Neuron Functioning KEY TERMS

Types of Neurons Sensory Neurons – send signals from your senses (eyes, ears, nose, taste buds, skin) toward the spinal cord and brain Motor Neurons – send signals from your brain and spinal cord toward your body

Reflex Arc Interneurons found within the spinal cord connect sensory and motor neurons creating an “arc.” Signals are rapidly sent along this arc to allow you to move quickly away from the potentially dangerous conditions.

The Spinal Cord Handles Reflexes No thinking is involved in a reflex – the brain does not process the information until AFTER the movement has already occurred.

Absolute Threshold An individual neuron will react to stimulation only if the level of stimulation reaches a certain trigger point. Absolute threshold refers to the minimum amount of stimulation necessary to cause a neuron to “fire” a signal.

All-or-Nothing Principle A neuron will either send a signal or not. No such thing as a 27% strength signal. YES or NO no such thing as “maybe” ON or OFF no such thing as a partial signal

ACTION POTENTIAL The neuron signal is called the “action potential” When a neuron has “fired” a signal, it takes time to reset and get ready to go again. This is called the refractory period.

RESTING POTENTIAL When a neuron is not sending a signal, it is at rest This is different than refractory period because when a neuron is at resting potential it is waiting to fire NOT unable to fire

Neuron Impulses are like…

Neurotransmitters Neurotransmitters are chemical molecules which are found in the terminal buttons of neurons. There are many different neurotransmitters. – Examples: Acetylcholine – activates muscles Serotonin – involved in regulating moods Dopamine – related to schizophrenia and Parkinson’s

Terminal buttons release the neurotransmitters into the synapse. Neurotransmitters Neurotransmitters float across the space to the dendrites of the next neuron in line.

Drugs work by imitating or blocking the action of natural neurotransmitters ANTAGONIST = a drug that blocks the effect of a neurotransmitter AGONIST = a drug that boosts the effect of a neurotransmitter

Computer Lab on Monday! Mouse Party We will see how drugs and neurotransmitters work to alter our behaviour