Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pathology 1 > RBC production and Survival > Flashcards

RBC production and Survival Flashcards

1
Q

What factors affect erythropoiesis?

A 
Eryhtropoietin 
Iron 
Vit B12
Folate 
Eryhtroid precursors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What treatment options are available for deficiencies in B12 & folate?

A

*B12 - Hydroxycobalamin 1mg im
Folate - Folic acid 5mg a day orally

*Hydroxycobalamin = injectible form of B12 given when B12 absorption problems in gut
B12 absorption involves IF made by gastric parietal cells.
TCI is secreted to prevent damage by salivary glands, protecing B12 from degradation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why does erythropoiesis occur?

A

Stimulated by hypoxia due to

  • Decreased RBC count
  • Decreased Hb
  • Decreased O2 availability
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What pathological factors is RBC production effected by?

A
  • Renal disease causes ineffective erythropoiesis
  • Reduced bone marrow erythroid cells causes aplastic
    anaemia and marrow infiltration by leukemia or other
    malignancies
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How is Iron obtained in the body?

A

Obtained via diet in meat, eggs, vegetables & dairy foods
5-10% absorbed (1mg) in duodenum and jejunum
Gastric secretion of HCl and absorbic acid aid absorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the different types of hereditary hemolytic anemia?

A

Hameoglobinopathies

  • Sickle cell diseases
  • Thalassemias

RBC enzymopathies

  • G6PD deficiency
  • PK deficiency

RBC Membrane disorders

  • Hereditary spherocytosis
  • Hereditary ellipocytosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the blood oxygen levels during homeostasis

A

Blood oxygen levels are normal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe Hereditary spherocytosis

A

Loss of membrane integrity - RBC becomes spherical

due to deficiency in proteins with vertical interactions between membrane skeleton and lipid bilayer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the causes of folate deficiency?

A

Inadequate intake
- Poor nutrition

Absorption defects

  • coeliac disease
  • Crohn’s dx
  • Tropical Sprue

Increased demands/losses

  • Pregnancy
  • Haemolysis
  • Cancer

Drugs
- anticonvulsants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the significance of the glycolytic pathway?

A

Glycolytic pathway generates ATP

  • to maintain RBC shape and deformabilty
  • Regulates intracellular [cation] via Na+/K+ pump
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the consequences of Pk deficiency?

A

PK deficiency is autosomal recessive
=> causes build up of glycolytic intermediates
(2,3-biphosphoglycerate which shifts oxygen diss.
curve to right) -> low O2 affinity
=> low intracellular ATP generation
affects membrane structure causing RBCs to have
arrowheads (irregularly contracted cells)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Outline the process of erythropoiesis due to hypoxia

A
  1. O2 levels reduced in blood
  2. Kidney (and liver) release EPO hormone
  3. Erythropoietin stimulates red bone marrow
  4. Enhanced erythropoiesis increases RBC count
  5. Increases O2 carrying ability of blood
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does the body destroy its own RBCs in AIHA?

A

AIHA anemic Red cells are coated with IgG alone or with a compliment enabling them to be taken up by rectoendothelial macrophages for degradation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How is folate transported around the body?

A

Folate weakly binds to albumin transport protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the evolutionary benefit of acute hemolysis?

A

G6PD deficiency is X linked
Pateints with G6PD deficiency have to avoid particular oxidative drugs
- (quinone based anti malaria drugs)
When G6PD deficiency is treated with primaquine leads to a mild/severe acute hemolytic anemia
stimulating H2O2 production
Providing protection against severe anemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the causes of iron deficiency?

A

Decreased uptake

  • inadequate uptake
  • malabsorption

Increased demand

  • pregnancy
  • growth spurt

Increased loss

  • GI bleed
  • Excess loss in menses
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the consequences of RBC integral proteins defetcs?

A

Defects in Ankyrin, Spectrin, Band 3 or protein 4.2 leads to destabilisation of the overlying lipid bilayer and release of lipids into microvesicles
Causes hereditary elipocytosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How does a PK deficiency cause mishapen RBCs?

A

ATP is depleted so cells lose large amounts of K+ & water
Cells become dehydrated and rigid
cation pump fails to function
Causes chronic non-spherocytic hemolytic anemia
=> excess haemolysis leads to jaundice and gall stones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the precursor stages of erythrocytes?

A

Hemocytoblasts -> proerythroblast -> early, late erythroblasts -> normoblast -> reticulocyte -> eyrthrocyte

20
Q

How does acute hemolysis occur?

A

Acute hemolysis caused by exposure to oxidant stress

Causes Hb to precipitate into heinz bodies

21
Q

What is menses?

A

Blood and other matter discharged rom the uterus during menstruation

22
Q

Where are globin genes found?

A

The genes for globin chains occur in clusters on chromosomes
- 11 ( Ɣ β δ and 𝜺 )
- 16 (α and ζ)
Expression of β and α globin chains is closely regulated

23
Q

What is the significance of Vit B12 and folate in erythropoiesis?

