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PoM > Red Blood cells > Flashcards

Red Blood cells Flashcards

1
Q

What are haemopoietic stem cells(HSCs)?

A

Differentiate into different blood cell types as they are multipotenet

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2
Q

What are the sites of haemopoeisis?

A

embryo-MESODERM 5-8 weeks -fetal liver After birth-bone marrow Adulthood-restricted tot he bone marrow of the pelvis, vertabrae+sternum, long bones(thighs and arms)

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3
Q

Draw the blood stem cell hieracrchy?

A

Multipotent haemopoeitic stem cell: ->common myeloid progenitor ->common lymphoid progenitor Common Myleoid: ->megakaryocyte ->Mast cell ->Erthrocyte ->myeloblast->neutrophil, eosinophil, basophil, monocyte->macrophage Common lymphoid progenitor: ->Natural killer cell ->small lymphocyte-> t cell + b-cell->plasma cell

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4
Q

What are the 2 essential characteristics of haemopoetic cells?

A

SELF RENEW-some daughter cells remain as HSCs so the pool is not depleted DIFFERENTIATE in to different types of blood cells

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5
Q

What do myeloid stem cells give rise too?

A

proerythroblasts->erythroblasts-> erythrocytes

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6
Q

How does being bioconcave help erythrocytes?

A

helps them manoevoure through the small blood vessels

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7
Q

What is the name of the process where red blood cell develop?

A

erythrpoeisis

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8
Q

What is needed to stimulate the development of red blood cells?

A

erythropoietin

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9
Q

Where are red blood cells produced?

A

90% in the JUXTATUBULAR INTERSTITIAL CELLS in the KIDNEYS 10% in the HEPATOCYTE and interstitial cells in the LIVER

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10
Q

Describe adult haemoglobin?

A

-4 globin chains(polypeptides)-> 2 alpha chains and 2 beta chains -each globin chain is attatched to a haem group -HAEM GROUP= fe2+ held in a PORPHYRIN RING

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11
Q

How does hsaemoglobin F differ form haemoglobin A?>

A

-has a higher affinity for oxygen -is made up of 2 alpha and 2 GAMMA CHAINS(INSTEAD OF BETA CHAINS) -facilitates the transport of oxygen from the mother to the foetus -structurally similar tbh

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12
Q

Where is iron absorbed and in what form?

A

-DUODENUM NON HAEM: - in Fe2+ form(FERROUS) which is most easily absorbed form - found in meat HAEM: -in the Fe3+ form (FERRIC)which is not as easily absorbed so take vitamin C(reduces it) with it to help absorption -usually found in soya beans etc

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13
Q

What is the problem of eating soya beans to get your iron from?

A

-It also contains PHYLATES which reduces absorption

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14
Q

Why is iron absorption tightly controlled?

A

-because too much can be TOXIC -and there is no mechanism to EXCRETE iron so only 1-2mg is absorbed from the diet per day

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15
Q

What blocks the absorption and release of storage iron?

A

HEPCIDIN-important to stop iron overload

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16
Q

How is iron absorption increased and decreased?

A

ERYTHROPOIETIC ACTIVITY: INCREASES -supresses hepcidin synthesis -increase ferroportin in duodenum enterocytes=increase in iron absorption BODY IRON STORE FULL/HIGH: DECREASES =HEPCIDIN SYTHESIS INCREASE=increases secretion from the liver. This then binds to the FERROPORTIN in the duodenum(where iron absorption occurs)and DEGRADES it =decreases iron absorption

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17
Q

What are enterocytes?

A

intestinal absorptive cells

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18
Q

What is the function of Ferroportin?

A

-Ferroportin is the only known iron exporter -After dietary iron is absorbed into the cells of the small intestine, ferroportin allows that iron to be transported out of those cells and into the bloodstream.

19
Q

What is needed for DNA synthesis?

A

-B12 and FOLATE-because these are needed for the synthesis of dTTPs,one of the 4 precursors of DNA

20
Q

What can the defficiency of B12 and Folate lead too ?

A

-effects all RAPIDLY DIVIDING CELLS: -bone marrow cells grow but cant divide properly -epithelial surface of the mouth an dgut -gonads

21
Q

What are sources of B12 and Folate?

A

B12: -meat -liver+kidney -fish -oysters and clams -eggs -milk and cheese -Fortified cereal Folate: -green leafy veg -cauliflower -brussel sprouts -liver and kidney -whole grain cereals -yeast -fruit

22
Q

How is B12 absorbed?

A

1) STOMACH: B12 combines with INTRINSIC FACTOR (IF) made in the GASTRIC PARIETAL CELLS 2)SMALL INTESTINE:B12-IF binds to The receptors in ILEUM

23
Q

What 3 main things can cause deficiency in B12?

