Neural and Hormonal Systems Will Explain Why We FEEL…… Pain Strong Sick Nervous

It all Starts with the Neuron

Neuron Structure Neurons do NOT touch each other- the space in between is call the synapse.

How a Neuron Fires It is an electrochemical process Electrical inside the neuron Chemical outside the neuron (in the synapse in the form of a neurotransmitter). The firing is call Action Potential.

The All-or None Response The idea that either the neuron fires or it does not- no part way firing. Like a gun

Steps of Action Potential Dendrites receive neurotransmitter from another neuron across the synapse. Reached its threshold- then fires based on the all-or-none response. Opens up a portal in axon, and lets in positive ions (Sodium) which mix with negative ions (Potassium) that is already inside the axon (thus Neurons at rest have a slightly negative charge). The mixing of + and – ions causes an electrical charge that opens up the next portal (letting in more K) while closing the original portal. Process continues down axon to the axon terminal. Terminal buttons turns electrical charge into chemical (neurotransmitter) and shoots message to next neuron across the synapse.

Action Potential

How Neurons Communicate

Neurotransmitters Chemical messengers released by terminal buttons through the synapse. We should know at least 4 types and what they do.

Acetylcholine Its function is motor movement and maybe memory. To much and you will…. Not enough and you will…. Lack of ACH has been linked to Alzheimer’s disease.

Dopamine Its function is motor movement and alertness. Lack of dopamine is associated with Parkinson’s disease. Overabundance is associated with schizophrenia.

Serotonin Function deals with mood control. Lack of serotonin has been linked to depression.

Endorphins Function deals with pain control. We become addicted to endorphin causing feelings.

Agonists and Antagonists

Types of Neurons Sensory Neurons Motor Neurons Inter Neurons

Sensory Neurons (Afferent Neurons) Take information from the senses to the brain.

Inter Neurons Take messages from Sensory Neurons to other parts of the brain or to Motor Neurons.

Motor Neurons (Efferent Neurons) Take information from brain to the rest of the body.

Divisions of the Nervous System

Sympathetic Nervous System Flight or Fight Response

A Simple Reflex

A Simplified Neural Network Neurons that learn to work together as a team.

The Endocrine System A system of glands that secrete hormones. Similar to nervous system, except hormones work a lot slower than neurotransmitters. Neurotransmitters Hormones

The Major Endocrine Glands