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Medical Studies 1 > 10.2 Erythropoiesis > Flashcards

10.2 Erythropoiesis Flashcards

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USMLE® Step 1 flashcards
1
Q

What are the functions of blood?

A
  • pH and electrolyte homeostasis
  • Has exchange
  • Temperature regulation
  • Hormone and cytokine distribution
  • Distribution of immune effectors
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2
Q

In which areas of bone marrow does haematopoeisis occur in adults vs infants?

A
  • Infants: all bone marrow is haematopoietic
  • Adults: axial skeleton; pelvis, ribs, sternum, skull
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3
Q

What % of adult bone marrow is fat?

A

30-70%

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4
Q

What does normal bone marrow contain?

A
  • Dissolved bubbles of fat
  • Haematopoietically active cells
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5
Q

How are mature cells released from bone marrow into peripheral circulation?

A

Through sinusoids (like in the spleen)

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6
Q

Why do our stem cells divide so slowly?

A

Because every time they do, there is a risk of mutation

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7
Q

List some normal stressors that can cause an increase in erythropoiesis

A
  • Vigorous exercise
  • Pregnancy
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8
Q

Do blood loss and infection increase or decrease haematopoiesis?

A

Increase

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9
Q

Wht are hematopoietic growth factors? How do they regulate haematopoiesis?

A
  • They are small glycoproteins
  • They can act in a paracrine/autocrine fashion locally, or an endocrine fashion throught the circulation
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10
Q

What is the purpose for the bi-concave structure of RBCs?

A

To wishstand shear forces and enable them to pass through small gaps

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11
Q

What is the main function of red blood cells?

A

To carry oxygen and deliver it throughout tissues in the body

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12
Q

As Hb binds to oxygen, does its affinity for more O2 increase or decrease?

A

It increases, until the Hb is saturated

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13
Q

Describe the structure of haemoglobin

A
  • 2 alpha-like chains
  • 2 beta-like chains
  • Complexed with haem molecule containing Fe, which is what oxygen binds to
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14
Q

Describe the structuure of a heme haem

A

Small molecule containing iron

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15
Q

What is the earliest precursor to an RBC?

A

Proerythroblast

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16
Q

What changes occur to a proerythroblast as it becomes an RBC?

A
  • Changes from blue, to purple, to red
  • Cell size decreases
  • Nucleus shrinks and disappears
17
Q

How does proerythroblast cytoplasm change colour during RBC development?

A
  • Starts out quite basophilic
  • Begins to accumulate haemoglobin
  • Takes on pale pink colour
18
Q

Which two vitamins are most important for DNA synthesis?

A
  • Folic acid
  • Vit B12
19
Q

Where does haem synthesis occur at different points in the process?

A
  • Starts in mitochondria
  • Then, occurs in cytoplasm
  • Finally, finishes up in mitochondria again
20
Q

Describe the different types of haemoglobin present before and after birth. How does this influence disease processes?

A
  • Until birth: Hb F [foetus] (alpha 2 gamma 2)
  • During first 6 months: replaced with Hb A [adult] (alpha 2 beta 2), and a little of Hb A2 (alpha 2 delta 2)
  • This means that, if there is some defect in the beta chain, it may not be seen until 6 months of age
21
Q

Does a small/large amount of haemoglobins molecular weight consist of glycosilation? How does this influence its biological activity?

A
  • High amount is glycosylation
  • This means it has high biological activity
22
Q

Where is EPO released from within the kidneys?

A

Juxtaglomerular apparatus: specialised interstitial fibroblasts

23
Q

Describe the different cells produced in the production of erythrocytes

A
  • Proerythoblast
  • Early/intermediate/late erythroblast
  • Nuclear extrusion
  • Reticulocyte (network cell)
  • RBC
24
Q

Describe the feedback loop of the kidneys in response to low O2 sats

A
  • Detected by kidneys
  • Kidneys release EPO into blood
  • Travels to bone marrow, and stimulates erythropoiesis
  • O2 carrying capacity increases
  • More blood returns to kidneys
  • EPO release is shut down
25
Q

Do RBCs have regenerative capacity?

A
  • No
  • They are bags of haemoglobin, there’s nothing they can do to fix themselves
26
Q

Describe RBC death

A
  • Loss of lipid membrane
  • Surface signs of oxidative stress
  • Detected by macrophages (e.g. in spleen)
  • Phagocytosed; iron recycled
27
Q

Does it make sense to produce lower or higher weight EPO when produced recombinant EPO for therapeutic purposes?

A

Higher -> more glycosylated -> more biologically active

28
Q

RBC lifespan is…

A

120 days

Medical Studies 1 (90 decks)

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