IMED1001 Lecture Notes - Lecture 21: Calcium Atpase, Endoplasmic Reticulum, Serca
12 Jul 2018
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Learning outcomes: outline the process of excitation-contraction coupling, explain the ca2+ regulation of contraction, understand the organization and function of the neuromuscular junction, understand how ca2+ regulation can result in wave summation and tetanus. Nerve talks to muscle> increase is ca2+ concentration > actin/ myosin crossbridges generate tension. When a nerve talk to a muscle it does so by neurotransmitters. Calcium channels open> calcium floods into muscle from outside and intracellular stores> this triggers contraction. The importance of ca2: ca2+ injection causes contraction, ca2+ deprivation prevents contraction, skinned fibres only contract in the presence of ca2+ and atp, if no ca2+ fibres will relax in the presence of atp. Ncx: na+ca2+ exchanger (secondary active etransport: the sarcoplasmic reticulum (sr) Modified er found in muscle- 100 000 x myoplasmic (ca2+) Calcium pump- serca: sarco/endoplasmic reticulum ca2+ atpase. Calsequestrin- sequesters sr calcium : attach calcium to er allows us to store more calcium there.
