Muscle Flashcards
actin
A thin myofilament contained in muscle cell which, with myosin, is involved in the sliding filament model of muscle contraction.
myosin
A thick myofilament contained in muscle cell which, with actin, is involved in the sliding filament model of muscle contraction.
troponin
A protein in muscle cells which, when it binds to calcium, is responsible for muscle contraction by shifting the position of tropomyosin which allows the binding of actin and myosin.
tropomyosin
Together with troponin, it covers the actin-myosin binding sites in muscle cells during relaxation.
muscle fiber
Muscle cells
sarcomere
The smallest unit of muscle contraction
sarcoplasmic reticulum
a form of smooth endoplasmic reticulum found in muscle cells which stores calcium ions
rigor mortis
The phenomenon in which calcium ions leak out of the sarcoplasmic reticulum after death, stiffening the body with muscle contractions, which stop after all the available ATP has been used
antagonistic muscle pairs
A set of two muscles which produce movement when one muscle contracts and the other relaxes. Example: bicep/tricep
extensor
The muscle in an antagonistic muscle pair which contracts during extension.
flexor
The muscle in an antagonistic muscle pair which contracts during flexion.
tendon
A band of connective tissue which attaches muscle to bone.
ligament
A band of connective tissue which connects bone to bone.
bicep
The flexor in the antagonistic muscle pair with the tricep.
tricep
The extensor in the antagonistic muscle pair with the bicep.
fast twitch muscles
type of muscle which contracts quickly when stimulate with little endurance.
slow twitch muscles
type of muscle which contracts slowly when stimulated with great endurance.
neuromuscular junction
The junction between a motor neuron and a skeletal muscle cell.
motor unit
One motor neuron and all the muscle cells it stimulates.
motor neuron
A neuron which carries information away from the brain and spinal cord to a muscle
summation and tetanus
The phenomenon of successive muscle action potentials (twitches) allowing sustained movement. Tetanus results when there is no time for relaxation in between muscle twitches, and can only last until ATP runs out, resulting in fatigue.
ATP
Energy source for cells. Stored ATP is the primary source of energy for muscle contractions
creatine phosphate
A high energy compound stored in muscle tissue that converts ADP to ATP when ATP stores in the muscle have been depleted.
anaerobic respiration
The process of converting glycogen stored in the muscles into glucose, used when creatine phosphate stores are depleted. Used for burst activities.
aerobic respiration
The process of utilizing oxygen in hemoglobin or myoglobin to produce ATP during prolonged activity.
List three different types of muscle.
Skeletal
Smooth
Cardiac
What do the three muscle types have in common?
All are excitable (respond to stimuli)
All are contractile (ability to shorten)
All are extensible (stretchy)
All are elastic (return to their original shape after stretching)
How is skeletal muscle different from smooth and cardiac muscle?
Skeletal muscle is large, long, and contains multiple nuclei per cell.
Describe the sliding filament model of muscle contraction.
Actin filaments slide along myosin filaments, shortening the sarcomere without the filaments themselves shortening.
What role does calcium play in muscle contraction?
Calcium binds to the troponin, causing it to change shape, move the tropomyosin, and allow the actin and myosin to bind.
What triggers the release of calcium into the cytoplasm?
A nerve impulse from a motor neuron
Which fatigues faster: fast twitch or slow twitch muscle?
fast twitch
Why are drugs like steroids and testosterone attractive to body builders?
Because they stimulate the body’s ability to build muscle
What are the side effects of using drugs like steroids and testosterone?
Damage to liver, cardiovascular damage, decreased testicle size, potential sterility, masculine traits in females.
What are the four necessary steps of muscle contraction in the sliding filament model?
1) Cross-bridge attachment: myosin heads attach to nearest actin
2) Power stroke: binding causes release of energy, which causes myosin head to jerk back to bent position
3) Cross-bridge detachment: ATP molecules bind to the myosin head, causing myosin head to disengage from actin.
4) Myosin reactivation: Myosin head splits ATP into ADP and inorganic phosphate, which restarts the contraction cycle.
Each time a muscle cell contracts (myosin and actin bind), two ATP molecules are used. List four sources for these ATP molecules.
1) stored ATP
2) creatine phosphate
3) anaerobic metabolic pathways
4) aerobic respiration
