Chapter 10 muscle tissue

Question 1

There are over ___ skeletal muscles and together they form the muscular system

More generally, there are three types of muscle tissue:
1.
2.
3.

Answer 1

There are over 700 skeletal muscles and together they form the muscular system

More generally, there are three types of muscle tissue:

1. Skeletal muscle
2. Cardiac muscle
3. Smooth muscle

Question 2

Properties of muscle tissue
1.
2.
3.
4.
5.

Answer 2

1. excitability
2. conductivity
3. contractility
4. elasticity
5. extensibility

Question 3

Elasticity:
Extensibility:

Answer 3

Elasticity: ability to return to resting length after shortening or lengthening

Extensibility: ability to be stretched beyond resting length

Question 4

Excitability:
Conductivity:
Contractility:

Answer 4

Excitability: ability to respond to stimuli

Conductivity: ability to transmit electrical events along the cell membrane

Contractility: ability to generate tension and shorten cell length

Question 5

characteristics of skeletal muscle tissue

Each skeletal muscle is considered an ___

Each muscle (e.g., biceps brachii) contains…

Histology: ___

Usually attached to ___

Muscles and muscle cells vary in….

Answer 5

Each skeletal muscle is considered an organ
—Each muscle (e.g., biceps brachii) contains all four tissue types

Histology: striated

Usually attached to bones

Muscles and muscle cells vary in shape and size

Question 6

Functions of Skeletal Muscle Tissue

1.
2.
3.
4.
5.

Answer 6

1. Body movement
2. Maintenance of posture
3. Protection and support
4. Regulating elimination of materials
   - –Sphincters at orifices
5. Heat production

Question 7

Structural Organization of Skeletal Muscle

1. A bundles of muscle fibers is called a ____
2. Individual muscle fibers contain…
3. Myofibrils are composed of ____

Answer 7

1. A bundles of muscle fibers is called a fascicle
2. Individual muscle fibers contain myofibrils (complex, cylindrical organelles)
3. Myofibrils are composed of myofilaments

Question 8

Connective Tissue Components

Muscles have multiple layers of ____within and around them

Connective tissue layers are composed mostly of…

The connective tissue provides….

Answer 8

Muscles have multiple layers of connective tissue within and around them

Connective tissue layers are composed mostly of collagen and elastic fibers

The connective tissue provides protection, sites for blood vessel and nerve distribution, and attachment to the skeleton

Question 9

Connective tissue components:

1. 
2.
3.
4.
5.

Answer 9

endomysium
perimysium
epimysium
deep fascia
superficial fascia

Question 10

Endomysium:

Perimysium:

Epimysium:

Deep fascia:

Superficial fascia:

Answer 10

Endomysium: surrounds and electrically insulates each muscle fiber
1. Areolar connective tissue with reticular fibers

Perimysium: surrounds fascicles
1. Dense irregular connective tissue with blood vessels and nerves

Epimysium: surrounds entire muscle
1. Dense irregular connective tissue

Deep fascia: large sheet external to epimysium

1. Surrounds each muscle, binds muscles with similar functions
2. Dense irregular connective tissue with vessels and nerves

Superficial fascia: separates muscle from skin
1. Areolar and adipose connective tissues

Question 11

muscle attachments

A tendon attaches a muscle to ….

1. Formed by merger of…
2. Ropelike structure

An ____ is a thin flattened connective tissue attachment

Answer 11

A tendon attaches a muscle to bone, skin, or another muscle

1. Formed by merger of connective tissues at end of muscle
2. Ropelike structure

An aponeurosis is a thin flattened connective tissue attachment

Question 12

Most muscles extend over a ___ and attach to ___ on either side of the joint

Muscle contraction usually causes one bone ___ while the other bone remains ___

1. The less moveable attachment is often called the ___; the more moveable attachment is often called the ____
2. Muscles that move the axial skeleton have…
3. Muscles that move the appendicular skeleton have a…

Answer 12

Most muscles extend over a joint and attach to bones on either side of the joint

Muscle contraction usually causes one bone to move while the other bone remains fixed

1. The less moveable attachment is often called the origin; the more moveable attachment is often called the insertion
2. Muscles that move the axial skeleton have a superior attachment and an inferior attachment
3. Muscles that move the appendicular skeleton have a proximal attachment and a distal attachment

