The peripheral nervous system (PNS) contains sensory nerves that sense changes in an individual’s environment
When a sensory neuron senses a change it sends an action potential to the spinal cord which sends the message to the brain
The brain or the spinal cord, which makes up the central nervous system, (CNS), depending on the severity of the change, interprets the message
The CNS sends back a response through an action potential back through a motor nerve which tells the muscle what to do in response to the change
Sensory neurons, the 5 senses, starts the neural message
The neuron is initially in a resting potential state where it is negative on the inside of the cell and positive on the outside. This is created by a sodium potassium pump that actively transports Na+ and K+ across the cell membrane.
Depolarization is the action potential traveling along the neuron. Depolarization begins when the stimuli opens sodium channels causing a temporary change in the cells polarization.(Relative to one another- positive on the inside, negative on the outside)
Repolarization begins immediately following depolarization where the resting potential is restored. This is known as the refractory period.
The gap between neurons is known as a synapse.
Communication across the synapse happens by Ca++ rushing into the neuron through voltage-gated channels.
This increase in Ca++ causes synaptic vesicles to fuse with the pre-synaptic messengers and spill neurotransmitters into the synaptic cleft by exocytosis.
Neurotransmitter is received by the post-synaptic cell because receptors recognize the neurotransmitter.
This causes ion channels to open and impulse is transmitted.
The somatic motor neuron that innervates skeletal muscle fibers is called a motor neuron.
The axon of the motor neuron extends to the muscle that it is responsible for innervating.
Once the axon reaches the muscle, which is known as the neuromuscular junction, it splits into collateral branches which innervates a single muscle fiber.
Each motor neuron and and all the muscle fibers that it innervates is known as a motor unit.
When a single motor neuron is activated, all of the muscle fibers that it innervates are stimulated to contract.
The more nerves there are telling the muscle to contract the higher an individual can jump, known as Neural-Plasticity.
Fast twitch muscles have to do with anaerobic metabolism due to due to less myoglobin and mitochondria
Fast twitch muscles fatigue quicker, b ut are better at generating more power in short bursts than slow twitch muscles are
Slow twitch muscles have a lot of myoglobin, which carries oxygen
Slow twitch muscles have higher aerobic metabolism and mitochondria and are therefore more capable of endurance activities or activities that do not require maximum strength.
Jumping uses more fast twitch muscles than it does slow twitch.
Muscle spindles are small sensory organs that are enclosed within a capsule
A muscle spindle detects changes in the stretch of the muscle
A muscle spindle assists in the regulation of movement and helps maintain posture.
A muscle spindle sends signals to the brain then the brain sends the signal back to the quadricept telling it how much to stretch or contract before a person is about to jump.
A golgi tendon is located at the insertion of skeletal into the muscle fibers of skeletal muscles.
They serve as “safety devices” that help prevent excessive force during muscle contraction.
Golgi tendon organs send how far the individual wants to jump to the spinal cord through sensory neurons which travels to the brain.
The brain interprets the sensory message and formulates a response, sends the message back through motor neurons which tells the gogli tendon organs how much to monitor the muscle contraction before the individual jumps.
Neuromuscular fatigue results when the synapse is not being communicated over
This happens when the neurotransmitter, acetylcholine, is blocked by free radicals and the impulse fails to cross the synaptic cleft
Therefore the muscles get a delayed message or no message at all to contract resulting in a less powerful jump.