True or False?

1. True or False? We only use about 10% of our brains

3. False We use 100% of our brains

4. 100 billion 900 billion

7. IV. Biological Bases of Behavior 8 – 10 % Neuroanatomy Functional Organization of Nervous System Neural Transmission Endocrine System Genetics Evolutionary Psychology

9. Nucleus Dendrites Cell Body (Soma) Myelin Sheath End Bulb Enlarged Vesicles (storing Nts) End Bulb Neurotransmitters

10. End Bulbs at

11. http://outreach.mcb.harvard.edu/animations/synaptic.swf http://outreach.mcb.harvard.edu/animations/actionpotential.swf

12. The Neural Impulse – The Electrochemical transfer of information • Resting Potential – when no information is being exchanged the neuron is polarized: overall neg. charge inside / pos. charge outside of the axon

13. When stimulated the neuron’s axon becomes depolarized – Sodium (Na +) flows in, temporarily changing the charge (becomes more positive inside) at a point along the axon creating an action potential

15. The action potential fires down the length of the axon, sending energy to the terminal button • Behind the action potential the axon becomes polarized again

16. Action potentials follow the all-or-none law: it fires or it doesn’t – the energy is always the same • The strength of the stimulus depends on the rate of action potentials (faster rate = stronger feeling)

17. The action potential’s energy causes the release of neurotransmitters (chemical messengers) • The neurotransmitters cross the synapse, to possibly bind at receptor sites of the adjacent neuron, muscle fiber, or organ

18. http://www.sumanasinc.com/webcontent/animations/content/actionpotential.htmlhttp://www.sumanasinc.com/webcontent/animations/content/actionpotential.html http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter14/animation__the_nerve_impulse.html

20. Part II: Postsynaptic Potentials • After the release of the neurotransmitters they may attach to a receptor site of the adjacent neuron, muscle fiber, or organ creating a postsynaptic potential (PSP) – a change in voltage at the receptor site

22. PSP’s can be either excitatory or inhibitory • Excitatory – increases the chance of another action potential (at the adjacent neuron) by increasing the voltage • Inhibitory – decreases the chance by decreasing the voltage at the receptor site

24. PSP’s do NOT follow the all-or-none law! Excitatory and inhibitory PSP’s can cancel each other out • If there are enough excitatory PSP’s to reach the threshold another action potential is created (or the muscle/organ responds) • Inhibitory actions are important to slow down or stop processes in body and brain • Some neurotransmitters are returned to the terminal button for reuse – this is called reuptake.