Week 3 Flashcards
Limitations of RBC
- Do not have any organelles: cannot replicate or make ATP aerobically
- Do not have ribsomes; cannot make proteins; the proteins originate in the cell; the RBC is packed with what they need to survive for 120 days
What is the role of glycolysis in RBC’s?
To produce ATP (4 in total, 2 to use)
End product of glycolysis?
Lactate; reduction reaction because NADH gives hydrogen to pyruvate to create lactate; enzyme is lactate - dehydrogenase
What is fate of NADH produced by glycolysis in RBC?
○ Reduces methemoglobin to ferrous iron;
○ used to convert pyruvate to lactate
What occurs with high NADH level produced by RBC?
the NADH/NAD ratio will go up stopping ETC, TCA, and pushing cells to anaerobic respiration
Different fates of G6P in RBC
- glycolysis
- pentose phosphate pathway
Pentose Phosphate Pathway
- will make ribose-5-phosphate (make 5 carbon sugar) and NADPH; rate limiting enzyme to shunt G6P to PPP is G-6-P dehydrogenase
What happens to the 5 carbon sugars?
used to make nucleic acid in other cells but in RBC they will be shunted back into glycolysis as Fructose-6-P or Glyceraldehyde-3-P (Hexose monophosphate shunt); enzymes are transketolase (co-enzyme: thiamine–Vit B1) and transaldelase
What is the role of NADPH in RBC’s
Maintains glutathione in reduced state so glutathione can protect RBC from reactive oxygen
Glutathione
: principle anti-oxidant enzyme at cellular levels; neutralizes free radicals (hydrogen peroxide to water and oxygen AND hydroxyl radical); reduced form is GSH will be oxidized to GSSG
What occurs with high free radical production?
- cell lysis due to lipids and proteins being attacked in cell membrane
- Will create permanent damage due to RBC not being able to make and replace damaged proteins
- Will oxidize Fe+2 to Fe+3
- Modifies hemoglobin to make heinz bodies
What is the role of 2,3 BPG shunt in RBC?
○ Only some glucose will shunt
○ Will produce 2,3 BPG which will help hemoglobin release oxygen by stabilizing deoxygenated form of hemoglobin
○ Lower the pH in the tissue, the higher the binding of BPG to hemoglobin
How does oxygen bind to hemogblobin?
Oxygen forces out hydrogen ion bound to hemoglobin therefore there is less hydrogen ion allowing for oxygen to bind to hemoglobin
Fetal vs Adult hemoglobin
- HbF less able to bind to 2,3 BPG
- Gamma chain has less binding spots for 2,3 BPG to bind as tightly as beta chain does in adult
- Fetal cells are less metabolically active than normal cells, which means it is less acidic (so less Hydrogen), will cause less tight binding of hemoglobin to 2,3 BPG
G6PD deficiency
- Low G6PD so glucose is not going to PPP so it is not creating NADPH which will prevent cell from being able to reduce glutathione and protect cell from oxidative insult
- High levels of bili-rubin is causing jaundice symptoms and is due to cell lysing because of oxidative insult
- Elevated lactate dehydrogenase is causing increased lactate which is causing decreased blood pH
- Anemia is caused by cells lysing due to oxidative insult because of low G6PD
A quantitative deficiency of the enzyme tansketolase will affect RBC metabolism by which of following mechanisms?
the oxidative part would work fine it would only affect the 5 carbon sugar going back into glucose so ATP production would decrease
What happens when GSSG increases?
- caused because of G6PD deficiency
- will decrease hydrogen peroxide from being broken down into water and Oxygen, which will increase oxidative stress in cell. The radicals will attack the proteins and lipids in cell membrane, causing it to rupture and causing the cell to lyse.
Heme
- function
- made from
- made
- rate limiting enzyme
- houses ferrous enzyme
- made from glycine (hydrophobic, allyphatic) and succinyl CoA ( in TCA)
- Made in bone marrow and liver
- Delta alla synthase is rate limiting enzyme; controlled by amount of heme
Hemoglobin degradation in normal state
- RBC lives for 120
- Macrophages will eat RBC and take to spleen
Steps of Hemoglobin degradation in normal state
- heme and globin separated
- heme will be oxidized (heme oxygenase) into billiverdin and then reduced (biliverdin reductase) into unconjugated bilirubin; globin will be changed into AA
- bilirubin will combine with albumin to be taken from spleen through the blood into the liver
- in the liver the bilirubin will loose albumin and gain UDP-glucouronate which will convert it to bilirubin diglucuronide
- bilirubin diglucuronide will be excreted into digestive system and bacteria will ferment into urobilinogen
- urobilinogen will then be excreted in feces and urine
Hemoglobin degradation in diseased state
- There will be a lot of hemoglobin in blood, and kidney will try to eliminate a lot of it stressing it out
- Body gets rid of Hgb in blood by having proteases chop it up into dimers, then haptoglobin will bind to hemoglobin dimers and takes them to macrophages and liver to be broken down as normal
- Free haptoglobin would be low in blood because they would be bound to the hemoglobin that spilled into the blood
Iron Hemostasis
- comes from
- converted to
- stored in
- Iron comes in through diet (meat) in ferric form
- Fe3+ (ferric) cannot get into cell and is converted into Fe2+ (ferrous) and is brought into enterocytes of the intestine through DMT1
- stored in cells through ferritin
Hepsidin
causes iron to be trapped in cells (enterocytes and macrophages in particular)
How is iron transported in blood?
When iron is transported in blood it is converted back to ferric form and combines with apotransferrin, which makes transferrin (free iron is toxic in blood and must be bound)
Hemosyderine
seen in iron overload
How is iron lost from body?
Iron builds up in cells and when those cells are sloughed off, iron is lost with cell
Anemia
low hemoglobin or hematocrit
Iron deficiency anemia
- Serum iron:
- Ferritin:
- TIBC:
- % Iron Saturation:
- Hepcidin:
- Serum iron: low
- Ferritin: low
- TIBC: high
- % Iron Saturation: low
- Hepcidin: low
- Anemia of chronic disease ○ Serum iron: ○ Ferritin ○ TIBC ○ % Iron Saturation: -Hepcidin
○ Serum iron: low ○ Ferritin: high ○ TIBC: low or normal ○ % Iron Saturation: low -Hepcidin: high; iron trapped in cells
hematocrit
the ratio of the volume of red blood cells to the total volume of blood.
Total iron binding capacity
blood test to see if you have too much or too little iron in your blood. Iron moves through the blood attached to a protein called transferrin. This test helps your health care provider know how well that protein can carry iron in your blood.
Why is hepcidin increased with anemia of chronic disease
- With inflammation there is increased IL-6 which increases hepcidin, which keeps iron in cells
Antigen
something that elicits an immune response, something that the antibody binds too (most common definition); can be inside the cell, outside the cell
Antibody
something produced to counter act foreign substances