Nervous System

• Monitors internal and external environment
• Determines appropriate responses
• Sends signals muscles and glands to respond

Brain and Spinal Cord

Nerves throughout the body that carry input to/from the brain and spinal cord

Carries information from sense organs to Central Nervous System

Sends information from central nervous system to muscles and glands

Carries information to skeletal muscles

Carries information to glands, cardiac muscles, and smooth muscle

fight or flight in autonomic nervous system

Rest and digest in autonomic nervous system

Excitable, conduct electrical signals, communicate with other neurons through chemical means, and typically has cell body (soma), dendrites, axon

Not usually excitable, maintains homeostasis, support neurons, and form myelin.

Includes nucleus and most other organelles; integrates all incoming info

Receive signals from other neurons or environments

Conducts electrical signal

Releases chemical signal (neurotransmitter) to communicate with other neurons, muscles, or glands

Protect neurons by scavenging infections agents, damaged neurons, etc

Anchor neurons to their blood supply; scavenge excess ions; recycle neurotransmitters; convert glucose to lactate to feed neurons

Wrap around axons to form myelin

Line ventricles of brain and produce cerebospinal fluid

• Uneven distribution of ions across plasma membrane because of phospholipid bilayer
• Membrane potential is usually around -70 mV (compared to ~1.5 V in AAA battery); negative indicates that the inside of the cell has more negative charge that the extracellular fluid

• Some ions can leak across the membrane through channels
• But the Na+/K+ pump pumps Na+ back out and K* back in

• Neurotransmitter binds to Na+ channel and opens it
• This might take membrane from -70 mV to -50 mV

• When the voltage changes, it can spread to axon and trigger action potential (conduction of electrical signal down axon)
• The action potential is merely a sequence of the opening and closing of several types of ion channels that repeats down the axon

Where the action potential begins

Oligodendrocytes in CNS and Schwann cells in PNS wrap around dendrite to insulate them

• Myelin allows action potential to travel faster
• Loss of myelin causes one of several diseases (including multiple sclerosis)

Released by motor neurons

• Glutamate: excitatory neurotransmitter
• GABA: inhibitory neurotransmitter

• Dopamine: reward, movement
• Norepinephrine: attention, sympathetic NS
• Serotonin: mood, apetite, sleep, memory, intestinal contractions

• Substance P: Pain
• Endorphins: analgesia and addiction
• Neuropeptide Y: hunger

Some activated receptors (like glutamate receptors) bring membrane potential closer to action potential threshold (called depolarization of excitatory postsynaptic potential)

Some activated receptors (like GABA receptors bring membrane potential farther from action potential threshold (called hyperpolarization or inhibitory postsynaptic potential)

Epilepsy, traumatic brain injury, huntington's disease, AIDS dementia complex, neuropathic pain, parkinson's disease, ALS, Rett syndrome, Alzheimer's, Tourettes, drug addictions, multiple sclerosis, depression, glaucoma

Parkinson's, Depression, anxiety, obesity, anorexia, bulimia, chronic pain, migraines, ADHD, restless leg syndrome, alzheimer's

• Some diffuses away from synapse
• Some are broken down by enzymes in synapse (MAO, COMT)
• Some taken back up into presynaptic cell to be recycled

In reality, most neurons receive input from tons of presynaptic neurons