The Muscular system Flashcards
Skeletal Muscle
locomotion of breathing
maintain posture
heat production
form smooth contours of body
vary in shape
under voluntary control
striated
cells are multinucleated
attached to bones
Cardiac Muscles
pumping mass of heart
under involuntary control
arranged in a spiral shape
cells behave as one unit
striated
Smooth Muscle
no striations
single nucleus
found mainly in the walls of hallow organs
slow contraction
under involuntary control
Function of Muscles
Produce movement
maintain posture
generate heat
stabilize joints
propel substances
Endomysium
located around a single muscle fiber(a connective tissue)
Perimysium
surrounds multiple fibers
Fasicle
bundle of fibers
Epimysium
covers the entire skeletal muscle
Sarcolemma
specialized plasma membrane
helps in synaptic transmission
Sarcoplasmic recticulum
specialized smooth endoplasmic reticulum which stores and pumps calcium ions
Myofibril
Bundles of muscle cells in a fascicle
I- Band
a band of myofilament that is made of actin(light band)
A-Band
a band of myofilament that is made of myosin(dark band)
Sarcomere
Contractile unit of a muscle fiber
contains thin and thick filaments
Myosin filaments
Thick filaments composed of the protein myosin
have heads(extensions or cross bridges)
has ATPase enzymes
Actin Filaments
filaments composed of the protein actin
overlap somewhat
have the proteins:troponin and tropomyosin attached to it
The Sliding filament theory of muscle contraction
Activation by nerves causes myosin heads to attach to binding cites on the thin filaments(only when the calcium ions bind with the proteins on the thin filaments)
myosin heads then bind to the next site of the thin filament and pull then towards the center of the sarcomere
results in a muscle that is shortened
Neuromuscular Junction
Association site of nerve and muscle
Neurotransmitter
chemicals released by nerve upon arrival of nerve impulse
Synaptic cleft
a gap between nerve and muscle
Motor unit
consists of a single motor neuron and all the muscle fibers it innervates.
Events that take place in the neuromuscular junction
Action potential reaches the motor end plate of the neuron.
Voltage-gated calcium channels open, and calcium enters the neuron.
Vesicles are stimulated to migrate to the end plate and release acetylcholine into the neuromuscular junction.