A

Both essential for RBC maturation and DNA synthesis
required for thymidine triphosphate formation
- (TTP nucleoside triphosphate used in vivo DNA
synthesis)

B12 is coenzyme for methionine synthase
- methylates homocysteine to methionine

24
Q

What is AIHA anemia?

A

Autoimmune hemolytic anemia is a group of rare but serious blood disorders caused by antibody
production by the body against own red cells
Divided into cold/warm depending on the antibody’s strength of reaction with red cell at 37℃ or 40℃

25
Q

What is sickle cell disease?

A

Group of Hb disorders with inherited sickle β globin gene

HbSS homozygous sickle cell is most common form

26
Q

What is eyrhropoietin?

A

Erythropoietin EPO is a glycoprotein cytokine secreted by kidneys in response to cellular hypoxia
=> stimulates erythropoiesis

27
Q

What is the effect of mutations in globin genes?

A

Abnormal synthesis of globin chains -> sickle cell disease

Reduced rate of normal globin synthesis -> Thalassemia

28
Q

What are the consequences of G6PD deficiency?

A

Hb and RBC usually protected by GSH from:

  • oxidant stress from H2O2 exposure
  • Certain medications
  • Infections
  • Foods

G6PD deficiency causes NADPH and GSH generation impairment

29
Q

What are the different forms of β thalassemia?

A

Mild microcytic anaemia - loss of 1 β globin gene
Thalassemia major - loss of both β globin genes
Ineffective erythrpoiesis caused by excess α chains precipitating in erythroblasts => haemolysis

30
Q

What is the consequnce of deficiencies in folate/B12?

A

Deficiencies in either can cause abnormal and diminished RBC production
- leading to failure of nuclear maturation
- cause megaloblastic anemia with macroovalocytes and
hypersegmentation

31
Q

Where in the gut is folate absorbed?

A

Absorbed at duodenum and jejunum

32
Q

What are the results of extra and intravascular hemolysis?

A

Extravascular haemolysis is normal in spleen and liver

Intravascular haemolysis releases Hb into plasma = abnormal

33
Q

How is Vitamin B12 obtained?

A

From animal origin foods, meat, fish, liver

Body stores 2-3mg daily sufficient for < 4 yrs

34
Q

Describe what acquired haemolytic anaemia is?

A

Can be immune

  • autoimmune
  • alloimmune
  • drug induced

or can be non immune

  • red cell fragmentation
  • infection
  • secondary
35
Q

How is eryhtropoiesis regulated?

A

Erythropoiesis is regulated by hormone EPO (eryhtropoietin)

36
Q

What is the significance of G6PD in the pentose phosphate pathway?

A
  1. G6PD catalyses the first step in the pathway necessary
    for NADPH production
  2. NADPH required for GSH (glutathionine) maintenance
    to protect RBC from oxidative damage

G6P converted to G6PD producing NADPH

37
Q

Where in the body is Vitamin B12 absorbed?

A

In the ileum

38
Q

How is α thalassemia caused?

A

Can be loss of 1,2,3 or 4 α globin chains

39
Q

What is hemolytic anemia?

A 
A form of anemia due to homolysis 
can be described as:
- Hereditary/Congenital 
- Intrinsic/Extrinsic
- Intravascular/Extravascular
40
Q

How is Vitamin B12 transported around the body?

A

Binds to TCI for transport

Binds to TCII for uptake

41
Q

What is the significance of the Pentose Phosphate pathway in RBCs?

A

10% of Red cell glucose is metabolised via Pentose phosphate pathway

42
Q

What is eryhtropoiesis?

A

The process of red blood cell production

43
Q

Where do we get folate into our body from?

A

Obtained from liver, greens and yeast
100-150g required daily
Body stores 10-12mg enough for 4 months

44
Q

What ar ethe 2 main enzymes involved in mature RBC metabolic pathways?

A 
Glucose-6-phosphate dehydrogenase (G6PD) : Glycolytic pathway 
Pyruvate Kinase (PK) : Pentose phosphate pathway
45
Q

What are the causes of Vitamin B12 deficiency?

A

Inadequate intake
- veganism

Absorption defect

  • Tropical sprue
  • Coeliac dx
  • Blind loop syndrome

Intrinsic Factor (IF) Deficiency

  • Pernicious anemia
  • Crohn’s
  • Gastrectomy etc.
46
Q

How are RBCs adapted to survive under stress?

A

Their life spans 120 days and can travel up to 300 miles through microcirculation in capillaries as small as 3.5um despite having a diameter of 7.8um

> red cells deformability enables them to squeeze
through spleenic sinus
RBC survival also dependent on cytoplasmic enzymes
involved in metabolic pathways

47
Q

What is hereditary elipocytosis?

A

Clinically milder than spherocytosis

Due to mutation sin horizontal protein, spectrin leading to defective spectrin-ankyrin association

Pathology 1 (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions