Red Blood Cells Function and Structure

by | Mar 4, 2021 | Health | 0 comments

Red blood cells

Red Blood Cells

Blood comprises form elements or blood cells and blood plasma. Blood components are erythrocytes (red blood cells), leukocytes (white blood cells) and platelets.

Erythrocytes are specialized red blood cells. The average lifespan of erythrocytes is 120 days. Increases in erythrocytes and hematocrit indicate erythrocytosis.

The term ‘erythrocytosis’ is usually replaced by the term ‘polycythemia’, as the amount of all blood cells is sometimes increased.

True polycythemia (erythrocytosis) is a type of chronic leukemia in which a clone of erythroid cells proliferates in the bone marrow, later involving the granulocyte and megakaryocyte branch.

They may cause secondary absolute erythrocytosis:

  • lung diseases (hypoventilation);
  • congenital heart disease;
  • location at altitude.

Secondary relative erythrocytosis can result from a physiological process in which the body’s fluid leaves the blood vessels at an increased rate and the erythrocyte mass increases relatively (if there is prolonged diarrhea and vomiting).

We may associate decreased erythrocyte counts with normochrome normocytic anemia or hyperchromic macrocytic anemia.

Changes in Erythrocyte Morphology

Anisocytosis is the change in the size of red blood cells and the distribution of red blood cells, which is characterized by the RDW (red blood cell size distribution) index. It increases RDW in patients with macrocytic anemia, myelodysplastic syndrome, etc.

Poikilocytosis – a change in the shape of erythrocytes.

Anisochromia – a variety of erythrocyte staining that indicates different hemoglobin content in them.

Hypochromia – Erythrocytes become hypochromic, they contain little hemoglobin.

Hyperchromy – Erythrocytes are rich in hemoglobin.

Erythrocytes are sized by normocytes (MCV 80-100 fl), macrocytes, megalocytes (MCV> 100 fl) and microcytes (MCV <80 fl).

Inclusions in erythrocytes:

  • Small, dark blue inclusions (one, less often two) indicate the presence of DNA;
  • Kebot rings – pale, pink inclusions in the form of a ring, ellipse or octagon. They are thought to be remnants of the nuclear membrane;
  • basophilic dots are 5-10 small dots – it is an abnormal precipitation of ribosomes;
    erythrocyte nucleus – normoblast;
    malaria plasmodium;
  • inclusions in patients with babesiosis.

We divide erythrocytes into macrocovalocytes (patients with megaloblastic anemia), ovalocytes, spherocytes, echinocytes, acanthocytes, stomacytes, target erythrocytes, schistocytes, sickle cells, “teardrop” erythrocytes.

Erythrocyte Sedimentation Rate (ESR)

Erythrocyte sink rate is the most commonly determined blood laboratory indicator used to diagnose and monitor diseases.

The rate of erythrocyte sinking is a non-specific indicator of the body’s pathological condition. Elevated ESR is a sensitive but non-specific test that indicates an active inflammatory process.

The rate of erythrocyte sinking suggests the stability of the erythrocyte suspension. The sinking of erythrocytes is their landing under the influence of the gravitational force of the earth.

The ESR is primarily a reaction to plasma proteins, such as fibrinogen, which increase during the acute phase reaction. The ESR is affected by changes in albumin and globulin ratios, changes in fibrinogen, gamma globulin and beta globulin concentrations,

changes in the number and shape of erythrocytes in the blood and other non-disease related factors (age, medication).

Assessment of Changes in ESR After Westergren Method

  1. Minor changes – up to 20 mm / h.
  2. Moderate changes – up to 50 mm / h.
  3. Significant changes – up to 90 mm / h.
  4. Very pronounced changes – more than 90 mm / h.
  5. Decelerated EGA – less than 2 mm / h.

If the ESR is greater than 100 mm / h, it shows that the patient is suffering from a serious systemic disease (connective tissue systemic disease, malignancy, infection, cirrhosis, etc.).

Elevated Values


  • tuberculosis;
  • acute hepatitis;
  • bacterial infections.

