Vocabulary Flashcards: Blood Formation, Hemoglobin, and Cardiac Conduction

Vocabulary flashcards covering key terms related to porphyrin/heme biology, erythropoiesis, iron metabolism, heme byproducts, and cardiac conduction/tunica intima anatomy.

Porphyrin

Ring-like organic compound that forms the heme group in hemoglobin; main function is to bind iron to enable oxygen transport in red blood cells.

Heme

Iron-containing component of hemoglobin that binds iron and carries oxygen.

Hemoglobin

Iron-containing protein in red blood cells that binds and transports oxygen.

Erythrocyte

Red blood cell; produced from myeloid progenitors and carries oxygen throughout the body.

Myeloid progenitor

Hematopoietic progenitor that gives rise to erythrocytes, platelets, granulocytes, and other myeloid cells.

Megakaryocyte

Large bone marrow cell whose cytoplasm fragments form platelets.

Platelet

Small cell fragment derived from megakaryocytes; essential for blood clotting.

Granulocyte

White blood cell from the myeloid lineage; includes neutrophils, eosinophils, and basophils.

Neutrophil

A granulocyte; first responder to infection and common in acute inflammation.

Eosinophil

A granulocyte involved in parasitic infections and allergic responses.

Basophil

A granulocyte that releases histamine during allergic reactions.

Erythropoietin (EPO)

Hormone driving RBC production; mainly produced by kidneys with a minor role for the liver in adults (major in fetus).

Kidney

Primary source of erythropoietin in adults.

Liver

Minor source of erythropoietin in adults; major source during fetal development.

Iron

Mineral essential for heme synthesis in red blood cells.

Vitamin B12

Vitamin required for DNA synthesis in RBC precursors.

Folate (Vitamin B9)

Vitamin required for DNA synthesis in RBC precursors.

Vitamin C

Vitamin that aids iron absorption by converting iron to the more absorbable Fe2+ form.

Ferrous iron (Fe2+)

Ferrous form of iron; better absorbed in the gut and used for heme synthesis.

Bilirubin

Bile pigment produced from heme breakdown; excreted in bile.

Urobilin/urobilinogen

Pigments derived from bilirubin excreted in feces as urobilin; some urobolinogen is reabsorbed and excreted.

Bile

Digestive fluid produced by the liver; bilirubin is excreted into bile.

Feces

Solid waste excreted from the digestive system; contains urobilin derived from bilirubin.

Cardiac skeleton

Thick fibrous tissue that anchors heart valves, separates atria from ventricles, and regulates electrical conduction.

SA node

Sinoatrial node; natural pacemaker that initiates the heartbeat.

AV node

Atrioventricular node; delays electrical impulse to allow atrial contraction before ventricles.

Bundle of His

Conduction pathway from the AV node to the bundle branches.

Bundle branches

Right and left pathways distributing cardiac impulses to the ventricles.

Purkinje fibers

Network that rapidly conducts impulses to ventricular muscle to coordinate contraction.

P wave

ECG wave representing atrial depolarization (atrial contraction).

QRS complex

ECG complex representing ventricular depolarization (ventricles contract).

T wave

ECG wave representing ventricular repolarization (ventricles reset).

Tunica intima

Innermost layer of a blood vessel; made of endothelial cells with elastic support.

Endothelial cells

Flat, squamous cells lining the interior surface of blood vessels; part of the tunica intima.

Simple squamous epithelium

Tissue type of endothelial cells lining vessels; thin and flat for efficient exchange.