Cardiovascular System Histology and Embryology

Vocabulary practice flashcards covering cardiovascular anatomy, embryological milestones, histology of the cardiac wall layers (endocardium, myocardium, pericardium), cardiac conducting and endocrine cells, and coronary blood supply.

Arteries

Cardiovascular conduits that supply tissues throughout the body with oxygen, nutrients, and hormones.

Veins

Blood vessels responsible for collecting carbon dioxide ($\text{CO}_2$) and metabolic waste products from tissues.

Capillaries

Microscopic vascular sites where physiological exchanges take place between circulating blood and surrounding tissues.

Lymph

Interstitial fluid originating from blood that accumulates in the interstitial space and circulates within lymphatic vessels to enable immune defense cell transit and food fat transport.

Cardiogenic plate

A horseshoe-shaped vascular plexus formed in front of the neural plate when two mesodermal cell cords migrate cephalad and converge around embryonic development.

Dorsal aortas

A pair of longitudinal embryonic vessels that form parallel to the midline from angioformative cell clusters and connect directly to the cardiac tube.

Primitive cardiac tube

A primary embryonic structure formed by the fusion of the two initial vascular tubes, which undergoes elongation, localized dilation, bending, and partitioning.

Fibrous skeleton of the heart

A collagenous framework composed of fibrous rings or tendinous circles surrounding the four openings at the base of the ventricles, providing insertion points for myocardial fibres and structural rigidity to valves.

Endocardium

The innermost cardiac wall layer lining heart chambers, valves, and chordae tendineae, characteristically thicker in the atria than in the ventricles.

Endothelium

A single layer of flattened cells resting on a basement membrane that secretes prostacyclin and tissue factor, modulates vascular tone via nitric oxide and endothelin-1, and regulates leukocyte migration.

Heart valves

Non-vascularised, deformable but inextensible endocardial folds enclosing an axial fibrous lamina (fibrosa) that receive nourishment solely through imbibition.

Chordae tendineae

Tendinous cords anchored to papillary muscles containing central collagen fibres surrounded by peripheral elastic fibres.

Myocardial cells proper

The predominant contractile cardiomyocytes, characterized as short, Y-shaped branched cylinders with a single central nucleus, rich myofibrils, and an absence of satellite cells.

Scalariform lines

Intercalated contact zones linking adjacent myocardial cells, equipped with gap junctions in their longitudinal segments for ion diffusion and action potential propagation.

Myoendocrine cells

Specialized atrial cardiomyocytes containing dense neurosecretory vesicles that synthesize and release atrial natriuretic factor (ANF) when atrial wall tension increases.

Atrial natriuretic factor (ANF)

A potent polypeptide hormone secreted by atrial myoendocrine cells that promotes water excretion (diuresis), sodium excretion (natriuresis), and cardiac muscle relaxation.

Nodal tissue

Specialized cardiac muscle tissue of embryonic histological appearance responsible for generating and conducting rhythmic electrical impulses throughout the heart.

Sinus node (Keith and Flack node)

Pacemaker nodal mass located within the wall of the right atrium adjacent to the superior vena cava opening, responsible for initiating the heart's beat.

Atrioventricular node (Ashoff and Tawara node)

A specialized cluster of nodal tissue situated in the posteroinferior region of the interatrial septum.

Bundle of His

An electrical conduction pathway that originates at the atrioventricular node, traverses the interventricular septum, and divides into two bundle branches.

Purkinje network

Subendocardial conductive cells branching throughout the ventricles, characterized histologically by pale glycogen-rich cytoplasm, a central nucleus, and sparse peripheral myofibrils.

Pericardium

A double-layered fibroserous sac enveloping the heart, consisting of an internal visceral layer (epicardium) and an external parietal layer separated by the pericardial cavity.

Mesothelium

A monolayer of cells joined by junctional complexes and desmosomes that provides a sealed boundary lining the pericardial cavity.

Terminal vascularisation

The circulatory pattern of the myocardium where coronary branches deliver blood via terminal arterioles to exclusive myocardial territories without functional anastomoses.

Angina

Cardiac pain caused by reduced oxygen delivery to the myocardium due to partial obstruction of the coronary arteries.

Myocardial infarction

Ischaemic necrosis of cardiac muscle tissue resulting from the total obstruction of a coronary artery branch and subsequent cessation of regional blood flow.