05a: Muscle Tissue Histology

Question 1

Contractile cells/tissues can be divided into which subcategories?

Answer 1

1. Single cell units

2. Multicellular tissues

Question 2

Give examples of contractile cells that work as single-cell units.

Answer 2

1. Myoepithelium
2. Myofibroblasts
3. Pericytes

Question 3

Which muscle tissue type(s) is/are striated?

Answer 3

Skeletal and Cardiac

Question 4

What are the types of skeletal muscle tissue?

Answer 4

1. Type I
2. Type IIa
3. Type IIb

Question 5

Type I skeletal muscle, aka (X), has (more/less) mitochondria than the other types.

Answer 5

X = red

More

Question 6

Smooth muscle is (unitary/multiunit).

Answer 6

Can be either

Question 7

Which muscle tissue type(s) is/are innervated by the autonomic NS?

Answer 7

Cardiac and smooth

Question 8

T/F: Skeletal muscle is multinucleated.

Answer 8

True

Question 9

T/F: Skeletal muscle fiber diameter can be as small as the diameter of RBC.

Answer 9

True (10 micrometers)

Question 10

The PM of muscle fiber is called:

Answer 10

Sarcolemma

Question 11

The cytoplasm of muscle fiber is called:

Answer 11

Sarcoplasm

Question 12

The specialized (X) ER of the muscle fiber is called (Y) and functions primarily to:

Answer 12

X = smooth
Y = sarcoplasmic reticulum

Sequester Ca

Question 13

Smallest functional unit of contraction.

Answer 13

Sarcomere

Question 14

Series of sarcomeres constitute (X). And a group of (X) constitutes (Y).

Answer 14

X = Myofibril
Y = Muscle fiber

Question 15

Going from one Z-band to the middle of the sarcomere, list all bands you’d encounter in order

Answer 15

1. Z band
2. I band
3. A band
4. H band
5. M band

Question 16

What’s nebulin?

Answer 16

Linear protein that controls actin filament length (template for precise filament assembly)

Question 17

Titin is a(n) (X) that attaches to (Y). What is/are its function(s).

Answer 17

X = protien
Y = Z-line and myosin

Functions to:

1. Confer elasticity
2. Keep myosin centered

Question 18

Desmin is a(n) (X) that functions to (Y).

Answer 18

X = intermediate filament (for muscle)
Y = keep sarcomeres in vertical array

Question 19

Which filament(s) shorten during muscle contraction?

Answer 19

No shortening! Sliding mechanism

Question 20

During contraction, the sarcomere shortens by (X)%.

Answer 20

X = 25

Question 21

Max range of contraction is related to (X). Max strength is related to (Y).

Answer 21

X = muscle length
Y = muscle diameter

Question 22

Skeletal muscle: T-tubules arranged in what fashion?

Answer 22

Precisely arranged at A-I interface of myofibrils

Question 23

Skeletal muscle: Terminal cisterns of (X) are associated with (Y). These components form a (diad/triad).

Answer 23

X = sarcoplasmic reticulum
Y = T-tubules

Triad

Question 24

Skeletal muscle: where, specifically, is Ca stored?

Answer 24

Terminal cisterns of sarcoplasmic reticulum

Question 25

T/F: Skeletal muscle membrane depolarization can be detected from outside/periphery of the fiber.

Answer 25

False - depolarization reaches fiber interior

Question 26

Skeletal muscle: (X) depolarization leads to (Y) depolarization and which subsequent event?

