Episode 3 RBCs, Blood Functions, and the Reticuloendothelial System Flashcards
Where and at what rate are RBCs synthesized?
Bone marrow at 200 Billion per day
Where in the fetus are RBCs synthesized?
Liver and spleen
Where is yellow marrow found?
In the medullary cavity (middle of long bones)
What does a stem cell become once it is committed?
Colony-forming unit (CFU) or Lymphocyte Progenitor cell.
What do CFUs go on to become?
RBCs, Myeloid WBCs, Monocytes, Megakaryocytes (platelets)
What do Lymphocyte progenitor cells go on to become?
T cells, B cells, and NK cells (all are lymphocytes)
What is the most important growth factor for controlling erythropoiesis?
Erythropoietin (EPO)
What organ releases EPO?
Kidneys
What do RBCs enter the circulation as?
Reticulocytes (have some residual organelles but no nucleus)
Do RBCs have mitochondria?
No. They produce ATP anaerobically only.
Where do reticulocytes remain to mature into RBCs?
Bone marrow or spleen
What are the absolute ingredients you need for making normal RBCs?
Amino acids, iron, folic acid, and Vit B12 - deficiency in these causes anemia
What is EPO production controlled by?
A negative feedback loop - kidneys sense level of oxygen delivery to tissues and decrease EPO production if sufficient
What happens to EPO levels during hypoxia?
EPO levels rise and RBC production increases until oxygenation returns to normal
How many major types of protein are found in the lipid bilayer cell membrane of RBCs?
10-15
T/F RBC cytopskeleton has unique protein filaments?
True
What is a Band-3 protein?
An integral protein that constitutes about 25% of total membrane protein
What anions does the Band-3 exchange across the membrane?
Bicarbonate for chloride exchange
What are glycophorins?
Little combinations of carbs that stick out from some of the integral proteins like Band 3.
What do glycophorins do?
Reduce interaction of RBCs so they don’t stick together
Which GLUT allows for facilitated diffusion of glucose into RBCs?
GLUT 1
What is the most important function of peripheral and cytoskeleton proteins?
Maintain the disc shape of RBCs yet allow for great flexibility for travel thru narrow blood vessels
What are four important peripheral proteins of an RBC?
Ankyrin, Protein 4.1, Protein 4.2, and Spectrin
What is hereditary spherocytosis?
Defects in RBC proteins - RBCs become sphere shaped rather than biconcave
How long do cells with spherocytosis live?
5-7 days
What is NADH needed for in the RBC?
maintain Hb’s iron in the ferrous (reduced) state (Fe++)
What is NADPH needed for in the RBC?
Required to maintain reduced glutathione
What is reduced glutathione needed for in the the RBC?
Needed to maintain shape
In the RBC, how much ATP and NADH is generated from each molecule of glucose?
2 ATP and 2 NADH
What percentage of glucose is metabolized in the PPP pathway?
10% (the 90% is by anaerobic glycolysis)
Which enzyme oxidizes Glucose-6-Phosphate, thereby allowing it to enter the PPP?
G-6-P Dehydrogenase
What does bilirubin leave the body as?
Feces, not in urine
Which organ is often injured in abdominal trauma?
Spleen
What percentage of NaCl is isotonic with plasma?
0.9% NaCl. Hypertonic solution causes RBCs to shrink, hypotonic to swell and burst leaving “ghosts”
What are the three buffer systems in blood?
Bicarbonate/Carbonic Acid, Phosphate, and Protein (Hb, albumin) - all function as buffers by taking on or releasing H+
How does blood participate in temperature regulation?
Vasoconstrictions reduce flow to surface of skin, thereby reducing heat loss
Cold temperatures do what to the SNS fibers?
Stimulate them to constrict blood vessels
What do warm temperatures do to blood vessels?
Dilate blood vessels to increase blood flow to surface of skin to cool down
By what receptors on the blood vessels does the SNS control smooth muscle constriction/relaxation
Alpha-1
