Ch 9.1 -- Anatomy of the Heart -- VTPP 435

Ch 9.1 -- Anatomy of the Heart -- VTPP 435

3 components of circulatory system

1) Heart -- pump that imparts pressure to blood to create pressure gradient
2) Blood Vessels -- passageways for blood to go to and from heart
3) Blood -- transport medium for nutrients and materials in body

Pumonary Circulation

-closed loop of vessels carrying blood between heart and lungs
-low pressure & resistance

Systemic Circulation

-circuit of vessels carrying blood between heart and body
-high pressure & resistance

Base

-top of heart with a broad base
-angled to the right

Apex

-bottom of heart
-angled to the left
-where the pumping is felt outside of body

Atria (singular atrium)

-upper chambers of heart that receive blood from veins
-transfer blood to ventricles below

Ventricles

-lower chambers that receive blood from Atria

Septum

-separates 2 halves of heart
-muscular partition that prevents blood mixing from 2 sides of heart

Aorta

-single large artery carrying blood away from left ventricle
-where major arteries branch off

Heart Valves

-open and close due to pressure gradient
-ensure one directional flow of blood
-four in heart

Atrioventricular (AV) Valves

-between atrium and ventricle
-let blood flow to fill ventricle
-Tricuspid (Right) Valve
-Mitral (Bicuspid) (Left) Valve

Chordae Tendineae & Papillary Muscles

-keeps AV flaps closed to prevent backward flow of blood and contract

Semilunar Valves

-lie at juncture where major arteries are before ventricle
-have 3 cusps
-Pulmonary (Right) Valve
-Aortic (Left) Valve

Fibrous Skeleton

-four interconnecting rings of dense connective tissue of heart
-surround & support heart valves
-separates atria from ventricles
-provides a rigid attachment for cardiac muscle

3 Distinct Layers of the Heart Wall

1) Endothelium -- thin, inner layer made of epithelial tissue
2) Myocardium -- middle, made of cardiac muscle
3) Epicardium -- thin, external layer

Intercalated Discs

-where cardiac muscles join to form branching fibers
-have desmosomes -- hold cells together to withstand mechanical stress
-have gap junctions -- area of low electrical resistance to spread action potentials

Functional Syncytium

-group of smooth or cardiac muscle cells that are interconnected by gap junctions
-function electrically and mechanically as a single unit

Pericardial Sac

-double walled membranous sac that encloses heart
-has tough outer fibrous covering
-has secretory inner lining with a pericardial fluid

Pericardial Fluid

-provides lubrication to prevent friction between pericardial layers as they glide over each other with every beat of heart

Pericarditis

-inflammation of pericardial sac
-results in painful friction between two pericardial layers
-occurs usually due to viral or bacterial infection