Chapter 10 muscle tissue Flashcards
There are over ___ skeletal muscles and together they form the muscular system
More generally, there are three types of muscle tissue:
1.
2.
3.
There are over 700 skeletal muscles and together they form the muscular system
More generally, there are three types of muscle tissue:
- Skeletal muscle
- Cardiac muscle
- Smooth muscle
Properties of muscle tissue 1. 2. 3. 4. 5.
- excitability
- conductivity
- contractility
- elasticity
- extensibility
Elasticity:
Extensibility:
Elasticity: ability to return to resting length after shortening or lengthening
Extensibility: ability to be stretched beyond resting length
Excitability:
Conductivity:
Contractility:
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
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….
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
Functions of Skeletal Muscle Tissue
1. 2. 3. 4. 5.
- Body movement
- Maintenance of posture
- Protection and support
- Regulating elimination of materials
- –Sphincters at orifices - Heat production
Structural Organization of Skeletal Muscle
- A bundles of muscle fibers is called a ____
- Individual muscle fibers contain…
- Myofibrils are composed of ____
- A bundles of muscle fibers is called a fascicle
- Individual muscle fibers contain myofibrils (complex, cylindrical organelles)
- Myofibrils are composed of myofilaments
Connective Tissue Components
Muscles have multiple layers of ____within and around them
Connective tissue layers are composed mostly of…
The connective tissue provides….
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
Connective tissue components:
1. 2. 3. 4. 5.
endomysium perimysium epimysium deep fascia superficial fascia
Endomysium:
Perimysium:
Epimysium:
Deep fascia:
Superficial fascia:
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
- Surrounds each muscle, binds muscles with similar functions
- Dense irregular connective tissue with vessels and nerves
Superficial fascia: separates muscle from skin
1. Areolar and adipose connective tissues
muscle attachments
A tendon attaches a muscle to ….
- Formed by merger of…
- Ropelike structure
An ____ is a thin flattened connective tissue attachment
A tendon attaches a muscle to bone, skin, or another muscle
- Formed by merger of connective tissues at end of muscle
- Ropelike structure
An aponeurosis is a thin flattened connective tissue attachment
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 ___
- The less moveable attachment is often called the ___; the more moveable attachment is often called the ____
- Muscles that move the axial skeleton have…
- Muscles that move the appendicular skeleton have a…
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
- The less moveable attachment is often called the origin; the more moveable attachment is often called the insertion
- Muscles that move the axial skeleton have a superior attachment and an inferior attachment
- Muscles that move the appendicular skeleton have a proximal attachment and a distal attachment
microscopic anatomy
Skeletal muscle fibers have many of the same components of a typical cell, but some are named differently
Examples:
3
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
two main structures are unique to muscle fibers:
transverse tubules
sarcoplasmic reticulum
Transverse tubules (T-tubules):
Sarcoplasmic reticulum:
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
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: ___ & ____
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
myofilaments
Thick filaments:
Composed of hundreds of bundled _____
Each myosin molecule has 2 strands: 2 ….
The heads form crossbridges with ___ during ___
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
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.
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:
- Tropomyosin: threadlike protein covering part of actin
- Troponin: attaches to actin and tropomyosin and can bind calcium
____ are structural and functional units within a myofibril
- A sarcomere contains overlapping…
- One sarcomere spans from one…
Sarcomeres are structural and functional units within a myofibril
- A sarcomere contains overlapping thick and thin filaments
- One sarcomere spans from one Z disc to the next
sarcomere
I band contains thin filaments but not ____
- I band is…
- I band ____ during contraction
A band contains ____ (appears dark)
- A band is located in..
- H zone is center of ___: contains thick but not ____
- —A-band does not…, but it’s H zone does - M line is ____ in center of H zone that attaches and aligns ____ filaments
I band contains thin filaments but not thick filaments
- I band is bisected by Z disc
- I band shortens during contraction
A band contains thick filaments (appears dark)
- A band is located in central part of sarcomere
- 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 - M line is transverse protein structure in center of H zone that attaches and aligns thick filaments
Contraction of skeletal muscle fibers
Contracting muscles pull on __ to____
To pull, muscles develop __as ___
For sarcomeres to shorten, ….
—The __ ___ theory explains muscle contraction
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
The Sliding Filament Theory
During contraction, thin filaments…
- Z discs move __ so ___
- Widths of A bands…, but ____ disappear
- I bands ____
Lengths of filaments __ ___ whether muscle is contracted or relaxed; only their __change
During contraction, thin filaments slide past thick filaments
- Z discs move closer together so sarcomeres shorten
- Widths of A bands remain constant, but H zones disappear
- I bands narrow
Lengths of filaments never change whether muscle is contracted or relaxed; only their relative positions change
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
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
Components of neuromuscular junction
1. 2. 3. 4. 5. 6.
