5 - Dougherty - Muscle Histology

Question 1

What are three basic types of muscle?

What do they all have in common/different?

Answer 1

Skeletal

Cardiac

Smooth

Same contractile proteins, Different organization, Different regulation

Question 2

Sarcolemma

Answer 2

Plasma membrane of muscle

Question 3

Sarcoplasm

Answer 3

Cytoplasm of muscle

Question 4

Sarcomere

Answer 4

Functional unit of contractile proteins (myofibril)

Repeating units run the length of the muscle fiber

Composed of thick (myosin) and thin (actin) filaments

Overlapping of filaments creates striation banding pattern

Question 5

Skeletal Muscle Major Hallmarks

Answer 5

Single, long, multinucleated

flattened, peripheral nuclei

Question 6

Cardiac Muscle Fiber

Answer 6

indeterminate number of cells joined end to end, 1 (maybe 2) rounded nuclei

Joined by intercalated disks

Question 7

Smooth Muscle

Answer 7

Single cell, with single central nucleus

Hot dog nucleus (longitudinal, circular in cross section)

Eosinophilic cytoplasm, minimal endomysium

Question 8

Skeletal Muscle Organization

[Fiber + Protective Covering]

Answer 8

Microfilaments (Actin/Myosin)

Myofibrils + Sarcoplasmic Reticulum

Fibers + Endomysium

Fasicle + Perimysium

Muscle + Pimysium

Question 9

Three Connective Tissue Coverings in Muscle

Answer 9

Loose, Smallest: Endomysium

Dense:

Perimysium (middle)

Epimysium (largest)

Question 10

Answer 10

Question 11

What are the thick and thin bands of the sarcomere?

Dark and Light?

Answer 11

Thick - myosin (more letters = thicker)

Thin - actin (less letters = thinner)

Dark = A bands

Light = I bands

Question 12

What is the point of attachment for the thin filaments?

What defines the length of the sarcomere?

Answer 12

Z-line

Z-line to Z-line = sarcomere

Question 13

I Band

Answer 13

Light band

Z line and thin filaments (actin)

Shortens during contraction

Question 14

A Band

Answer 14

Dark band

Full length of the thick filaments (myosin)

Thin filaments overlap here

No change in size during contraction

Question 15

Muscle Triad

Answer 15

2 segments of sarcoplasmic reticulum bisected by T-Tubule

Located at the A-I Junction

Question 16

Answer 16

Question 17

What type of cells?

Orientation L and R?

Answer 17

L = Cross Section

R = Longituduinal Section

Question 18

Answer 18

Motor End Plates

Question 19

Type of Muscle?

Answer 19

Cardiac

Peep them center nuclei, branching, and intercalated disks

Question 20

Type of Muscle

Answer 20

Cardiac

Center nucleus, branching

Question 21

What makes the diad in cardiac muscle?

Answer 21

T-tubules at Z lines with sarcoplasmic reticulum

Question 22

What cellular structure is required for coordination and propagation of action potentials between cells?

Answer 22

Gap Junctions

Question 23

What binds intermediate filaments of two muscle cells together?

What are the intermediate filaments?

Answer 23

Desmosomes

Desmin, Vimentin

Question 24

Purkinje Fibers

Answer 24

Note purkinje fibers are lighter in color and sub-endothelial.

Question 25

Answer 25

Purkinje Fibers (cardiac)

Reduced, disorganized myofibrils

“swirly” look

Question 26

Type of Muscle, and orientation

Answer 26

Smooth muscle

Question 27

What is unique about smooth muscle when contracted vs uncontracted?

What binds intermediate filaments and actin?

Answer 27

When contracted, mesh network will “crunch” nucleus

dense bodies bind intermediate filaments and actin to the membrane

Question 28

What are major differences between smooth and striated muscle?

Answer 28

Smooth:

No Sarcomeres

No T-Tubules

Regulated by: Hormones, Stretch, Gap Junctions