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42 Cards in this Set
- Front
- Back
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how is iron regulated in the intestine when taken in? |
1) on the apical side (toward the lumen) of the intestine there is DMT1 (divalent metal transporter) that takes in H+ and Fe2+ 2) Fe2+ gets stored as Fe3+ by protein Ferritin 3) iron moves down its conc. gradient through ferroportin which is on the basolateral side 4) on ECM side it is secreted as Fe2+ |
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what happens when you what to stop getting iron? |
you use hepicidin, which is secreted by liver cells, it binds to ferrroportin and blocks it |
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what is the role of ferritin? |
it is a iron recycling bin in enterocytes and liver |
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how can iron be used? |
50% by Hb 30% liver |
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what are the trends in iron absorption in the body? |
it is slow despite diet high in iron iron depletion is ongoing iron stores must be replaced |
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Why is it important to regulate iron absorption? |
it can build up in the body and cause problems to a variety of issues when the liver stores become saturated total body levels of iron are carefully controlled at the level of iron absorption |
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How is iron taken into cells? |
transferrin cycle |
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what kind of affinity does transferrin with Fe3+ have with the receptor at neural ph? |
high affinity (at ECM) |
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what kind of affinity does transferrin without Fe+3 have with the receptor at acidic ph (5.0)? |
high affinity with receptor |
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what kind of affinity does transferrin without Fe+3 have with the receptor at neutral ph? |
low affinity |
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when does transferrin have high affinity for the receptor? |
when it has Fe3+ bound at neutral ph (at ECM) cell surface and when without Fe3+ at acidic ph in endosome! |
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what are the steps of transferrin cycle? Briefly. |
1) Fe+3 loaded transferrin binds to cell surface receptor (transferrin receptor) at neutral ph (7.4) 2) transferrin internalizes via endocytosis in membrane coated vesicle 3) ph of endosome lumen becomes acidic and Fe+3 dissociates, transferrin remains stuck to the receptor 4) apo-trasnferrin (no Fe+3) dissociates from the receptoral at neutral ph. |
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what is anemia? |
lack of red blood cells or hemoglobin |
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what causes anemia? |
loss of blood deceased red blood cell production due to iron deficiency increased destruction of red blood cells: hemolytic anemias |
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what is a hemolytic anemia? |
increased destruction of red blood cells |
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what is hemochromatosis? |
iron overload hereditary forms, as well as non-hereditary |
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what causes hemochromatosis? |
severe forms result from: hepcidin resistant ferroprotin |
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what organs does hemochromatosis affect? |
liver heart endocrine organs |
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What are the characteristics of lipid transport? |
absorption is not straight forward through our intestinal tract proper absorption requires emulsification (bile action) by the liver transport in body requires transport vesicles |
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How does dietary lipid absorption work? Briefly. |
1) bile salts from liver coat fat droplets in the lumen of small intestine 2) here, they are made smaller and smaller due to emulsion and are turned into micelles 3) pancreatic lipase and colipase break down fats into monoglycerides and fatty acids stored into micelles ----- 4) monoglycerides andfatty acids move out of micelles and enter cells of small intestine by diffusion 5) cholesterol is transported into cells as well 6) in the ER, fats combine with cholesterol and proteins in the intestinal cells to form chylomicrons 5) golgi apparatus secretion of chylomicrons to the interstitial fluid 6) lacteals in lymphatic system remove chylomicrons |
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what is the lipoprotein structure? (chylomicrons) put together in enterocytes (intestine) |
Apolipoprotein phospholipids tryglycerides cholesterol |
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does lipid get into our bloodstream? |
only through the lympathic system (leads to vena cava) |
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what does lipid transport post-absorption consist of? |
1) from lacteals to the blood stream, lipids travel in chylomicrons throught the body 2) adipose cells can extract lipids (lipoprotein lipases) 3) chylomicrons remnants are metabolized by the liver 4) excess cholesterol and triglycerides can be stored by the liver 5) liver can send lipids to the rest of the body in water-soluble carriers: these are not chylomicrons, called LDL 6) adipose can send lipids to the liver in similar carriers |
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what are the types of lipoproteins? |
Chylomicrons VLDL = very low density lipoprotein LDL = low density lipoprotein HDL = high density lipoprotein |
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What type of lipoprotein comes from the intestine? |
Chylomicron |
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what type of lipoprotein comes from the liver? |
made by liver: very low density lipoprotein (VLDL) low density lipoprotein (LDL) |
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which type of lipoprotein is the major transporter of cholesterol? |
LDL |
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which type of lipoprotein is returned to the liver? |
HDL |
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Which type of lipoprotein has the most triglycerides? |
chylomicrons and least protein |
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what is up with familial hypercholesterolemia (FH)?
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-genetic inheritance - severity depends on # of mutant genes, most mutation are in the receptor -heterozygotes - 2x LDL in blood develop cardiovascular disease -homozygotes -4-6x LDL in blood - heart attack in 20s |
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what is the lipid bilayer? |
dynamic structure composed of phospholipids |
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why is the lipid bilayer dynamic? |
continuous replacement through recycling recycling between existing membranes: grows by inserting individual components like proteins and lipids |
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what are characteristics of lipid bilayer? |
dynamic membranes contain lipid, protein and also glycolipids and glycoproteins compositions vary |
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What is the membrane composition of liver? |
Lipid: 52% Protein: 44% Carbohydrate: 4% |
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What is the membrane composition of Erythrocytes (Red blood cells)? |
lipid: 43% protein: 49% carbohydrates: 8% |
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what is the membrane composition of Myelin? |
lipid: 79% protein: 18% carbohydrate: 3% |
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What is the membrane composition of mitochondrial inner membrane? |
lipid: 24% protein: 76% carbohydrate: 0% |
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which of liver, erythrocyte, myelin or mitochondrial inner membrane has the highest protein % in membrane? |
mitochondrial inner membrane 76% |
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which of liver, erythrocyte, myelin or mitochondrial inner membrane has the highest lipid % in membrane? |
Myelin 79% |
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liver, erythrocyte, myelin or mitochondrial inner membrane has the highest % carbohydrate in membrane? |
erythrocyte 8% |
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what does the asymmetry of lipid bilayer consist of? |
inner & outer leaflets have different lipid types |
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what is the point of asymmetry of lipid bilayer? |
provides curvature of membranes - directs overall shape of cell or organelle |
