Human Anatomy and Physiology: Cardiovascular, Blood, and Endocrine Systems

A set of comprehensive vocabulary flashcards covering cardiac anatomy, blood components and hemostasis, and endocrine histology.

Mediastinum

Anatomical region situated between the lungs in the thoracic cavity containing the heart, great vessels, trachea, esophagus, and thymus.

Fibrous Pericardium

The superficial, tough layer of dense connective tissue surrounding the heart that protects, anchors, and prevents overfilling of the heart.

Parietal Layer of Serous Pericardium

The outer layer of the serous pericardium that lines the internal surface of the fibrous pericardium.

Epicardium (Visceral Layer of Serous Pericardium)

The inner layer of the serous pericardium that adheres directly to the outer surface of the heart wall (myocardium).

Pericardial Cavity

The potential space between the parietal and visceral layers of serous pericardium containing a small volume of serous fluid to reduce friction during cardiac contraction.

Myocardium

The middle layer of the heart wall, composed of cardiac muscle tissue responsible for pumping blood.

Endocardium

The innermost endothelial lining of the heart wall that covers the interior of the heart chambers and valve leaflets.

Auricle

A small, wrinkled pouch-like extension located on the external surface of each atrium that increases atrial capacity.

Fossa Ovalis

An oval depression located in the interatrial septum of the right atrium, representing the remnant of the fetal foramen ovale.

Pectinate Muscles

Parallel muscular ridges lining the anterior wall of the right atrium and extending into the right auricle.

Trabeculae Carneae

Irregular muscular ridges located on the internal surface of the ventricular walls.

Chordae Tendineae

Fibrous tendinous cords that anchor the cusps of the atrioventricular valves to the papillary muscles within the ventricles.

Septomarginal Trabecula (Moderator Band)

A muscular ridge in the right ventricle extending from the interventricular septum to the base of the anterior papillary muscle.

Tricuspid Valve

The right atrioventricular valve containing three cusps, located between the right atrium and right ventricle.

Bicuspid Valve (Mitral Valve)

The left atrioventricular valve containing two cusps, located between the left atrium and left ventricle.

Coronary Sinus

A large venous vessel on the posterior surface of the heart that collects deoxygenated blood from coronary veins and returns it to the right atrium.

Great Cardiac Vein

Coronary vein traveling alongside the anterior interventricular artery in the anterior interventricular sulcus.

Middle Cardiac Vein

Coronary vein traveling alongside the posterior interventricular artery in the posterior interventricular sulcus.

Small Cardiac Vein

Coronary vein traveling alongside the right marginal artery along the inferior margin of the heart.

Hematocrit

The percentage of total blood volume occupied by erythrocytes, normally $40\%-54\%$ in adult males and $36\%-48\%$ in adult females.

Buffy Coat

The thin layer of centrifuged whole blood containing leukocytes and platelets, making up less than $1\%$ of total blood volume.

Albumin

The most abundant major plasma protein ($\sim 58\%$), synthesized by the liver, which maintains blood colloid osmotic pressure and fluid retention in capillaries.

Globulins

Major plasma proteins ($\sim 37\%$) involved in lipid and iron transport, as well as immune defense in the form of antibodies.

Fibrinogen

Major plasma protein ($\sim 4\%$) synthesized by the liver that serves as the soluble precursor to insoluble fibrin during blood coagulation.

Hematopoiesis

The continuous process of blood cell production occurring in red bone marrow and lymphoid organs, originating from pluripotent hematopoietic stem cells (HSCs).

Oxyhemoglobin

The reversible compound formed when oxygen binds to the iron ($\text{Fe}^{2+}$) core of a hemoglobin molecule ($\text{Hb} + \text{O}_2$).

Carbaminohemoglobin

The reversible compound formed when carbon dioxide binds directly to amino acids in hemoglobin ($\text{Hb} + \text{CO}_2$).

Carboxyhemoglobin

The compound formed when carbon monoxide binds tightly to the iron core of hemoglobin, preventing oxygen transport due to irreversible binding.

