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Stage 1 Blood > BL3 Haemoglobin > Flashcards

BL3 Haemoglobin Flashcards

1
Q

Name 2 RBC disorders:

A

Sickle cell and thalassaemias

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2
Q

What is the other name for RBC?

A

erythrocytes

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3
Q

Give 2 of the main functions of erythrocytes

A

1) oxygen transport: lungs to cells

2) carbon dioxide transport: cells to lungs

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4
Q

1) What is the committed progenitor cells of erythrocytes?

2) What cells come after it? (state when your in bone marrow or blood)

A

1) proerythroblast

2) erythroblast (in bone marrow) then reticulocyte (in the blood), then erythrocyte (in the blood obvs)

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5
Q

1) How do we go from a proerythroblast to a erythroblast?
2) What stages between erythroblast and reticulocyte?
3) How long does it take the reticulocyte to become a erythrocyte?

A

1) proerythroblast become large, nucleated erythroblasts
2) a) erythroblast nucleus is exocytosed (pinched off)- nucleus is phagocytized by bone
marrow macrophages
c)mitochondria metabolised= reticulocyte,
3) 24 hrs

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6
Q

What shape are erythrocytes?

A

biconcave discs

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7
Q

What holds the erythrocytes in a biconcave shape?

A

spectrin (cytoskeletal protein that lines the intracellular side of the plasma membrane ) and actin(a microfilament) in the cell cortex
complex cytoskeleton composed of filaments linked to transmembrane proteins

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8
Q

1) How do RBC die?

2) What happens to them after?

A

1) No nucleus or endoplasmic reticulum so no synthesis of new proteins – increasing loss of membrane integrity
= older cells are fragile and rupture in narrow capillaries or engulfed by macrophages as they pass through the spleen

2) a)Many components of the destroyed cells are recycled. e.g. Amino acids from the globin chains of hemoglobin are used in new proteins, and some iron from the heme groups is reused to make new heme groups.
b) The spleen and liver convert remnants of the heme groups to a colored pigment called bilirubin.
c) Bilirubin is carried by plasma albumin to the liver,
i) d) here it is metabolized and incorporated into a secretion called bile.
e) Bile is secreted into the digestive tract, and the bilirubin metabolites leave the body in the feces.
ii) Small amounts of other bilirubin metabolites are filtered from the blood in the kidneys, where they contribute to the yellow color of urine.

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9
Q

Name 2 RBC disorders:

A

sickle cell and thasselaemmias

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10
Q

What is another word used instead of RBC:

A

erythrocyte

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11
Q

RBC have no mitochondria, where do they get their ATP from?

A

glycolysis

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12
Q

Why do older cells become fragile and rupture?

A

No nucleus or endoplasmic reticulum so no synthesis of

new proteins –therefore increasing loss of membrane integrity

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13
Q

What is within the membrane of RBC?

A

enzymes (for glycolysis), cytosol and haemoglobin

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14
Q

How many amino acids is a-globin made up of?

A

141

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15
Q

How many amino acids is b-globin made up of?

A

146

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16
Q

1) Describe the structure of haemoglobin in most vertebrates:
2) What is it?

A

2 a-globins, 2 B-globins and 4 haem groups

2) oxygen-carrying protein

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17
Q

Describe the evolution of the globin gene family which has led to differences in affinity between a mam’s haemoglobin and a babys:

A

1) single chain globin ( at start)
2) Duplication occured and mutation (500 million years ago) = a globin and b globin
3) (some time later when different mammals diverged from their common ancestor) b-globin duplicated and diverged = 2nd B-like globin gene expressed in a fetus with a higher affinitiy for O2

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18
Q

Describe the evolution of the globin gene family which has led to differences in affinity between a mam’s haemoglobin and a babys:

A

1) single chain globin ( at start)
2) Duplication occured and mutation (500 million years ago) = a globin and b globin
3) (some time later when different mammals diverged from their common ancestor) b-globin duplicated and diverged = Foetal β globin contains a γ version that has a higher affinity for oxygen

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19
Q

How many haem groups are there in 1 haemoglobin?

2) describe haem groups’s structure
3) What percentage of the body’s iron is in haem?

