Red blood cells- creation, function and destruction

Question 1

What is haematocrit?

Answer 1

the packed cell volume or the amount of RBC’s in the total blood volume.

Question 2

What is generally the make up of the blood in people with anaemia?

Answer 2

less RBC’s in proportion to WBC’s and plasma than usual but normally the same amount of blood volume.

Question 3

Describe the structure of RBC’s

Answer 3

A biconcave disc with a high surface areas to volume ratio.

Question 4

What are the main functions of RBC’s?

Answer 4

Transport of O2 and CO2 and maintaining the acid/base balance of the blood.

Question 5

Brief description of RBC’s?

Answer 5

Bag of Haemoglobin (Hb) and enzymes for glycolysis- unable to divide and create new proteins.

Question 6

How does bone marrow move from birth to adulthood.

Answer 6

Widespread throughout body after birth but redistributed to the axial skeleton by adulthood.

Question 7

Name the stroma of the bone marrow

Answer 7

Fibroblasts, macrophages, endothelium and fat cells.

Question 8

What other cells do red blood cells develop around?

Answer 8

Red blood cells mature and develop around macrophages in the bone marrow

Question 9

What is the function of the macrophages in the bone marrow?

Answer 9

Macrophages are the main store of iron in the bone marrow and feed this to developing RBC’s.

Question 10

What is reticulin?

Answer 10

remnants of mRNA left once the nucleus of a maturing RBC has been extruded, removed by the spleen within 1-2 days.

Question 11

what form must iron be in to be absorbed and used?

Answer 11

ferrous form

Question 12

when is there a higher need for iron?

Answer 12

During pregnancy/Blood loss

Question 13

What does hepcidin do in the body?

Answer 13

It regulates iron absorption and release from macrophages- increased in inflammatory disease so less available iron.

Question 14

What are some causes of iron loss from the body?

Answer 14

Blood sampling, menstrual loss, minor trauma, GI approx 1ml per day, very small amounts in urine/skin shedding.

Question 15

what is the role of transferrin?

Answer 15

Transport/recycling, transferrin receptors increased when iron is deficient.

Question 16

What is ferritin?

Answer 16

The insoluble storage form of iron (it is a better measure of iron stores).

Question 17

What are B12 and folate(folic acid) involved in?

Answer 17

They are important in the production of RBC’s

Question 18

When is erythropoetin produced?

Answer 18

Tissue hypoxia and anaemia, high altitude and certain epo producing tumours (renal).

Question 19

What is produced when at low oxygen levels?

Answer 19

erythropoetin (epo).

Question 20

What is the most important driver of RBC production?

Answer 20

Erythropoetin (epo)

Question 21

What is spectrin and what properties does it give to RBC’s?

Answer 21

It gives RBC’s their flexibility and ability to return to shape after squeezing through tiny capillaries etc.

Question 22

What does haem do and where are they found?

Answer 22

It binds to oxygen and one is found per globin chain.

Question 23

What does haemoglobin need? (adults)

Answer 23

Two alpha chains and two beta chains

Question 24

What does haemoglobin need? (foetal)

Answer 24

Two alpha chains and two gamma chains

Question 25

What is Thalassaemia in relation to globin chains?

Answer 25

An inherited defect in globin chain production.

Question 26

What is sickle cell anaemia in relation to globin chains?

Answer 26

One amino acid change in the beta chain.

Question 27

What does the glycolytic pathway ending in lactate and pyruvate supply energy for?

Answer 27

Maintaining membrane integrity, Prevent oxidation of enzymes and Fe++, Maintain gradients of of K+ and Ca++

Question 28

what can cause anaemia by increased haemolysis (increased rate of RBC breakdown).

Answer 28

Enzyme deficiencies e.g; pyruvate kinase.

Question 29

What will acidosis and increased temperature cause?

Answer 29

will cause more oxygen to be delivered to the cells.

Question 30

what causes an increase of 2,3 DPG?

Answer 30

Exercise, anaemia and high altitude.

Question 31

What happens with the buildup of 2,3 DPG?

Answer 31

It works its way in between the globin strands and forces the chains apart to allow more oxygen to be released.

Question 32

Where is Myoglobin located?

Answer 32

In skeletal muscle.

Question 33

What is Myoglobin used for?

Answer 33

A ‘last ditch’ store of O2 for immediate use in cases of extreme exertion.

Question 34

What is the acid-base balance?

Answer 34

The regulation of H+ ions in the body fluids

Question 35

Why is the acid-base balance important?

Answer 35

Enzymes work optimally at physiological pH, Cell membranes become leaky in acidosis and Neurones become less able to transmit in acidosis and hyperactive in alkalosis.

Question 36

What are buffer systems used for?

Answer 36

Used to regulate the amount of hydrogen ions in the body by providing a buffer against extreme changes in hydrogen ions

Question 37

which buffer system accounts for 60% of the available buffer?

Answer 37

Bicarbonate reaction using carbon anhydrase as the catalyst.

Question 38

Which buffer system accounts for 30% of the available buffer?

Answer 38

Haemoglobin binds to H+ ions after the loss of oxygen and then Hb reacts with CO2 (more H+ ions are buffered and absorbed than are released in this reaction).

Question 39

What happens as red blood cells age?

Answer 39

Membrane becomes more rigid, loses glycolytic enzymes and neoagents are exposed on the cells surface

Question 40

Examples of RBC loss or destruction?

Answer 40

Some RBC loss into GI/menstrual loss/into soft tissues and some RBC’s are destroyed within the body

Question 41

How does the spleen/liver recycle RBC’s?

Answer 41

• Free Hb “mopped up” by haptoglobin- cleared by liver. (Any excess can appear in urine).
• Globin chains broken up into amino acids
• Iron bound to transferrin and returned to macrophages
• Porphyrin ring becomes bilirubin- bound to albumin and “conjugated” to glucuronide- excreted in bile