The Nervous System

Biology and BehaviorThe Nervous System is our bodies “Blueprint”:

– It gathers & processes information– Responds to stimuli– Coordinates the workings of different cells– Regulates our internal functions

Nervous System is involved in psychological processes such as: - thought - movement - emotion - sensation

Nervous System: The Building Blocks• Neurons (nerve cells) are the

basic units of the nervous system• Location They run throughout

our whole body!• Purpose communicate with one

another by sending & receiving messages from the structures of our body

Held in place & fed by Glial Cells: - provide nutrition, support, & insulation to neurons

Nervous System: The Building Blocks

• Types of Neurons:– Motor send information

onward to control muscles– Sensory bring senses in

from other senses– Associative provide links

between neurons

Structure of a Neuron

• Cell Body (Soma): directs actions of the cell• Nucleus: contains genetic material for the cell• Dendrites: enables neuron to receive information• Axon: carry electrical signals (messages) out of the cells, sends a

chemical message to adjacent neurons via Axon/Terminals• Myelin: insulates & protects Axons w/a fatty substance

Nervous System: Communication

• The Process of Communication:– In order for message to be sent from

one neuron to another… must cross a Synapse

junction between dendrites via Axon Terminals (where communication takes place)

• Neurons send messages across synapses (junctions) by releasing… Neurotransmitters chemicals

stored in sacs in the axon terminals (look like “buttons”)

Nervous System: Communication

Types:

Fives Main Types of Neurotransmitters:

Nervous System: Communication

Serotonin – affects mood, sleep, sensory perception, and other functions, may play a role in psychological disorders like depression

Acetylcholine – involved in memory, muscle action, sleep, emotions, those w/ Alzheimer’s have lower levels

Dopamine – affects movement, attention, memory, learning, plays role in addiction

Norepinephrine – affects learning, memory, emotions, eating, alertness, etc.

Epinephrine – emotions, memory storage

Neurons are Communicating

Nervous System: Two Main Parts

Nervous System: Two Main Parts

Part 1: Central Nervous System– Consist of brain & spinal cord– Function receives, processes,

interprets, and stores sensory information

Responsible for Spinal Reflexes: - automatic & require no conscious effort - Ex: touch something hot and immediately remove hand

Nervous System: Two Main PartsPart II: Peripheral Nervous System– Consist of all parts of the nervous system

outside the brain and spinal cord– Function handles the central nervous system’s input & output

Sensory Nerves: - carry messages from receptors to brain

Motor Nerves: - carry messages from CNS to muscles, glands, and internal organs PNS has two branches……

Somatic Nervous System– Controls skeletal muscles– Permits voluntary actions

Autonomic Nervous System– Regulates body’s vital functions

(blood vessels, internal organs)– Permits self-regulating actions– Has two divisions:

Parasympathetic System: - calms & relaxes the body - Ex: Feel sick to your stomach

Sympathetic System: - mobilizes body for action - increases energy output - Ex: Fight or Flight