Question 13

microscopic anatomy

Skeletal muscle fibers have many of the same components of a typical cell, but some are named differently

Examples:
3

Answer 13

Skeletal muscle fibers have many of the same components of a typical cell, but some are named differently

Examples:
Sarcolemma: Plasma membrane
Sarcoplasm: Cytoplasm
Sarcoplasmic reticulum: Smooth ER

Question 14

two main structures are unique to muscle fibers:

Answer 14

transverse tubules

sarcoplasmic reticulum

Question 15

Transverse tubules (T-tubules):

Sarcoplasmic reticulum:

Answer 15

Transverse tubules (T-tubules): Deep invaginations of the sarcolemma that extend into the sarcoplasm
Carry impulses from sarcolemma to help stimulate contraction

 Sarcoplasmic reticulum: internal membrane complex
Stores calcium (used to initiate contraction)
Includes terminal cisternae adjacent to T-tubules
Triad = two terminal cisternae + one T-tubule

Question 16

Myofibrils:

Cylindrical structures within muscle fibers that run the..

Make up __ of fiber volume

Have the ability to ___, resulting in ____ of the muscle fiber

Contain ___: strands of proteins that allow for ___

Two types of myofilaments: ___ & ____

Answer 16

Myofibrils:

Cylindrical structures within muscle fibers that run the length of the cell

Make up 80% of fiber volume

Have the ability to shorten, resulting in contraction of the muscle fiber

Contain myofilaments: strands of proteins that allow for contraction

Two types of myofilaments: thick filaments and thin filaments

Question 17

myofilaments

Thick filaments:
Composed of hundreds of bundled _____

Each myosin molecule has 2 strands: 2 ….

The heads form crossbridges with ___ during ___

Answer 17

Thick filaments:
Composed of hundreds of bundled myosin molecules

Each myosin molecule has 2 strands: 2 intertwined tails, each with a head

The heads form crossbridges with thin filaments during contraction

Question 18

Myofilaments

Thin filaments:
Composed mainly of two strands of ____ twisted around each other

Each actin strand is made of hundreds of ____

Two regulatory proteins are also part of the thin filament:
1.
2.

Answer 18

Thin filaments:
Composed mainly of two strands of filamentous actin (F-actin) twisted around each other

Each actin strand is made of hundreds of globular actin (G-actin) molecules

Two regulatory proteins are also part of the thin filament:

1. Tropomyosin: threadlike protein covering part of actin
2. Troponin: attaches to actin and tropomyosin and can bind calcium

Question 19

____ are structural and functional units within a myofibril

1. A sarcomere contains overlapping…
2. One sarcomere spans from one…

Answer 19

Sarcomeres are structural and functional units within a myofibril

1. A sarcomere contains overlapping thick and thin filaments
2. One sarcomere spans from one Z disc to the next

Question 20

sarcomere

I band contains thin filaments but not ____

1. I band is…
2. I band ____ during contraction

A band contains ____ (appears dark)

1. A band is located in..
2. H zone is center of ___: contains thick but not ____
   - —A-band does not…, but it’s H zone does
3. M line is ____ in center of H zone that attaches and aligns ____ filaments

Answer 20

I band contains thin filaments but not thick filaments

1. I band is bisected by Z disc
2. I band shortens during contraction

A band contains thick filaments (appears dark)

1. A band is located in central part of sarcomere
2. H zone is center of A band: contains thick but not thin filaments
   - —A-band does not shorten during contraction, but it’s H zone does
3. M line is transverse protein structure in center of H zone that attaches and aligns thick filaments

Question 21

Contraction of skeletal muscle fibers

Contracting muscles pull on __ to____

To pull, muscles develop __as ___

For sarcomeres to shorten, ….
—The __ ___ theory explains muscle contraction

Answer 21

Contracting muscles pull on tendons to produce movement

To pull, muscles develop tensions as their sarcomeres shorten

For sarcomeres to shorten, thick filaments attach to thin filaments and pull them toward the centers of the sarcomeres
The sliding filament theory explains muscle contraction

Question 22

The Sliding Filament Theory

During contraction, thin filaments…

1. Z discs move __ so ___
2. Widths of A bands…, but ____ disappear
3. I bands ____

Lengths of filaments __ ___ whether muscle is contracted or relaxed; only their __change

Answer 22

During contraction, thin filaments slide past thick filaments

1. Z discs move closer together so sarcomeres shorten
2. Widths of A bands remain constant, but H zones disappear
3. I bands narrow

Lengths of filaments never change whether muscle is contracted or relaxed; only their relative positions change

Question 23

Neuromuscular Junctions

Skeletal muscles are ___

• Skeletal muscle fibers are excited by _____
• –Each ____ is controlled by..

