Components of Blood

Question 1

What is blood plasma?

Answer 1

The liquid of the blood

Question 2

What does blood plasma contain?

Answer 2

Red blood cells, white blood cells and platelets. The plasma also contains lots of clotting factors such as fibrinogen.

Question 3

What is blood serum?

Answer 3

Once the clotting factors are removed from the blood plasma what is left is called the serum.

Question 4

What does blood serum contain?

Answer 4

1. Glucose
2. Electrolytes such as sodium and potassium
3. Proteins such as immunoglobulins and hormones

Question 5

Where is bone marrow mostly found?

Answer 5

Bone marrow is mostly found in the pelvis, vertebrae, ribs and sternum.

Question 6

What do all blood cells start out as and what do they initially become?

Answer 6

Pluripotent Haematopoietic Stem Cell

These are undifferentiated cells that have the potential to transform into a variety of blood cells. They initially become:

• Myeloid Stem Cells
• Lymphoid Stem Cells
• Dendritic Cells (via various intermediate stages)

Question 7

What do red blood cells develop from?

Answer 7

Red blood cells (RBCs) develop from reticulocytes that comes from the myeloid stem cells. Reticulocytes are immature red blood cells. Red blood cells survive up to 3 months.

Question 8

What do platelets develop from?

Answer 8

Platelets are made by megakaryocytes. Their lifespan is 10 days. The normal count is 150000 – 450000 /mm3. Their role is to clump together (platelet aggregation) and plug gaps where blood clots need to form.

Question 9

Where do the white blood cells originate from in the myeloid lineage?

Answer 9

Myeloid stem cells become promyelocytes that can become:

Monocytes then macrophages
Neutrophils
Eosinophils
Mast Cells
Basophils

Question 10

Where do the white blood cells originate from in the lymphoid lineage?

Answer 10

Lymphocytes come from the lymphoid stem cells and become B cells or T cells.

B lymphocytes (B cells) (mature in the bone marrow) and differentiate into:

Plasma Cells
Memory B Cells
T lymphocytes (T cells) (mature in the thymus gland) and differentiate into:

CD4 cells (T helper cells)
CD8 cells (Cytotoxic T Cells)
Natural Killer Cells

Question 11

What is anisocytosis on blood film?

Answer 11

Anisocytosis refers to a variation in size of the red blood cells. These can be seen in myelodysplasic syndrome as well as some forms of anaemia.

Question 12

What are target cells on blood film?

Answer 12

Target cells have a central pigmented area, surrounded by a pale area, surrounded by a ring of thicker cytoplasm on the outside. This makes it look like a bull’s eye target. These can be seen in iron deficiency anaemia and post-splenectomy.

Question 13

What are heinz bodies seen on blood film?

Answer 13

Heinz Bodies are individual blobs seen inside red blood cells caused by denatured globin. They can be seen in G6PD and alpha-thalassaemia.

Question 14

What are Howell-Jolly bodies seen on blood film?

Answer 14

Howell-Jolly bodies are individual blobs of DNA material seen inside red blood cells. Normally this DNA material is removed by the spleen during circulation of red blood cells. They can be seen in post-splenectomy and in patients with severe anaemia where the body is regenerating red blood cells quickly.

Question 15

What are reticulocytes seen on blood film?

Answer 15

Reticulocytes are immature red blood cells that are slightly larger than standard erythrocytes (RBCs) and still have RNA material in them. The RNA has a reticular (“mesh like”) appearance inside the cell. It is normal to have about 1% of red blood cells as reticulocytes. This percentage goes up where there is rapid turnover of red blood cells, such as haemolytic anaemia. They demonstrate that the bone marrow is active in replacing lost cells.

Question 16

Schistocytes?

Answer 16

Schistocytes are fragments of red blood cells. They indicate the red blood cells are being physically damaged by trauma during their journey through the blood vessels. They may indicate networks of clots in small blood vessels caused by haemolytic uraemic syndrome, disseminated intravascular coagulation (DIC) or thrombotic thrombocytopenia purpura. They can also be present in replacement metallic heart valves and haemolytic anaemia.

Question 17

Sideroblasts?

Answer 17

Sideroblasts are immature red blood cells that contain blobs of iron. They occur when the bone marrow is unable to incorporate iron into the haemoglobin molecules. They can indicate a myelodysplasic syndrome.

Question 18

Smudge cells?

Answer 18

Smudge cells are ruptured white blood cells that occur during the process of preparing the blood film due to aged or fragile white blood cells. They can indicate chronic lymphocytic leukaemia.

Question 19

Spherocytes?

Answer 19

Spherocytes are spherical red blood cells without the normal bi-concave disk space. They can indicated autoimmune haemolytic anaemia or hereditary spherocytosis.