Cardiac Muscle Cell Anatomy

Question 0

Where are cardiac muscle fibers found?

Answer 0

Only in the heart

Question 1

Describe a cardiac muscle cell

Answer 1

Striated
Branched
Single nucleus
Intercalated disks and Gap junctions
Auto rhythmic

Question 2

What regulates cntx in heart muscle cells?

Answer 2

Ca++

Question 3

Elongated branching cells usually contain ____ nuclei

Answer 3

1-2

Question 4

Where is the nucleus of a cardiac myofiber located?

Answer 4

Centrally

Question 5

A dark zigzag lines shows up on stained pics if cardiac muscle. What is it?

Answer 5

Intercalated disk–specialized cell to cell contact

Question 6

What holds the cardiac myofibers together, end to end?

Answer 6

Desmosomes

Question 7

How do intercalated disks increase cell to cell communication?

Answer 7

Increased membrane surface area from interdigitation
Gap junctions allow action potentials to move from one cell to the next
—allows the AP to travel continuously and cells cntx as one unit

Question 8

What specialized features do intercalated disks have?

Answer 8

Desmosomes to hold cells together and gap junctions to increase the efficiency at which the AP can travel from cell to cell

Question 9

Electrically, cardiac muscles of the______________behave as single units.

Answer 9

Atria and ventricles

Question 10

Describe the difference between the t-tubule-Sarcoplasmic reticulum configuration of skeletal muscle vs cardiac muscle

Answer 10

Skeletal muscle has triad -terminal cisternae-t tubule-terminal cisternae that allow the AP to facilitate release of Ca++ from the terminal cisternae. Cardiac muscle has no triad and Sarcoplasmic reticulum has no terminal cisternae, though t tubule still carries AP down to SR and effects Ca++ distribution.
Skeletal muscle has 2 triads per sarcomere to facilitate quick Ca++ use by troponin. Cardiac muscle has 1 t tubule per sarcomere (located at each z disk).
T tubule in cardiac muscle is larger in diameter.