A

-Inadequate intake e.g. veganism -inadequate secretion of IF e.g. pernicious anaemia leads to atrophy of stomach so cant absorb B12 -Malabsorption

24
Q

What is the life cycle of a red blood cell?

A

1-circulates the blood for 120 days 2- destroyed by macrophages in the SPLEEN 3-Iron from haemoglobin is stored in macrophages as FERRITIN or HAEMOCYDRIN 4-Fe-transferinin in the blood plasma transports iron from the haem in macrophages to the bone marrow=recycled to from new red blood cells

25
Q

What does Fe-transferin do?

A

transports iron from the haem in macropahges to the bone marrow=recycled to form new red blood cells

26
Q

How do you describe the size of a red blood cell?

A

Microcytic-smaller than normal Normocytic -bigger than normal Macrocytic-larger than normal

27
Q

What are the types of macrocytes and how does this help with the diagnosis?

A

POLYCHROMATIC ROUND OVAL -people defficient in B12 + folic acid have both round and oval macrocytes =helps diagnosis

28
Q

What should the colour of red blood cells be when stained?

A

-1/3 of the diameter is pale due to the centre of RBCs having LESS Hb

29
Q

What is hypochromia? What other cell feature/type is often seen with hypochromia?

A

-LARGER area of CENTRAL PALLOR than normal(more larger pale centre of cell) -indicates too little Hb and FLATTER CELLs -MICROCYTOSIS- as both result from a lack of Hb

30
Q

What is polychromasia? What other cell feature/type is often seen with polychromsia?

A

-BLUE TINGE to CYTOPLASM of the RBC -indicates cell is young -MACROCYTE

31
Q

How do we detect young RBCs/Reticulocytes?

A

-hard to do based on colour(blue tinge) alone as this can be objective -use special stain(methyl blue) as this stains there higher RNA content

32
Q

What is reticulocytosis?

A

-Increased number in reticulocytes-could be response to bleed or red blood cell destruction or anaemia

33
Q

What is anisocytosis and poikilocytosis?

A

Anisocytosis-red cells show more variation in SIZE than normal Poikilocytosis-red cells show more variation in SHAPE than normal

34
Q

What are the 6 different shapes of Poikilocytes?

A

SPHEROCYTES-spherical IRREGULARLY CONTRACTED CELLS-irregular SICKLE CELLS-cresent shape TARGET CELLS-has a dot in middle ELLIPTOCYTES-elliptical shaped FRAGMENTS-piece of red cell

35
Q

Describe ‘target cells’ and when they develop?

A

-red blood cell with an accumulation of Hb in the centre of area of central pallor Develop when: -obstructive Jaundice -liver disease -haemoglobinopathies-abnormal haemoglobin -hyposplenism-spleen removed/non-functioning spleen

36
Q

How do sickle cells form?

A

POLYMERISATION of Hb S happens when the cell is exposed to low oxygen -occurs when 1 or 2 copies of abnormal B GLOBIN GENE are inherited -if 2 copies of the abnormal gene is inherited then you get sickle cell anaemia as 95% of Hb is Hb S -If you get 1 copy then only 45% of your Hb is Hb S - no sickle cell anaemia

37
Q

What is a sympton vs a sign?

A

Sympton-How a patient feels sign-physical ting

38
Q

What is a sign of anaemia vs symptom?

A

symptom-patient feels tried sign-blood is thin due to less Hb so when blood is viewed theres lots of space between the RBCa

39
Q

What is the ‘normal’ affected by?

A

-age -gender -ethnic origin -physiological statis -altitude -nutritional status -cigarette smoking -alcohol intake e.g. people living at higher altitudes have a different normal level of Hb

40
Q

What is the reference range and how is it derived?

A

-something you refer back too from a refernce population that is carefully defined: -samples collected from healthy people with DEFINED CHARACTERISTIC -analysed using INSTRUMENT AND TECHNIQUES used for patient samples -data analysed by appropriate STATISTICAL TECHNIQUE

41
Q

How is the normal range usually derived?

A

from comparing many reference ranges

42
Q

How do you analyse data with normal and non-normal distribution?

A

NORMAL -determine the mean and standard deviation and take mean +2SDs (1.96 to be precise) as 95% range NON-NORMAL- find appropriate statistical technique then take the mean and SDs -not all the data outside reference range is abnormal as we’ve excluded top and bottom 2.5% and not all results within range are normal

43
Q

How do you interpret red cells on blood count?

A

Examine and describe: -shape, size, age, poikilocytes Check fro clues in blood count and clinical history Question whether your reference range represents health for certain individuals

PoM (4 decks)

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