Module 6.1: RBC Structure and Function

PART 1 (this shi so long bruh i can't)

Hemoglobin

main component of RBC

Glucose molecule

main energy source of RBC, responsible for the viscosity of the blood in the peripheral circulation

Biconcave disc

• allows the deformability of RBC

• facilitates O₂ and CO₂ transport

deformability

could squeeze in easily into tissue spaces without being destroyed of being disrupted

salmon pink area

What area of RBC denotes the amount or level of Hemoglobin contained in a particular RBC?

Function of Membrane Composition and Structure

• Separate the intracellular fluid environment of the cytoplasm from the extracellular fluid

• Selectivity pass nutrients and ions into and out of the cells

Extracellular fluid

Amount of fluid or liquid component of the blood that is outside the RBC.

Intracellular fluid

Fluid found in the cytoplasm of a Red Blood Cell.

phosphate head and lipid tail

composition of phospholipid bilayer (RBC plasma membrane)

Phosphate Head

• polar group

• water soluble

• most external surface of RBC membrane

Lipid Tail

• non-polar group

• water insoluble

• away from the water content from the environment

Integral Proteins

What do we call the proteins that are embedded, such that it traverses the entire length of the plasma membrane bilipid layer?

Peripheral Proteins

What do we call the proteins that attach themselves in the Phosphate Head Group, not traversing the lipid layer or when it is just on the sides?

Cytoskeleton

What is responsible for the flexibility and deformability of the phospholipid bilayer?

Hereditary Spherocytosis

What is the disease associated with the given information:

Genetics: Autosomal dominant / autosomal recessive

RBC: Spherocyte

Defect: Ankyrin (50%- 60%) or Spectrin (20%)

Band 3 (15%- 20%)

Identify the defect based on the following information:

Genetics: Autosomal dominant

RBC: Spherocyte, pincered

Protein 4.2 (<5%)

Identify the defect based on the following information:

Genetics: Autosomal recessive

RBC: Ovalocyte, stomatocyte

RhAG (<:1%)

Identify the defect based on the following information:

Genetics: Autosomal recessive

RBC: Stomatocyte, spherocyte

Disease: Hereditary elliptocytosis

Defects: α-Spectrin (65%), β-Spectrin (30%), Protein 4.1 (5%)

Identify the disease and defect based on the following information:

Genetics: Autosomal dominant

RBC: Elliptocyte

Disease: Southeast Asian ovalocytosis

Defect: Band 3 (100%)

Identify the disease and defect based on the following information:

Genetics: Autosomal dominant

RBC: Macroovalocytes

Double Bilayer

Lipid bilayer leaflet

Polar Heads

Hydrophilic

Tails

• Hydrophobic, non-polar fatty acid chain

• Face the leaflet interior

Cholesterol

It maintains the surface area to volume ratio by regulating membrane fluidity and permeability to electrolytes and nonelectrolyte.

Protein

• Bounds to lipids throughout the membrane

• Classified as integral and peripheral proteins

Peripheral Protein

Protein found inner OR outer surfaces of the cell membrane.

Integral Protein

Protein found inner AND outer surfaces of the cell membrane.

α and ß spectrin (Bands 1 and 2)

• Long, rod shape molecules

• Help maintain the cytoskeleton of the RBC

Actin (Band 5) / Ankyrin

Short filaments

Protein 4.1

• Mediate the linkage between spectrin and actin

• Giving the RBC cell membrane the viscoelastic properties

Protein 4.2

Linkage between spectrin and ankyrin

Band 3

Inorganic ion (Cl-HCO3-) transport channel

Glycophorin

• Bears the ABO blood group antigens

• Rh antigens contain sialic acid

• Negative charge (zeta potential)

Zeta Potential

• sum of all the charges of molecules in the RBC membrane

• negative charge of the surface of an RBC

• Na+, K+ ATPase

• Ca2+, Mg2+ ATPase

2 Important Membrane Enzyme Systems

Na+, K+ ATPase

• Active transport of sodium and potassium

• Transports Na (sodium) out, and K (potassium) inside.

Ca2+, Mg2+ ATPase

• Calcium pump

• Calcium is involved in regulation and stabilization of membrane phospholipid structure, high intracellular calcium makes less deformable.

Heinz Bodies

Rigid cells inclusions Abnormal Hemoglobin

HbS (Sickle Hemoglobin)

Sickle cell anemia

• Iron atom of heme ring

• Sulfhydryl group (-SH) located in certain points of globin chain

2 sites on Hb molecule are particularly prone to oxidation

Embden-Meyerhof Pathway (EMP)

Anaerobic Pathway

PPP – Pentose Phosphate Pathway (HMP)

Aerobic Pathway

Embden-Meyerhof Pathway

• 90-95% of glucose used by the cell is metabolized by this method

• end product of this mechanism is the production of ATP

2 ATP

How many ATPs are produced when 1 molecule of Glucose is being metabolized anaerobically?

NAD+ and NADH+

Cofactors methemoglobin reduction

Rapaport-Luebering Shunt

Involved in the formation 2-3 DPG

Hexose Monophosphate Shunt (HMP)

• also known as the “Gluthathione Reduction Pathway"

• Presence of free radicals is reduced, decomposed by the molecule Gluthatione

Glucose6-Phosphate Dehydrogenase (G6PD)

• lysis due to oxidant drugs

• Has a role in the decomposition of oxidants

• has an antioxidant property.

Lactate

What is a common product of the anaerobic metabolism of Glucose?

Ribulose-5-PO4 to Fructose-6-PO4

Which particular step in the EMP are ATP molecules produced, particularly the 1st ATP?

Reticulocytes

What do we call when an immature RBC loses its nucleus, and it migrates into the peripheral blood in Romanowsky smear?

Polychromatophilic macrocytes

What do we call when an immature RBC loses its nucleus, and it migrates into the peripheral blood in Wright’s stain?

Hypoxic (Hypoxia) States

What state increases production of Erythropoietin?

decreased production of Erythropoietin

When there is increase oxygen or normal levels of oxygen, what happens to the production of erythropoietin?

• Carries oxygen from the lungs

• Carries oxygen to other body tissues

• Delivers CO2 from the tissues to the lungs

What are the roles of RBC in the circulation or in the body in general?