Cardiac Cells and Vessels Quiz

Characteristics of Cardiac Cells and Vessels

• The SA node myocytes have an irregular shape, large amounts of collagen and elastic fibers, and are smaller in diameter than regular cardiac muscle cells.
• Purkinje fibers are larger than cardiac muscle cells, have few myofibrils, no T-tubules, and are connected by desmosomes and gap junctions.
• Cardiomyocytes are elongated, cylindrical, striated muscle cells with intercalated discs, T-tubules, and a centrally located single nucleus.
• There are three main types of vessels in the arterial system: elastic arteries, muscular arteries, and arterioles.
• Elastic arteries, such as the aorta, have small vessels to supply the wall, a wide tunica media with concentric layers of elastic fibers and few smooth muscle cells, and a single layer of flattened epithelial cells in the tunica intima.
• Muscular arteries, such as the femoral artery, have a broad tunica adventitia, a tunica media mainly formed of layers of smooth muscle with few elastic fibers, and a single layer of flattened endothelial cells in the tunica intima.
• Arterioles have a tunica adventitia that merges with surrounding tissue, a tunica media consisting mainly of smooth muscle cells, and a single layer of flattened endothelium in the tunica intima.
• Veins can accommodate 70% of the blood volume and possess unidirectional valves that allow blood to drain back to the heart.
• The venous tunica intima is composed of a traditional continuous endothelium and forms venous valves.
• The venous tunica media is composed mainly of a thin layer of smooth muscle cells and no internal elastic lamina.
• The venous tunica adventitia is prominent and composed of collagenous connective tissue.
• There are three types of capillaries: continuous, fenestrated, and sinusoidal, each with different levels of permeability and basement membrane continuity.