[Hema1] Week 4 - Hemoglobin Structure and Metabolism and RBC Metabolic Pathways

A metabolic pathway that produces 2,3-bisphosphoglycerate (2,3-BPG), which regulates oxygen delivery to tissues.

A left-shifted curve indicates increased oxygen affinity, often caused by decreases in 2,3-bisphosphoglycerate (2,3-BPG), H+ ions (raised pH), partial pressure of carbon dioxide (PCO2), and/or temperature.

The cyanmethemoglobin method is the reference method for hemoglobin assay, where hemoglobin is lysed and combined with potassium ferricyanide to form methemoglobin, which then combines with potassium cyanide to form stable cyanmethemoglobin.

Hemoglobin binds to nitric oxide, forming S-nitrosohemoglobin, which helps preserve and transport NO to hypoxic microvascular areas, stimulating vasodilation.

Adult hemoglobin (Hb A) is composed of two alpha globin chains and two beta chains.

The iron atom (heme) and the sulfhydryl group (globin chains).

Oxygen is released from hemoglobin, enhancing the delivery of oxygen to tissues.

Deoxygenated hemoglobin (HHb) is hemoglobin with ferrous iron but no oxygen, characterized by its dark red color and found in venous blood.

Dyshemoglobins are dysfunctional hemoglobins that are unable to transport oxygen, including methemoglobin, sulfhemoglobin, and carboxyhemoglobin, often resulting from exposure to certain drugs or environmental chemicals.

ALA synthase catalyzes the condensation of glycine and succinyl coenzyme A to form aminolevulinic acid (ALA), which is the initial step in heme synthesis.

Carboxyhemoglobin results from the combination of carbon monoxide with heme iron, having an affinity for hemoglobin that is 240 times greater than oxygen, and is often referred to as the 'silent killer'.

Heme biosynthesis involves several steps starting from the condensation of glycine and succinyl CoA to form ALA, followed by transformations to porphobilinogen, coproporphyrinogen III, protoporphyrinogen IX, and finally to heme.

Hemoglobin contributes to acid-base balance by binding and releasing H+ ions, helping to maintain blood pH.

Increased 2,3-DPG leads to increased oxygen delivery to tissues by decreasing hemoglobin's oxygen affinity.

Six structural genes code for six globin chains, which combine with heme to form heterodimers and ultimately a complete hemoglobin molecule.

The globin structure in hemoglobin comprises four globin chains that consist of two identical pairs of unlike polypeptide chains, each containing 141 to 146 amino acids.

Transferrin is a plasma protein that carries iron in its ferric form to develop erythroid cells.

High oxygen affinity is required for hemoglobin to efficiently bind oxygen in the lungs, while low oxygen affinity is necessary for unloading oxygen to tissues.

Methemoglobin is formed by the reversible oxidation of heme iron to the ferric state (Fe3+), preventing it from binding to oxygen. Levels above 30% can cause cyanosis and hypoxia, while levels above 50% may lead to coma or death.

The P50 value is defined as the partial pressure of oxygen (PO2) needed to saturate 50% of hemoglobin.

Hemoglobin composition changes with prenatal gestation and postnatal age, reflecting the activation and inactivation of globin genes.

Sulfhemoglobin is formed by the irreversible oxidation of hemoglobin by drugs or exposure to sulfur, resulting in a greenish pigment and an absorption peak similar to methemoglobin.

A metabolic pathway that maintains iron in the hemoglobin in its reduced state, preventing oxidation.

It competes with oxygen for the oxygen-binding site of hemoglobin, enhancing oxygen release and delivery to tissues.

Oxyhemoglobin (HbO2) is hemoglobin bound with ferrous iron and oxygen, characterized by its bright red color and commonly found in arterial blood.

Hemoglobin biosynthesis occurs in the mitochondria and cytoplasm of bone marrow erythroid precursors.

A right shift can be caused by elevations in 2,3-BPG, H+ ions (lowered pH), PCO2, and/or temperature.

Heme consists of a ring of carbon, hydrogen, and nitrogen atoms called protoporphyrin IX, with a central atom of ferrous iron (Fe2+) that can reversibly combine with one oxygen molecule.

The hexose monophosphate shunt is a metabolic pathway that provides the only means of generating NADPH, which is crucial for glutathione reduction, protecting erythrocytes from oxidative damage.

The function of hemoglobin is to bind oxygen in the lungs, transport it to tissues, and bind carbon dioxide from tissues to return to the lungs for exhalation.

Hb A1c is a glycated form of hemoglobin used as a gold standard for testing diabetes mellitus, indicating the average blood glucose levels over a period.

Carbonic anhydrase facilitates the reaction where carbon dioxide diffuses into RBCs and combines with water to form carbonic acid (H2CO3).

The four levels of hemoglobin protein structure are primary (amino acid sequence), secondary (chain arrangements), tertiary (arrangement of helices), and quaternary (complete hemoglobin molecules).

Protoporphyrin IX is formed from protoporphyrinogen IX and binds with iron (Fe2+) in the presence of ferrochelatase to produce heme.

The main function of hemoglobin is to transport oxygen from the lungs to tissues and carbon dioxide from tissues to the lungs for exhalation.

The Embden-Meyerhof pathway is a non-oxidative, anaerobic glycolysis process that requires glucose to generate ATP, producing a net of 2 ATPs, which are important for maintaining cell shape and flexibility.

Heme inhibits the transcription of the ALA synthase gene, leading to decreased heme production, which is a negative feedback mechanism.

When ferrous iron in heme is oxidized to the ferric state, it loses its ability to bind oxygen, resulting in oxidized hemoglobin, known as methemoglobin.

Hemoglobin is a protein in red blood cells that transports oxygen from the lungs to tissues and carbon dioxide from tissues to the lungs for exhalation, constituting approximately 95% of the whole RBC cytoplasm.