quiz 2 Flashcards
sarcolemma
muscle cell membrane (surrounds myofibrils)
sarcoplasm
cytoplasm of a cell
-glycogen storage, myoglobin, mitochondria
tranverse tubules
carry action potential deep into muscle fiber
sarcoplasmic reticulum
calcium storage
myofibrils
functional contractile units of skeletal muscle
-constructed of many sarcomeres
sarcomeres
basic contractile element of skeletal muscle -smallest unit within the muscle
-run end to end for full myofibril length
actin
thin myofilaments
3 proteins make up thin filaments
- actin
- troponin
- tropmyosin
troponin
binds to calcium released from SR
moves tropomyosin exposing myosin binding sites
tropomyosin
covers myosin binding site on actin enabling muscle to relax when no SR CA2
-covers myosin binding site when calcium is within SR
myosin
thick filamentt
-heads contain actin binding sites
-use atp to “ratchet”
-have ATPASE enzyme
myosin is stabilized by
titin
how does the muscle shorten
overlap is changing because of ratcheting
-z disc gets closer
titin
stabilizes myosin and anchors myosin to Z line
voluntary muscle contraction starts in ____ and requires
brain
-requires nervous system
-muscle cells
- interdependence
motor unit
single alpha motor neuron and all the fibers it innervates
-more operating motor units = greater contractile force
site of communication between neuron and muscle
and consists of synapse between a motor neuron and muscle fiber
NMJ
excitation coupling step 1
action potential starts in brain and moves along spinal cord
which 2 pumps require ATP
NA - K pump and CA pump
excitation coupling step 2
Ap travels along a single motor neuron towards NMJ
excitation coupling step 3
AP arrives at NMJ causes release of acetylcholine
excitation coupling step 4
ACH crosses synapse, binds to ACH receptors on plasemalemma
excitation coupling step 5
AP travels down sarcolemma and into t-tubules as they appear
excitation coupling step 6
AP inside t-tubules, triggers CA release from Sarcoplasmic reticulum
- then goes to bind to troponin
excitation coupling step 7
released CA enables actin - myosin contraction
-CA binds to troponin that causes tropomyosin to uncover myosin binding sites
-myosin binds to newly uncovered binding sites on actin and ratchets
cross-bridge cycling (actin myosin contraction) step 1
myosin heads are energized but muscle is relaxed
- myosin atpase has created energy
cross-bridge cycling (actin myosin contraction) step 2
cross bridge froms upon binding site uncovering
cross-bridge cycling (actin myosin contraction) step 3
myosin head ratchets using the energy described above
cross-bridge cycling (actin myosin contraction) step 4
myosin head binds new ATP causes release of Actin
cross-bridge cycling (actin myosin contraction) step 5
myosin atpase breaks atp down energizing myosin head
cross-bridge cycling (actin myosin contraction) step 6
If CA Is still present the myosin head binds to another actin site further down to increase shortening
is their calcium in a relaxed muscle
no
tropomyosin is covering binding sites when muscle is __
relaxed
what causes SR to release CA into sarcoplasm
AP
type 1 muscles
slow twich
-oxidative
-fatigue resistant
-more mito - krebs and ETC
-slower ATP ase
-less developed SR
-slower speed of contraction
type 2 muscles
white, fast twitch
-fast glycolitic
-more glycolitic enzymes
-fewer mito
-faster ATP generation
-higher phosphocreatine and creatine kinase
-more developed SR
which type has higher oxidative capacity
type 1
what fuel is best for type 1
fat
what fuel is best for type 2
glucose
fuel mix
- motor recruitment
- stress hormone
- CHO availability
