1. Starting small: The Neuron
neuron: a nerve cell; receives signals from other neurons or sensory organs, processes these signals, and sends signals to other neurons, muscles, or bodily organs
the basic unit of the nervous system

2. The Neuron 3 types of neurons:
1. sensory neurons: respond to input from sensory organs (skin, eyes, etc.)
2. motor neurons: send signals to muscles to control movement
3. interneurons: connect the sensory neurons and motor neurons
most of the neurons in the brain = interneurons
average human brain  100 billion neurons

3. Structure of the Neuron

4. Structure of the Neuron
cell body (soma): the central part of the neuron, contains the nucleus
regulates cell functioning
dendrites: the branching part of the neuron that receives messages from other neurons and relays them to the cell body

5. Structure of the Neuron
axon: the long, cable-like extension that delivers messages to other neurons
myelin sheath: layer of fatty tissue that insulates the axon and helps speed up message transmission
multiple sclerosis: deterioration of myelin leads to slowed communication with muscles and impaired sensation in limbs
knobs: structure at the end of one of the axon’s branches that releases chemicals into the space between neurons, when the neuron is fired

6. From Neuron to Neuron
≈100 billion neurons in a human brain, connected to an average of 10,000 others; some up to 100,000
synapse: the place where an axon of one neuron meets with the dendrite/cell body of another neuron

7. From Neuron to Neuron

8. From Neuron to Neuron
neurotransmitters: a chemical that sends signals from one neuron to another over the synapse

9. From Neuron to Neuron
Neurotransmitters are stored in vesicles in the knobs, and bind to receptors on the cell membrane of the next neuron.
Each receptor can only bind with one kind of neurotransmitter.

10. (Some) Neurotransmitters
Function
Examples of malfunctions
Acetylcholine (ACh)
Enables muscle action, learning & memory
Alzheimer’s disease  less ACh production
Dopamine
Influences movement, learning, attention, & emotion
Excess  schizophrenia
Undersupply  Parkinson’s disease
Serotonin
Affects mood, hunger, sleep, and arousal
Undersupply  depression
Norepinephrine
Helps control alertness & arousal
Undersupply  depressed mood
Glutamate
Excitatory neurotransmitter involved in memory
Excess  overstimulation of brain, seizures

11. The Nervous System The Nervous System Central Nervous System (CNS)
Peripheral Nervous System (PNS)
Brain
Spinal Cord
Motor Neurons
Sensory Neurons
Somatic Nervous System
voluntary movements via skeletal muscles
Autonomic Nervous System
organs, smooth muscles
Sympathetic
- “Fight-or-Flight” responses
Parasympathetic
- maintenance

12. The Nervous System peripheral nervous system Made up of the
1. central nervous system
and the
peripheral nervous system

13. Peripheral Nervous System: links central nervous system to organs
The Nervous System
The Central Nervous
- brain and spinal cord
Peripheral Nervous System: links central nervous system to organs
comprised of the somatic nervous system and the autonomic nervous system (sympathetic and parasympatheic nerves)

14. CNS
PNS
Sensory division
Motor division
Sympathetic
division
Autonomic
nervous
system
Somatic
nervous
system
Parasympathetic
division