111

How is the Nervous System Organized?

Chapter 3-Neuroscience: The Brain and Behavior

2

Class Objectives:

Identify and define the structures of the neuron

Identify and discuss the role of neurotransmitters on behavior

3

The Neuron

The neuron is the basic building block of the nervous system

‐ They are often grouped in bundles called nerves.

4

5

6

4 parts of the neuron

1. Dendrites are specialized to receive signals from neighboring neurons and carry them back to the cell body

Thin, bushy-like structures that receive information from outside the neuron

‐ Relays the information into the cell body

7

The Neuron

2. The Cell body contains the cell nucleus

The cell body relays the information down to the axon

8

The structure of a neuron3. Axon: A thin, long structure that

transmits signals from the cell body to the axon terminal.

4. Axon Terminal is the last step for the relay of information inside the neuron.

9

The cell body is covered

with Axon

Terminals

101010

Once the information hits the terminal, it is

transmitted outside the cell by

neurotransmitters, which reside in the axon

terminal.

111111

-Electrical Communication-Chemical Communication

How do Neurons Communicate?

12

13

The Electrical Part

Action potential is an electrical current sent down the axon.

The activity within the neurons is electrical. This current causes the neuron to “fire”

‐ This is an “all-or-none” process

14

Action potentials travel down the axon like a wave of energy

15

Synaptic transmission

The Synapse is the space between neurons‐ The synaptic gap or cleft

• Information must be transmitted across the synapse to other neurons via the neurotransmitters.

• This is an electrochemical process

16

Let’s Review!

171717

Now, Let’s DANCE!

Time to do the Neuron Dance

18

Presynaptic Neuron

________________________

__________

________

________

____________

19

Neurotransmitters

Neurotransmitters are chemical substances that reside in the axon terminals

• They communicate to other neurons by binding to receptors on neighboring neurons

20

Chemical Communication

The communication between neurons is chemical

Neurotransmitter are either neutralized by an enzyme or taken back up by the neuron that released it in reuptake.

‐ At least 50 different types of neurotransmitters have been identified

21

Chemical Communication

22

Synaptic Transmission

The neurotransmitters are released from the vesicles and then attach to receptors located on the postsynaptic neuron.

These neurotransmitters are in contact with the dendrite of the postsynaptic neuron only briefly.

‐ The chemical is almost immediately destroyed or reabsorbed

23

Neurotransmitters

At least 50 different types of neurotransmitters have been identified

‐ Acetylcholine‐ GABA‐ Serotonin‐ Dopamine‐ Norepinephrine‐ Endorphins

24

Acetylcholine

Activates motor neurons controlling skeletal muscles

Contributes to the regulation of attention, arousal and memory

25

Examples of Neurotransmitters

Gamma-aminobutyric acid (GABA) is involved in experiences of anxiety, alcohol abuse, seizure disorders, and sleep disorders

Serotonin is involved in sleep and mood regulation and appetite (appetite for carbohydrates)

26

Dopamine

Involved in movement, thought processes, emotion, feelings of reward and pleasure

Implicated in schizophrenia, attention deficit disorder, and drug abuse

27

Norepinephrine

Involved in arousal reactions (increasing heart rate, respiration, sweating, and dilation of pupils)

May also be involved in hunger, eating, and sexual activity

282828

How do drugs effect behavior?

29

Drugs Impact on the Brain

Common drugs can alter the amount of a neurotransmitter released at the synapses

Some drugs can mimic/facilitate the action of the neurotransmitters while others can block the action of the neurotransmitter.

30

Agonists versus Antagonists

Agonists mimic or facilitate the actions of a neurotransmitter

Antagonists oppose/block the actions of a neurotransmitter

AntagonistAgonist

31

Next Class…

The BrainHow do the neurons work together?‐ The Central Nervous System‐ The Peripheral Nervous System