Muscle 2 (Brief)
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Where does the energy for muscle contraction come from?
Hydrolysis of ATP
What is muscle fatigue?
A state that Is caused by repeated muscle stimulation
What is muscle fatigue dependent on?
Fibre type Length of contraction Fitness of individual
What does muscle fatigue prevent?
Prevents muscles using us vast amounts of ATP which would cause rigor
Myosin has high ATPase activity in
Fast shortening skeletal muscle fibres
Myosin has low ATPase activity in
Slow shortening skeletal muscle fibres
Describe oxidative fibres. (4)
These fibres have more mitochondria for oxidative phosphorylation They are more vascular to allow for the delivery of oxygen and nutrients They contain myoglobin to help with oxygen delivery Red fibres with low diameters
Describe glycolytic fibres. (4)
Few mitochondria Higher concentration of glycolytic enzymes and glycogen Lower blood supply White fibres with low diameters
Describe the 3 specific types of skeletal muscle fibres.
Slow oxidative (I) - resist fatigue Fast oxidative (IIa) - intermediate resistance to fatigue Fast glycolytic (IIb) - Fatigue quickly
State the order of activation of specific skeletal muscle fibres.
Slow oxidative Fast oxidative Fast glycolytic
Describe smooth muscle. (6)
Mononucleate Divide throughout life Non-straited Exist in hollow organs (airways, bladder, GI tract) Also has a cross bridge cycle and uses calcium ions Innervated by ANS
How are myosin and actin filaments different in smooth muscle when compared to skeletal muscle?
The filaments are arranged diagonally across cells and are anchored to membranes and cell structures by dense bodies
What does smooth muscle lack that skeletal muscle have
Troponin
Describe the process of smooth muscle contraction. (6)
Ca2+ is released from the sacroplasmic reticulum/ECF Ca2+ binds to calmodulin Ca2+ - calmodulin binds to myosin light chain kinase (activating MLCK) Active MLCK phosphorylates the myosin cross bridges with ATP The phosphorylates myosin cross bridges then bind to actin filaments Contraction + Tension occurs