Haemoglobin Flashcards
give an overview of haemoglobin
Carries Various Substances: Hemoglobin serves as a carrier for oxygen, carbon dioxide, nitric oxide, and excess glucose in the bloodstream.
Effective pH Buffer: Hemoglobin acts as an effective buffer to help maintain the pH balance in the blood.
Abundance in Vertebrates: Hemoglobin is found in almost all vertebrates, making up approximately one-third of the normal volume of blood.
Dominant Component in Erythrocytes: Hemoglobin constitutes a significant portion of the dry weight of erythrocytes (red blood cells), making up around 96% of their composition.
Healthy Adult Levels: A healthy adult typically has 12 to 20 grams of hemoglobin for every 100 mL of blood.
Presence in Other Cells: Hemoglobin is also found in other cells of the body, such as some neurons and alveolar cells, where it serves as an antioxidant and plays a role in regulating iron levels.
Stages of Synthesis: Approximately two-thirds of hemoglobin is synthesized during the erythroblast stages, while the remaining one-third is synthesized during the reticulocyte stage.
Abundance in Red Blood Cells: Each red blood cell contains around 640 million molecules of hemoglobin, underscoring its role in oxygen transport.
explain the structural and functional aspects of haemoglobin
Globin Structure: Hemoglobin has a globin structure, which gives it a spherical or ball-like shape.
Conjugated Protein: Hemoglobin is classified as a metalloprotein, indicating that it contains a metal ion (iron) as an integral part of its structure.
Quaternary Structure: Hemoglobin exhibits a quaternary structure, which means it consists of multiple protein subunits joined together to form a functional protein complex.
Subunit Components: Each subunit of hemoglobin, typically referred to as a chain, consists of two essential components: haem (heme) and globulin. The haem component contains the iron atom, which binds to oxygen, while the globulin component forms the protein structure of hemoglobin.
explain the structure of the heme component of hemoglobin and the process of heme synthesis
Heme Structure: Heme consists of a central iron atom, which is typically in its ferrous (Fe²⁺) state. This iron atom is held within a heterocyclic ring known as a porphyrin.
Porphyrin Composition: The porphyrin ring consists of four pyrrole molecules cyclically linked by methane bridges. This structure is essential for binding the iron atom and enabling the reversible binding of oxygen.
Heme Synthesis: The synthesis of heme primarily occurs in the mitochondria of cells. This process involves multiple enzymatic steps and is a critical component of overall hemoglobin production.
explain the structure of the globulin component of hemoglobin and the process of globin synthesis
Globulin Structure: Each globulin, a component of hemoglobin, consists of polypeptide chains. These chains play a role in helping to maintain the iron atom within the heme group in its ferrous (Fe²⁺) state, which is necessary for oxygen binding and transport.
Globin Synthesis: The synthesis of globin proteins primarily occurs in polyribosomes, which are cellular structures responsible for the production of proteins.
give an overview of different hemoglobin variants and their distribution in various stages of life.
Hemoglobin Variants: There are over a dozen hemoglobin variants, some of which are associated with diseases and are referred to as hemoglobinopathies. Others are non-pathological variants of normal hemoglobin.
Fetal Hemoglobin (HbF): Hemoglobin F, composed of two alpha (α) and two gamma (γ) subunits (α2γ2), is the predominant hemoglobin in the fetus, especially during the first weeks of gestation. Small amounts of HbF can also be found in adults, often combined with other hemoglobin variants in adult blood.
Adult Hemoglobins: After birth, the composition of hemoglobins in adults changes. The most common is Hemoglobin A1 (HbA) consisting of two alpha (α) and two beta (β) subunits (α2β2), making up approximately 95% of an adult’s hemoglobin. Hemoglobin A2 (HbA2), with two alpha (α) and two delta (δ) subunits (α2δ2), accounts for about 2% to 3% of an adult’s hemoglobin.
Disease-Associated Variants: Some hemoglobin variants, such as Hemoglobin H (HbH) and Hemoglobin Barts (HbBarts), are associated with diseases, particularly thalassemias, which are a group of inherited blood disorders. These variants can lead to abnormal hemoglobin production and function.
explain the normal range for red blood cell count (RBCC) and reticulocyte count
Red Blood Cell Count (RBCC):
Male: 4.3 - 5.7 x 10^12 per liter (L) or 4,300 - 5,700 x 10^9 per liter (L)
Female: 3.9 - 5.0 x 10^12 per liter (L) or 3,900 - 5,000 x 10^9 per liter (L)
These ranges represent the typical concentrations of red blood cells in the blood, and they can vary somewhat between different individuals.
Reticulocytes:
Male: 35 - 125 x 10^9 per liter (L)
Female: 25 - 115 x 10^9 per liter (L)
Reticulocytes are immature red blood cells, and their count is a useful indicator of the bone marrow’s ability to produce new red blood cells. The reference ranges for reticulocyte counts are generally lower than the reference ranges for mature red blood cell counts.
explain the normal reference ranges within typical clinical parameters
Red Blood Cell Count (RBCC):
Male: 4.3 - 5.7 x 10^12 per liter (L)
Female: 3.9 - 5.0 x 10^12 per liter (L)
These ranges represent the typical concentrations of red blood cells in the blood and may differ slightly based on the reference values used by the specific laboratory.
Reticulocytes: Reticulocytes are typically expressed as a percentage of the total red blood cell count (RBCC), and values can vary somewhat. The typical range you mentioned is 0.5% to 3.5% of the RBCC.
Hemoglobin:
Male: 135 - 170 grams per liter (g/L)
Female: 120 - 150 grams per liter (g/L)
Hemoglobin values can vary somewhat based on age, sex, and specific laboratory reference ranges. The ranges you provided are within the typical clinical parameters.
