Cardio Histology Flashcards
What do cardiac muscle cells look like?
short, branched, and Y-shaped
nuclei in the middle ( NOT at periphery like sk m)
What are intercalated discs?
transverse junctions at the ends of cells that allow passage of electrical current
prevent physical damage/tearing
(perpendicular to striations)
What makes up the pericardial cavity?
space btw parietal and visceral serous pericardium
What makes up the epicardium
layer of mesothelium (simple squamous)
areolar CT w/ collagen and elastic fibers and fat
What makes up the endocardium
endothelium = innermost, simple squamous
thin layer of areolar CT
Where are the coronary arteries embedded?
in the adipose tissue of the epicardium
What are the 3 types of cells in the myocardium?
cardiomyocytes nodal cardiomyocytes (in SA and AV nodes) myoendocrine cardiomyocytes
What are the 2 types of transverse junctions btw cardiomyocytes?
fascia adherens
desmosomes
What are fascia adherens?
actin filaments at the ends of terminal sarcomeres
transmit contractile forces
most predominant
What/where are desmosomes?
transverse junctions, provide anchorage for intermediate filaments of the cytoskeleton
What is the one longitudinal junction?
gap/ nexus junctions
allow excitation to pass btw cells
What makes up the dyad?
Where are they found?
1 T tubule + 1 SR cisterna
found at Z-lines –> uniform contraction
What are lipofuscin granules?
small bodies that accumulate w/ age in stable non-dividing cells
contain material derived from residual bodies after lysosomal digestion
What are atrial granules?
in myoendocrine cells
contain precursor of atrial natriuretic factor (ANF)
What is ANF?
atrial natriuretic factor
in myoendocrine cells in atria –> targets kidneys to decrease Na+ and H2O retention
How does the endocardium differ btw atria and ventricles?
thicker in ventricles - has a subendocardial layer of CT w/ smooth muscle and purkinje fibers
Where are purkinje fibers in the atria?
in endocardium, often closer to endothelium and intermixed w/ myocardium
(in subendocardial layer in ventricles)
What characterizes purkinje fibers?
larger and typically seen at periphery of myocardium
mostly lack T tubules
often won’t see nuclei
elongated (not Y-shaped or branched)
What makes up the cardiac skeleton?
4 rings, 2 trigones
dense irregular CT in endocardium
What is the function of the cardiac skeleton?
anchors valves and surrounds AV canals to maintain shape
contributes to septa
insertion of cardiac muscle
electrical insulator btw atria and ventricles
What are the heart valves made of?
core of fibroelastic CT covered by endothelium
continuous w/ cardiac skeleton
What is a valve ring?
fibroelastic layer of endocardium condensed
creates central portion of the valve
