Presentation is loading. Please wait.

Presentation is loading. Please wait.

Structure and function of Haemoglobin Dr. Tariq M Roshan Department of Hematology KSU.

Similar presentations


Presentation on theme: "Structure and function of Haemoglobin Dr. Tariq M Roshan Department of Hematology KSU."— Presentation transcript:

1 Structure and function of Haemoglobin Dr. Tariq M Roshan Department of Hematology KSU

2 The main function of red blood cell The main function of red blood cell Transfer of O 2 from lungs to tissue Transfer of O 2 from lungs to tissue Transfer of CO 2 from tissue to lungs Transfer of CO 2 from tissue to lungs To accomplish this function red cells has haemoglobin (Hb) To accomplish this function red cells has haemoglobin (Hb) Each red cell has 640 million molecules of Hb Each red cell has 640 million molecules of Hb Introduction

3 Introduction Haemoglobin (Hb), protein constituting 1/3 of the red blood cells Haemoglobin (Hb), protein constituting 1/3 of the red blood cells Synthesis begins in proerythroblast Synthesis begins in proerythroblast 65% at erythroblast stage 65% at erythroblast stage 35% at reticulocyte stage 35% at reticulocyte stage Two parts Two parts Haem Haem Globin Globin

4 Synthesis of Haemoglobin (Hb) Haem & globin produced at two different sites in the cells Haem & globin produced at two different sites in the cells Haem in mitochondria Haem in mitochondria Globin in polyribosomes Globin in polyribosomes Well synchronized Well synchronized

5 Synthesis of Haemoglobin

6 Synthesis of Haem Protoporphyrin ring with an iron atom in centre Protoporphyrin ring with an iron atom in centre The main site is mitochondria as it contains ALAS The main site is mitochondria as it contains ALAS Mature red cell does not contain mitochondria Mature red cell does not contain mitochondria

7 Structure of Haem

8 Synthesis of globin

9 Various types of globin combines with haem to from different haemoglobin Various types of globin combines with haem to from different haemoglobin Eight functional globin chains, arranged in two clusters the Eight functional globin chains, arranged in two clusters the - cluster (,, and globin genes) on the short arm of chromosome 11 - cluster (,, and globin genes) on the short arm of chromosome 11 - cluster ( and globin genes) on the short arm of chromosome 16 - cluster ( and globin genes) on the short arm of chromosome 16

10 Globin gene clusters

11 Globin synthesis, starts at 3 rd week of gestation Embryonic Embryonic Haemoglobin Gower I ( 2 2 ) Haemoglobin Gower I ( 2 2 ) Haemoglobin Portland ( 2 2 ) Haemoglobin Portland ( 2 2 ) Haemoglobin Gower II ( 2 ) Haemoglobin Gower II ( 2 ) Fetal : HbF ( 2 2 ), HbA ( 2 2 ) Fetal : HbF ( 2 2 ), HbA ( 2 2 ) Adult : HbA, HbA2 ( 2 2 ), HbF. Adult : HbA, HbA2 ( 2 2 ), HbF. Synthesis of globin

12 Globin chain switch

13 Alpha & beta chains

14 Hb A Hb A 2 Hb F structure a 2 2 a2d2a2d2a2d2a2d2 Normal % % % % Adult haemoblobin

15 Functions of Haemoglobin Oxygen delivery to the tissues Oxygen delivery to the tissues Reaction of Hb & oxygen Reaction of Hb & oxygen Oxygenation not oxidation Oxygenation not oxidation One Hb can bind to four O 2 molecules One Hb can bind to four O 2 molecules Less than.01 sec required for oxygenation Less than.01 sec required for oxygenation chain move closer when oxygenated chain move closer when oxygenated When oxygenated 2,3-DPG is pushed out When oxygenated 2,3-DPG is pushed out chains are pulled apart when O 2 is unloaded, permitting entry of 2,3-DPG resulting in lower affinity of O 2 chains are pulled apart when O 2 is unloaded, permitting entry of 2,3-DPG resulting in lower affinity of O 2

16 Oxy & deoxyhaemoglobin

17 Oxygen-haemoglobin dissociation curve O 2 carrying capacity of Hb at different Po 2 O 2 carrying capacity of Hb at different Po 2 Sigmoid shape Sigmoid shape Binding of one molecule facilitate the second molecule binding Binding of one molecule facilitate the second molecule binding P 50 (partial pressure of O 2 at which Hb is half saturated with O 2 ) 26.6mmHg P 50 (partial pressure of O 2 at which Hb is half saturated with O 2 ) 26.6mmHg

18 Hb-oxygen dissociation curve

19 The normal position of curve depends on The normal position of curve depends on Concentration of 2,3-DPG Concentration of 2,3-DPG H + ion concentration (pH) H + ion concentration (pH) CO 2 in red blood cells CO 2 in red blood cells Structure of Hb Structure of Hb Hb-oxygen dissociation curve

20 Right shift (easy oxygen delivery) Right shift (easy oxygen delivery) High 2,3-DPG High 2,3-DPG High H + High H + High CO 2 High CO 2 HbS HbS Left shift (give up oxygen less readily) Left shift (give up oxygen less readily) Low 2,3-DPG Low 2,3-DPG HbF HbF Hb-oxygen dissociation curve

21 Summary Normal structure including the proportion of globin chains are necessary for the normal function of haemoglobin Normal structure including the proportion of globin chains are necessary for the normal function of haemoglobin Reduced haemoglobin in the red blood cells due to any abnormality of any of its constituents result into a clinical situation called anaemia Reduced haemoglobin in the red blood cells due to any abnormality of any of its constituents result into a clinical situation called anaemia Metabolic & other abnormalities result into abnormal oxygen supply to the tissue Metabolic & other abnormalities result into abnormal oxygen supply to the tissue


Download ppt "Structure and function of Haemoglobin Dr. Tariq M Roshan Department of Hematology KSU."

Similar presentations


Ads by Google