Red Blood cells

Question 1

What are haemopoietic stem cells(HSCs)?

Answer 1

Differentiate into different blood cell types as they are multipotenet

Question 2

What are the sites of haemopoeisis?

Answer 2

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)

Question 3

Draw the blood stem cell hieracrchy?

Answer 3

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

Question 4

What are the 2 essential characteristics of haemopoetic cells?

Answer 4

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

Question 5

What do myeloid stem cells give rise too?

Answer 5

proerythroblasts->erythroblasts-> erythrocytes

Question 6

How does being bioconcave help erythrocytes?

Answer 6

helps them manoevoure through the small blood vessels

Question 7

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

Answer 7

erythrpoeisis

Question 8

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

Answer 8

erythropoietin

Question 9

Where are red blood cells produced?

Answer 9

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

Question 10

Describe adult haemoglobin?

Answer 10

-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

Question 11

How does hsaemoglobin F differ form haemoglobin A?>

Answer 11

-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

Question 12

Where is iron absorbed and in what form?

Answer 12

-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

Question 13

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

Answer 13

-It also contains PHYLATES which reduces absorption

Question 14

Why is iron absorption tightly controlled?

Answer 14

-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

Question 15

What blocks the absorption and release of storage iron?

Answer 15

HEPCIDIN-important to stop iron overload

Question 16

How is iron absorption increased and decreased?

Answer 16

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

Question 17

What are enterocytes?

Answer 17

intestinal absorptive cells

Question 18

What is the function of Ferroportin?

Answer 18

-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.

Question 19

What is needed for DNA synthesis?

Answer 19

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

Question 20

What can the defficiency of B12 and Folate lead too ?

Answer 20

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

Question 21

What are sources of B12 and Folate?

Answer 21

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

Question 22

How is B12 absorbed?

Answer 22

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

Question 23

What 3 main things can cause deficiency in B12?

Answer 23

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

Question 24

What is the life cycle of a red blood cell?

Answer 24

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

Question 25

What does Fe-transferin do?

Answer 25

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

Question 26

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

Answer 26

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

Question 27

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

Answer 27

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

Question 28

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

Answer 28

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

Question 29

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

Answer 29

-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

Question 30

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

Answer 30

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

Question 31

How do we detect young RBCs/Reticulocytes?

Answer 31

-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

Question 32

What is reticulocytosis?

Answer 32

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

Question 33

What is anisocytosis and poikilocytosis?

Answer 33

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

Question 34

What are the 6 different shapes of Poikilocytes?

Answer 34

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

Question 35

Describe 'target cells' and when they develop?

Answer 35

-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

Question 36

How do sickle cells form?

Answer 36

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

Question 37

What is a sympton vs a sign?

Answer 37

Sympton-How a patient feels sign-physical ting

Question 38

What is a sign of anaemia vs symptom?

Answer 38

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

Question 39

What is the 'normal' affected by?

Answer 39

-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

Question 40

What is the reference range and how is it derived?

Answer 40

-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

Question 41

How is the normal range usually derived?

Answer 41

from comparing many reference ranges

Question 42

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

Answer 42

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

Question 43

How do you interpret red cells on blood count?

Answer 43

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