A contraction begins when…

The ____ is the place where the motor neuron communicates with the muscle fiber

Answer 23

Skeletal muscles are voluntary

• -Skeletal muscle fibers are excited by axons of somatic motor neurons
• —Each muscle fiber is controlled by one motor neuron

A contraction begins when a motor neuron impulse stimulates an impulse in a muscle fiber

The neuromuscular junction is the place where the motor neuron communicates with the muscle fiber

Question 24

Components of neuromuscular junction

1.
2.
3.
4.
5.
6.

Answer 24

synaptic knob

synaptic vesicles

synaptic cleft

motor end plate

ACh receptors

acetylcholinesterase (AChE)

Question 25

Components of neuromuscular junction ``` Synaptic knob: Synaptic vesicles: Synaptic cleft: Motor end plate: ACh receptors: Acetylcholinesterase (AChE): ```

Answer 25

Components of neuromuscular junction: Synaptic knob: Expanded tip of neuron axon Synaptic vesicles: Membrane sacs in synaptic knob, filled with acetylcholine (ACh) Synaptic cleft: Narrow space separating synaptic knob and motor end plate Motor end plate: Region of sarcolemma with many folds (increased surface area) under the synaptic knob ACh receptors: Proteins that bind Ach on the motor end plate Acetylcholinesterase (AChE): Enzyme in synaptic cleft that breaks down Ach (prevents continuous stimulation of muscle)

Question 26

physiology of muscular contraction 1. A nerve impulse causes vesicles to release... A. ACh binds to____, initiating a muscle fiber impulse B. Ach that is not bound to receptor is... 2.. Spread of the impulse down T-tubules causes...

Answer 26

1. A nerve impulse causes vesicles to release ACh into the synaptic cleft A. ACh binds to receptors on the motor end plate, initiating a muscle fiber impulse B. Ach that is not bound to receptor is quickly broken down by AChE 2. Spread of the impulse down T-tubules causes calcium to leak out of terminal cisternae and into the sarcoplasm

Question 27

Physiology of Muscle Contraction cont'd 3. Calcium ions bind to ___, and then... A. Troponin moves ___, exposing active sites on actin B. Myosin heads bind to... 4. In the presence of ATP,... A. Repeating cycle of attach-pivot-detach-return... 5. When stimulation ceases, __ is_______ A. Tropomyosin blockade resumes and filaments passively return to ____ state

Answer 27

Physiology of Muscle Contraction cont'd 3. Calcium ions bind to troponin, and troponin changes shape A. Troponin moves tropomyosin, exposing active sites on actin B. Myosin heads bind to actin’s active sites and form crossbridges 4. In the presence of ATP, myosin pulls actin toward center of sarcomere A. Repeating cycle of attach-pivot-detach-return shortens sarcomere 5. When stimulation ceases, calcium is pumped back into sarcoplasmic reticulum A. Tropomyosin blockade resumes and filaments passively return to relaxed state

Question 28

A motor unit: A motor unit contains ____ in an entire muscle When a motor unit is stimulated, ____ 1. Size of motor unit and degree of control provided are __ ___ A. Small motor units provide ____l, and vice versa B. Eye muscles have ____; lower limb muscles ____ Movements that require more force recruit...

Answer 28

A motor unit: a single motor neuron and the muscle fibers it controls A motor unit contains only some of the muscle fibers in an entire muscle When a motor unit is stimulated, all muscle fibers within it contract Size of motor unit and degree of control provided are inversely related Small motor units provide precise control, and vice versa Eye muscles have small units (few fibers); lower limb muscles have large units (many fibers) Movements that require more force recruit more motor units

Question 29

Muscle tone refers to the... 1. Motor units are stimulated randomly to avoid ___ Two types of muscle contraction: 1. ___ contraction: 2. ____ contraction: T A. ____ contraction: Muscle is shortening B. ____ contraction: Muscle is lengthening

Answer 29

Muscle tone refers to the constant tension in a resting muscle Motor units are stimulated randomly to avoid fatigue Two types of muscle contraction: 1. Isometric contraction: Length is constant; tension is changing 2. Isotonic contraction: Tension is constant; length is changing A. Concentric contraction: Muscle is shortening B. Eccentric contraction: Muscle is lengthening

Question 30

Concentric means? eccentric means?

