1. The Nervous System

2. 4 Functions of the Nervous System
Gathers information both from the outside world and from inside the body.
Transmits the information to the processing area of the brain and spinal cord.
Processes the information to determine the best response. 
Sends information to muscles, glands, and organs (effectors) so they can respond correctly. 

3. The Central Nervous System (CNS)
consists of the Brain and the Spinal Cord
the Spinal Cord carries messages from the body to the Brain where they are analyzed and interpreted
response messages are then passed from the Brain through the Spinal Cord and to the rest of the Body.

4. The Peripheral Nervous System (PNS)
consists of the neurons NOT Included in the Brain and Spinal Cord
Afferent Neurons Collect Information from the Body and Transmit it TOWARD the CNS. 
Efferent Neurons Transmit Information AWAY from the CNS. 

5. The Somatic Nervous System
regulates activities that ARE UNDER CONSCIOUS CONTROL, movement of skeletal muscles.
many nerves within this system are part of reflexes and can act automatically.

6. The Autonomic Nervous System
regulates involuntary activities
are not under conscious control
is responsible for maintaining homeostasis in the functioning of organs
EXAMPLES:  heart beat, digestion, breathing

7. Sympathetic Nervous System
generally ACTIVATES ORGANS or SPEEDS UP

8. Parasympathetic Nervous System
generally RETARDS ORGANS or SLOWS DOWN
Most organs are under control of both Sympathetic and Parasympathetic Neurons.

9. The Neuron

10. The Cell Body contains the nucleus and much of the cytoplasm
responsible for most of the metabolic activity of the cell, including the generation of ATP and synthesis of protein

11. Dendrites short branch extensions spreading out from the cell body
dendrites receive STIMULI and carry IMPULSES from the environment or from other neurons and carry them TOWARD the cell body.

12. AXON long fiber that carries impulses AWAY from the cell body
each neuron has only ONE AXON
ends in a series of small swellings called AXON TERMINALS
Axons of most Neurons are covered with a Lipid Layer known as the MYELIN SHEATH.

13. The Myelin Sheath
both Insulates and Speeds Up transmission of Action Potentials through the Axon
In the PNS, is produced by SCHWANN CELLS, which surround the Axon
GAPS in the Myelin Sheath along the length of the Axon are known as the NODES OF RANVIER

14. Characteristics of Neurons
Nervous messages are called impulses. 
A Neuron carries impulses in only ONE direction
Impulses are in the from of electric signals

15. Interneurons, Efferent or Motor Neurons, Afferent or Sensory Neurons
Types of Neurons
Interneurons, Efferent or Motor Neurons, Afferent or Sensory Neurons

16. Afferent Neurons (Sensory)
carry impulses from the SENSE ORGANS to the Brain and Spinal Cord
detect external or internal changes and send the information to the Central Nervous System by way of the Afferent Neurons

17. Efferent Neurons (Motor)
carry impulses from the Brain and Spinal Cord to MUSCLES or GLANDS
in response to impulses, Muscles Contract and Glands Secrete

18. Interneurons
Connect Sensory and Motor neurons and carry impulses between them 
are found entirely within the Central Nervous System