Erythrocytes

Question 1

What are the cellular constituents of blood?
(3)
composition ?

Answer 1

• RBC (MOST COMMON CELL=45% of blood and 99% of all cells)
  -WBC ( 5 MAIN TYPES )
  -PLATLETS
  blood is split into :
  plasma=60% =plasma proteins, other solutes, water
  Buffy coat (WBC, platelets ) RBC

Question 2

Outline erythropoiesis

5

Answer 2

1) stem cell in red bone marrow myeloid stem cell differentiates
2) Pro-erythroblast
2) Early Erythroblast = ribosome synthesis Starts to occur
3) Late erythroblast = Hb levels rise
4) Normoblast =Nucleus is lost and it becomes a Reticulocyte (immature red blood cell)
5) Reticulocyte (stays in bone marrow/circulation for three days to mature) –>erythrocyte@

Question 3

structure and function of an erythrocyte ?

4

Answer 3

Function of RBC :

• transport of gases
• buffers

structure:

• Bioconcave disc ( increased SA:V for gas exchange)
• no organelle or Nucleus
• packed with Hb
• life span is 120 days
• 7-8um = squeeze through capillaries = very flexible

Question 4

structure and function of Hb?

4

Answer 4

Hb is a quaternary protein :
allosteric protein (it changes shape when O2 binds)
-2 alpha chain
-2 beta chains
-Haem group = perforin ring containing IRON ION group ( this is where O2 binds) red colour when O2 binds
-controlled by partial pressure of O2 ( dissociates at tissue)

Question 5

Describe the control of Erythropoiesis via aterial blood , oxygen content and formation of erythropoietin hormone ?
(3)

Answer 5

Hypoxic = low O2 levels
Kidney recognises the low O2 level =releases Erythropoetin = this triggers Erythropoiesis = more RBC to transport more O2

stimulus = Hypoxia
Detector =Kidey
Effector = EPO (Erythropoietin)

Question 6

Case study of anaemia

symptoms
signs
causes

Answer 6

Reduces the O2 capacity of blood .
Common symptoms :
-low energy
-short of breath ( lungs are working hard to increase O2 availibitly to the blood)
-Palpitations - heart pumps faster to supply enough O2 to tissues-
Headache /DIzziness - lack of O2

Signs :

• pallor of eyes , lips , skin
• Poor condition of nails /lips/tongue (nails = brittle, sores on tongue and lips )
• lower eye of eye is pale
• Hair loss
• Tachycardia . heart murmurs,

causes:

1) Abnormalities in erythropoeis ( low Iron, B12, FOLIC ACID, EPO, bone marrow aplasia )
2) Deficiency of Erythrocytes
- hemolysis = too much destruction
- blood loss
- Hypersplenism ( increased RBC destruction by spleen )

Question 7

explain the break down of Hb ? and its excretion ?
(4)
pathology = too much bilirubin

Answer 7

1) Hb broken down by macrophages in spleen into:
- >Globin
- >Heme group

Globin :
->broken down into Amino acids

Heme Group : (Fe2+ and Bilirubin )

• > Porforin ring Converted into BILIRUBIN (Taken to LIVER = excreted into faeces or liver)
• > Fe2+ —> liver to become Fe3+ . Fe3+ transported in the blood via protein called Transferin .

Pathology :
- increased levels of bilirubin ( lots of RBC break down )
deposited in fatty tissues of the body .
=jaundice

Question 8

what role does Vitamin B12 and Folate play in RBC synthesis ?

Answer 8

1) Vitamin B12 is really important in DNA synthesis = supplies essential methyl groups for protein synthesis /
(without it = no RBC )
2) Folic acid = needed for cell differentiation so if the cells don’t have B12 OR folic acid = can’t replicate or DNA synthesis can’t occur = cell death !

remember the RBC cant divide but the STEM cells can ! so the VITB12 AND FOLIC ACID IS IMPORTANT FOR ERYTHROPOESIS

Question 9

How can the different anemia’s be classed?
(3)
according to the RBC properties !

Answer 9

According to Level of Hb (xxx-chromic) and size of cells (xxx-cytic)

1) Hyperchromic/Macrocytic =MCV /MCH decreased (Big cells with a lot of Hb = lots of Hb but not enough cells can lead to anemia =B12/Folate defficiency can cause this ! Not enough CELL differentiation = MACROCYTIC ANEMIA ( cells are too big!)
2) Normochromic /normocytic
3) Hypochromic /Hypocytic ( low level of Hb ad small cells)

SIZE AND LEVEL OF HB