Answer 30

Concentric contraction: Muscle is shortening Eccentric contraction: Muscle is lengthening

Question 31

Isometric contraction: Isotonic contraction:

Answer 31

Isometric contraction: Length is constant; tension is changing Isotonic contraction: Tension is constant; length is changing

Question 32

Types of Skeletal Muscle Fibers Skeletal muscles consist of a mixture of 3 fiber types: 1. ______ fibers – Type I Small, aerobic, fatigue resistant 2. _____ fibers – Type IIa Intermediate 3. _____ fibers – Type IIb Large, anaerobic, only contract for short burst An individual muscle typically has some of....

Answer 32

Skeletal muscles consist of a mixture of 3 fiber types: 1. Slow oxidative (SO) fibers – Type I Small, aerobic, fatigue resistant 2. Fast oxidative (FO) fibers – Type IIa Intermediate 3. Fast glycolytic (FG) fibers – Type IIb Large, anaerobic, only contract for short burst An individual muscle typically has some of each fiber type

Question 33

1. Slow oxidative (SO) fibers – Type I details? 2. Fast oxidative (FO) fibers – Type IIa ______ 3. Fast glycolytic (FG) fibers – Type IIb details?

Answer 33

1. Slow oxidative (SO) fibers – Type I Small, aerobic, fatigue resistant 2. Fast oxidative (FO) fibers – Type IIa Intermediate 3. Fast glycolytic (FG) fibers – Type IIb Large, anaerobic, only contract for short burst

Question 34

Distribution of Fiber types A skeletal muscle usually contains... A single motor unit contains only ... Slow fibers dominate ___ ___, such as those in the back and calf, which contract almost ___ There are no ____ in muscles that require_____, such as those in the eye and hand

Answer 34

A skeletal muscle usually contains all three fiber types A single motor unit contains only muscle fibers of the same type Slow fibers dominate postural muscles, such as those in the back and calf, which contract almost continually There are no slow muscle fibers in muscles that require swift but brief contractions, such as those in the eye and hand

Question 35

Skeletal Muscle Fiber Organization Muscle fibers are organized into fascicles ``` Four patterns of fascicle arrangements 1. 2. 3. 4. A. --- B. --- C. --- ```

Answer 35

Muscle fibers are organized into fascicles ``` Four patterns of fascicle arrangements 1. Circular 2. Parallel 3. Convergent 4. Pennate A. ---Unipennate B. ---Bipennate C. ---Multipennate ```

Question 36

Description of Circular Muscle fibers: Fibers arranged... Functions as a ____ to close a passageway or opening (e.g., orbits, mouth, anus)

Answer 36

Fibers arranged concentrically around an opening | Functions as a sphincter to close a passageway or opening (e.g., orbits, mouth, anus)

Question 37

Pattern of Parallel muscle fibers Fascicles are ___ to the long axis of the muscle ____ increases in diameter with contraction High ___, not very ____

Answer 37

Fascicles are parallel to the long axis of the muscle | Body of muscle increases in diameter with contraction High endurance, not very strong

Question 38

Pattern of convergent muscle fibers ___muscle with common attachment site Direction of pull of muscle can be ___ Does not ___as equal-sized parallel muscle

Answer 38

Triangular muscle with common attachment site Direction of pull of muscle can be changed Does not pull as hard as equal-sized parallel muscle

Question 39

Pattern of Pennate muscle fibers Muscle body has... ___ at oblique angle to tendon _____ than a parallel muscle of equal size ____: All muscle fibers on the same side of the tendon ____: Muscle fibers on both sides of the tendon _____: Tendon branches within the muscle

Answer 39

Muscle body has one or more tendons Fascicles at oblique angle to tendon Pulls harder than a parallel muscle of equal size Unipennate: All muscle fibers on the same side of the tendon Bipennate: Muscle fibers on both sides of the tendon Multipennate: Tendon branches within the muscle

Question 40

Exercise and skeletal muscle Muscle hypertrophy: An increase in ____ 1. Building muscle increases ___ but not ___ A. --Number of myofibrils per fiber ___ B. --More ___ and more ___ stored in the cells 2. Results from... Muscle atrophy: ________ ---Reduced stimulation results in....

