Normal Physiology Flashcards

Question

Metarubricyte (Orthochromic Normoblast)

Answer 1

Cytoplasm: Mostly pink or salmon color, Due to concentration of hemoglobin, Looks very similar to the surrounding RBCs, Retains a slight basophilic hue Nucleus: Last stage with a nucleus, Low N:C Ratio, Dark, heavily condensed chromatin, Often eccentric

Answer 2

Before a developing RBC enters circulation the nucleus is extruded from the cytoplasm and digested by BM macrophages After nuclear extrusion the cell is known as a reticulocyte Flattened-disc shape, membrane is not biconcave, Central pallor is not apparent on smear, Last 20% of hemoglobin is made in this stage Normally 0.5-2.5% of all circulating RBCs are retics

Answer 3

Supravital stain Microscopic ID can only be made using a supravital stain New Methylene Blue commonly used (makes residual RNA visible) Wright stain Cannot definitively visualize residual RNA Retics have a slight bluish tinge- polychromatophilic erythrocytes

Answer 4

Unable to synthesize new proteins (hgb) or lipids Pink color Biconcave disc shape (During the retic stage, the membrane is remodeled until it becomes biconcave), Size 7-8 µm in diameter, volume 80-100 fL, Central pallor

Answer 5

Oxygen transport, Durability/strength to survive for 120 days, Balances ion and water concentrations, Flexibility to fit through small vessels Some integral proteins are called anion exchange proteins: function in the exchange of CO2 at the lungs, Peripheral proteins are mostly on the cytoplasmic face of the RBC

Answer 6

Phospholipid bilayer complex: Lipids – mostly cholesterol, Affects surface area and membrane permeability, Integral proteins: Embedded in the bilayer, Function in the transport of molecules across membrane, Responsible for the zeta potential (negative charge), Blood group antigens Peripheral proteins: Forms the cytoskeleton, Provides a flexible, fluid structure

Answer 7

Increased cholesterol absorbs onto RBC Causes expansion of the outer phospholipid leaflet Abnormal membrane projections

Answer 8

Production of energy (ATP) through anaerobic glycolysis (Previously known as the Embden-Meyerhof pathway), No citric acid/TCA/Kreb’s cycle ATP is necessary to maintain intracellular ion concentration Important enzyme: Pyruvate kinase (PK)

Answer 9

Normal in splenic circulation, Deficiency in pyruvate kinase Results: May disrupt intracellular ion balance, Allows excessive water to enter, Cell loses biconcave shape, Assumes spherocytic shape, Becomes fragile, Culled by spleen or hemolyzed

Answer 10

An offshoot of the glycolytic pathway, Protects hgb from being chemically oxidized (Oxidation prevents oxygen transport) HMP maintains the function of glutathione, Glutathione becomes oxidized instead of hemoglobin, The main antioxidant is glutathione Important enzyme: Glucose-6-phosphate dehydrogenase (G6PD)

Answer 11

An offshoot of the glycolytic pathway, Helps return methemoglobin (Fe3+) to reduced state (Fe2+), Ensures that hgb can bind and transport O2 Important enzyme: Methemoglobin reductase, Deficiency results in a buildup of oxidized heme, Decreased O2 carrying capacity, Hypoxia results in cyanosis

Answer 12

Porphyrin ring structure, Called “protoporphyrin IX”, Combines with one centrally located ferrous ion (Fe2+), Each iron ion can bind one molecule of O2 There are 4 heme subunits per hgb molecule, Each heme subunit is bound to a globin chain, 4 subunits and 4 globin chains

Answer 13

Iron ions in the ferrous state

Answer 14

Iron ions in the ferric state

Answer 15

Occurs in the mitochondria and cytoplasm of erythrocyte precursors

Answer 16

Produces 2,3 bisphosphoglycerate Competes with O2 for a binding site; the concentration of O2 at the lungs is much higher than 2,3 BPG so O2 “wins” the competition at high concentrations bound and ready for transport In hypoxic tissues 2,3 BPG facilitates the release of oxygen; 2,3 BPG pushes O2 off of the RBC where it diffuses into the tissue, increasing the amount of oxygen being released to tissues

Answer 17

The predominant form in healthy adults | α2β2

Answer 18

``` The predominant form in a developing fetus and newborns: α2γ2 A gamma (γ) globin chain is simply a beta chain with serine in place of histidine at the 143rd position, Serine interferes with the function of 2,3 BPG Allows a Hgb F to have a higher affinity for O2 than Hgb A; Hgb F essentially “takes” O2 from maternal circulation ```

Answer 19

``` Hgb A: α2β2 >95% Hgb A2: α2δ2 1-4% Hgb F: α2γ2 <2% ```

Answer 20

Hgb S: Sickle cell anemia | Hgb C: Hgb C disease

Answer 21

Methemoglobin: Hgb with iron in the ferric state, Cannot bind O2 Sulfhemoglobin: Sulfur bound to heme, Severely decreased O2 affinity Carboxyhemoglobin: Hgb has much higher affinity for carbon monoxide (CO) than O2, Produces cherry red appearance to blood and skin, O2 cannot bind, CO poisoning can be lethal

Answer 22

``` Usually simply the result of aging Erythrocyte disorders Shorten the lifespan of the RBC, Or result in immediate destruction Two methods Extravascular/Intravascular destruction ```

Answer 23

Conserves and recycles important RBC components RBCs are culled by the spleen (BM and liver can also participate) RBCs are required to pass through small openings and endure hypoglycemia (Healthy cells survive unharmed) while aged, rigid, damaged or poikilocytic cells become spherocytic and are culled

Answer 24

Iron from heme, Amino acids from globin chains Heme is further broken down to unconjugated bilirubin, Carried to the liver and converted to conjugated bilirubin and excreted in the feces Excessive extravascular hemolysis: Caused by several types of anemia, May result in spleen overload/failure, Jaundice

Answer 25

Most RBCs are extravascularly destroyed but some lyse in circulation, Released hemoglobin circulates freely (Free hgb may be toxic in high levels-Can induce apoptosis in surrounding cells) Hgb is bound by haptoglobin and rendered non-toxic then carried to the liver to be recycled Excessive intravascular hemolysis: Caused by several hemolytic anemia's, Causes a depletion of haptoglobin

Answer 26

That the hemoglobin is holding on to oxygen more tightly, reducing oxygen delivery

Answer 27

storage iron

Normal Physiology Flashcards

(52 cards)