- Starts with a nerve cell called a neuron
Neuron Anatomy
- Neurotransmitter - chemical held in terminal button that travels through synaptic gap
- Cell Body - the cells support center
- Dendrites - Receive messages from other cells
- Axon - passes messages away from the cell body to other neurons, muscles or glands
- Terminal Branches of Axon - forms junctions with other cells
- Mylin Sheath - covers the axon of some neurons and helps speed up neural impulse
- Neural Impulse - electrical signal traveling down the axon
- Synapse - a structure the permits a neuron to pass a chemical or electrical signal to another cell
How Does a Neuron Fire?
- Resting Potential - Slightly negative charge
- Reach the threshold when enough neurotransmitters reach dendrites
How a Neuron Fires
- an electrochemical process
- electrical inside neuron
- chemical outside neuron in the synapse in the form of a neurotransmitter
- the firing is called action potential
All or None Response
- idea that either the neuron fires or not - no part way firing
- No fire - trouble
Neurotransmitters
- chemical messengers released by terminal buttons through synapse
4 Types of Neurotransmitters
- Acetylcholine (AcH)
- Deals with motor movement and memory
- Lack of AcH has been linked to Alzheimer's Disease
- Dopamine
- Deals with motor movement and alertness
- Lack of dopamine has been linked to Parkinson's disease
- Too much dopamine = schizophrenia
- End of relationship = lower dopamine levels
- Serotonin
- involved in mood control
- lack of serotonin has been linked to clinical depression
- Endorphins
- involved in pain control
- many of our most addictive drugs deal with endorphins
Drugs can be...
- Agonists - make neuron fire
- Antagonists - stop neural firing
3 Types of Neurons
- Sensory Neurons - (Afferent Neurons) Take info 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
The Nervous System
- The Central Nervous System - Brain and Spinal Cord
- Peripheral Nervous System - (PNS) all nerves that are not encased in bone. everything but the brain and spinal cord. Divided into 2 categories:
- Somatic Nervous System - controls voluntary muscle movements and uses motor neurons
- Autonomic Nervous System - controls the automatic functions of the body. Divided into 2 categories:
- Parasympathetic Nervous System - Automatically slows the body down after a stressful event. Heart rate and digestion speeds up
- Sympathetic Nervous System - Flight or fight response. Automatically accelerates heart rate, breathing dilates pupils, slows down digestion.