Answer 40

Muscle hypertrophy: An increase in fast muscle fiber size 1. Building muscle increases fiber size but not number of fibers A. --Number of myofibrils per fiber increases B. --More mitochondria and more glycogen stored in the cells 2. Results from repetitive, exhaustive stimulation of muscle Muscle atrophy: A wasting of muscle that reduces fiber size --Reduced stimulation results in reduced muscle size, tone, and power

Question 41

Levers and Joints Biomechanics A ____ is an elongated, rigid object that ___ around a fixed point called a ____ Rotation occurs when an ___ applied to one point of the lever __ a .... Three classes of levers in human body 1. 2. 3.

Answer 41

A lever is an elongated, rigid object that rotates around a fixed point called a fulcrum Rotation occurs when an effort applied to one point of the lever exceeds a resistance located at some other point Three classes of levers in human body: 1. First-class levers 2. Second-class levers 3. Third-class levers

Question 42

Actions of Skeletal Muscles Agonist: ____ produces the movement; also called the ____ --Example: The triceps brachii is the agonist for forearm extension Antagonist: A muscle whose action.... --Example: The biceps brachii is the antagonist for forearm extension; it is antagonistic to the triceps brachii Synergist: A muscle that... --Includes stabilizing fixators

Answer 42

Agonist: Contraction produces the movement; also called the prime mover --Example: The triceps brachii is the agonist for forearm extension Antagonist: A muscle whose action opposes that of an agonist --Example: The biceps brachii is the antagonist for forearm extension; it is antagonistic to the triceps brachii Synergist: A muscle that assists the agonist in performing its action --Includes stabilizing fixators

Question 43

``` Muscles are named according to several criteria: 1. 2. 3. 4. 5. 6. ```

Answer 43

``` Muscle action Specific body regions Muscle attachments Orientation of muscle fibers Muscle shape and size Muscle heads/tendons of origin ```

Question 44

Characteristics of Cardiac and Smooth Muscle In addition to skeletal muscle, muscle tissue includes two involuntary types:

Answer 44

In addition to skeletal muscle, muscle tissue includes two involuntary types: Cardiac muscle Smooth muscle

Question 45

Cardiac (heart wall) muscle cells 1. ___ 2. One or two ____, many ____ (aerobic) 3. Form ___ branches 4. Join adjacent cardiac muscle cells at____ - --Discs composed of gap junctions and desmosomes 5. ____: able to generate electrical impulses without ____ 6. ____: autonomic nervous system influences ___ & ____

Answer 45

Cardiac (heart wall) muscle cells 1. Striated 2. One or two nuclei, many mitochondria (aerobic) 3. Form Y-shaped branches 4. Join adjacent cardiac muscle cells at intercalated discs - --Discs composed of gap junctions and desmosomes 5. Autorhythmic: able to generate electrical impulses without nerve stimulation 6. Involuntary control: autonomic nervous system influences rate and strength of contraction

Question 46

Smooth muscle is found in walls of viscera and blood vessels Smooth muscle cell traits: 1. Short___ cells 2. One centrally located ___, no ___ 3. Thin filaments attached to ___ 4. ____ is sparse, T-tubules are absent 5. Contain ____, not troponin - --Activity stimulates entry of ____ from outside cell; Ca++ binds to calmodulin - --Calmodulin activates ___ that activates myosin to pull __ 6. Generate ....

Answer 46

Smooth muscle is found in walls of viscera and blood vessels Smooth muscle cell traits: 1. Short fusiform cells (wide in the middle, tapered at each end) 2. One centrally located nucleus, no striations 3. Thin filaments attached to dense bodies 4. Sarcoplasmic reticulum is sparse, T-tubules are absent 5. Contain calmodulin, not troponin - --Activity stimulates entry of Ca++ from outside cell; Ca++ binds to calmodulin - --Calmodulin activates kinase that activates myosin to pull actin 6. Generate slow, efficient, fatigue-resistant contractions