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

2. The Nervous System Central Peripheral Autonomic SympatheticParasympathetic Somatic

3. Central v. Peripheral Central contains brain & spinal cord –In a computer, this is your central processing unit (CPU) Peripheral – sensory & motor neurons that transmit messages between brain and muscles & glands –In a computer, this includes your keyboard, mouse, CD-ROM, printer, etc.

4. Autonomic v. Somatic Somatic – voluntary - controls purposeful body movements, movements for balance & posture –Consciously perceived sensations Autonomic – involuntary – automatic activities such as heartbeat, respiration, digestion, dilation of pupils, etc. –Some can be under conscious control (i.e. respiration) –Smooth & cardiac muscle, some glands

5. 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

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

8. 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

9. Myelin: fatty substance that speeds up transmission of impulse Terminal buttons: bulb-shaped structure at end of axon

11. Types of Neurons Afferent (sensory) neurons: send messages from sensory receptors to the spinal cord & brain Efferent (motor) neurons: relay messages from brain & spinal cord to muscles & glands Interneurons: transmits neural stimulus between sensory & motor neurons

12. 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

13. Neural Networks Clusters of neurons that form a network of cells The learn together as a team

14. Today’s Goal  You will be able to…. Describe how a neural impulse is generated and how neurons communicate in the brain and throughout the body.

15. 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

17. Neural Impulse: electrochemical firing of a nerve cell Resting potential: electric potential when neuron not firing (-70 millivolts) Depolarization: neuron reduces resting potential by becoming positively charged Action Potential: neuron fires when it reaches +30-40 millivolts

18. Repolarization: internal charge becomes more negative Refractory period: phase after firing an impulse, neuron will not fire All-or-none principle: neuron will fire or not fire, no in-between Threshold: level of stimulation required to trigger a neural impulse (excitatory – inhibitory = threshold)

19. Resting potential

20. 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

21. Neurotransmitters Excitatory NT: increases the likelihood that postsynaptic neuron will fire Inhibitory NT: decreases likelihood that postsynaptic neuron will fire

22. Neurotransmitters Acetylcholine (ACh) Function: Muscle contractions, learning, memory EXCITATORY (sometimes inhibitory) Malfunctions: Alzheimer’s Disease

23. Dopamine (DA) Function: Voluntary movement, sensations of pleasure & reward Malfunctions: Too little  Parkinson’s, Too much --> Schizophrenia Agonists  cocaine & amphetamines Antagonists  Ritalin, alcohol Neurotransmitters

24. Serotonin Function: Mood, appetite, sleep, impulsivity, concentration Malfunctions: Depression, Eating Disorders Agonists  LSD, Prozac Neurotransmitters

25. Norepinephrine Function: Alertness, arousal, mood, heart rate/appetite Inhibitory & excitatory Malfunctions: Depression Agonists  Cocaine, amphetamines Neurotransmitters

26. GABA (most prevalent inhibitory NT) Function: Decrease anxiety, sleep, reduce seizures Malfunctions: Anxiety disorders, tremors, insomnia Glutamate (main excitatory NT) Function: Memory & learning Malfunctions: Migraines, seizures, addictions Endorphins Function: Pain control Malfunctions: None