Neutrophils

The most abundant leukocytes ($50\%-70\%$), characterized by multi-lobed nuclei ($2\text{--}5$ lobes), that perform phagocytosis of bacteria and diapedesis.

Eosinophils

Granulocytes ($1\%-4\%$ of leukocytes) with bi-lobed nuclei and red-staining granules, specialized in destroying parasitic worms.

Basophils

The least common leukocytes ($0.5\%-1\%$), featuring bi-lobed or S-shaped nuclei obscured by dark basophilic granules that release histamine and heparin.

Lymphocytes

The most common agranulocytes ($20\%-40\%$ of leukocytes), containing large, dark spherical nuclei with minimal cytoplasm, responsible for adaptive immune responses.

Monocytes

Large agranulocytes ($2\%-8\%$ of leukocytes) with indented or kidney-shaped nuclei, serving as precursors to tissue macrophages.

Platelets (Thrombocytes)

Small, basophilic cell fragments ($150\text{,}000\text{--}400\text{,}000\,\text{per mm}^3$) derived from megakaryocytes that initiate hemostasis and blood clotting.

von Willebrand Factor (vWF)

A glycoprotein secreted by endothelial cells and platelets that mediates platelet adhesion to exposed subendothelial collagen during primary hemostasis.

Thromboxane A2 (TXA2)

A mediator synthesized and released by activated platelets that promotes further platelet aggregation and vascular smooth muscle contraction (vasoconstriction).

Prostacyclin (PGI2)

An endothelial cell secretion that causes vasodilation and inhibits platelet activation and aggregation, preventing platelet plug spread to uninjured vessel sites.

Fibrinolysis

The enzymatic breakdown of a blood clot, in which plasminogen activators convert plasminogen to active plasmin, which degrades cross-linked fibrin into soluble fragments.

Endocrine Gland

A ductless gland that secretes hormones directly into surrounding interstitial fluid and blood vessels to regulate distant target organs.

Exocrine Gland

A gland that secretes non-hormonal products (such as enzymes, sweat, or saliva) through ducts onto epithelial surfaces or into body cavities.

Adenohypophysis

The anterior lobe of the pituitary gland, composed of glandular epithelial cells (basophils and eosinophils) that produce and secrete multiple tropic and direct hormones.

Neurohypophysis

The posterior lobe of the pituitary gland, composed of pale-staining neural tissue containing unmyelinated nerve axons whose cell bodies reside in the hypothalamus.

Infundibulum

The narrow stalk of neural tissue that connects the pituitary gland superiorly to the hypothalamus.

Thyroid Follicles

Spherical functional units of the thyroid gland lined by simple cuboidal follicular cells and filled with gel-like colloid.

Colloid

The protein-rich fluid stored in the lumen of thyroid follicles, consisting predominantly of thyroglobulin precursor protein.

Parafollicular Cells (C Cells)

Large, pale-staining endocrine cells located between thyroid follicles that secrete calcitonin to reduce elevated blood calcium levels.

Parathyroid Hormone (PTH)

A peptide hormone secreted by cells of the parathyroid glands in response to low blood calcium levels, acting to increase blood calcium concentration.

Chromaffin Cells

Modified postsynaptic sympathetic neurons in the adrenal medulla that release catecholamines (epinephrine and norepinephrine) directly into the blood during stress.

Zona Glomerulosa

The outermost layer of the adrenal cortex, characterized by rounded clusters of cells that produce mineralocorticoids such as aldosterone.

Zona Fasciculata

The middle and thickest layer of the adrenal cortex, composed of parallel cords of lipid-rich cells that produce glucocorticoids.

Zona Reticularis

The innermost layer of the adrenal cortex, consisting of a net-like arrangement of branching cell cords that synthesize gonadocorticoids.

Pancreatic Islets (Islets of Langerhans)

Spherical clusters of pale-staining endocrine cells dispersed throughout the exocrine pancreas ($\sim 2\%$ of total tissue) that secrete hormones regulating blood glucose.