A forest ecosystem can support a limited number of bears. This is because available energy is lost from one trophic level to the next. (flies, trout, then bears)
A tiny solid suspended in the athmosphere
Sensory" Neuron
"Associative Neuron"
"Motor" Neuron
A stimulus, the cockroach is sensed by your eyes.
Your eyes transmit nerve impulses from the optic nerve, the a group of sensory neurons, to the brain, the central nervous system.
In the brain, the impulse is then transferred by relay / association neurons to the motor neurons which signals the effector which is the muscle in your legs to contract, making you jump in shock