Blood Components and Erythrocyte Physiology

Vocabulary flashcards based on lecture notes covering blood plasma components, erythrocyte structure, hemoglobin dynamics, hematopoiesis, and red blood cell disorders.

Globulins

Plasma proteins categorized into alpha, beta, and gamma types.

Serum

Blood plasma with clotting proteins removed.

Hematocrit

The percentage of whole blood volume occupied by erythrocytes, normally $40\text{--}45\%$.

Erythrocyte Physical Characteristics

Very small cells measuring 7.5\,\text{\mu m} in diameter, shaped as flexible biconcave discs to maximize surface area to volume ratio, with a total count of about $30\text{ trillion}$ per adult.

Erythrocyte Structural Organization

Cells bound by a plasma membrane lacking a nucleus and most organelles; they generate ATP exclusively through anaerobic methods to preserve carried $O_2$.

Hemoglobin (Hb)

A gas-transport protein that constitutes $97\%$ of an erythrocyte's cell content (excluding water), with approximately $280\text{ million}$ molecules per RBC.

Hemoglobin Structure

A protein composed of four subunits (containing $2\,\alpha$ and $2\,\beta$ protein chains), with each subunit containing $1$ heme pigment bound to the protein globin.

Heme

A red pigment containing $1$ iron ($Fe$) atom at its center capable of binding $1$ molecule of $O_2$.

Normal Hemoglobin Range

$12\text{--}18\,\text{g/100\,ml}$ of blood.

Oxyhemoglobin

The bright ruby red form of hemoglobin resulting from oxygen binding to iron in the lungs.

Deoxyhemoglobin

The dark red form of hemoglobin resulting from the release of oxygen to tissue cells.

Hematopoiesis

The process of blood cell formation occurring in the red bone marrow.

Erythropoiesis Pathway

The developmental sequence of red blood cells: hematopoietic stem cell $\rightarrow$ myeloid stem cell $\rightarrow$ proerythroblast $\rightarrow$ series of nucleated cells $\rightarrow$ reticulocyte $\rightarrow$ erythrocyte.

Reticulocyte

An immature red blood cell produced in $15\text{ days}$ from a stem cell; it enters the bloodstream and takes about $2\text{ days}$ to mature into a functional erythrocyte.

Erythropoietin (EPO)

A hormone secreted by the kidneys that stimulates erythrocyte production when low blood $O_2$ levels are detected.

Erythrocyte Lifespan and Production Rate

Erythrocytes live for $90\text{--}120\text{ days}$ (or $100\text{--}120\text{ days}$) and are produced at a rate of $2\text{ million/second}$.

Fate of Heme

During RBC destruction by macrophages, heme is separated from globin, its iron is recycled, and the remaining pigment is degraded to yellow bilirubin, secreted into bile, and excreted in feces.

Fate of Globin

The protein chain of hemoglobin that is metabolized back into amino acids upon RBC breakdown.

Anemia

A clinical sign characterized by an abnormally low oxygen-carrying capacity of the blood, presenting symptoms such as fatigue, paleness, shortness of breath, and feeling cold.

Hemorrhagic Anemia

Anemia caused by blood loss, categorized as acute (rapid loss, e.g., stabbing) or chronic (slow, persistent loss, e.g., ulcer).

Iron Deficiency Anemia

Anemia resulting from inadequate $Fe$ intake or impaired $Fe$ absorption, producing microcytic and hypochromic red blood cells.

Pernicious Anemia

An autoimmune disorder causing a deficiency in intrinsic factor needed to absorb vitamin $B12$, producing macrocytic and normo- to hypochromic cells.

Renal Anemia

Anemia caused by a lack of EPO secretion due to renal disease.

Aplastic Anemia

Anemia caused by the destruction of red bone marrow, frequently due to exposure to drugs, chemicals, or radiation.

Hemolytic Anemia

Anemia caused by premature lysis of erythrocytes due to structural defects, hemoglobin abnormalities, bacteria, or parasites.

Thalassemia

A genetic hemolytic anemia common in individuals of Mediterranean descent where one globin chain is faulty or absent, resulting in thin, delicate, microcytic, hypochromic RBCs with low Hb.