Lecture 12 Flashcards
Muscular system:
-___% body mass
-large blood supply
-through all the body
-3 types:
50%
skeletal
cardiac
smooth
__________ muscles (muscles attached to skeleton) = _________ muscles (under our conscious control) = ________ muscles (looks striped)
skeletal; voluntary; striated
5 functions of muscles
1.
2.
3.
4.
5.
- movement (body and body contents: breathing circulation, digestion) (communication through speech, writing, nonverbal)
- stability
- control of openings and passageways (sphincters)
- Heat production
- Glycemic control (glucose storage)
Muscle compartment
-intermuscular septa:
very thick fascia that separate one compartment from another
Fascia
made up of sheets of connective tissue that is found below the skin
-can be classified as superficial, deep, visceral, or partial
Epimysium
fibrous sheath surrounding entire skeletal muscle (deep fascia)
perimysium
wrapped around muscle fascicles
-thicker layer that contains nerves, blood vessels, and stretch receptors (muscle spindles)
Muscle fascicle
bundle of muscle fibers
Endomysium
thin sleeve of loos connective tissue around EACH muscle fiber
-allows room for capillaries & nerve fibers
-provides chemical environment for the cell
strength of muscle and direction of its pull are determined partly by the _________ of its _______
- the skeletal muscles of the body typically come in ___ different shapes
-orientation; fascicles
-7
7 shapes of muscles
Fusiform
Parallel
Triangular
Circular
Unipennate
Bipennate
Multipennate
Fusiform shape of muscle:
-______ in the middle and _______ at each end
-relatively _______
ex:
-thick; tapered
-strong
-biceps brachii
Parallel shape of muscle:
-uniform width
-parallel fascicles to the long axis of the muscle
-produce _____ force
-the _______ in body
ex:
-less
-majority
-rectus abdominis
Triangular (convergent) shape of muscle:
-______ at 1 end and narrow at the other
-relatively _______
ex:
-broad
-strong
-pectoralis major
Circular (sphincter) shape of muscle:
-forms _____ around body openings
ex:
-rings
-orbicularis oculi
Unipennate, Bipennate, and Multipennate shape of muscles:
Unipennate:
-fascicles approach tendon from ______
ex:
Bipennate:
-fascicles approach tendon from _____
-shaft like in feather
ex:
Multipennate:
-bunches of feathers converge at ______
ex:
the STRONGEST muscle shape
-one side
ex: palmar interosseous
-both sides
ex: rectus femoris
-single point
ex: deltoid
Skeletal muscles usually work as __________ pairs to produce the movement
antagonistic
Movement in a DIRECT manner
little separation between muscle and bone
Movement in an INDIRECT manner
-tendon
-aponeurosis
Tendon:
-cord like, fibrous connective tissue (_____________)
-mainly consists of _______ fibers running parallel to the force generated by the muscle to which they are attached
-also contains ______ proteins, which improve the tendons’ elasticity
-attaches _______ to _______
-_________ tendon is the thickest and strongest tendon in the body
-_________: connective tissue band that covers the tendons from a group. of muscles and helps hold them in place
-dense regular
-collagen
-elastic
-muscle; bone
-achilles
-retinaculum
Aponeurosis:
-large, ______ -like layers of connective tissue with a similar composition to tendons
-provides structure and distributes tension across wider area or large number of muscle groups
-can also connect _______ to adjacent _______
-can attach muscles to the ________
-allows bones of the _____ to bear all weight of the body
-sheet
-muscles; muscles
-facial dermis
-feet
there are also skeletal muscles that do not pull against skeleton for movements, for example the muscles that produce __________
facial expressions (they are in contact with the skin)
the muscle that provides the major force to complete the movement
agonist (prime mover)
muscle that opposes the action of the prime mover (relaxes or contracts)
antagonist
muscle that prevents movement of bone while prime movers act
fixator
muscle that aids the prime mover
-may contribute to additional force
-modify the direction of movement
-stabilize a nearby joint
synergist
Universal characteristics of muscle
1.
2.
3.
4.
5.
- Excitability
- Conductivity
- Contractility
- Extensibility
- Elasticity
Excitability
-responsiveness (to chemical signals, stretch)
-ability to respond to a stimulus
Conductivity
local electrical excitation sets off a wave of excitation that travels along the muscle fiber
Contractility
muscle shortens when stimulated
Extensibility
capable of being stretched between contractions
Elasticity
returns to its original rest length after being stretched
single muscle fibers are formed from the fusion of embryonic __________ cells. Each retains its nucleus during fusion
myoblasts
__________ cells (muscle stem cells) are involved in the muscle regeneration following injury or disease
satellite
Inside of each muscle fiber:
sarcolemma
plasma membrane of a muscle fiber
Inside of each muscle fiber:
sarcoplasmic reticulum
smooth ER that forms a network of tubular canals and sacs around each myofibril
-acts as a Ca2+ reservoir (for contraction)
Inside of each muscle fiber:
T tubules
deep invaginations of the sarcolemma
-run between each pair of terminal cisternae
-conduct each impulse to the deepest regions of the muscle fiber
Inside each muscle fiber:
Triad
the complex of the T tubule flanked by 2 terminal cisterns
Inside each muscle fiber:
Myofibril
rodlike contractile organelles
-occupy most of sarcoplasm
-composed of sarcomeres arranged end-to-end
-striations are alternating ________(dark) and ________ (light)
-striations result form the precise organizations of ______ (thick) and ______ (thin) in cardiac and skeletal muscle cells
A-bands; I-bands
-myosin; actin
sarcomere=
segment from Z disc to Z disc
Connectin (elastic filament, Titin)
-giant, springy protein
-interconnects thick filament with ________
-helps stabilize and position thick filament
-prevents _________ and provides _________
-Z disc
-overstretching; recoil
Thick filaments
contains:
-double gobbler heads
-top of heads are _____ binding sites
-bottoms of heads are ______ binding site
actin; ATP
Thin filaments
-troponin:
-tropomyosin:
-string of _______________ subunits each with an active site that can bind to head of _______ molecules
-Ca-binding protein on each tropomyosin molecule
-Each blocking 6-7 active binding sites on G actin subunits
-globular (G) actin; myosin
Several other proteins associate with myofilaments to anchor, align, and regulate them
dystrophin
links actin in outermost myofilaments to membrane proteins that link to endomysium
Genetic defects in _______ produce disability disease _____________
Dystrophin; muscular dystrophy