Cardiac pathologies:

  • acute myocardial infarction;
  • active rheumatism.

Abdominal diseases:

  • after heart surgery;
  • acute pelvic inflammatory disease;
  • rupture for women with ectopic pregnancy;
  • from the 3rd month of pregnancy to approximately three weeks after delivery.

Joint pathologies:

  • rheumatoid arthritis.

ESR values tend to correlate with rheumatoid arthritis activity and can be used to monitor the effectiveness of treatment for this disease;

  • pyogenic arthritis.

Different pathologies:

  • tissue necrosis, especially in patients with tumors (malignant lymphoma, colon, breast cancer);
  • increase in serum globulins (including myeloma, cryoglobulinaemia, macroglobulinaemia);
  • hypoalbuminemia;
  • hypothyroidism and hyperthyroidism;
    acute bleeding;
  • nephrosis, kidney disease with uraemia;
  • lead and arsenic intoxication;
  • giant cell vasculitis.

No Changes


  • typhoid fever;
  • undulant fever;
  • malaria attack;
  • infectious mononucleosis;
  • uncomplicated viral infections.

Cardiac pathologies:

  • angina;
  • acute kidney and heart disease.

Abdominal pathologies:

  • acute appendicitis (first 24 hours);
  • ectopic pregnancy without rupture;
  • early pregnancy.

Joint pathologies:

  • degenerative arthritis.

Different pathologies:

  • peptic ulcer;
  • acute allergy.

Basophilic Puncture of Erythrocytes

basophilic pituitary puncture is an aggregation formed by ribosomes and iron-containing mitochondria.

Erythrocyte basophil puncture can be found in patients with:

  • lead intoxication;
  • sideroblast anemia;
  • megaloblastic anemia.

What You Need To Know About Blood?

Blood Type and Rhesus Affiliation

Blood type and rhesus affiliation are determined by genes inherited from parents. Each individual can have one of four blood groups: O, A, B or AB. They do not change during life.

Rhesus affiliation is determined by the presence of rhesus D antigen in an individual’s erythrocytes. If a person has the D antigen, he is rhesus positive, but if he is not, he is rhesus negative.

Rhesus-positive parents can have both rhesus-positive and rhesus-negative children, but rhesus-negative parents can only have rhesus-negative children.

There are other important antigens in the Rhesus system – C, c, E, e, etc., the detection of which is called phenotyping.

Clarification of Rhesus D antigen is very important for donors. Sometimes, when an individual has a very weak D antigen in their blood, we define it as a Rhesus-positive donor and a Rhesus-negative recipient.

This means that this person has to shed rhesus – negative blood – if necessary.

What is Kell Antigen?

In addition to these two blood group systems, there are several other important blood group systems, such as the Kell antigen system.

The presence of Kell antigen is not harmful to humans. But a blood transfusion from a Kell-positive donor to a Kell-negative recipient can cause serious complications – similar to an erythrocyte transfusion from a rhesus-positive donor to a rhesus-negative patient.

Autologous Blood and Blood Components

Autologous blood / blood components are prepared from the patient and should only be transfused. Any unused autologous blood / blood components should be discarded.

Contraindications To the Preparation of Autologous Blood:

  • the patient’s age is over 70 years;
  • patients have a life expectancy of less than 5 years;
  • children weighing less than 10 kg;
    bacterial infection;
  • hemoglobin (Hb) concentration less than 100 g / l;

Positive Virus Markers:

  • Hepatitis B surface antigen (HbsAg);
  • antibodies to hepatitis C virus (anti-HCV);
  • antibodies to human immunodeficiency virus (anti-HIV);
  • severe aortic stenosis;
  • severe arterial hypertension;
  • angina.

Various Facts

  • Most transfusions lack rhesus-negative blood because only 15% of people are rhesus-negative.
  • The blood of all groups and rhesus is equally valuable! In an adult, blood is about 7% of body weight (about 5 l).
  • A healthy person has about 25 trillion erythrocytes.
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