Muscular System Flashcards
Sarcolemma and plasma membrane
Sarcolemma- cell membrane
Plasma membrane- The sarcolemma
Sarcomere
The functional unit of muscle fibers
Made of actin and myosin
Actin vs Myosin structure an activity in muscle
Actin
Thin Filament (Act=Actor=thimottee chaleme= thin)
Actin contains myosin binding sites covered by regulatory proteins (green) until calcium ions are present.
Myosin
Thin Filament
Myosin molecules (purple) have a club-shaped (Mickey mouse club house) head that will extend toward and bind to actin (gray).
Largest to smallest structures of skeletal muscle (5 structures)
Fascicle (FATTEST)
muscle fiber (MUSCLESSS)
myofibril (MYO=mayo will make u kinda big)
sarcomere,
myofilament (film= flimsey= weak = smol)
4 Functions of the muscular system
- movement of the body
- maintaining posture and body position
- Generating heat
- Moving substances
Calcium function during skeletal muscle contraction
Will expose the myosin binding site on Actin
- Mechanical force of contraction and actin filaments
Actin is sliding past the myosin
- Skeletal muscles cell and neurotransmitter junction structures
The end of each motor neuron branches into axon terminals (1).
Each axon terminal forms a junction with the sarcolemma (2) of a muscle cell.
Skeletal muscle cell, sarcoplasmic reticulum, calcium
Calcium is storedin the sarcopasmic retiuclum
Striations and myrofilaments
Striations are caused by the arrangement of micro filaments
Acetylcholine and Skeletal muscles
Release when a nerve impulse reaches the axon terminal
Acetylcholine, action potential, sodium
ACh causes temporary permeability to sodium to trigger skeletal muscle action potential
Skeletal muscle twitch vs tetany
Twitch- brief and jerky
Tetany- prolonged contraction
Creatine Phosphate, energy storage, ATP
ATP - Provides energy for muscle contraction
Generated in 3 ways:
Breakdown of creatine phosphate
Aerobic cellular respiration
Anaerobic glycolysis
Isotonic vs. Isometric contraction w/examples
Isotonic- Isotonic contractions occur when the muscle shortens, and movement occurs
Examples: bicep curls, push-ups, pull-ups
Isometric- Isometric contractions occur when the muscles do not shorten; no movement occurs
Examples: Plank, Squats, Wall sits
Skeletal muscle fatigue & ATP
Muscle fatigue is due to lack of ATP from consumption
Anaerobic glycolysis and Muscles
Anaerobic glycolysis produces ATP
If the oxygen supply is depleted, the cells will utilize anaerobic glycolysis to produce a small amount of ATP. The byproduct of this process is lactic acid which leads to muscle soreness.
Antagonist
Produces the opposite effect on the same bones (opposite of agonist)
I band
band of sacromere with only actin filaments
A band
Band with both actin and myosin
Z discs and actin
Z dics allow for the attachement of the thin (actin) filiments, as well as an elastic protein.
H zone
Just myosin
Ions that signal “go” for muscle contraction
Calcium
Where is Acetylcholine released?
By the motor end plates into the synaptic cleft
Aerobic respiration requirement
Aerobic respiration requires oxygen (O2) to create ATP
Extension
Extension- Increase angle of joint
Rotation
Rotation- move bones around longitudinal axis
Pronation
Pronation- when forearm rotation so palm faces posteriorly
Flexion
Flexion- decrease angle of joint
Abduction (aliens take you away)
Abduction – Move limb away from midline
Sarcoplasmic reticulum and calcium
Sarcoplasmic reticulum stores calcium ions needed for contraction
Frontalis (Muscle Action)
Raises eyebrows
Orbicularis Oris
Closes moth and protrudes lips
Masseter
Closes jaw and elevates mandible
Sternocleidomastoid
Flexes the neck, rotates the head
Pectoralis Major
Adducts and flexes the humerus
Pectoralis Minor
Draws scapula down
Rectus Abdominus
Flexes vertebral columb and compresses abdominal contents
External Oblique
Rotate trunk and bend it laterally
Deltoid
Arm abduction
Biceps Brachii
Supinates forearm, flexes elbow
Triceps brachii
Elbow extension
Biceps femoris
Knee, internal and external rotation and hip extension
Sliding filament theory of muscle contraction steps
Nerve impulse reaches the axon terminal
Acetylcholine (Ach) is released into synapse
ACh crosses synapse & binds to receptors on sarcolemma
ACh causes change in membrane permeability; Action potential is generated
Calcium ions are released from sarcoplasmic reticulum
Ca2+ binds to regulatory proteins on actin, exposing binding sites for myosin
Myosin heads bind to actin forming crossbridges
Actin filaments are pulled toward center of the sarcomere
The sarcomere shortens and the muscle contracts