1. Intro to the Nervous System
Intro to the Nervous System-Crash Course- Resources page

2. Neurons
Neurons are nerve cells that transfer information within the body
Neurons use two types of signals to communicate: electrical signals (long-distance) and chemical signals (short-distance)

3. Neuron Structure and Function
Most of a neuron’s organelles are in the cell body
Most neurons have dendrites, highly branched extensions that receive signals from other neurons
The axon is typically a much longer extension that transmits signals to other cells at synapses
The cone-shaped base of an axon is called the axon hillock
Most neurons are nourished or insulated by cells called glia

4. Processing Information
Processing of information takes place in simple clusters of neurons called ganglia or a more complex organization of neurons called a brain
Nervous systems process information in three stages: sensory input, integration, and motor output

5. The Nervous System
Many animals have a complex nervous system that consists of
A central nervous system (CNS) where integration takes place; this includes the brain and a nerve cord
A peripheral nervous system (PNS), which carries information into and out of the CNS
The neurons of the PNS, when bundled together, form nerves

6. Central Nervous System (CNS)
In vertebrates
The CNS is composed of the brain and spinal cord
The peripheral nervous system (PNS) is composed of nerves and ganglia
Invertebrates usually have a ventral nerve cord while vertebrates have a dorsal spinal cord
The spinal cord and brain develop from the embryonic nerve cord
The nerve cord gives rise to the central canal and ventricles of the brain

7. Central Nervous System
The spinal cord conveys information from and to the brain
The spinal cord also produces reflexes independently of the brain
A reflex is the body’s automatic response to a stimulus

8. Peripheral Nervous System (PNS)
The PNS transmits information to and from the CNS and regulates movement and the internal environment
In the PNS, afferent neurons transmit information to the CNS and efferent neurons transmit information away from the CNS

9. Peripheral Nervous System
The PNS has two efferent components: the motor system and the autonomic nervous system
The motor system carries signals to skeletal muscles and is voluntary
The autonomic nervous system regulates smooth and cardiac muscles and is generally involuntary

10. Autonomic System
The sympathetic division regulates arousal and energy generation (“fight-or-flight” response)
The parasympathetic division has effects on target organs and promotes calming and a return to “rest and digest” functions
The enteric division controls activity of the digestive tract, pancreas, and gallbladder

12. Nervous Systems in Animals
Nervous system organization usually correlates with lifestyle
Sessile molluscs (for example, clams and chitons) have simple systems, whereas more complex molluscs (for example, octopuses and squids) have more sophisticated systems

13. Nervous Systems in Animals
The simplest animals with nervous systems, the cnidarians, have neurons arranged in nerve nets
A nerve net is a series of interconnected nerve cells
More complex animals have nerves

14. Neurons Video
How Neurons Work- Bioflix- Resources Page

15. Neuron Activity