Blood Components and Physiology Flashcards

Vocabulary flashcards covering blood composition, formed elements, WBC types, hemostasis, blood typing, and related blood pathologies.

Hematocrit

The percentage of red blood cells in a blood sample, averaging about 45% in a normal centrifuged sample.

Hemoglobin

A tetramer metalloprotein found in red blood cells that comprises four globin subunits, each containing an iron atom bound to heme, responsible for delivering oxygen to tissues.

Plasma

The clear, straw-colored liquid matrix of blood that constitutes approximately 55% of total blood volume and is 92% water.

Serum

The liquid component of blood remaining after coagulation, devoid of clotting factors such as fibrinogen ($\text{serum} = \text{plasma} - \text{fibrinogen}$).

Albumin

The most abundant plasma protein (60% of total), synthesized in the liver, which helps maintain colloid osmotic pressure.

Non-protein Nitrogenous Substances

Molecules in plasma that contain nitrogen but are not proteins, including urea, uric acid, amino acids, creatine, and creatinine.

Hematopoiesis

The process of blood cell formation, which occurs in red bone marrow from hemocytoblasts or hematopoietic stem cells.

Erythrocytes

Red blood cells; non-nucleated biconcave discs containing hemoglobin that function in gas transport and have a lifespan of approximately 120 days.

Erythropoietin

A hormone released by the kidneys and liver in response to low blood oxygen levels to stimulate red blood cell production.

Anemia

A condition characterized by a reduced oxygen-carrying capacity of the blood due to a deficiency of red blood cells or hemoglobin.

Sickle Cell Disease

An inherited red blood cell disorder caused by a genetic mutation in hemoglobin, resulting in abnormally shaped crescent/sickle red blood cells that can block blood flow.

Granulocytes

A category of white blood cells with granular cytoplasm and short lifespans, comprising neutrophils, eosinophils, and basophils.

Agranulocytes

A category of white blood cells that lack noticeable cytoplasmic granules, comprising monocytes and lymphocytes.

Diapedesis

The process by which leukocytes squeeze between endothelial cells of capillary walls to exit the bloodstream and migrate toward infection sites.

Neutrophils

Phagocytic granulocytes with a 2–5 lobed nucleus that stain light purple, representing 54%–62% of leukocytes, and serving as the first responders to bacterial infections.

Eosinophils

Granulocytes with bi-lobed nuclei and deep red granules, constituting 1%–3% of leukocytes, that defend against parasitic worm infestations and moderate allergic reactions.

Basophils

Granulocytes with deep blue granules, representing less than 1% of leukocytes, that release histamine to promote inflammation and heparin to inhibit blood clotting.

Monocytes

The largest white blood cells by size, making up 3%–9% of leukocytes, which leave the bloodstream to differentiate into macrophages that phagocytize large particles.

Lymphocytes

Agranulocytes with a large spherical nucleus nearly filling the cell, comprising 25%–33% of leukocytes, that provide immunity via T cells and antibody-producing B cells.

Platelets

Anucleated cellular fragments derived from megakaryocytes in red bone marrow that play a key role in hemostasis and release serotonin to induce vasoconstriction.

Hemostasis

The physiological process that halts bleeding from a damaged blood vessel, involving vascular spasm, platelet plug formation, and blood coagulation.

Extrinsic Clotting Mechanism

A coagulation pathway triggered by damaged blood vessel walls or external tissues releasing tissue thromboplastin (Factor III).

Intrinsic Clotting Mechanism

A coagulation pathway triggered when blood contacts a foreign surface (such as collagen) without external tissue damage, initiating via Hageman factor XII.

Thrombus

An abnormal blood clot that forms inside an intact blood vessel.

Embolus

A blood clot or clot fragment that dislodges and travels through the bloodstream until it lodges in a narrower vessel.

Universal Donor

Type O blood, which lacks A and B surface antigens on its red blood cells, allowing it to be transfused into recipients of any ABO blood type.

Universal Recipient

Type AB blood, which lacks anti-A and anti-B antibodies in its plasma, enabling an individual with this type to receive red blood cells of any ABO blood group.

Rh Factor

An antigen protein (most importantly antigen D) located on the surface of red blood cells; individuals possessing it are Rh-positive, while those lacking it are Rh-negative.

Erythroblastosis Fetalis

Also known as hemolytic disease of the newborn; a condition in which maternal anti-Rh antibodies cross the placenta and destroy the red blood cells of an Rh-positive fetus.

Hemophilia A

An X-linked recessive hereditary clotting disorder characterized by a deficiency in Factor VIII (antihemophilic factor), resulting in abnormal bleeding tendencies.