Red Blood cells

Question 1

What factors lead to a variation in RBC count.

Answer 1

Sex, age, fitness level, altitude, polycythaemia and anemia

Question 2

What are 4 functions of RBC’s

Answer 2

Transport O2 from lungs to tissue
Transport CO2 from tissue to lungs
Haemoglobin acts as buffer
Carry blood group antigens

Question 3

What are properties of RBC’s and how does this aid in their function?

Answer 3

Biconcave, no organelles, small

increased SA:V for efficient oxygen delivery

Question 4

Outline the composition of haemoglobin?

Answer 4

Oxygen and carbon dioxide carrying, 4 polypeptide, 4 haem groups, responsible for red colour.

Question 5

List 4 causes of iron deficiency?

Answer 5

1. Inadequate iron intake (e.g. vegetarian diet, poor
   diet in children)
2. Iron malabsorption can result from gastrectomy,
   chronic diarrhoea, malabsorption syndromes such
   as coeliac disease, etc.
3. Chronic blood loss due to GI bleeding (ulcers, use
   of anti‐coagulants, aspirin, etc.) or menstrual
   disorders.
4. Increased demand for iron (growing children,
   pregnancy

Question 6

Where does haemoglobin synthesis take place?

Answer 6

RBC’s

Question 7

Hypoxia will lead to an increased production of what in RBC’s ?

Answer 7

2.3-diphosphoglycerate which is produced in anearobic conditions and reduces the Hb- molecules affinity for oxygen causing it to be released to the tissues for a given decrease in PO2.

Question 8

Outline the composition of Globin in adults and foetuses.

Answer 8

2 alpha subunits and 2 beta subunits
2 alpha and 2 gamma subunits in foetuses

Question 9

HbF function

Answer 9

Foetal haemoglobin has a higher affinity for oxygen which facilitates transfer of oxygen from maternal to foetal circulation.

Question 10

HbA2

Answer 10

Minor adult heamoglobin ( 2 alpha subunits, 2 sigma subunits)

Question 11

How do sickle cells form

Answer 11

V sub for E at position 6 of B-chain in SHb which aggregates into a distorted RBC

Question 12

What effects do sickle cells have in blood ?

Answer 12

Increase blood viscosity and have a decreased half-life

Question 13

What are the three alternative reactions of haemoglobin ?

Answer 13

Methaemoglobin (MetHb)
Oxidizing agents (certain drugs)
Fe2+ (In Hb) → Fe3+ (MetHb)
Binding of O2 with metHb is irreversible
Converted back to Hb by methaemoglobin
reductase

Carbaminohaemoglobin
CO2combines loosely with the amino groups
(‐NH2) of the Hb‐molecules (not with Fe‐part of
the Hb)

Carboxyhaemoglobin
CO binds to Fe2+ of Hb
Hb has 250x more affinity for CO than O2
CO displaces O2 from Hb

Question 14

What accounts for the decreased life-span of RBC’s

Answer 14

Lack of organelles which prevent them from self-repairing

Question 15

Outline the breakdown of heam?

Answer 15

Converted to Biliruben, iron, globin and CO2
Co2 is exhaled, Iron and Globin are added to iron pools and protein pools respectively.

Biliruben is processed in the liver.

Question 16

Why is jaundice common in newborns ?

Answer 16

developing liver cant process all biliruben

Question 17

Effects of Anemia

Answer 17

Abnormally low number of circulating RBCs or
level of Hb or both
Results in decreased O2 carrying capacity
Not a disease
Indication of disease process

Question 18

Causes of anemia

Answer 18

Blood loss

Haemolytic anemia:
Hereditary from membrane, enzyme and haemoglobin defects. Acquired from parasitic infection, drugs and autoimmune disease.

Defective RBC production or Hb synthesis in bone marrow:
Aplastic anemia from drugs, radiation, bad diet, iron deficiency, folic acid deficiency, B12 deficiency.
Kidney damage which leads to inadequate production of erythropoietin

Question 19

Red blood cell indicates

Answer 19

MCV (average volume of RBC’s) and MCH (amount of Hb per cell) and MCHC (concentration of haemoglobin in grams per decilitre as a percentage)

Question 20

Where and how is iron recycled in the blood ?

Answer 20

In the spleen via macrophages, stored in liver and travels to red bone marrow when needed.

Question 21

What is the result of decreased Hb production?

Answer 21

Microcytic hypochromic RBC’s

Question 22

Outline the metabolic activity of RBC’s

Answer 22

Forms carb-aminohaemoglobin with CO2

Carbonic anhydrase forms carbonic acid
H2CO3 dissociates to H+ and HCO3^-

maintains hight intracellular sodium and low extracellular potassium for ATPase

Holds enzymes that control glucose metabolism

Question 23

How does an increase in carbon dioxide in the blood lead to acidosis.

Answer 23

Carbon dioxide and water make carbonic acid in the blood which dissociates into bicarbonate ions and protons.

Question 24

What is methaemoglobin

Answer 24

when haem groups form irreversible bonds with oxygen which oxidizes the iron atom and reduced the carrying capacity of RBC’s