Test 2: Skeletal Muscles Flashcards
Arrangement of muscle, small to large
myoblasts -> filaments -> sarcomere -> myofibrils -> muscle fiber -> fascicle -> skeletal muscle
myoblasts
basic cellular units, fuse into muscular fiber with the help of satellite cells, which augment existing muscle fibers to form new fibers
muscle fiber
multiple nuclei, mitochondria, lots of ATP necessary
fascicle, coverings
multiple muscle fibers, endomysium surrounds each muscle fiber while perimysium surrounds the entire fascicle
muscle coverings
epimysium surrounds the muscle, tendons and fascia are extension of epimysium
Creatine phosphate
Creatine -> Creatine phosphate -> Creatine
Creatine -> Creatine phosphate creates ADP, relaxed muscle
Creatine phosphate -> Creatine creates ATP, active muscle
short intense bursts of energy
Anaerobic cellular respiration
Glycolysis
Makes ATP from glucose
Aerobic cellular respiration
Mitochondria
Makes ATP from glucose
Nomenclature muscle
Rectus - parallel to long axis Transverse - perpendicular to long axis Oblique - on an angle Teres - long and round Brevis - short Magnus - large Major - larger Maximus - largest Minor - small Minimus - smallest
Anatomical muscle classification
Red Muscle Fiber
high myoglobin, more mitochondria, more energy stores, greater blood supply
White Muscle Fiber
less myoblin, less mitochondria, less energy stores, less blood supply
Types of muscles (by energy)
Slow oxidative, fast and slow glycolytic
slow oxidative fiber
red muscle fibers smallest, weakest, slowest high fatigue resistance, endurance maintains posture Most activities of daily life aerobic cellular respiration
fast glycolytic fiber
white muscle fibers largest, fastest, strongest low fatigue resistance less mito, myo, blood Anaerobic cellular respiration rapid, brief contractions weightlifting
fast oxidative fiber
aerobic cellular respiration intermediate thickness and strength red muscle aerobic and anaerobic walking, sprinting
Parts of a sarcomere, thick and thin filaments
Z-discs separate sarcomere, boundary
M-line middle of sarcomere
A-band length of thick filament
I-band thin filaments at edge of sarcomere
H-zone thick filaments in center of sarcomere
Thin filaments Mostly actin Myosin binding sites located on actin Troponin and tropomyosin Thick filaments Mostly myosin
Sarcomere change during contraction
H zone shrinks, Z discs get closer together, I bands both shrink
Sliding filament model, calcium release pathway
The neuromuscular junction is where the motor neuron interacts with the muscle
Acetylcholine binds to receptors on the motor end plate
The receptors allow sodium ions to flow into sarcoplasm
potassium ions flow out, causing local depolarization of motor end plate
depolarization initiates action potential on sarcolemma
action potential travels along t-tubules
action potential causes voltage dependent calcium release on sarcoplasmic reticulum
acetylcholine moves off the receptors and is degraded with acetylcholinesterase
Sliding filament model, contraction cycle
Calcium binds to troponin which changes the shape of the troponin tropomyosin complex, uncovers myosin binding sites on actin
At the same time, myosin head hydrolyzes ATP giving it energy to bind actin
The myosin-actin cross bridges rotate toward center of sarcomere
Binds ATP, cross bridges detach
Cycle begins again with the binding of ATP
Full pathway of sliding filament model
1) Synapse from motor nerve
2) Acetylcholine binds to Na+ channel on muscle fiber
3) Na+ channel opens Na+ comes into muscle fiber, producing muscle action potential
4) Acetylcholinesterases destroy Ache in synaptic cleft
5) Muscle action potential travels along T-tubule, opening Ca+ channel in sarcoplasmic reticulum
6) Ca+ binds to troponin
7) Troponin-tropomyosin complex changes shape, uncovers myosin binding site
8a) Myosin heads hydrolyze ATP
8b) Myosin binds to actin
9) Myosin cross bridges rotate toward center of sarcomere
10) Myosin heads bind ATP, cross-bridges detach from actin
divisions of the muscular system
Axial muscles
Position head and spinal column, move rib cage
60% of skeletal muscles
Appendicular muscles
Support pectoral and pelvic girdles, support limbs
40% of skeletal muscles
spasms and cramps
spasms
painless involuntary contraction
Cramps
painful involuntary contraction
dehydration, heavy exercise, mediations, muscle fatigues
inadequate blood flow or electrolyte levels
Tetanus
infection that causes calcium to remain in sarcoplasm
painful muscle contractions, fibers remain contraction
Fibrosis
Replacement of muscle fibers by excessive amount of connective tissues / scar tissue
Aging on muscles
skeletal muscles become smaller, less elastic
takes longer to recover
decreased strength
Describe the primary function of muscle by contrasting the similarities and differences between the nervous system and the muscular system
Muscles have the ability to respond to a stimulus (excitable)
Muscles, unlike nerves, can contract or extend, and are elastic
Primary function of muscles is to create motion, working with nerves bones and joints
Fascicle arrangment - parallel
Most skeletal muscles in body
Fibers parallel to the long axis of muscle
Biceps
Fascicle arrangement - convergent
Broad area converges on attachment site
Pecs
Muscle fibers pull in different directions
Fascicle arrangment - Pennate
From an angle with the tendon Don’t move as far as parallel muscles Unipennate Fibers on one side of tendon Bipennate Fibers on both sides of tendon Multipennate Fibers surrounding tendon Deltoid
Fascicle arrangement - circular
Sphincters, form a circle
Mouth, etc