Answer 26

``` X = membrane Y = t-tubule (triad) ``` Opening of Ca channels in terminal cistern

Question 27

Which muscle type capable of repeated contraction without fatigue?

Answer 27

Type I (red)

Question 28

(Slow/fast)-twitch, glycolytic muscle appears (red/white/intermediate) and is (quick/resistant) to fatigue.

Answer 28

Fast; white; quick

Question 29

Intermediate skeletal muscle type is (slow/fast)-twitch.

Answer 29

Fast

Question 30

PAS stain is a stain for:

Answer 30

Glycogen

Question 31

Which skeletal muscle type would be most PAS positive? Which color would they appear in the slide?

Answer 31

White (fast-twitch, glycolytic); appear most pink of the fibers in the slide

Question 32

Which LM technique can be used to visualize mitochondria levels in skeletal muscle?

Answer 32

Cytochrome oxidase (via enzyme cytochemistry)

Question 33

In skeletal muscle slide using cytochrome oxidase, to portray (X) levels, how does the appearance of red/white muscle types differ?

Answer 33

X = mitochondria Red: smallest, darkest fibers White: largest, lightest fibers

Question 34

Which skeletal muscle type used for posture?

Answer 34

Slow-twitch, oxidative (red/type I)

Question 35

Which skeletal muscle type used for sprinting?

Answer 35

Fast-twitch, glycolytic (white/type IIb)

Question 36

T/F: All body muscles have mixture of skeletal muscle fiber subtypes.

Answer 36

True

Question 37

T/F: The skeletal muscle fiber subtype cannot be altered once the muscle has developed.

Answer 37

False - subtype based on neuron that innervates fiber. So these innervations, and the subtype, can change

Question 38

Describe basic steps in skeletal muscle formation.

Answer 38

1. Myoblast matures 2. Myoblasts fuse (form syncytium, then myotube) 3. New myoblasts fuse at ends/sides and fiber grows in diameter 4. Satellite cells attach peripherally and fiber is innervated

Question 39

What are satellite cells?

Answer 39

Muscle (multi-potent) stem cells

Question 40

Upon activation, what's the function of satellite cells?

Answer 40

Can re-enter the cell cycle to proliferate and differentiate into myoblasts

Question 41

Sarcopenia is:

Answer 41

Age-related involuntary loss of skeletal muscle

Question 42

Loss of muscle mass in older people parallels gain of:

Answer 42

fat mass

Question 43

Cachexia is:

Answer 43

Muscle-wasting stage of disease; body breaks down skeletal muscle for glucose (to keep brain function)

Question 44

Which diseases can eventually lead to Cachexia?

Answer 44

Cancer, AIDS, chronic forms of kidney disease, heart failure

Question 45

Where, wrt the heart, is cardiac muscle found?

Answer 45

In heart walls and septum

Question 46

What are the cardiac muscle equivalent of skeletal muscle satellite cells?

Answer 46

There is none

Question 47

Describe some key artifacts in the cardiac muscle histology slide.

Answer 47

1. Intercalated disc 2. Sarcoplasmic cone 3. Less clear banding pattern (due to high mitochondria levels)

Question 48

Primary function of intercalated discs.

Answer 48

Hold cells together

Question 49

Intercalated disc is a complex of:

Answer 49

3 Intercellular junctions (fascia adherens, gap junction, desmosome)

Question 50

The fascia adherens in (X) muscle is critical for connecting (Y) of cells.

Answer 50

``` X = cardiac Y = myofibrils' actin ```

Question 51

Which structure(s) are responsible for the spread of depolarization in cardiac muscle?

Answer 51

Gap junctions (part of intercalated disc)

Question 52

Which intercellular junction, part of (X) in cardiac muscle, acts like zonular adherens?

Answer 52

X = intercalated disc Fascia adherens

Question 53

The intermediate filament, (X), is important in which cardiac muscle structure(s)?

Answer 53

X = desmin In desmosome of intercalated disc

Question 54

Cardiac muscle: T-tubules arranged in what fashion?

Answer 54

Located at Z-lines

Question 55

Cardiac muscle: location/storage of Ca.

Answer 55

Ca bound to external lamina in T-tubule

Question 56

External lamina (is/isn't) charged.

Answer 56

Is; negatively-charged

Question 57

What differs about the connection of the sarcoplasmic reticulum and the T-tubules between cardiac and skeletal muscle?

Answer 57

Cardiac: not as extensive of sarcoplasmic reticulum network, so association with T-tubule forms DIAD, not triad

Question 58

What's ANP in (X) muscle?

Answer 58

X = cardiac Atrial Naturietic Peptide; a powerful vasodilator

Question 59

ANP released in response to (X) and acts on (Y).

Answer 59

``` X = stretch of atrial walls Y = kidneys (reduce body fluid/BP) ```

Question 60

Purkinje and Bundle fibers have an increase in which characteristic(s) of cardiac muscle?

Answer 60

1. Size of cardiac cells 2. Number of gap junctions 3. Glycogen content

Question 61

Purkinje and Bundle fibers have an decrease in which characteristic(s) of cardiac muscle?

Answer 61

Number of myofibrils

Question 62

Smallest smooth muscle fibers found in (X). Largest found in (Y).

Answer 62

``` X = vessels (metarterioles) Y = uterus ```

Question 63

Shape of smooth muscle cell.

Answer 63

Fusiform

Question 64

T/F: Skeletal and Smooth muscle are capable of mitotic division.

Answer 64

False - only smooth muscle; skeletal muscle incapable once syncytium formed

Question 65

(X) muscle is capable of (synthesizing/secreting) fibers and nonfribrillar ECM.

Answer 65

X = smooth Both synthesizes and secretes

Question 66

(X) muscle behaves more like viscous mass (plasticity).

Answer 66

X = smooth

Question 67

Compare the contraction rate/energy use of smooth muscle and skeletal muscle.

Answer 67

Smooth muscle contraction takes 10x longer, can be prolonged, and requires less energy

Question 68

(X) are electron-dense structures in smooth muscle tissue, to which actin is attached.

Answer 68

X = dense plaques and bodies

Question 69

T/F: Gap junctions found in all smooth muscle types.

Answer 69

False - in unitary type smooth muscle

Question 70

Cytoplasm of smooth muscle dominated by:

Answer 70

Cytoplasmic filaments (primarily actin)

Question 71

Nucleus of smooth muscle cells is slightly (heterochromatic/euchromatic/nonexistent).

Answer 71

Euchromatic