BIOL 220: Ch. 10 Flashcards
Terms and concepts from Ch. 10: Muscles
three types of muscles in the body
skeletal, cardiac, smooth
there are over ____ skeletal muscles and together they form the _____
700; muscular system
properties of muscle tissue (4)
excitability
contractility
elasticity
extensibility
excitability
muscle cells are responsive to input from stimuli
contractility
stimulation of muscle fiber can lead to contraction and shortening of the muscle fiber
elasticity
contracted muscle cell can return to resting length when applied tension is removed
extensibility
ability of a muscle fiber to be stretched beyond its resting length
each skeletal muscle is considered an organ because it contains…
all four tissue types
skeletal muscle is ____ in appearance, _____ in movement, and usually attached to ____
striated; voluntary; bones
functions of skeletal muscle tissue (5)
body movement maintenance of posture temperature regulation storage and movement of materials support
fascicles
bundles in which muscle fibers are organized to comprise each muscle; covered by perimysium
muscle fibers contain…
myofibrils
myofibrils are composed of…
myofilaments
each muscle has ____ layers of concentric ____ ____ composed of ____ and _____ fibers
three; connective tissue; collagen; elastic
CT provides ____, _____, and _____.
protection, sites for blood vessel and nerve distribution, a means of attaching the muscle to the skeleton
CT components of skeletal muscle from outer to inner (5)
superficial fascia deep fascia epimysium perimysium endomysium
superficial facia
dense irregular connective tissue comprising the epimysium; separates muscle from skin
deep fascia
dense irregular connective tissue comprising the epimysium; surrounds each muscle and separates muscles from each other
epimysium
surrounds the entire muscle
perimysium
dense irregular connective tissue surrounding the fascicles
endomysium
areolar connective tissue comprising the innermost layer that surrounds and electrically insulates each muscle fiber
muscle
multiple fascicles housing many many muscle fibers, connective tissue coverings, blood vessels, nerve fibers
muscle fibers
elongated, multinucleated cylindrical fiber (cell); contains myofibrils, separated from other fibers by delicate layer of areolar connective tissue (endomysium); exhibits striations
myofibrils
long, cylindrical contractile element within muscle fiber; composed of myofilamants; exhibits striations
myofibrils are as long as the ____ _____ itself
muscle fiber
myofilaments
short, contractile proteins of two types: thick (myosin) and thin (actin, tropomyosin, and troponin)
at the ends of each muscle, all of the CT merge to form a _____
tendon
tendon attaches muscle to..
bone, skin, or another muscle
tendons are usually cordlike in appearance, but some appear as a flat sheet, termed an _____
aponeurosis
Upon conraction of a muscle, one of the articulating bones _____ and the other one does not
moves
origin
less moveable point of attachment
insertion
more moveable point of attachment
sarcolemma
plasma membrane of skeletal muscle fiber
sarcoplasm
cytoplasm of a skeletal muscle fiber
sarcoplasmic reticulum
smooth ER of skeletal muscle fiber
two main structure unique to skeletal muscle
transverse tubules (T-tubules terminal cisternae
transverse tubulues
deep invaginations of the sarcolemma that extend into the sarcoplasm; orms a network of tubules that enables muscle impulses to spread quickly internally
terminal cisternae
blind sacs of the sarcoplasmic reticulum
triad
two terminal cisternae + T-tubule
myofibrils have the ability to ____, resulting in the contraction of the _____
shorten; muscle fiber
myofilaments do not run the entire length of the muscle fiber, but they are organized into…
repetitive groupings
two type of myofilaments
thick (myosin)
thin (actin)
thick filaments diameter
11 nm (twice thin)
thick filaments are composed of bundled molecules of…
myosin
myosin has a _____ and elongated ___
head;tail
the heads of myosin form ______ with the thin filaments during contraction
crossbridges
thin filaments diameter
5-6 nm
thin filaments are comprised of two strands called _____ and ____ twisted around each other
F-actin
G-actin
F-actin is…
filamentous
G-actin is..
globular
regulatory proteins of thin filament (2)
tropomyosin
troponin
muscle function
metabolic activities; contraction
sarcolemma function
surround muscle fiber and regulates entry and exit of materials
sarcoplasm function
site of metabolic processes for normal muscle fiber activities
sarcoplasmic reticulum function
stores calcium ions needed for muscle contraction
terminal cisterna function
site of calcium ion release to promote muscle contraction
transverse tubule function
quickly transports impulse from the sarcolemma throughout the entire muscle fiber
thick filament function
bind to thin filament and cause contraction
thin filament function
thick filaments bind and cause contraction
actin and function
double-stranded contractile protein; binding site for myosin to shorten a sarcomere
tropomyosin and function
double-stranded regulatory protein; covers the active sites on actin, preventing myosin from binding to actin when muscle fiber is at rest
troponin and function
regulatory protein that holds tropomyosin in place and anchors to actin; when calcium ions bind to one of its subunits, troponin changes shape, causing the tropomyosin to move off the actin active site, and this permits myosin binding to actin
connectin and function
single molecular filament of a giant protein; plays role in organization of the sarcomere and helps provide passive tension within sarcomere
nebulin and function
filament of giant protein; possibly to regulate the length of the thin filament
what causes the striated appearance of skeletal muscle?
think and thick filaments
dark bands are called ____
A bands
A bands contain..
the entire myosin molecule and an overlapping portion of actin
light bands are called ____
I bands
I bands contain…
thin filaments, but no thick filaments
I bands also contain the protein ____
titin
H zone (H band)
light, central region of the A band where there are no thin filaments
M line
protein meshwork in the H zone that keeps the thick filaments aligned
Z disc (Z band)
protein structure in the middle of the I band that serves as the attachment site for one end of the thin filament
sarcomere
functional contractile unit in a skeletal muscle fiber; are between two adjacent Z discs
myofibrils contain multiple and repeating..
sarcomeres
each sarcomere ___ as the muscle fiber contracts
contracts
does the sarcomere shorten when the muscle contracts?
yes
does the A band shorten when the muscles contracts?
no