haematology: red cell physiology Flashcards

1
Q

What is erythropoiesis

A

Production of red blood cells

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2
Q

Where does erythropoiesis in fetus vs adult

A

Fetus: yolk sac then liver/spleen then bone marrow
Adult: bone marrow

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3
Q

What is the survival time of RBC & how are they removed

A

120 days
Removed from circulation by macrophages in the spleen

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4
Q

What is the development pathway of RBC

A

Stem cells becomes pro-erythroblast & ribosome synthesis occur forming early erythroblast
Hemoglobin accumulation occurs forming late erythroblast & nomoblast
Reticulocyte forms as nucleus gets rejected with some DNA fragment
Erythrocyte form once all DNA is removed

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5
Q

What hormone stimulates erythropoiesis

A

Erythropoietin

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6
Q

What is the pathway of EPO

A
  1. Cortical peritubular cells in kidney detect low oxygen
  2. EPO released & binds to EPO receptors triggering erythropoiesis
  3. Increase in RBC increase oxygen carrying capacity
  4. Adequate oxygen levels leading to decreased EPO production & RBC production
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7
Q

What is 4 structure & function relations in RBC

A
  1. Biconcave & discoid shape due to constant oxygen exchange over large surface area
  2. No nucleus due to low oxygen requirement for metabolism & carry oxygen for tissue
  3. Lipids & protein in cell membrane due to gaseous exchange
  4. Metabolic pathways due to ATP generation, maintain Hb in reduced state, reduce oxidative stress & generates 2,3-DPG to decrease affinity
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8
Q

What is the structure of hemoglobin in adults vs children <1 years

A

Tetramer with 2 pairs of globin chains with hemoglobin attached
Adults: HbA
Children: HbF

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9
Q

Where is hemoglobin synthesised

A

Mitochondria

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10
Q

What is the relaxed state of hemoglobin

A

Oxyhemoglobin
Release of oxygen at tissue due to decreased partial pressure of oxygen & low pH

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11
Q

What is the tense state of hemoglobin

A

Deoxyhemoglobin
Binds 2,3 -DPG leading to lower oxygen affinity (not rebind at tissue level) & binds to carbon dioxide & transport to lungs

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12
Q

What 4 things shifts the hemoglobin dissociation curve to the left

A

Increased pH, decrease 2,3-DPG, HbF, hypothermia

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13
Q

What 4 things shifts the hemoglobin dissociation curve to the right

A

Decreased pH, increase 2,3-DPG, HbS, hyperthermia

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14
Q

Is oxygen easily released in left or right shift

A

Oxygen is easily released at right shift due to higher P50 & decrease affinity for oxygen

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15
Q

What nutrients are required for synthesis of haemoglobin

A

Folate & vitamin B12 for DNA
Iron & amino acids for hemoglobin

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16
Q

What is the life cycle of RBC

A
  1. EPO from the kidneys stimulates erythropoiesis
  2. Erythrocyte is released into vessel & circulate for 120 days
  3. Spleen macrophages break down old erythrocytes into bilirubin, iron & amino acids
  4. Amino acids & iron get re-used in erythropoiesis as it circulates back to the bone marrow
  5. Liver processes bilirubin into bile & some gets excreted in feces & other in urine
17
Q

What does hemoglobin levels in FBC assess for

A

Anemia status

18
Q

What is hemoglobin levels in anemia indicating

A

Reduced levels leading to reduced oxygen carrying capacity

19
Q

What does MCV levels in FBC assess for & categories

A

Size of RBC
Microcytic: smaller than normal
Normocytic: normal
Macrocytic: larger than normal

20
Q

What does MCH/MCH levels in FBC assess for & categories

A

Color of red blood cells
Hypochromic: less hemoglobin & less color (bigger pale)
Normochromic: normal amount of hemoglobin
Hyperchromic: more hemoglobin & more color (no pale)

21
Q

What does MCHC measure

A

Correlates hemoglobin content with volume of cells (Hb/Hct)

22
Q

What does MCH measure

A

Average amount of hemoglobin in single RBC (Hb/RCC)

23
Q

What does RDW levels in FBC assess for

A

Variation in size & volume of RBC

24
Q

What does RCC levels in FBC assess for

A

Measurement of number of RBC

25
What does hematocrit/packed cell volume levels in FBC assess for
Volume of RBC/whole blood volume
26
What does reticulocyte count levels in FBC assess for
Immature RBC produce in bone marrow & released into peripheral blood (mature 1-2 days) Reflects RBC production
27
When is reticulocyte count elevated
Bleeding, nutrient repletion or EPO therapy
28
What is the purpose of peripheral blood morphology
Assess size & shape of RBC Used with FBC to provide clues for underlying disease