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Clinical Pathology > UNIT 1 - Lecture 1: RBC Production, Structure, & Function > Flashcards

UNIT 1 - Lecture 1: RBC Production, Structure, & Function Flashcards

1
Q

What are the 2 main functions of RBCs?

A
  1. Transport O2 to tissues
  2. Transport CO2 and H+ to the lungs
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2
Q

What is an erythron?

A

Refers to ALL erythroid cells in the body (mature/immature, in bone marrow, spleen, and circulation)

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3
Q

What is hematopoiesis?

A

Production of all blood cells

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4
Q

What is erythropoiesis?

A

RBC production in bone marrow

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5
Q

What is granulopoiesis?

A

WBC production in bone marrow

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6
Q

What is thrombopoiesis?

A

Platelet/thrombocyte production in bone marrow

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7
Q

What are hematopoietic cells?

A

All precursors to blood cells found in blood or tissues (immature cells)

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8
Q

What is anemia?

A

Decreased #s of RBCs

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9
Q

Anemia results in decreased _____ capacity.

A

oxygen carrying

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10
Q

When does anemia occur?

A

When RBC production is < RBC loss

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11
Q

What is absolute erythrocytosis?

A

Increased #s of RBCs

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12
Q

What can absolute erythrocytosis result in?

A

“sluggy” blood

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13
Q

When does absolute erythrocytosis occur?

A

When RBC production is > RBC loss

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14
Q

Where does hematopoiesis primarily happen?

A

Bone marrow - particularly axial and long bone central cavities in mammals

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15
Q

What organs are involved in extramedullary hematopoiesis (fetal and adult)?

A

Fetal = spleen, liver

Adult = spleen, liver (but can occur in other sites)

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16
Q

Bone marrow is tissue enclosed by _____ and _____ bone comprised primarily of _____ cells, _____, and supportive _____ tissue.

A

cortical, trabecular, hematopoietic, fat, stromal

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17
Q

How are nutrients delivered to bone marrow?

A

Through arteries entering the cortical bone

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18
Q

How do new hemic cells enter blood?

A

Through walls of the bone marrow sinuses

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19
Q

New blood cells develop in supportive microenvironment controlled by local and systemic _____ and _____.

A

cytokines, hormones

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20
Q

What are Howell-Jolly bodies?

A

Small fragments of non-functional nuclear material not extruded when the RBC left the bone marrow.

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21
Q

In health, ___% of old cells are destroyed each day and balanced by replacement with new cells.

A

~1%

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22
Q

When may the bone marrow respond with increased or decreased hematopoiesis?

A

In disease states

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23
Q

How long does maturation from rubriblast to erythrocyte take?

A

~5-7 days

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24
Q

What is the last RBC stage with a nucleus?