A

1)4
2) Carbon-hydrogen-nitrogen porphyrin ring
Iron atom at the centre
3) 70%

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20
Q

Most haemoglobin is 2 alpha and 2 beta globin molecules, as well as 4 haem groups, what percentage of the other form is present and what does its structure consist of?

A

2.5%

2 alpha and 2 delta globin molecules, as well as 4 haem groups

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21
Q

What are the sources of iron in the diet?

A

red meats, fish, and poultry

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22
Q

How much haemoglobin is in a RBC?

A

Several hundred million , so lots

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23
Q

Describe what happens to Fe after after it has been ingested:

A

1) absorbed by active transport in intestine
2) binds to transferrin in plasma
3) a) stored as ferritin in liver
b) or bone marrow make haemoglobin and RBC, then HB goes into blood within RBC

24
Q

Why is excess iron stored in liver?

2) What is it stored as?

A

1) excess is toxic

2) Ferritin

25
Q

1) What causes hyperbilirubinemia?
2) What is this condition called?
3) What does 2) cause?

A

1) elevated levels of bilirubin in the blood
2) jaundice
3) causes the skin and whites of the eyes to take on a yellow cast.

26
Q

give 2 possible causes of jaundice?

A

1) liver disease, in which the liver is unable to process or excrete bilirubin
2) new borns are more susceptible as their fetal hemoglobin is being broken down and replaced with adult hemoglobin.

27
Q

How long are RBC able to circulate blood for?

A

about 4 months, 120 +- 20days

28
Q

Do RBC use the O2 they transport?

A

no, remeber they get ATP from glycolysis an anaerobic reaction

29
Q

What percentage of O2 is transported by haemoglobin?

Why is this not 100%?

A

98.5%

as oxygen is poorly soluble in plasma, so can be transported directly in plasma

30
Q

Explain why haemoglobin can appear red and blue?

A

Due to its iron content it appears reddish when combined with oxygen (oxyhaemoglobin) and bluish when deoxygenated.

31
Q

What 2 factors govern Hb’s ability to bind to O2:

A

1) the partial pressure of O2 (PO2) (which determines % saturation)
2) the number of free O2 binding sites available in the molecule. (Hb content per RBC x No. RBCs)

32
Q

A)State the percentage oxygen saturation of Hb at:
1) lungs
2) resting cell
3) excersizing tissue (aerobic)
B) In excersizing tissue (aerobic) compare its ppO2 to resting tissue:
C) Describe the reason for haemoglobin’s change in affinity for O2 when anaerobic respiration takes place:
D) What is the advantage of this?
E) What is this effect called?

A

1) almost 100%
2) 75%
3) lower than 75%,
B) less than that of resting (~40),
C) lactic acid is produced which reduces pH,= conformational change= reduce affinity
D) the lower affiniity means that more oxygen is released at active tissues
E) the bohr effect

33
Q

What 6 things can haemoglobin bind to?

A

1) O2
2) CO2
3) protons (H+ ions)
4) carbon monoxide
5) nitric acid
6) glucose

34
Q

1) Where does CO2 bind to on Hb?
2) What is the effeect of CO2 binding?
3) what percentage of venous blood CO2 is carried on HB?

A

1) covalently bind to the amino terminus of Hb
2) stabilise deoxyhaemoglobin favouring O2 release
3) 23%

35
Q

1) What generates protons in the blood?
2) Why does haemoglobin acts as a buffer?
3) What effect does the presence of oxygen have on haemoglobin bonded to a H+ ion have?

A

1) lactic acid from the reaction CO2 + H2O -> H+ + HCO3-
2) Haemoglobin can accept H+ as it has histidine, which is a basic amino acid. Moreover, deoxygenated haemoglobin has higher tendency to accept H+ ( it’s a better base as compared to oxygenated haemoglobin)
3) promotes H+ dissociation from Hb , so would favour formation of CO2 from H+ and bicorbante ion due to shift in equilibrium , and favours release of CO2 from Hb at lungs

36
Q

1) Why can carbon monoxide kill?

2) What are the sources of carbon monoxide?

A

1) out competes O2 for haem= no transport of O2

2) cigarette smoke and exhaust fumes.

37
Q

What effects does nitric oxide have within the body?

