26: Muscle Tissue

Question 1

Myofibers

Answer 1

Myocytes

Question 2

Nuclei of skeletal muscle vs smooth vs cardiac

Answer 2

Skeletal: multinulceate, around periphery
Cardiac: 1 centrally located
Smooth: 1 centrally located

Question 3

T tubules in skeletal vs cardiac muscle

Answer 3

Skeletal: triad with T tubule + terminal cisternae on either side
Cardiac: diad with T tubule + 1 terminal cisterna

Question 4

Terminal cisternae

Answer 4

Dilated ends of SR

Question 5

Where are T tubules found?

Answer 5

At z lines

Question 6

Three layers of CT that organize skeletal muscle into an organ

Answer 6

Endomysium: separates myofibers
Perimysium: separates fascicles
Epimysium: around the entire muscle

Question 7

Z-line vs M-line in sarcomere

Answer 7

Z-line: anchor site for actin

M-line: anchor site for myosin

Question 8

I-band, H-zone, and A-band of sarcomere

Answer 8

I-band: actin only
H-zone: myosin only
A-band: entire extent of myosin

Question 9

Tropomyosin

Answer 9

Runs in groove of F-actin strands, binds troponin

Question 10

Three parts of troponin

Answer 10

T: binds tropomyosin
I: inhibits myosin and actin binding
C: binds Ca2+

Question 11

Is cardiac muscle striated or not?

Answer 11

Striated

Question 12

Intercalated discs of cardiac muscle

Answer 12

Cell adhesion: combination of gap and desmosomal junction

Question 13

Where are intercalated discs found?

Answer 13

Where Z lines are in cardiac muscle

Question 14

Cardiac cell composition

Answer 14

Are branching

Question 15

Three parts of an intercalated disc junction and their orientation

Answer 15

1. Fascia adherens (transverse)
2. Desmosomes (transverse)
3. Gap junction (longitudinal)

Question 16

Fascia adherens

Answer 16

Actin at the end of terminal sarcomeres inserts into intercalated disc junction -> contractile force transmits between cells

Question 17

Where is a site of low electrical resistance in cardiac cells

Answer 17

Gap junctions (AKA nexus junctions) -> allows excitation to pass between cells

Question 18

How do smooth muscle cells communicate?

Answer 18

Gap junctions - cells contract as a slow, sustained unit?

Question 19

Smooth muscle cell control (two things)

Answer 19

1. Autonomic NS

2. Hormones

Question 20

Dense bodies

Answer 20

Where myofilaments attach in smooth muscles (in place of Z lines)

Question 21

Two intermediate filament types that make up dense bodies

Answer 21

Densin, vimentin

Question 22

Innervation to skeletal muscles vs cardiac and smooth muscles

Answer 22

Skeletal: every muscle receives an axon terminal

Smooth and cardiac: not every cell is directly innervated

Question 23

Axon terminal function

Answer 23

Stores and releases neurotransmitters