muscle 2 Flashcards
active tension lengths >2.2
active forces lowers as overlap between
filaments reduces, reducing the number of cross bridges
active tension lengths <2.0 μm
filaments collide and interfere with each other reducing
force developed
Total tension
sum of the active
tension dependent on the sarcomere
length AND the passive tension
for ISOMETRIC
contractions
what influences force
length
how does Ach release into neuromuscular junction
action potential goes down motor neuron and allows ca2+ ions to open and calcium trigger ach to release onto cleft
what does opening of
the ligand (ACh) gated ion channels cause
movement of predominantly Na + into the
muscle cell making it less negative
If sufficient ligand gated
channels are opened the end
plate potential reaches
threshold and what happens
Voltage gated Na+ channels
open and an action potential is
triggered along sarcolemma into t tubules
action potential in skeletal muscle
Na channels open to allow Na+ to rush in and depolarise. Na channel closes and K+ opens which repolarises.
how is Calcium released from the SR
action potential goes down t tubule and contacts SR which releases calcium into cytosol
what happens when Ca2+ concentrations
reach a critical threshold
myosin binding sites on the
actin filament are exposed
allowing the cross-bridge cycle
to occur
Sources of ATP for muscle metabolism
creatine, aerobic, anaerobic
type 1 muscle fibre
aerobic, slow, small diameter, high mitochondria/blood supply
type 2 muscle fibre
anaerobic, fast, large diameter, low supply
whats Regulation of Force dependant on
Rate of stimulation of individual motor units
The number or motor units recruited
fused and unfused (on diagram)
fused - fast stimulation in short period of time
unfused - amplitude gets slightly higher with each stimulation