A

This is a vasodilator and binds preferentially to OxyHb (not at haem group, thiol), changes haem affinity for O2

38
Q

1) Describe the reaction that binds glucose to Hb:
2) What is the resultant molecule called?
3) What can this molecule being present in the blood indicate?

A

1) covalent bond formed using no enzeymes and is an irreversible reaction
2) glycated hemoglobin, glycohaemoglobin, HbA1C
3) indicate long term glucose fluctuations (8-12 weeks of fluctuations)

39
Q

What are the 2 classes of inherited disorders that decrease oxygen transport?

A

1) Haemoglobinopathies

2) Thalassaemias

40
Q

What is Haemoglobinopathies?

Give an example:

A

genetic defect that results in abnormal structure of one of the globin chains of the hemoglobin molecule.
sickle cell anemia

41
Q

What is Thalassaemias?

Give an example:

A

1) . Globin chains are normal, but are produced in decreased amounts, or are absent because of defects at the level of gene expression.
2) no example

42
Q

What is the difference between α thalassaemia, and β thalassaemia t?

A

In α thalassaemia, the production of α globin is deficient, while in β thalassaemia the production of β globin is defective.

43
Q

What are the symptoms of thalassaemia?

A 
Enlarged Spleen
Anaemia, small abnormally shaped RBC
Growth failure
Bone deformity in the face
Jaundice
44
Q

What are the effects of a thalassaemia on the body?

A

excess β chain production in adults. The excess β chains form unstable tetramers causing abnormal oxygen dissociation curves.

45
Q

What are the effects of β thalassaemia on the body?

A

excess α chains are produced, but these do not form tetramers: rather, they bind to the red blood cell membranes producing membrane damage, and at high concentrations have the tendency to form toxic aggregates.

46
Q

What is the molecular cause of sickle cell anemia?

2) Why does this result in change of shape?
3) Give the genotype of a person with sickle cell anaemia:
4) Where is the sickle gene more common?

A

The 6th amino acid, glutamate, in the 146-amino acid beta chain of hemoglobin is substituted for valine.

2) An abnormal haemoglobin (HbS) will crystalises when it gives up its oxygen ( as it is less soluble than normal haemoglobin), this produces long crystals of HbS that form fibrous intracellular precipitates. this pulls the cell into a sickle shape.
3) homozygote, HbSS
4) afro-caribbeans

47
Q

Why are sickle cell shaped RBC non advantageous?

A

1) There will be fewer RBC present as sickle cell shape is more fragile and rupture more frequently than normal RBC.
2) The sickle cell shape means RBC become tangled in smaller blood vessels= blockages = tissue damadge and pain from hypoxia.

48
Q

1) What is hypoxia?

2) Give one condition that may cause it?

A

1) deficiency in the amount of oxygen reaching the tissues.
2) homozygous sickle shaped RBC, Sickle cell shaped RBC become tangled in smaller blood vessels= blockages= tissue damage and pain from hypoxia

49
Q

Why is sickle cell anemia more common in afro-Caribbeans?

A

provides malaria resistance, someone who has the trait means the malaria parasite cannot manipulate their blood cells (actin).

50
Q

Define infarct

A

a small localized area of dead tissue resulting from failure of blood supply.

51
Q

What is sometimes mistaken for toothache?

A

painful infarcts in the jaw

52
Q

Give the symptoms of anaemia:

A

weakness, fatigue , dizziness, headaches and breathlessness,

and in the case of sickle cell anemia it causes painful infarcts in the jaw

53
Q

What are the disadvantages of blood transfusions?

A

1) the side effects
2) cost of storage
3) poor availability can cause donation shortages

54
Q

What are the possible side effects of receiving a blood transfusion?

A

1) transmission of infectious diseases,
2) patient is given immunosuppressions =higher incidence postop infection,
3) acute lung injury.- no idea why

55
Q

What is the treatment for thalassaemia?

A

Blood transfusions – regular blood transfusions are given to treat and prevent anaemia; in severe cases these are needed around once a month.
Chelation therapy – treatment with medications to remove the excess iron from the body that builds up as a result of having regular blood transfusions.

Stage 1 Blood (7 decks)

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