lec3: Regulation of erythropoeisis Flashcards
Requirements for erythropoiesis:
-Normal functioning : bone marrow , kidneys , liver Hormones Proteins iron Vitamin B12 and folic acid
the site of erythropoiesis is ………………….
Bone marrow
Kidneys secrete ……………….of erythropoietin hormone
85%
iron and vitamin B12 stores in
liver
where does the globin part of hemoglobin synthesizes?
in liver
liver secretes ……………….. of erythropoietin
10 %
which hormones are stimulate erythropoiesis
Androgens
thyroxine
glucocorticoids
which hormones are inhibits erythropoiesis
estrogen
why Proteins of high biological value are important in erythropoiesis?
to build up the globin part of Hb.
the principle constituent of Hb molecule……..
iron
why Vitamin B12 and Folic acid are called “Maturation factors”??
as they are essential for normal formation of DNA and cell division
Deficiency of vitamin B12 and Folic acid results in
……………………….
megaloblastic or macrocytic anemia
cofactors for the formation of Hb…………… , …………..
Copper and cobalt
the most important regulator of erythropoiesis is
Tissue oxygenation
Erythropoietin is ……………….
Glycoprotein
Erythropoietin Comes from:
❖………………. kidneys
❖ ……………….. liver
85-90% kidneys
15-10% liver
Negative feedback control of erythropoiesis
Hypoxia
Stimulates
erythropoeitin production
Increase RBCs production
Factors stimulating erythropoietin secretion:
- Hypoxia
- Hormones
- Alkalosis as in high altitudes
Hormones stimulating erythropoietin secretion:
androgens (testosterone), catecholamines,
corticosteroids, growth hormone, and thyroxin increase
erythropoietin secretion
………………..is associated with anemia that can
be treated only by erythropoietin
Renal failure
in……………. the stem cells do not respond to erythropoietin
aplastic anemia
-Iron intake ……………
15-20 mg%
Absorbed iron ……………………………
(3-6%of the intake)
-Iron homeostasis depends on………………………………
control of iron absorption from the intestine (Duodenum)
Iron functions in the body
HB synthesis
myoglobin synthesis
cytochrome oxidase , peroxidase , catalase
total body iron ……….
4-5 g
Iron absorption in …………….
duodenum
Heme absorption Through the enterocyte ………………….
Heme carrier protein (HCP-1)
Iron is released from heme by …………………..
Heme oxygenase enzyme
Fe2+ is transported out of the enterocyte by the …………………………………………
basolateral membrane protein (ferroportin)
Ferrous iron is transported into the enterocyte with a proton via a …………………………………………
divalent metal transporter (DMT-1).
Ferric is reduced by ferric reductase helped by ………………. to ferrous iron
HCL,
vitamin C
Hepcidin Hormone Released from ………….when …………………..
liver
iron levels are high
which hormone Inhibit ferroportin transporter?
Hepcidin
Hepcidin deficiency causes……………………………….
tissue iron over load
Regulation of iron absorption by
hepcidin
Hypoxia, erythropoeisis Depleted iron stores increase iron absorption Saturated iron stores Liver releases hepcidin Hepcidin inhibits ferroportin
Factors Increase iron absorption
Gastric acidity, vitamin C aids iron reduction Increased erythropoietic activity e.g. bleeding, hemolysis, high altitude. Increased demamd Infancy, adolescence
Factors Decrease iron absorption
Phytic acid, oxalates and phosphates form insoluble salts Iron overload Calcium in dairy food
Heme iron is absorbed better than…………………..
inorganic iron.
Ferrous iron is absorbed better than ……………
ferric iron
Iron is transported as transferrin normally …………. saturated
35%
Iron is stored as………….. in the…………………..
ferritin
hepatocytes
…………… is the predominant storage form. It keeps
iron in a ………….. and …………..form
Ferritin
soluble
non-toxic
Excess iron is stored as…………………….
hemosiderin
Iron deficiency Can result in …………………… due to ……………………………………..
microcytic hypochromic anemia
decreased hemoglobin synthesis and RBC size.
…………………and…………………… are
essential for normal formation of DNA and hence for nuclear maturation.
vitamin B12 and folic acid
……………………. is absent from plant sources
Vitamin B12
The minimum requirement of Vitamin B12 is ……………….
1-3 microgram/day
Folic acid and vitamin B12 Absorbed in terminal ileum by ………………………
endocytosis
Vitamin B12 deficiency Leads to a condition called …………….
pernicious anemia or megaloblastic anemia (macrocytic anemia).
in Vitamin B12 deficiency Neurological disorders are due to ………………………..
progressive demyelination of nervous tissue
pernicious anemia……………………………………………….
Large immature erythrocytes
…………………. is the site for blood cells production.
Bone marrow
………………….. is the most essential regulator of RBC production and erythropoietin
Tissue hypoxia
………….. is the principle stimulus for RBCs production in low O2 states,
Erythropoietin hormone
………………of Erythropoietin hormone comes from the kidneys
85-90%
Anemia occurs in ……………………………..
kidney diseases
High altitude, lung diseases, anemia, poor blood flow and relative lack of oxygen in athletes lead to…………..and stimulate……………………………..
hypoxia
erythropoietin hormone secretion
………………… forms the heme part of Hb
Iron
iron is absorbed from the intestine helped by …………….
gastric
HCL and Vitamin c is carried as ……………
transferrin
HCL and Vitamin c is stored as ……….and…………..
ferritin and hemosiderin.
Vitamin B12 absorption depends on the presence of the…………. secreted from the parietal cells in the stomach.
intrinsic factor
…………….. is important for myelin sheath production
Vitamin B12
Healthy bone marrow and normal liver and kidneys are essential for ……………………….
erythropoiesis