A

metarubricyte

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25
What are the 3 major "pools" for blood cells and what cell types are in each?
1. Bone marrow = precursors 2. Blood = RBCs 3. Spleen = RBCs in health; precursors during increased EMH
26
What is erythropoietin (EPO) and where is it produced?
Main hormone promoting erythropoiesis, produced in the kidney (mostly) and liver.
27
What stimulates EPO synthesis?
Tissue hypoxia
28
High EPO levels promotes increased _____ to help increase \_\_\_\_\_.
erythropoiesis, oxygenation
29
Other than EPO, what else regulates erythropoiesis?
Cytokines, other hormones, growth factors
30
What two things cause decreased erythropoiesis?
Inflammatory cytokines and abnormally high levels of estrogen
31
What is the structure of RBCs in most mammalian spp and why?
Biconcanve discs; allows for deformability so that RBCs can move through small vessels without loss of structural integrity
32
What shape RBC do camelids have?
oval
33
What type of RBC do birds, fish, and reptiles have?
nucleated
34
What spp has the most evidence of RBC central pallor?
dogs
35
What are the main RBC components?
1. Hgb 2. Membrane & cytoskeleton 3. Enzymes for metabolism
36
What is the structure of Hgb?
2 alpha and 2 beta globin chains Heme unit (protoporphyrin IX ring with ferrous iron in center)
37
What is the structure of the RBC membrane?
Lipid bilayer embedded with cholesterol and membrane proteins
38
What is the cytoskeleton structure of an RBC?
Protein web attached to lipid bilayer via the membrane proteins
39
Normal heme molecules contain _____ iron.
ferrous
40
Normal heme molecules have ___ electron pairs.
6
41
What are the electron pairs of normal heme molecules bound to?
4 = protoporphyrin ring 1 = histidine of globin chain 1 = available for binding oxygen
42
Methemoglobin has _____ iron.
ferric
43
Methemoglobin has ____ electron pairs.
5
44
Which electron pair does Methgb lack?
1 needed to bind O2
45
How much of total Hgb is methgb?
\< 1%
46
Hgb synthesis requires \_\_\_\_\_.
mitochondria
47
What are the 3 major steps of Hgb synthesis?
1. Series of porphyrin reactions 2. incorporation of ferrous iron into protoporphyrin IX to form heme 3. Binding of the 4 ferriheme and 4 globin molecules to form Hgb
48
What are porphyrins?
Heme precursors from porphobilinogen to protoporphyrin IX
49
What is porphyria?
Increased concentrations of porphyrins in RBCs, plasma, and urine.
50
Porphyria can be _____ or \_\_\_\_\_.
congenital, acquired
51
5-ALA synthase, porphobilinogen synthase, and ferrochelatase are inhibited by _____ in porphyria.
lead
52
Some porphyrins absorb UV light causing oxidative damage, leading to _____ in some animals.
photosensitivity
53
Some porphyrias result in a _____ anemia.
hemolytic
54
Defects of the _____ can impact RBC deformability and result in abnormal RBC shapes.
cytoskeletal proteins
55
What are some examples of disorders of the RBC cytoskeleton?
1. Hereditary band 3 deficiency - Japanese black cattle 2. Hereditary elliptocytosis in dogs 3. Spectrin mutation 4. Spectrin deficiency
56
What RBC metabolic pathway is used for energy?
Embden-Meyerhoff pathway (anaerobic glycolysis)
57
What RBC metabolic pathway is used to maintain Hgb?
Pentose phosphate pw Methgb reductase pw
58
What RBC metabolic pathway is used for oxygenation?
Rapaport-Luebering pathway (DPG shunt)
59
The DPG shunt produces _____ at the expense of \_\_\_\_\_.
DPG, ATP
60
What are some things that RBCs use energy for?
1. Maintain shape and deformability 2. Phosphorylate membrane phospholipids and proteins 3. Have active membrane transport 4. Synthesize nucleotides 5. Synthesize glutathione (antioxidant)
61
The main substrate for energy is _____ in all domestic spp except the \_\_\_\_\_. _____ is the major substrate in their RBCs.
glucose, pig, inosine
62
The pentose phosphate pathway produces \_\_\_\_\_.
NADPH
63
How does the pentose phsophate pathway maintain Hgb?
Reduces glutathione --\> reduced glut. neutralizes oxidants that denatures Hbg
64
Enzyme deficiency in the Mthgb pathway results in \_\_\_\_\_.
methgb accumulation
65
What is the fate of aged RBCs?
Phagocytosed by MPs in the spleen, liver, or bone marrow
66
What is significant about cat spleens and RBC senescence?
Cats have closed splenic circulation --\> blood does not flow thru red pulp --\> less efficiency removing damaged RBCs --\> lack large RBC reserve pool
67
What happens to free Hgb that is released directly into circulation?
Dissociates into dimers --\> bind haptoglobin --\> complex broken down in liver --\> bilirubin, globin, iron
68
What happens to free heme in circulation?
Binds hemopexin --\> complex broken down in liver --\> bilirubin, globin, iron
69
Other than binding haptoglobin, what else can happen to free Hgb?
Can be filtered thru the kidney (can be nephrotoxic); Some can be resorbed but if capacity is exceeded you will see hemoglobinuria.
70
Birds and reptiles lack biliverdin reductase enzyme, so they do not produce \_\_\_\_\_.
bilirubin
71
How is Hgb recycled?
Heme porphyrin ring --\> biliverdin --\> bilirubin Iron --\> stored in marrow and liver
72
Where is iron from senescent RBCs stored?
In Fe/protein complexes inside MPs or hepatocytes as ferritin or hemosiderin
73
Fe circulates in blood bound to \_\_\_\_\_.
apotransferrin

Clinical Pathology (22 decks)

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