Heart

Question 1

what types of junctions do intercalated discs have?

Answer 1

• gap junctions = transportation of ions; electrical continuity between cytosol of cells
• desmosomes/macula adherens = structural strength

Question 2

what is the differences between cardiac and skeletal muscle?

Answer 2

• intercalated discs

- single central nucleus per cell

Question 3

describe blood flow through the body

Answer 3

superior/inferior vena cava > right atrium > right ventricle > pulmonary arteries > lungs > pulmonary veins > left atrium > left ventricle > aorta > rest of body

Question 4

how do valves open/close?

Answer 4

papillary muscles in ventricles connect to chordae tendinea that attach to valves and aid in closing/opening of valves

Question 5

what causes heartbeat sounds?

Answer 5

valves closing

Question 6

in what layer are Purkinje fibers located?

Answer 6

endocardium

Question 7

what are Purkinje fibers and why do they stain lighter?

Answer 7

• are modified cardiomyocytes for signal transduction

- contain significant stores of glycogen; glycogen is lost during fixation so they will appear lighter

Question 8

what are the types of cardiocytes in the myocardium?

Answer 8

• modified cardiomyocytes for signal transduction
• myoendocrine cardiocytes = producing atrial natriuretic factor (hormones that help regulate heart function)
• nodal cardiocytes = specialized to control the rhythmic contraction of the heart (initiate contraction)

Question 9

what do trabeculae carne do?

Answer 9

foldings in ventricular walls that prevent suction from occurring as ventricle contacts and expands

Question 10

what does the epicardium contain?

Answer 10

mostly adipose and loose CT

Question 11

what is the fibrous skeleton made of?

Answer 11

collagen fibers / dense CT

Question 12

what are the 3 layers of the valves (i.e. A.V valve)?

Answer 12

1) ventricularis = faces ventricle; dense irregular CT
2) fibrosa = internal/middle; dense regular CT; continuous with fibrous skeleton
3) spongiosa = faces atrium; loose CT

Question 13

what do the chordae tendinae do?

Answer 13

connect valve to papillary muscle to help regulate opening/closing of valve

Question 14

explain coordinated action of heart conducting system?

Answer 14

impulses initiate in sinoatrial node > atrioventricular node > bundle of Histone > Purkinje fibers > ventricular walls (entire ventricle contracts at once