in the smear
Among thousands of red cells, find a lymphocyte and click it.
To do
Shift the curve right (Bohr effect)
Change the conditions so that P50 rises to at least 32 mmHg — hemoglobin then releases oxygen more easily.
To do
Transfuse blood 5 times in a row without error
Five compatible transfusions in a row — no agglutination and no Rh sensitization.
To do
Parents who can have a child of any ABO type
In the inheritance calculator, set the parents' genotypes so that the child could be type A, B, AB or 0.
To do

How does it work?

Blood in simple words and a few formulas

A tissue that flows

Blood is a connective tissue: cells (red cells, white cells and platelets) suspended in liquid plasma. It distributes oxygen, nutrients, hormones and heat, carries away CO₂ and metabolic waste, defends against microbes and seals damage on its own. Blood cells form in the red bone marrow from stem cells. Adults typically have 65–75 mL of blood per kilogram of body mass:

V_blood ≈ 70 mLkg · m → 70 kg · 70 mL/kg ≈ 4.9 L

The fraction of blood volume taken up by red cells is called the hematocrit. It is measured by spinning blood in a thin tube:

Hct = height of the red cell columnheight of the whole blood column · 100%

In a centrifuge the sample feels an acceleration a = ω²r. At 3,000 rpm and a radius of 10 cm, that's about 1,000 times Earth's g — which is why the cells settle in a few minutes rather than a few hours.

Hemoglobin and the dissociation curve

A red blood cell contains about 270 million hemoglobin molecules. Each has four hemes with an Fe²⁺ ion and can bind four O₂ molecules. The percentage of occupied sites (the saturation S) at a given partial pressure of oxygen is well described by the Hill equation:

S = pO₂ⁿP₅₀ⁿ + pO₂ⁿ, n ≈ 2.7, P₅₀ ≈ 26.8 mmHg

At 100 mmHg (lungs) this gives about 97%, at 40 mmHg (tissues at rest) about 75%, and at 20 mmHg (working muscle) about 31%. A coefficient n > 1 means cooperativity: the curve is S-shaped, so in the lungs hemoglobin becomes almost saturated, and in the tissues it releases oxygen easily. The amount of oxygen in a liter of arterial blood:

CO₂ ≈ 1.34 mL O₂g Hb · Hb · S + 0.03 mL O₂L · mmHg · pO₂ ≈ 1.34 · 150 · 0.97 + 3 ≈ 198 mL/L

The Bohr effect: more CO₂, a more acidic environment (lower pH), higher temperature and more 2,3-BPG all raise P50 — the curve shifts right and hemoglobin releases oxygen more easily where it is needed. Fetal hemoglobin binds 2,3-BPG weakly, so its P50 is about 19–20 mmHg and it “takes” oxygen from the mother's blood in the placenta.

log P₅₀ ≈ log 26.8 + 0.40·(7.40 − pH) + 0.06·logpCO₂40 + 0.024·(T − 37) + 0.025·(BPG − 5)

This is the approximation used in the simulation (coefficients from the physiology literature, rounded). Carbon monoxide: at equilibrium the ratio of COHb to O₂Hb ≈ M·pCO/pO₂ with M ≈ 230 (the Haldane equation).

Blood types

Red blood cells carry molecules — antigens A, B and D. From early childhood, the plasma contains antibodies against the ABO antigens a person doesn't have. If the recipient's antibodies meet foreign antigens, they clump the red cells together (agglutination) and destroy them — a dangerous transfusion reaction. Anti-D antibodies form only after contact with Rh+ red cells.

Clotting

After an injury the vessel constricts, platelets stick to the exposed collagen and form a plug, and a cascade of clotting factors produces thrombin. Thrombin converts fibrinogen dissolved in plasma into strands of fibrin that wrap around the plug and the blood cells. As the wound heals, the enzyme plasmin dissolves the clot (fibrinolysis).

Did you know…?

You have about 25 trillion red blood cells — roughly 4 out of 5 cells in your body (counting cells, not mass).
Bone marrow makes about 2–3 million red cells per second, and in the same time the spleen and liver remove roughly as many old ones.
A mature human red blood cell has no nucleus and no mitochondria. It gets its energy from glucose without using oxygen — it doesn't consume the oxygen it carries.

What we simplified

Centrifuge: time and speed are sped up, and the layers settle evenly. The smear is computer-drawn in typical proportions.
The dissociation curve is the Hill equation with approximate corrections for pH, CO₂, temperature and 2,3-BPG. The carbon monoxide curve is a qualitative sketch.
The transfusion game considers only the ABO and RhD systems. For plasma we ignore Rh (plasma usually has no anti-D antibodies).
The clotting cascade is cut down to the most important factors.

Blood pump → Heart Gas exchange → Lungs Blood filter → Kidneys Plasma proteins → Liver Lymphocytes → Lymphatic system Structure → Cell

Blooda river of life in 5 liters

Laboratorium

Plasma — what floats in it?

Centrifuge

Layers after spinning

How much blood do you have?

Why is a red cell biconcave?

White cells — percentages

How many cells in a microliter of blood?

Hemoglobin

Tissue conditions

Carbon monoxide (CO)

Inheritance of blood types

Child — blood type probability

Transfusion

Red cell compatibility: donor → recipient

Antigens and antibodies

Blood types in Poland

From history

Stages

The cascade in brief

Liver, vitamin K, hemophilia

Voluntary blood donation

One donation, several patients

Challenges

Spin the blood and read the hematocrit

Find a lymphocyte in the smear

Shift the curve right (Bohr effect)

Transfuse blood 5 times in a row without error

Parents who can have a child of any ABO type

How does it work?

A tissue that flows

Hemoglobin and the dissociation curve

Blood types

Clotting