Cardio Histology

Question 1

What do cardiac muscle cells look like?

Answer 1

short, branched, and Y-shaped

nuclei in the middle ( NOT at periphery like sk m)

Question 2

What are intercalated discs?

Answer 2

transverse junctions at the ends of cells that allow passage of electrical current
prevent physical damage/tearing
(perpendicular to striations)

Question 3

What makes up the pericardial cavity?

Answer 3

space btw parietal and visceral serous pericardium

Question 4

What makes up the epicardium

Answer 4

layer of mesothelium (simple squamous)

areolar CT w/ collagen and elastic fibers and fat

Question 5

What makes up the endocardium

Answer 5

endothelium = innermost, simple squamous

thin layer of areolar CT

Question 6

Where are the coronary arteries embedded?

Answer 6

in the adipose tissue of the epicardium

Question 7

What are the 3 types of cells in the myocardium?

Answer 7

cardiomyocytes
nodal cardiomyocytes (in SA and AV nodes)
myoendocrine cardiomyocytes

Question 8

What are the 2 types of transverse junctions btw cardiomyocytes?

Answer 8

fascia adherens

desmosomes

Question 9

What are fascia adherens?

Answer 9

actin filaments at the ends of terminal sarcomeres
transmit contractile forces
most predominant

Question 10

What/where are desmosomes?

Answer 10

transverse junctions, provide anchorage for intermediate filaments of the cytoskeleton

Question 11

What is the one longitudinal junction?

Answer 11

gap/ nexus junctions

allow excitation to pass btw cells

Question 12

What makes up the dyad?

Where are they found?

Answer 12

1 T tubule + 1 SR cisterna

found at Z-lines –> uniform contraction

Question 13

What are lipofuscin granules?

Answer 13

small bodies that accumulate w/ age in stable non-dividing cells
contain material derived from residual bodies after lysosomal digestion

Question 14

What are atrial granules?

Answer 14

in myoendocrine cells

contain precursor of atrial natriuretic factor (ANF)

Question 15

What is ANF?

Answer 15

atrial natriuretic factor

in myoendocrine cells in atria –> targets kidneys to decrease Na+ and H2O retention

Question 16

How does the endocardium differ btw atria and ventricles?

Answer 16

thicker in ventricles - has a subendocardial layer of CT w/ smooth muscle and purkinje fibers

Question 17

Where are purkinje fibers in the atria?

Answer 17

in endocardium, often closer to endothelium and intermixed w/ myocardium
(in subendocardial layer in ventricles)

Question 18

What characterizes purkinje fibers?

Answer 18

larger and typically seen at periphery of myocardium
mostly lack T tubules
often won’t see nuclei
elongated (not Y-shaped or branched)

Question 19

What makes up the cardiac skeleton?

Answer 19

4 rings, 2 trigones

dense irregular CT in endocardium

Question 20

What is the function of the cardiac skeleton?

Answer 20

anchors valves and surrounds AV canals to maintain shape
contributes to septa
insertion of cardiac muscle
electrical insulator btw atria and ventricles

Question 21

What are the heart valves made of?

Answer 21

core of fibroelastic CT covered by endothelium

continuous w/ cardiac skeleton

Question 22

What is a valve ring?

Answer 22

fibroelastic layer of endocardium condensed

creates central portion of the valve