synaptic knob
synaptic vesicles
synaptic cleft
motor end plate
ACh receptors
acetylcholinesterase (AChE)
Components of neuromuscular junction
Synaptic knob: Synaptic vesicles: Synaptic cleft: Motor end plate: ACh receptors: Acetylcholinesterase (AChE):
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)
physiology of muscular contraction
- 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…
- 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 - Spread of the impulse down T-tubules causes calcium to leak out of terminal cisternae and into the sarcoplasm
Physiology of Muscle Contraction cont’d
- Calcium ions bind to ___, and then…
A. Troponin moves ___, exposing active sites on actin
B. Myosin heads bind to… - In the presence of ATP,…
A. Repeating cycle of attach-pivot-detach-return… - When stimulation ceases, __ is_______
A. Tropomyosin blockade resumes and filaments passively return to ____ state
Physiology of Muscle Contraction cont’d
- 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 - In the presence of ATP, myosin pulls actin toward center of sarcomere
A. Repeating cycle of attach-pivot-detach-return shortens sarcomere - When stimulation ceases, calcium is pumped back into sarcoplasmic reticulum
A. Tropomyosin blockade resumes and filaments passively return to relaxed state
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…
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
Muscle tone refers to the…
- 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
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
Concentric means?
eccentric means?
Concentric contraction: Muscle is shortening
Eccentric contraction: Muscle is lengthening
Isometric contraction:
Isotonic contraction:
Isometric contraction: Length is constant; tension is changing
Isotonic contraction: Tension is constant; length is changing
Types of Skeletal Muscle Fibers
Skeletal muscles consist of a mixture of 3 fiber types:
1. ______ fibers – Type I
Small, aerobic, fatigue resistant
- _____ fibers – Type IIa
Intermediate - _____ fibers – Type IIb
Large, anaerobic, only contract for short burst
An individual muscle typically has some of….
Skeletal muscles consist of a mixture of 3 fiber types:
1. Slow oxidative (SO) fibers – Type I
Small, aerobic, fatigue resistant
- Fast oxidative (FO) fibers – Type IIa
Intermediate - Fast glycolytic (FG) fibers – Type IIb
Large, anaerobic, only contract for short burst
An individual muscle typically has some of each fiber type
- Slow oxidative (SO) fibers – Type I
details? - Fast oxidative (FO) fibers – Type IIa
______ - Fast glycolytic (FG) fibers – Type IIb
details?
- Slow oxidative (SO) fibers – Type I
Small, aerobic, fatigue resistant - Fast oxidative (FO) fibers – Type IIa
Intermediate - Fast glycolytic (FG) fibers – Type IIb
Large, anaerobic, only contract for short burst
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
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
Skeletal Muscle Fiber Organization
Muscle fibers are organized into fascicles
Four patterns of fascicle arrangements 1. 2. 3. 4. A. --- B. --- C. ---
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
Description of Circular Muscle fibers:
Fibers arranged…
Functions as a ____ to close a passageway or opening (e.g., orbits, mouth, anus)
Fibers arranged concentrically around an opening
Functions as a sphincter to close a passageway or opening (e.g., orbits, mouth, anus)
Pattern of Parallel muscle fibers
Fascicles are ___ to the long axis of the muscle
____ increases in diameter with contraction High ___, not very ____
Fascicles are parallel to the long axis of the muscle
Body of muscle increases in diameter with contraction High endurance, not very strong
Pattern of convergent muscle fibers
___muscle with common attachment site
Direction of pull of muscle can be ___
Does not ___as equal-sized parallel muscle
Triangular muscle with common attachment site Direction of pull of muscle can be changed
Does not pull as hard as equal-sized parallel muscle
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
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
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….
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
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.
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:
- First-class levers
- Second-class levers
- Third-class levers
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
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
Muscles are named according to several criteria: 1. 2. 3. 4. 5. 6.
Muscle action Specific body regions Muscle attachments Orientation of muscle fibers Muscle shape and size Muscle heads/tendons of origin
Characteristics of Cardiac and Smooth Muscle
In addition to skeletal muscle, muscle tissue includes two involuntary types:
In addition to skeletal muscle, muscle tissue includes two involuntary types:
Cardiac muscle
Smooth muscle
Cardiac (heart wall) muscle cells
- ___
- One or two ____, many ____ (aerobic)
- Form ___ branches
- Join adjacent cardiac muscle cells at____
- –Discs composed of gap junctions and desmosomes - ____: able to generate electrical impulses without ____
- ____: autonomic nervous system influences ___ & ____
Cardiac (heart wall) muscle cells
- Striated
- One or two nuclei, many mitochondria (aerobic)
- Form Y-shaped branches
- Join adjacent cardiac muscle cells at intercalated discs
- –Discs composed of gap junctions and desmosomes - Autorhythmic: able to generate electrical impulses without nerve stimulation
- Involuntary control: autonomic nervous system influences rate and strength of contraction
Smooth muscle is found in walls of viscera and blood vessels
Smooth muscle cell traits:
- Short___ cells
- One centrally located ___, no ___
- Thin filaments attached to ___
- ____ is sparse, T-tubules are absent
- Contain ____, not troponin
- –Activity stimulates entry of ____ from outside cell; Ca++ binds to calmodulin
- –Calmodulin activates ___ that activates myosin to pull __ - Generate ….
Smooth muscle is found in walls of viscera and blood vessels
Smooth muscle cell traits:
- Short fusiform cells (wide in the middle, tapered at each end)
- One centrally located nucleus, no striations
- Thin filaments attached to dense bodies
- Sarcoplasmic reticulum is sparse, T-tubules are absent
- 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 - Generate slow, efficient, fatigue-resistant contractions
