| − | The [[Myofibril|myofibril]] is organised in repeating units called [[Sacromeres|sacromeres]]. These contain thick and thin filaments. Muscle contraction occurs when the thin filaments slide along the thick filament by hydrolysing [[ATP|ATP]] <ref>Berg J., Tymoczko J and Stryer L. (2001) Biochemistry, 5th edition, New York: WH Freeman.</ref> by what is known as the [[The Sliding Filament Theory|Sliding Filament Theory]].
| + | == Cardiac Muscle == |
| − | Contraction in a muscle cell is produced by an [[Action potential|action potential travelling]] along a motor neurone and arriving at a [[Synapse]]. The voltage gradient causes voltage-gated calcium [[Ion channels|ion channels]] in the [[Presynaptic|presynaptic neurone]] to open, triggering [[Vesicles|vesicles]] containing [[Neurotransmitter|neurotransmitters]], specifically acetylcholine, to travel towards the [[Sarcolemma|sarcolemma]]; fusing with the [[Plasma membrane|membrane and]] releasing acetylcholine into the [[Synaptic cleft|synaptic cleft]] <ref>Bowness E, Braid K, Brazier J, Burrows C, Craig K, Gillham R, Towle J. (2009), A2-level Biology The Revision Guide Exam Board AQA, page 57-60, Newcastle-upon-Tyne: CGP books.</ref>. They diffuse across the cleft where they bind to specific [[Receptor|receptors]] called [[Nicotinic cholinergic receptors|nicotinic cholinergic receptors]] on the [[Sarcolemma|sarcolemma]], where the [[Depolarisation|depolarisation]] travels along the membrane and deep into the cell via [[T-tubules|T-tubules]] <ref>Bowness E, Braid K, Brazier J, Burrows C, Craig K, Gillham R, Towle J. (2009), A2-level Biology The Revision Guide Exam Board AQA, page 57-60, Newcastle-upon-Tyne: CGP books.</ref>. Therefore it allows the [[Sarcoplasmic reticulum|sarcoplasmic reticulum]] to become depolarised, releasing [[Calcium|calcium]] [[Ions|ions]] and triggering muscle contraction to take place by the [[The Sliding Filament Theory|sliding filament theory]] <ref>Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walter P. (2008), Molecular Biology of The Cell, page 1028-1029, 5th edition, New York:Garland Science.</ref>.
| + | See [[Cardiac Muscle|Cardiac Muscle]] |
