RBCs, RBC indices and reticulocytes

Question 1

What are the main functions of erythrocytes ?

Answer 1

Haemoglobin and 02 and CO2 transport

Question 2

What are the very basic RBS indices ? What are their units ?

Answer 2

Red blood cell count (=RBC) g/l
Haemoglobin concentration (=Hb) g/l
Packed cell volume (=PVC=haematocrit), how much V occupied by just RBCs after centrifugation l/l

Question 3

What absolute indices are there ?

Answer 3

Mean corpuscular volume (MCV)= how much V of one RBC = PCV/RBC (femtoliters)

Mean Corpuscular Haemoglobin (MCH)= average amount of haemoglobin in one red cell= Hb/RBC (pictograms)

Mean Corpuscular Haemoglobin Concentration (MCHC)= average concentration of haemoglobin in one cell= MCH/MCV or Hb/PCV (g/dl or g/l)

Question 4

What are conditions where RBCs are too small ? Too big ?

Answer 4

Microcytic and macrocytic anaemia

Question 5

What color is the buffy coat ? The plasma

Answer 5

White. Yellow.

Question 6

What happens in drug-induced haemolysis ?

Answer 6

Hematocrit decreases (volume of RBC in blood). Reticulocyte production therefore increases to compensate for haemolysis before it decreases due to maturation into erythrocytes.

Question 7

What is anaemia ?

Answer 7

The reduction in haemoglobin or red cell concentration in blood. Results in reduced supply of oxygen to tissues (tissue hypoxia)

Question 8

What are symptoms and signs of anaemia ?

Answer 8

Symptoms: Fatigue, weakness, breathlessness, headaches, palpitations

Signs: Face –> pallor (e.g. conjunctiva)
Mouth –> glossitis (inflamed tongue) and angular stomitis (inflammation of one or both corners of mouth)
Finger nails –Koilonychia (thin, spoon-shaped)

Question 9

What are the possible causes of anaemia ?

Answer 9

Not manufacturing the cells due to:

1. defect in process
2. Not manufactured correctly (e.g. inherited defects)
3. Lack of building materials

OR

Loss of cells due to
1. Bleeding

2. Change in the lifespan due to (possibly drugs):
   i. cells destroyed prematurely (e.g. autoimmune anaemias)
   ii. defective cells

Question 10

What is the lifespan of a platelet ?

Answer 10

5-9 days

Question 11

What is the lifespan of an erythrocyte ?

Answer 11

120 days

Question 12

How are they produced

Answer 12

Produced by megakaryocytes in the bone marrow:
megakaryocytes expand into large cells. Cells start to fragment into massive processes. Invaginations occur. Fragments into platelets and nucleus is expelled.

Question 13

What is the function of platelets ?

Answer 13

Clot formation.

Question 14

How are old platelets destroyed ?

Answer 14

Old platelets are destroyed by phagocytosis in spleen and liver (kupffer cells in liver)

Question 15

What is normal haemostasis ? What are the steps of it ?

Answer 15

Process by which haemorrhage following a vascular injury is arrested.

1. Vasoconstriction which kicks off coagulation cascade
2. Platelet adhesion, aggregation, and fibrin formation: “platelets aggregate thanks to fibrinogen binding. Fibrin then forms from the fibrinogen.”

Question 16

Which pathological processes are involve platelets ?

Answer 16

Thrombosis and Emboli

Question 17

What is thrombosis ?

Answer 17

Heamostasis at the wrong place at the wrong time. Mass formed in blood vessels resulting in aggregation of platelets. Results in blood clot obstructing circulation.

Question 18

What is an Embolus ?

Answer 18

Thrombus fragmentation and moving off to other parts.

Question 19

Give a specific example of a site where an embolus may be fatal. Is there any possible treatment to that ?

Answer 19

If venous thrombus breaks off (embolus) and moves to lungs where it is trapped, becomes pulmonary embolism. This may limit areas of the lung working properly, leading to lower amounts of oxygen taken up.
There are new effective clot bursting drugs.