Ch 11-13 Flashcards
What are the three layers of connective tissue surrounding muscle and muscle fibers?
Epimysium=surrounds entire muscle, separates it from other tissue & sonnets to deep fascia
Perimysium=divides muscle into compartments called fascicles (bundles)
Endomysium=surrounds individual muscle fibers
What are the functions of muscle?
movement (contraction pulls bones for movement), maintains posture/body position
supports soft tissue, holds in place as well as protects
guards openings, voluntary control of openings
maintains body temp
store nutrient reserves
How is muscle attached to bone?
Directly=muscle to bone (rare)
Tendons=bundles of the ends of epi, peri & endo come together
aponeurosis=broad sheet attachment
What makes up the anatomy of a muscle fiber?
sarcolemma=cell membrane around muscle fiber, maintains a transmembrane potential, sarcoplasm=cytoplasm, transverse tubules=extends into sarcoplasm, filled with ECF, electrical impulses conduct into cell, myofibrils=ea. fiber contains 1000s, contains protein filaments (myofilaments), sarcoplasmic reticulum=wraps around each myofibril, is connected to t-tubules, contains lots of Ca
What is a sarcomere?
The smallest functional unit of muscle fiber. 10,000/myofibril.
thick filaments=myosin
thin filaments=actin
proteins stable and regulate filaments
How are sarcomeres organized?
A band=(dArk) center of sarcomeres, length of thick filament
M Line=center point of thick filament
H Zone=area of thick filament with no thin filament
Zone of overlap=area where thin & thick filaments overlap (darkest of dark)
I Band=(lIght) thin filaments only
Z lines=mark boundary b/t adjacent sarcomeres
Titin=elastic protein, keeps thin & thick aligned
What is tropomyosin?
Acts as the “door,” the strand that covers G actin to prevent binding with myosin
What is troponin?
Acts as the “lock,” globular protein on tropomyosin strand, binds with Ca to unlock active sites
What is myosin and its structure?
The thick filament that binds with actin during muscle contraction. Looks like a “golf club.” has a head that projects toward thin filament (actin) with a tail bound with other myosin molecules in thick filament, points toward M-line, a hinge that lets head pivot at its base=act of contraction.
What is cross bridges?
the connection made when myosin head connects with G actin active sites
What is the function of calcium in muscle contraction?
Acts as the “key.” binds to receptor on troponin molecule, troponin-tropomyosin complex changes, exposes active site of G actin
What is the sliding filament theory?
thin filaments are sliding toward center of sarcomere (pulled by thick filaments
Describe the sliding filament theory.
H-zones & I-bands get smaller (shorter)->Zones of overlap get larger->Z-lines move closer together->Width of A-band remains constant
Where does the neuron meet muscle fiber?
neuromuscular junction
what is the branch ends of the axon at the neuromuscular junction?
synaptic terminal
What are the membranes that send and receive ACh (acetylcholine)?
motor end plates
what is the sudden change in the transmembrane potential?
action potential (increase in sodium ions in sarcolemma)
What is ACh?
acetylcholine, a neurotransmitter, changes permeability & properties of another cell’s membrane. (causes sodium-ion rush into sarcoplasm)
What is the process of muscle stimulation?
- action potential arrives
- release of ACh
- ACh binds at motor end plate
- action potential in sarcolemma
- repolarize
What is the process of the contraction phase?
- expose active site
- Form cross-bridges
- myosin heads pivot
- cross-bridge releases
- reactivation of myosin
What is the relaxation phase?
end of stimulation at neuromuscular junction, runs out of Ca in sarcoplasm, runs out of energy (ATP) to power contraction -> contraction stops, muscle returns to initial length passively
What is rigor mortis?
a fixed muscular contraction after death, lasts 15-25 hours, no ATP to release cross-bridges
What are the phases of twitches?
Latent Period=action potential moves thru sarcolemma causing Ca2+ release
Contraction Phase=calcium ions bind, tension builds to peak
Relaxation Phase=Ca2+ levels fall, active sites covered, tension falls to resting levels
What is treppe?
repeated stimulations IMMEDIATELY AFTER relaxation phase
What is wave summation?
repeated stimulations BEFORE THE END of relaxation phase, causes increasing tension of summation of twitches
What is incomplete and complete tetanus?
