A&P - Chapter 17 (Part 2) Flashcards
What is released when you transmit a nerve impulse across a synapse?
Neurotransmitters
How do nerve impulse’s work? (6)
- Neurotransmitters cross the synapse
- Binds with receptors on the muscle fibres sarcolemma
- Excites the sarcolemma
- Initiates a nerve impulse across the sarcolemma
- Triggers the SR to release Ca into the sarcoplasm
- Resulting in muscle contraction
What plays a critical role in a series of events that allow binding of myosin and actin?
Ca released from the SR
What are the steps of muscle contraction? (4)
- Each myosin head in the thick filament moves into a resting position after an ATP molecule binds and transfers its energy
- Ca released from the SR binds to troponin in the thin filament
- this allows tropomyosin to shift from its position blocking the active sites of actin - Each myosin head binds to an active site on a thin filament and displaces the remnants of ATP hydrolysis
- The release of stored energy from step 1 brings everything back to the original position
- pulls actin along
What are the remnants of ATP hydrolysis? (2)
- ADP
2. P
When will each head of actin stay bound?
Until another ATP molecule binds to it and pulls it back into its resting position
What happens to myosin during contraction?
It binds to actin which forms cross bridges that act as levers to pull the myofilaments past each other
What happens to the myofilaments as the muscles contract?
They slide past each other
What do contractions require? (2)
- Ca
- cross bridge formation - ATP
- energy
What actively removes Ca in order to stop contractions?
SR
What are 2 basic energy source pathways for muscle contraction?
- Aerobic
2. Anaerobic
Aerobic
Occurs when lots of O2 is available in blood
- very slow process
Anaerobic
Occurs when O2 levels in the blood are low
- very fast process
What energy system would you use for long term activities?
Aerobic
What energy system would you use for short term activities?
Anaerobic
