Topic 7: Red blood cells and the haemoglobin Flashcards

1
Q

What should be mentioned in this topic?

A
  • Red blood cells - Hemoglobin - Age effect - Transport of Blood Gases - Hemoglobin as a buffer - Degradation of the hemoglobin - Factors affecting RBC Synthesis
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2
Q

Red Blood Cells:

A
  • No mitochondria -Average lifetime: Horse, dog - 120 days Cattle, Swine – 60 Birds – 30
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3
Q

Red Blood Cells: Hemoglobin amount (Hb)

A

120-180g/L 35% haemoglobin concentration in 1g RBC.

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4
Q

RBC - data:

A
  • Mean Corpuscular Hemoglobin Concentration (MCHC) - Mean Corpuscular Hemoglobin (MCH) - Mean Corpuscular Volume (MCV)
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5
Q

Hemolysis

A

Hemolysis is the leakage or disruption of blood cells. Osmotic hemolysis: - RBC in isotonic solution – Cell does not change - RBC in hypotonic solution – Water flows into cell, cell swells up - bursts - RBC in hypertonic solution – Water leaves cell and cell shrinks.

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6
Q

Red Blood Cells: Osmotic resistance

A

RBCs can adapt to slight changes easily. This is called osmotic resistance. The minimal resistance is 70-120mmol/L NaCl. The maximal resistance is 50-90mmol/L NaCl. Osmotic resistance is due to spectrin protein molecules on the internal side of the membrane giving it flexibility. These molecular springs are fixed forming a net on the internal side of the cell by ankyrine, actin and smaller connective molecules.

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7
Q

Haemoglobin

A

It is the pigment colouring the red blood cells and plays a main role in the transport of the blood gases and the forming of the blood’s buffer capacity. Synthesis requires Fe, Cu, Co, Mn, Zn, Pyridoxin B6 among others.

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8
Q

Haemoglobin: ferro-protoporphyrine

A

-The haem is a ferro-protoporphyrine. -In the porphyrine base, iron only has 4 coordination sites. - The two other valences involved are bound to the imidazole ring of the protein under and over the porphyrine base. - Only the iron atom can bind the Oxygen reversibly – Oxygenation (not oxidation). The oxygenated derivative is methaemoglobin. -This binds oxygen irreversibly and is produced under normal conditions too but it is reversed by the methaemoglobin-reductase – NADPH system.

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9
Q

Haemoglobin: Age effect.

A

Adult animal: Hb-A = 2 alpha + 2 beta chains Foetal period: Hb-F = 2 alpha + 2 gamma chains

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10
Q

Transport of gases: O2

A

-Binds to Fe2+ -1 hem binds 1 O2

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11
Q

Transport of gases: CO2

A
  • Carbamino-haemoglobin - Responsible for about 20% of the complete CO2 blood-transport - Hb-NH2 + CO2 = Hb-N-COOH
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12
Q

Transport of gases: CO

A
  • Binds reversibly though with 200 times larger affinity than to Oxygen
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13
Q

Transport of gases: OH and Cl radicals

A
  • Binds irreversibly
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14
Q

Haemoglobin as Buffer

A

Hb- anion is one of the two most important buffer bases in the blood. Buffer action is ensured by: - HHb/Hb- - 35% of the buffer capacity of the blood is provided by haemoglobin. The deoxygenated Hb is a better proton acceptor than the oxygenated one

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15
Q

Factors affecting RBC Synthesis:

A
  • Oxygen supply - Kidney status - Age
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16
Q

Membrane hemolysis:

A

Physical effects: -Freezing, Dissolving, Shaking, Shocking Chemical effects: -Acids, Liposolvents, -Surface tension reducers Toxin Effect: -Bacterial, Snake, Plant

17
Q

Globin

A

The sterical structure of globin mainly determines the characteristics of the oxygen binding. This structure allows allosteric stimulation, and it is able to bind a new oxygen even stronger after accepting the former one.

18
Q

Degradation of the hemoglobin:

A

During the degradation of the hemoglobin phagocytes convert the HEM part to bilirubin. Albumin binds Bilirubin in the circulation. This is called bilirubin-I or indirect bilirubin or non-conjugated bilirubin.