Chapter 6: The Muscular System Flashcards
What are the 3 types of muscles?
Skeletal Muscle
Cardiac Muscle
Smooth Muscle
What is the location of skeletal muscle?
Attached to bone or skin (for some facial muscles)
What is the location of cardiac muscle?
walls of the heart
What is the location of smooth muscle?
mostly in walls of visceral organs (other than the heart)
What do skeletal muscle cells look like ?
Single, very long, cylindrical, multinucleate cells with very obvious striations
What do cardiac muscle cells look like ?
branching chains of cells, uninucleate, striations, intercalated discs
What do smooth muscle cells look like ?
single, fusiform, uninucleate, no striations
What are the connective tissue components of skeletal muscle?
Endomysium, perimysium, and epimysium
What are the connective tissue components of cardiac muscle?
endomysium
What are the connective tissue components of smooth muscle?
endomysium
Endomysium
encloses a single muscle fiber
perimysium
wraps around a fascicle (bundle) of muscles fibers
Epimysium
covers the entire skeletal muscle
fascia
on the outside of the epimysium
What is the direct attachment from muscle to bone?
epimysium
What are 2 indirect attachments from muscle to bones?
tendon and aponeurosis
Name the descending order of size muscle structures.
Muscle Muscle fascicle Muscle fiber (AKA muscle cell) Myofibril myofilaments = actin & myosin
Tendon
cord-like structures
mostly collagen fibers
often cross a joint due to toughness and small size
aponeuroses
sheet-like structures
attach muscles indirectly to bones, cartilages, or connective tissue coverings
skeletal muscle attachement sites
bones
cartilages
connective tissue coverings
skeletal muscle functions (4)
produce movement, maintain posture, stabilize joints, generate heat
sacrolemma
specialized plasma membrane
myofibrils
long organelles inside muscle cell
sacroplasmic reticulum
specialized smooth endoplasmic reticulum
What are the bands of myofibrils?
I band - light band, contains only thin filaments
A band = dark band, contains the entire length of the thick filaments
sacromere
contractile unit of a muscle fiber
contains myofilaments
Myofilaments
thick filaments = myosin filaments
thin filaments = actin filaments
thick filaments
myosin filaments
composed of the protein myosin, has ATPase enzymes, myosin filaments have heads (extensions, or cross bridges), myosin and actin overlap somewhat
Thin filaments
actin filaments
Composed of the protein actin, anchored to the Z disc
What kind of filaments are in the A band.
It has myosin, and lacks actin filaments
sacroplasmic reticulum
stores and releases calcium
surrounds the myofibril
excitability
aka responsiveness or irritability
ability to receive and respond to a stimulus
contractility
ability to shorten when an adequate stimulus is received
extensibility
ability of muscles cells to be stretched
elasticity
ability to recoil and resume resting length after stretching
motor unit
one motor neuron and all the skeletal muscle cells stimulated by that neuron
neuromuscular junction
association site of axon terminal of the motor neuron and muscle
synaptic cleft
gap between nerve and muscle
nerve and muscle do not make contact
area between nerve and muscle is filled with interstitial fluid