Anatomy of the Heart. Part 2. Atria. Atria Low pressure chambers Separated from each other by the inter-atrial septum RA receives deoxygenated blood from the SVC, IVC and CS LA receives oxygenated blood from the 4 pulmonary veins. Atria. Atria
Actin Myofibril Contains two proteins:
These two proteins inhibit the formation of
cross bridges with myosin.
When cross bridge formation is inhibited
the muscle is relaxed.
Each muscle cell is surrounded by a cell
membrane called the sarcolemma.
Each muscle fibers contain T tubules that
are extensions of the cell membrane.
Another system of tubules called the
sarcoplasmic reticulum stores calcium.
Calcium enters the cytoplasm from:
Cardiac Muscle Fibers
The heart consist of two syncytia:
Impulses can only be conducted
from the atrial syncytium into
ventricular syncytium by means
of the atrioventricular junction.
Each atrio-ventricular valve consists
The base of the leaflets are attached to
the fibrous annulus.
The tips of the AV valves are attached to
thin strands of fibrous tissue called fibrous
connective tissue chordae tendineae.
The chordae tendineae are attached to
small mounds of myocardium called