1. Neurons & the Nervous System
Chapter 2: The Brain and Behavior

2. Today’s Goal  You will be able to….
Identify the parts of a neuron and their functions in creating & sending neural messages.

4. Parts of the Neuron Neurons: nerve cells
Dendrites: branch-like end of neuron which receives messages
Cell body (soma): contains nucleus
Axon: long tail-like end of neuron which transmits (sends) messages

5. Myelin: fatty substance that speeds up transmission of impulse
Axon terminals/Terminal buttons: contain neurotransmitters, release them during neural impulse
Terminal buttons (axon terminal): bulb-shaped structure at end of axon

6. Types of Neurons
Sensory neurons: send messages from sensory receptors to the spinal cord & brain
Motor neurons: relay messages from brain & spinal cord to muscles & glands
Interneurons: transmits neural stimulus between sensory & motor neurons (found only in Central nervous system)

7. Simple Reflex Arc
Communication goes directly from interneurons in spinal cord to motor neurons to move (reflexively) at the same time the info is going to the brain to be perceived

8. The Nervous System
Central
Peripheral
Autonomic
Sympathetic
Parasympathetic
Somatic

9. Central v. Peripheral Central contains brain & spinal cord
Peripheral – sensory & motor neurons that transmit messages between brain and muscles & glands

10. Autonomic v. Somatic
Somatic – voluntary - controls purposeful body movements
Autonomic – involuntary – automatic activities
heartbeat, respiration, digestion, dilation of pupils, etc.

11. Sympathetic v. Parasympathetic
Sympathetic = “Fight-or-flight” response
Uses energy reserves to cope with stress or emergency
Adrenaline!
Parasympathetic = “Rest and digest”
Conserves & builds up stored energy reserves

13. Today’s Goal  You will be able to….
Describe how neurons communicate to send messages in the brain and body

14. The Synapse
Synapse (synaptic cleft): gap between dendrites of one neuron and axon of another
Receptor sites: parts of dendrite which receive neurotransmitters
Neurotransmitters: chemical substances involved in sending neural impulses

16. Neural Impulse: electrochemical firing of a nerve cell
Resting potential: electric potential when neuron not firing (-70 millivolts)
Threshold: level of stimulation required to trigger a neural impulse (excitatory – inhibitory = threshold)

17. Neural Impulse: electrochemical firing of a nerve cell
Action potential: when a neuron fires the impulse (sends the message)
Refractory period: phase after firing an impulse, neuron will not fire
All-or-none principle: neuron will fire or not fire, no in-between

18. Resting potential

19. Synapses
Excitatory neurotransmission: increases the likelihood that postsynaptic neuron will fire
Inhibitory neurotransmission: decreases likelihood that postsynaptic neuron will fire

20. Today’s Goal  You will be able to…
Discuss how the major neurotransmitters affect the body and one’s behavior

21. Substances that Affect Neurotransmitters
Agonist: similar to the NT, mimics its effects
Antagonist: inhibits the release of NT by sending neuron, or blocks receptor site for NT on receiving neuron

22. Neurotransmitters Acetylcholine (ACh)
EXCITATORY (sometimes inhibitory)
Memory, muscle contractions, learning
Malfunctions: Alzheimer’s Disease

23. Neurotransmitters Serotonin Dopamine (DA)
Reward/pleasure, movement, attention
Malfunctions: Too little  Parkinson’s, Too much  Schizophrenia
Serotonin
Mood regulation, sleep and appetite regulation, concentration, learning
Imbalance  depression

24. Neurotransmitters Norepinephrine
Involved in autonomic nervous system (sympathetic) arousal
Imbalances: Depression, seizures
GABA
Function: Reduce anxiety, relax for sleep
Imbalance: Anxiety disorders, tremors, insomnia
Endorphins  pain control