Muscle Tissue - Chapter 10 Flashcards
3 types of muscle in the body:
skeletal, cardiac, and smooth
4 unique characteristics of muscles
excitability, contractability, elasticity, extensibility
Excitability
outside stimuli can initiate electrical charges in muscle fibers that lead to contraction.
Contractability
stimulation of muscle fiber leads to contraction or shortening of fiber
Elasticity
muscle fiber able to return to original length when contraction is released
Extensibility
muscle fiber able to be stretched
what are some of the functions of Skeletal muscle tissue?
Body movement, maintenance of posture, temperature regulation, storage and movement of materials, support
Muscle fibers are organized into bundles called what?
fascicles
What are fascicles?
bundles of muscle fibers
muscle fibers contain what?
myofibrils
Myofibrils are composed of what?
myofilaments
what are myofilaments composed of?
actin and myosin
Each muscle is comprised of 3 layers of concentric connective tissue, what are those tissues comprised of?
mainly collagen and elastic fibers
The 3 layers of connective tissue found in each muscle is:
Endomysium, perimysium, epimysium
Endomysium function
surrounds and electrically insulates each muscle fiber
Perimysium function
surrounds individual fascicles
Epimysium function
surrounds the entire muscle fiber
Deep fascia is composed of what type of connective tissue(s)?
dense irregular connective tissue
What is the function of deep fascia?
surround each muscle and separate muscles from each other
Superficial fascia is composed of what type of connective tissue(s)?
areolar and adipose connective tissue
What is the function of superficial fascia?
separates muscle from skin
What does a tendon attach?
muscle to a bone (cord-like in appearance)
Aponeurosis is what?
flat tendon
point of attachment to the bone that does not move
origin
point of attachment to the bone that moves
insertion
Myofibrils
cylindrical structures that extend the entire length of the muscle fiber
The Sacroplasm of a muscle fiber contains what?
myofibrils (~100-1000)
what is the ability of a myofibril?
to shorten: which results in contraction and production of motion
what are the 2 types of myofilaments?
thin and thick
What is thin filament comprised of?
- 2 strands of f-actin and g-actin of bead shaped molecules twisted around each other
- 2 regulatory proteins
what are the 2 regulatory proteins in thin filament?
Tropomyosin and troponin
What is thick filament comprised of?
bundled molecules of myosin
Action of myosin during contraction
heads form cross bridges with thin filaments
What is the structure of a myosin molecule?
head and elongated head (golfclub like appearance)
What is the composition of an A-band?
contain entire myosin molecule and portion of actin
Myosin is found only found in which filament?
thick filament
What is the I band composed of?
only thin filaments
Where is the H-zone (H-band)?
light, central region of A band, NO thin filament present
What is the M-line?
Central, protein network in H-zone that keeps thick filament aligned
Where is the Z-disc (Z band)
protein structure in middle of I band
What is the function of Z-disc?
attachment site for one end of thin filaments
What is a sarcomere?
the functional contractile unit in a skeletal muscle fiber
Where is a sarcomere located?
Between 2 adjacent Z discs
What happens to a sarcomere during contraction of muscle fibers?
they shorten
What is Sliding Filament Theory?
during contraction, thick and thin filament will interact and slide past each other
What changes happen to a sarcomere during contraction?
- A bands remain constant
- H zone disappears
- Z discs move closer together
- I bands narrow
- thin and thick filaments never change
What is the neuromuscular junction?
region where the motor neuron comes into close proximity to the muscle fiber
What does a motor unit consist of?
a single motor neuron and the muscle fiber it controls
Larger muscle have
more motor units
what is the all-or-none principle?
a muscle fiber contracts completely or not at all
What happens when a motor unit is stimulated?
all muscle fibers under its control contract
Skeletal muscle is comprised of 3 different types of muscle fibers. what are they?
slow, intermediate, fast
What do muscle fibers do?
determine the speed of muscle contraction and sustainability of the contraction
Slow muscle fibers
Type 1, slow oxidative
Intermediate muscle fibers
Type IIa, fast aerobic
fast muscle fibers
Type IIb, fast anaerobic
What is the function of myoglobin in muscles?
increase the ability of muscles to hold oxygen
High myoglobin present
muscle has red color
low or no myoglobin present
muscle has white/pale color
slow muscle fibers are mostly found in muscles that…
contract continuously
What are the 4 different patterns of fascicle arrangement?
circular, parallel, convergent, pennate
Circular fascicle arrangement
fibers arranged concentrically around opening
Parallel fascicle arrangement
fibers arranged parallel to long axis
Convergent fascicle arrangement
triangular muscle with common attachment site
Pennate fascicle arrangement
muscle body has one or more tendons
What is a lever?
elongated, rigid object what rotates around a fixed point
what are the 3 classes of lever?
Agonist (prime mover), Antagonist, Synergist
Agonist lever
produces specific movement when it contracts
Antagonist lever
a muscle whose action opposes agonist
Synergist lever
a muscle assists the agonist lever
