33: Synaptic Transmission And Excitation-Contraction Coupling Flashcards
Two types of synapses and which is common in humans
Electrical, chemical (common in humans)
Best example of human electrical synapse
Cardiac myocytes
Chemical synapse
Neurotransmitter used to diffuse across synaptic cleft -> receptor
Specificity of general chemical synapse pre- and post-synaptic cells
Pre-synaptic: can signal 1 or many post-synaptic
Post-synaptic: can receive signals from 1 or many pre-synaptic
Specificity of NMJ pre- and post-synaptic cells
Pre-synaptic: innervates 1 or many muscle cells
Post-synaptic: receives signal from only one pre-synaptic axon
Motor end plate
Specialized synaptic region in NMJ
What happens when an AP reaches a muscle cell?
Activates DHP receptors -> physically alter ryanodine receptors -> Ca channels in SR open -> Ca into sarcoplasm
How does Ca get removed from muscle cell at the end of an AP?
Ca/ATPase pump sequesters Ca back into SR
Peripheral vs central fatigue
Peripheral: depletion of ATP
Central: feeling of fatigue due to increased levels of byproducts (H ions, lactic acid)
Three ways muscle cells can get ATP
Phosphocreatine, glycolysis, oxphos
Three types of skeletal muscle fibers
- Slow twitch oxidative
- Fast twitch glycolytic
- Fast twitch oxidative
Slow twitch oxidative muscle fibers
Red (myoglobin and mito present), small, fatigue resistant
Fast twitch glycolytic muscle fibers
White, large diameter
Preferred energy use for slow twitch vs fast twitch fibers
Slow twitch: O2
Fast twitch: phosphocreatine, glucose
Four things that alter the force of muscle contraction
- Starting length of sarcomere
- How rapidly fiber is stimulated by nerve
- Innervation type
- Muscle type