{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

251Ch102010

4 steps to contraction cycle atp hydrolysis

Info iconThis preview shows pages 36–48. Sign up to view the full content.

View Full Document Right Arrow Icon
4 steps to contraction cycle ATP hydrolysis attachment of myosin to actin to form crossbridges power stroke detachment of myosin from actin Cycle keeps repeating as long as there is ATP 2+ level near thin filament
Background image of page 36

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Steps in the Contraction Cycle Notice how the myosin head attaches and pulls on the thin filament with the energy released from ATP
Background image of page 37
ATP and Myosin Myosin heads are activated by ATP Activated heads attach to actin & pull (power stroke) ADP is released. (ATP released P & ADP & energy) Thin filaments slide past the thick filaments ATP binds to myosin head & detaches it from actin All of these steps repeat over and over Ca+ level near the troponin-tropomyosin complex is high
Background image of page 38

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
ATP MOLECULE
Background image of page 39
RECREATING ATP WITH PCr
Background image of page 40

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
OXIDATIVE PHOSPHORYLATION ¯
Background image of page 41
Overview: From Start to Finish Nerve ending Neurotransmittor Muscle membrane Stored Ca+2 ATP Muscle proteins
Background image of page 42

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Relaxation Acetylcholinesterase (AChE) breaks down ACh within the synaptic cleft Muscle action potential ceases Ca 2+ release channels close Active transport pumps Ca 2+ back into storage in the sarcoplasmic reticulum Calcium-binding protein (calsequestrin) helps hold Ca 2+ in SR (Ca 2+ concentration 10,000 times higher than in sarcoplasm) Tropomyosin-troponin complex recovers binding site on the actin
Background image of page 43
The Motor Unit Motor unit - one somatic motor neuron & all the skeletal muscle cells (fibers) it stimulates muscle fibers normally scattered throughout belly of muscle One nerve cell supplies on average 150 muscle cells that all contract in unison. Total strength of a contraction depends on how many motor units are activated & how large the motor units are.
Background image of page 44

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
produces greatest number of crossbridges and the greatest amount of tension As stretch muscle (past optimal length) If muscle is overly shortened (less than optimal) thick filaments crumpled by Z discs Normally resting muscle length remains between 70 to 130% of the optimum Length of Muscle Fibers
Background image of page 45
Length - Tension Curve Graph of Force of contraction (Tension) versus Length of sarcomere Optimal overlap at the top of the graph When the fiber is too stretched little force is produced When the fiber is too short, again little force is produced
Background image of page 46

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Events Occurring After a Nerve Signal Arrival of nerve impulse at nerve terminal causes release of ACh from synaptic vesicles ACh binds to receptors on muscle motor end plate opening the gated ion channels so that Na+ can rush into the muscle cell Inside of muscle cell becomes more positive, triggering a muscle action potential that travels over the cell and down the T tubules The release of Ca 2+ from the SR is triggered and the muscle
Background image of page 47
Image of page 48
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page36 / 70

4 steps to contraction cycle ATP hydrolysis attachment of...

This preview shows document pages 36 - 48. Sign up to view the full document.

View Full Document Right Arrow Icon bookmark
Ask a homework question - tutors are online