Incomplete=if rapid stimulation continues & muscle is not allowed to relax, twitches reach maximum level of tension
Complete=if stimulation if high enough, muscle never begins to relax, and is in continuous contraction (not allowed to relax completely)
What are motor units?
they contain hundreds of muscle fibers, contract at the same time and controlled by a single motor neuron
What is recruitment R/T muscles?
in a whole muscle or group of muscles, smooth motion & increasing tension is produced by slowly increasing size or number of motor units stimulated
What is the tension and firmness of a muscle at rest called?
muscle tone
What are isotonic contractions?
Skeletal muscle changes length, resulting in motion
Concentric=muscle tension>resistance, muscle shortens
Eccentric=muscle tension<resistance, muscle lengthens
What are isometric contractions?
skeletal muscle develops tension, but is prevented from changing length (pushing on door frame, FAH)
How is ATP generated?
aerobic=metabolism in the mitochondria WITH OXYGEN
Anaerobic=glycolysis in the cytoplasm WITHOUT OXYGEN
What happens at peak exertion? And muscle fatigue?
muscles lack oxygen to support mitochondria, muscles rely on glycolysis for ATP, pyruvic acid builds ups, is converted to lactic acid.
when muscles can no longer perform a required activity, they are fatigued due to lactic acid build-up
What happens during the recovery period?
the time required after exertions for muscles return to normal, oxygen becomes available, mitochondrial activity resumes.
What is the Cori Cycle?
the removal & recycling of acetic acid by th liver, back to glucose
What are the hormones that affect the muscular system?
Growth hormones and testosterone stimulate synthesis & enlargement of skeletal muscles
Thyroid hormones raise the level of metabolism (energy consumption)
Epinephrine increases duration of stimulation & force of contraction
What is the difference between white and red fibers?
White=fast, contract very quickly, strong contractions, fatigue quickly, have large diameter, large glycogen reserves, few mitochondria, pale (ex: chicken breast)
Red=slow, are slow to contract, slow to fatigue, have small diameter, more mitochondria, have high oxygen (blood) supply, contain myoglobin (binds oxygen), dark (chicken legs)
What are most human muscles made of?
Intermediate fibers=pink, mid-sized, have low myoglobin, have more capillaries than fast fiber, slower to fatigue, mixed fibers=pink
What is hypertrophy and atrophy?
Hypertrophy=muscle growth from heavy training
Atrophy=lack of muscle activity reduces muscle strength, mass, tone
What is the origin, insertion and belly of a muscle?
Origin=1 FIXED point of attachment
Insertion=1 MOVING point of attachment
Belly=central, body portion of muscle
What is the action and innervation?
action=movements produced by muscle contraction
innervation=distribution of nerves to muscle or muscle group
What are the agonist and antagonist?
agonist=prime mover, produces a particular movement
antagonist=opposes movement of particular agonist
What is a smaller muscle that assists a larger agonist by starting motion or by stabilizing origin of agonist?
Synergist
What are fixators (r/t synergists)?
synergist that assists by preventing movement at another joint or by stabilizing the origin of a muscle
What are parallel muscles?
fibers parallel to the long axis o muscle (biceps)
What are convergent muscles?
broad area converges on attachment site, fibers pull in different directions, depending on stimulation (pectoralis)
What are pennate muscles?
forms an angle with the tendon
unipennate=fibers on one side of tendon
bipennate=fibers on both sides of tendon
multipennate=tendon branches within muscle
What are circular muscles?
sphincter=guards entrances of body (mouth, eye, rectum)
How is each bone a lever?
mechanically, each bone is a lever
joint=fulcrum
muscles=applied force
applied force required to overcome resistance
What are the classes of levers?
First=see-saw, force and resistance are balanced
Second=wheelbarrow, small force moves a large weight
Third=MOST COMMON in body, greater force moves smaller resistance, maximizes speed & distance traveled..
What is the CNS and PNS?
CNS=Central Nervous System, consists of spinal cord, brain. Processes, coordinates sensory data and motor commands
PNS= Peripheral Nervous System, nervous tissue outside of CNS, (eyes, ears, special senses)