Histology - Muscle

Question 1

Qualities common to all muscle

Answer 1

Mesodermally derived
Elongated parallel to axis of contraction
Numerous mitochondria

Question 2

Qualities of skeletal muscle

Answer 2

Up to 30cm, peripheral nuclei

Question 3

Qualities of cardiac muscle

Answer 3

Branched fibers, central nuclei, cells connected via intercalated discs

Question 4

Qualities of smooth muscle

Answer 4

Individual cells, central nuclei, no striations, sarcomeres, or T-tubules. Less vascularization, organized in bundles or sheets

Question 5

Connective tissues of skeletal muscle

Answer 5

Epimysium, perimysium, endomysium

Question 6

Type I muscle mnemonic

Answer 6

ONE SLOW RED OX

Question 7

Type II muscle mnemonic

Answer 7

TWO FAST WHITE SUGAR

Question 8

How to distinguish type I vs type II

Answer 8

Type I is lighter and larger

Question 9

Loss of checkerboard fiber distribution is indicative of _________

Answer 9

Denervation

Question 10

Function of epimysium

Answer 10

Surrounds whole muscle and plays a structural role in transmitting contraction to bone

Question 11

Function of perimysium

Answer 11

Surrounds a fascicle (bundle of muscle fibers)

Question 12

Function of endomysium

Answer 12

Surrounds muscle fibers

Question 13

Qualities of a muscle fiber

Answer 13

Up to 30 Cm long, 10-120 micrometers wide, peripheral nuclei

Question 14

Differentiating CT and muscle at the myo-tendonal junction

Answer 14

CT has no striating and spindly nuclei, muscle is striated with peripheral nuclei

Question 15

Definition of sarcomere

Answer 15

From Z line to Z line

Basic contractile unit of muscle

2.2 micrometers

Question 16

A band

Answer 16

Thick myosin filaments

Question 17

H zone

Answer 17

Central region of A band containing only thick myosin filaments; width decreases during contraction

Question 18

M line

Answer 18

Lateral connections between adjacent thick filaments

Question 19

I band

Answer 19

Region where actin doesn’t overlap with myosin

Question 20

Actin filaments are attached to the _________

Answer 20

Z disc

Question 21

In the sliding filament model, resting myosin is bound to ________ and does not interact with _______

Answer 21

ADP + P, actin

Question 22

In the sliding filament model, ____ binds troponin and induces a structural change that leads to the interaction of _______ and ________

Answer 22

Calcium, actin and myosin

Question 23

In the sliding filament model, the power stroke occurs when the ______ changes conformation and _______ is released, allowing _____ to bind

Answer 23

Myosin head, ADP+P, ATP

Question 24

In the sliding filament model, ______ hydrolyzes ATP and releases _______

Answer 24

Myosin, actin

Question 25

When muscle is relaxed, the sarcomere is LONG/SHORT and the I band is WIDE/NARROW

Answer 25

Long, wide

Question 26

When muscle is contracted, the sarcomere is LARGE/SMALL and the I band is VISIBLE/NOT VISIBLE

Answer 26

small, not visible

Question 27

Qualities of myosin

Answer 27

Makes thick filaments, shaped like 2 headed golf club Head region contains light chain proteins and ATP hydrolyzing machinery

Question 28

Qualities of actin

Answer 28

Major component of thin filaments Formed from globular monomeric actin molecules which make a filament There are G and F forms, two F strands intertwine to make a filament

Question 29

Qualities of tropomyosin

Answer 29

Long protein molecule that lies in the groove of an actin filament. Prevents interaction of actin and myosin in relaxed state

Question 30

Subunits of troponin

Answer 30

TnT - binds tropomyosin TnC - binds calcium TnI - inhibits actin-myosin interaction

Question 31

Invaginations in the plasma membrane are called ________, and run throughout muscle fiber at the _____ junction

Answer 31

T tubule, A-I

Question 32

Each T tubule is associated with two _____ of the sarcoplasmic reticulum

Answer 32

Cisterna

Question 33

The __________ is the outer covering of muscle cells

Answer 33

Sarcolemma

Question 34

T -tubules are located at the _______ in skeletal muscle and _______ in cardiac muscle

Answer 34

A-I band junction, Z line

Question 35

The ________ ________ is the internal membrane system of muscle fibers

Answer 35

Sarcoplasmic reticulum

Question 36

The sarcoplasmic junctions with the T-tubule to form ______ in skeletal muscle and ______ in cardiac muscle

Answer 36

Triads, dyads

Question 37

Describe the steps of a neuromuscular impulse

Answer 37

1. Nerve impulse releases Ach 2. The binding of Ach on muscle causes depolarization to spread from the sarcolemma along T-tubules 3. Ca is released from the terminal cisternae into the sarcoplasm 4. Ca binds troponin C, causing troponin I to reveal myosin binding sites on actin

Question 38

One nerve innervates ONE/MANY myofibers

Answer 38

Many

Question 39

How do skeletal muscles grow?

Answer 39

Satellite cells proliferate, fuse, and nature following injury. Skeletal muscles increase mass via hypertrophy and contribute to repair

Question 40

Connective tissue between cardiac muscle fibers

Answer 40

Endomysium

Question 41

Components of intercalated discs

Answer 41

Macula adherens: binds individual cells, found in transverse and lateral regions of ID Fascia adherens: actin filaments of terminal sarcomere anchor to PM, major structure on transverse face of ID Gap junction: electrical continuity between cells

Question 42

Describe cardiac muscle contraction

Answer 42

SA node initiates beat which spreads through atria to AV node Purkinje fibers generate and transmit contractile impulse Depolarization also spreads via intercalated discs, doesn’t require direct innervation

Question 43

Smooth muscles communicate via _____ ________

Answer 43

Gap junctions

Question 44

Smooth muscle receives only ____ nerve input

Answer 44

Autonomic

Question 45

Smooth muscle increases mass by ______ and ______

Answer 45

Hypertrophy and hyperplasia

Question 46

Smooth muscle contraction responds to ______

Answer 46

Hormones

Question 47

In smooth muscle, the actin myosin interaction is mediated by _________

Answer 47

Calmodulin