muscles quiz Flashcards
muscle functions
movement
movement of food along digestive tract
supports body
ruglating blood pressure
guarding exit and entrances of body
maintain body temp
human muscle cells
highly specialized to convert atp to kinetic energy
cadiac muscle cell
in the heart, continually working
stirated tubular and branched
each has a single nuclear
many mitochondria
contract involentary
found in heart walls
smooth muscles cell
non stirated
contract involuntary
sustains prolonged contraction with no fatigue
found in walls of internal organs such as arteries
skeletal muscle cells
stirated and tubular
contract voluntarily
usally attached to bones of skeleton through tendons
long, cylindrical and multi nucleated
each independent cell is stimulated by a branch from neutron
skeletal muscle function
1, support - oppresses forces of gravity
2. movement
3. maintain body temp- atp breakdown releases heat
4. protection- pads bones and cushions organs
5. stabilizes joints tendons help hold bones to joints
what is contraction of muucsles
shortening of the muscles, work
relaxation of muscles
lengthening of muscles no work
why are muscles found in pairs
one action always has a opposing action
bicep contracts- tricep relaxes
what is a muscle
organ surrounded by connective tissue
largest unit: attached to bone by tendons
muscle fibers
organized into larger bundles up to 20cm long
connective tissue wraps fibers
myofibris
thousands of cylindrical subunits
what does prefix myo mean
muscles
what is the sacrolemma
membrane of muscle fibres
regulates entry and exit of materials
what is the hiearchy of muscle structure
muscle–> muscle fibre bundle—> muscle fibre-> myofibrilis—> myofilaments
what is the sacromere
functional unit of a muscle
composed of myofilaments
contractile unit
myofilaments
protein structure responisble for muscle contractions
what are the 2 types of myofilaments
Actin- thin filament
Myosin- thick filament
4 parts to muscle cell
myoglobin, sacrolemma, sarcoplasma , sacroplasmic reticulum
what does prefix sacro mean
in the flesh (in the cell)
what is myoglobin
oxygen binding protein
stores oxygen for muscle contractions
sacrolemma
membrane of muscle fibres
regulates entry and exit of materials
sacroplasma
cytoplasma of muscle fibres
site of metabollic processes
contains myoglobin and glycogen
sacroplasmic reticulum
smooth er in muscle fibres, stores calcium ions
what are actin composed of
- globular actin proteins
- ion receptor proteins called troponin and tropomyosin
what are myosin composed of
2 polypeptide chains wrapped around each other
each have globular heads
how do muscles contract
sliding filament model
sliding of actin past myosin during muscle contractions
major steps during sliding filament modle
- calcium ions allow myosin heads to attach to actin
- mysoin head flexes pulling on actin filament
- myosin head relxes and unflexes via ATP
- myosin reattches to actin further down the fibre
- sacromere shortens causing muscle fibres to contract
how doe muscles relax (calcium ions)
tropomyosin blcoks myosin binding sites along actin molecules
how do muscles contract (calcium ions)
ions bind to troponion on action, causes tropomyosin to repostion and expose myosin binding sites
sliding filament theory
- signal to muscle from nerve to contract
- sacroplasmic recitcult releases calcium ions
3, calcium ions bind to troponin - when bound to calcium ions, troponin helps lift tropomyosin off of actin binding site
- myosin heads attach and slide actin filaments closer together
- ATP disloges myosin heads and they reset to attach again at new spot on actin
- calcium is retuned to SR through active transport
3 methods to aquire atp for muscles
- creatine phosphate, no oxygen anerobic, only enough for 8 seconds of muscle activity
- fermentation: no oxygen anerobic, glucose broken down into latic acid released as by products, last 2-3 min
- aerobic cell resp: oxygen required, glucose completely oxided, forms many ATP molecules, long term energy
myoglobin
oxygen carrying molecule like hemoglobin only found in muscle cells, temporially stores oxygen
what is oxygen debt
athletes muscles demand more atp then can b provided
- generates atp anerobically (fermentation)
- atp is replensied areobically after exercise
what happens when atheltes train muscles
increase in mitochondria, increase in aerobic resperation, descrease amount of oxygen debt nessacry
isotonic contraction
tension (load) on muscle stays constant but length changes during movement
isometric contraction
no change in length of muscle even as tension increases
length stays constant during contraction
origin of muscle
attachment that remains fixed
insertion of muscle
muscle attachment that moves
action of muscle
what joint movement muscle produces
latent period of eletricl impulse
time between stimulation and initation of contraction
contraction period ofelectrical impulse
muscle twitch
relaxation period of electrical impulse
muscle returns to normal length
what is summation
rapid, repetive stimuli add up and can cause larger contractions without relaxation
what is tetanus
maximal sustained contraction (contuies until fatigue)
what is fatigue
no contraction despite stimulation
slow twitch fibres type 1
takes longer ti contract (100ms)
cointains more myoglobin, gives red colors to muscle, more blood, more mitochondria
atp produced aerobically (oxygen)
- do not fatigue as fast, high resistance to fatigue
do not increase in size with training
fast twich fibres type 11X
fast contractions (7ms)
- anaerobic atp (no oxygen)
- glocygen rich white color
- fatigue quick
- low resistance to fatigue
- increase in thickness
atrophy
reduction in size of muscle caused by inactivity, muscle size decrease can become permanent
hypertrophy
increase in muscle mass due to high intensity exercise or steriods
