22 - Red Blood Cells (erythrocytes) - count and function. Erythrocyte sedimentation rate (ESR). Haemoglobin. Control of erythropoiesis and erythrocyte count.

sections

RBC/erythrocytes in men and women

role of RBC/erythrocytes

haemoglobin

normal haemoglobin types

haemoglobin count in men and women

erythrocyte sediment rate

physiologically and pathologically increased ESR

control of erythropoiesis

RBC/erythrocytes in men and women

• Men - 4.5-6.0 x 10¹²/l

• Women - 3.9-5.3 x 10^12/l

role of RBC/erythrocytes

• transport haemoglobin-which carries oxygen from the lungs to the tissues around the body.

• Has carbonic anhydrase- this catalyses the reversible reaction between carbon dioxide and water to produce carbonic acid red blood cells

• control ph. of blood by acting as a buffer.

• People living on higher altitude have greater numbers of RBCs

haemoglobin

• Haemoglobin found in all red blood cells, gives the pigment and involved in shape

• bind oxygen and transport in the lungs, forming oxyhaemoglobin

• Haemoglobin can also carry co2 forming carboxyhaemoglobin,

normal haemoglobin types

• Hemoglobin A1 (about 95% - 98%): Hgb A contains two alpha (α) chains and two beta (β) chains

• Hgb A2 (2% - 3%): has two alpha (á) and two delta (ä) chains

• Hgb F (up to 2%): the primary haemoglobin produced by the fetus during gestation; its production usually falls to a low level shortly after birth; Hgb F has two alpha (α) and two gamma (γ) chains

haemoglobin count in men and women

• Men: 140-180 g/L

• Women:120-160 g/L

• blood count depends on testosterone level

erythrocyte sediment rate

• ESR: blood test that measures the sedimentation velocity of erythrocytes (red blood cells) in anticoagulated whole blood over a fixed period

  • It is used to detect inflammatory activity.

process:

1. When a blood sample is placed in a tall, thin tube

2. the red blood cells (erythrocytes) gradually settle to the bottom.

3. The rate at which they fall—measured in millimeters per hour—is the ESR.

4. If there's inflammation, certain proteins in the blood (like fibrinogen) cause red blood cells to clump together and sink faster, resulting in a higher ESR

   • ……………………………

Under normal physiological conditions, erythrocytes are negatively charged and repel each other, maintaining a slow settling rate. The proteins neutralise the negative charge promoting rouleux formation (stacking of rbc like coins) more dense structure, falls rapidly

physiologically and pathologically increased ESR

• Physiologically increased ESR: over the age of 60, pregnancy.

• Pathologically increased ESR: infarction, inflammation, malignancies, myocardial infarction.

control of erythropoiesis

• Kidneys detect reduced o2- levels in the blood

• Kidneys respond by secreting erythropoietin into bloodstream

• Erythropotin stimulates erythropoiesis in bone marrow

• Addition of circulatory erythrocytes increases o2- carrying capacity of blood

• which then secrete the hormone erythropoietin

• Testosterone increases RBC number