|
skeletal muscle
|
make up"flesh" of the body, maintain posture, voluntary movement, aid in breathing/eating/speech, provide facial expression, generate reflexes, produce body heat
|
|
Step 1 (embryonic mesoderm cells)
|
Embryonic mesoderm cells undergo cell division (to increase number) and enlarge
|
|
Step 2 (myoblasts)
|
Several myoblasts fuse together to form a myotube
|
|
Step 3 (myotube)
|
Myotube matures into skeletal muscle fiber
|
|
Step 4
|
Mature skeletal muscle fiber
|
|
Endomysium
|
around single muscle fiber
|
|
Perimysium
|
around a fascicle (bundle) of fibers
|
|
Epimysium
|
covers the entire skeletal muscle
|
|
Fascia
|
on the outside of the epimysium
|
|
Tendon
|
attachment, cord-like structure
|
|
Aponeurosis
|
attachment, sheet-like structure
|
|
Slow oxidative fibers (slow)
|
Red color due to myoglobin, obtain energy from aerobic metabolic reactions, contain a large # of mitochondria, richly supplied w/ cappilaries, contract slowly and resist fatigue, fibers are small in diameter
|
|
Fast oxidative fibers (intermediate)
|
Have an intermediate diameter, contract quickly like fast glycolytic fibers, oxygen dependent, high myoglobin content and rich supply of capillaries, kinda fatigue resistant, more powerful than slow oxidative fibers
|
|
Fast glycolytic fibers (fast)
|
Contain little myoglobin and few mitochondria, about twice the diameter of slow-oxidative fibers, contain more myofilaments and generate more power, depend on anaerobic pathways, contract rapidly and tire quickly
|
|
Step 1
|
Nerve impulse travels down the axon and reach axon terminal
|
|
Step 2
|
Calcium VGC open > calcium influx into axon terminal
|
|
Step 3
|
Exocytosis of ACh into synaptic cleft (calcium dependent event)
|
|
Step 4
|
ACh interaction with Na+/K+ channels on sarcolemma > opening of the channels
|
|
Step 5
|
Na+ influx at higher rate than K+ efflux > leads to depolarization
|
|
Step 6
|
Spreading of the depolarization in the muscle fiber through t-tubules
|
|
Step 7
|
Opening of the calcium VGC associated with the T-tubules and release of calcium into sarcoplasm
|
|
Step 8
|
Interaction of calcium with regulatory protein troponin
|
|
Step 9
|
Eventual muscle contraction
|
|
1.
|
Electrical impulse of neuron
|
|
2.
|
Electrical impulse in skeletal muscle
|
|
3.
|
Muscle contraction
|
|
Muscle response to changes in stimulus strength
|
|
Recruitment works on size principle
|
|
Motor units w/ smallest muscle fibers are recruited first
|
|
Motor units with larger and larger fibers are recruited as stimulus intensity increases
|
|
Largest motor units are activated only for the most powerful contractions
|
|
Motor units in muscle usually contract asynchronously
|
|
Muscle response to changes in stimulus frequency
|
|
If stimuli frequency increases, muscle tension reaches maximum
|
|
Referred to as fused (complete) tetanus bcuz contractions "fuse" into one smooth sustained contraction plateau
|
|
Prolonged muscle contractions lead to muscle fatigue
|
|
Latent Period
|
events if excitation-contraction coupling (no muscle tension seen)
|
|
Period of Contraction
|
cross bridge formation (tension increases)
|
|
Period of Relaxation
|
Ca2+ reentry into SR (Tension declines to zero)
|
|
Removal of ACh by AChE
|
|
Electrical impulse from neuron must cease
|
|
ATP?
|
|
Calcium must be removed by pumps (active process vs. channel [passive])
|
|
What is it?
|
The shortening of the sarcomeres in a myofibril produces the shortening of a myfribril
|
|
I Band
|
Narrows/shortens
|
|
H zone
|
Narrows/shortens
|
|
A band
|
Unaffected
|
|
Z disk
|
unaffected
|
|
Step 1
|
ACh is broken down by AChE, ending action potential generation in the sarcolemma
|
|
Step 2
|
The SR reabsorbs calcium ions, and the concentration of calcium ions in the sarcoplasm declines
|
|
Step 3
|
When calcium ion concentrations approach normal resting levels, the troponin-tropomyosin complex returns to its normal position. This change re-covers the active sites and prevents further cross-bridge interaction
|
|
Step 4
|
Without cross-bridge interactions, further sliding cannot take place, and the contraction ends
|
|
Step 5
|
Muscle relaxation occurs, and the muscle returns passively to its resting length
|
|
Dorsiflexion
|
Lift up toes
|
|
Plantarflexion
|
move toes down
|
|
Inversion
|
when sole of foot point inward
|
|
Eversion
|
when sole of foot points outward
|
|
Protraction
|
to move anteriorly; shoulders, madible
|
|
Retraction
|
to move part posteriorly
|
|
Elevation
|
to raise part superiorly; shoulders
|
|
Depression
|
to lower part; open mouth
|
|
Rotation
|
pivot on an axis; shake head no, can rotate head and shoulder
|
|
Circumduction
|
to draw a circle with body part; shoulder, head
|
|
Pronation
|
turn hand downward
|
|
Supination
|
refers to arms; supinate; want a bowl of soup
|
No comments yet.
Cheatography n. The art of mapping complex subjects into clear, instantly navigable reference guides.
