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Fundamentals Of Pathology > Haemoglobin Structure And Function > Flashcards

Haemoglobin Structure And Function Flashcards

1
Q

What is haemoglobin made up of?

A

2 alpha and two beta chains

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2
Q

How much of RBCs is comprised of a globular haemoprotein

A

1/3

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3
Q

What is a haemoprotein?

A

A group of specialised proteins that contain haem as a tightly bound prosthetic group

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4
Q

What is haem a complex of?

A

Protoporphyrin IX and ferrous iron Fe2+

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5
Q

How is the iron held in the centre of the haem molecule?

A

Bonds to the 4 nitrogens of a porphyrin ring

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6
Q

How much Hb is synthesised in the erythroblasts?

A

65%

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7
Q

How much Hb is synthesised at the reticulocyte stage?

A

35%

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8
Q

What is haemoglobin synthesis stimulated by?

A

Tissue hypoxia (lack of oxygen)

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9
Q

How is Hb synthesis stimulated by tissue hypoxia?

A

Hypoxia causes the kidneys to increase EPO production which increases RBC and Hb production

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10
Q

What does EPO Stand for?

A

Erythropoietin

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11
Q

What molecule delivers iron to the reticulocyte?

A

Transferrin

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12
Q

Where does synthesis of protoporphyrins take place?

A

In the mitochondria of RBC precursors

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13
Q

What is synthesis of protoporphyrins mediated by?

A

EPO and vitamin B6

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14
Q

Protoporphyrin + iron->

A

Haem

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15
Q

What are the starting reactants in the synthesis of protoporphyrin?

A

Glycine + succinyl CoA

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16
Q

What is the iron stored as if you don’t need it?

A

Ferritin

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17
Q

Where does synthesis of globin happen?

A

In the ribosome and RER

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18
Q

What does proper globin synthesis depend on?

A

Genes

19
Q

How many functional globin chains are there?

A

8

20
Q

What are the two clusters of globin called?

A

A and B

21
Q

What genes are in the B-cluster?

A

Beta, gamma, epsilon and delta

22
Q

Where are the B-cluster genes found?

A

On the short arm of chromosome 11

23
Q

What genes are in the A-cluster?

A

Alpha and zeta

24
Q

Where are the A-cluster genes found?

A

Short arm of chromosome 16

25
Q

What types of globulin are found in foetal Hb?

A

Alpha and gamma

26
Q

What types of globulin are found in adult Hb?

A

Alpha and beta

27
Q

What are the functions of haemoglobin?

A
  • carry oxygen from the lungs to the tissues
  • remove CO2
  • buffering action- maintains blood pH as it changes from oxyhaemoglobin to deoxyhaemoglobin
28
Q

How many oxygens can one Hb bind to?

A

Four

29
Q

How long does it take for Hb oxygenation?

A

Less than 0.1 seconds

30
Q

What happens (physically) to the Hb when it’s oxygenated?

A

2,3-DPG is pushed out and the beta chains move closer

31
Q

What does DPG stand for?

A

Disphosphateglycerate

32
Q

What does the amount of o2 bound to hb and released to tissues depend on?

A

pO2
pCO2
Affinity of hb for O2

33
Q

What does oxygen affinity determine?

A

The proportion of o2 released to the tissues or loaded onto the cells at a given pressure

34
Q

What is the Bohr effect?

A

Alterations in the blood pH shifted the oxygen dissociation curve

35
Q

What happens to the oxygen dissociation curve in acidic pHs?

A

The curve shifts to the right

36
Q

What happens when the oxygen dissociation curve shifts to the right?

A

Results in an enhanced capacity to release o2 where it is needed

37
Q

What does the normal position of the haemoglobin oxygen dissociation curve depend on?

A

2,3 DPG concentration
Hydrogen ion conc (pH)
CO2 in RBC
Structure of Hb

38
Q

What are standard conditions for the Hb- O2 dissociation curve?

A

37 Celsius
pH 7.4
BE =0

39
Q

What are the three mechanisms for CO2 transport?

A

Dissolution in the plasma
Formation of carbonic acid
Binding to form carbaminohaemoglobin

40
Q

What is oxyhaemoglobin made up of?

A

Hb and 02

41
Q

What is deoxyhaemoglobin made up of?

A

Hb - o2

42
Q

What is methemoglobin made up of?

A

Hb with Fe3+

43
Q

What is carbaminohaemoglobin made up of?

A

CO2 binds non-covalently to globin chain of Hb

Fundamentals Of Pathology (20 decks)

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