ANHB2214 Study Guide - Midterm Guide: Heart Valve, Aorta, Proteoglycan
3 Jun 2018
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Cardiovascular System:
• Endothelium
o Epithelium lining the vascular system
o Simple squamous epithelium with flattened nuclei
o Selectively permeable layer
o Non-thrombogenic layer
o Functions
▪ Modulate blood flow and vascular resistance
▪ Work with immune cells
▪ Synthesize chemical messengers
▪ Oxidize lipoproteins
▪ Affect relaxation and contraction of smooth muscle cells in
tunica media
• Cardiac muscle
o Central nucleus
o Striations
o Intercalated discs → irregular arrangement
▪ Fascia adherens → holds muscle cells end to end
▪ Gap junctions → allows transmission of ions between cells
o Cardiac muscle is thicker in the ventricles than atria → have more
distance to pump blood
o 2 types of cardiac muscle cells
▪ Contractile cells
▪ Impulse generating/conducting cells
• The heart
o Muscular organ that contracts rhythmically, pumping blood
through the circulatory system
o Endocardium
▪ Homologous with tunica intima of blood vessels
▪ Single layer of squamous endothelial cells
▪ Rests on a thin subendothelial layer of loose connective
tissue
▪ Subendothelial cartilage → between endocardium and
myocardium → contains veins, nerves, Purkinje fibers
o Myocardium
▪ Thickest of the tunics
▪ Consists of cardiac muscle cells arranged in layers
o Epicardium
▪ Serous covering of the heart
▪ Forms visceral layer of pericardium
▪ Externally covered by simple squamous epithelium
supported by a thin layer of connective tissue
▪ Subepicardial layer contains veins, nerves and nerve
ganglia
▪ Adipose tissue that surrounds heart accumulates here
o Fibrous skeleton
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▪ Composed of dense connective tissue with thick collagen
fibers
▪ Insertion point of cardiac muscle
▪ Septum
• Dense connective tissue
• Separating atria and ventricles
o Heart valves
▪ Stops backflow of blood during contraction of atria and
ventricles
▪ Either separate atria and ventricles or ventricles and blood
vessels
▪ Central core → fibrosa → strongest component joins with
fibrous skeleton
▪ Spongiosa → thin layer, elastic, dampens force of vibration
of heart beat
▪ Ventricularis → adjacent to ventricular space, continuous
with chordae tendinae, dense connective tissue
• Impulse generating system of the heart
o SA node
▪ Pacemaker of the heart
▪ Located close to superior vena cava, in right atrium
o Atrioventricular Bundle of His
▪ Purkinje cells
▪ Penetrate fibrous skeleton
▪ Divide into right and left atrioventricular bundles
o Impulse generating cardiac muscle cells have a greater diameter
than normal cardiac muscle cells
o Stimulus for ventricular contraction moves from apex to base
• Types of circulation
o Pulmonary circulation → right atrium and ventricle
o Systemic circulation → left atrium and ventricle
o Portal system
▪ Liver → hepatic portal system
▪ Pituitary gland → hypothalamic-hypophyseal portal system
• General structure of blood vessels
o Tunica intima
▪ Layer of endothelial cells lining the vessel’s interior surface
▪ Cells rest on a basal lamina
▪ Beneath endothelium → subendothelial layer → loose
connective tissue and smooth muscle arranged
longitudinally
o Tunica media
▪ Concentric layers of helically arranged smooth muscle cells
▪ Interposed amongst smooth muscle cells are elastic fibers,
collagen fibers and proteoglycans
▪ Media is separated from the intima by the internal elastic
lamina
▪ Media is separated from the adventitia by the external
elastic lamina
find more resources at oneclass.com
find more resources at oneclass.com
