1. Bio 12 NEURONS

2. Joke of the day: Wouldn’t that be great!

3. Review: Neuron  Neurons: cells that conduct nerve impulses. They function electrically to create thought and action in our bodies  Three types of neurons: 1.Sensory neurons 2.Interneurons 3.Motor neurons

4. Parts of a neuron:  Label diagram together

5. Parts of a neuron: 1.Cell body  controls the metabolism and growth of the cell  contains the nucleus. 2.Dendrites  projections of cytoplasm which receive electrochemical messages from the axons of other nerve cells. They conduct impulses towards the cell body.

6. 3.Axon  extension of the cytoplasm which carries nerve impulses away from the cell body towards other neurons, glands or muscles (away from the cell body)  the end of the axon is subdivided into many filaments, forming the end brush  transmit impulses away from the cell body Parts of a neuron:

7. Parts of a neuron cont’d: 4.Myelin sheath:  this is the extra covering along the axon of a neuron because they require the insulation to work properly.  it is a glistening white coat of a fatty protein which also provides nourishment to the axon.  Axons that have a myelin sheath are said to be myelinated. 5.Schwann cells:  these are special Glial cells that surround the axon and form the myelin sheath.

8. 6.Nodes (Nodes of Ranvier):  the areas between the sections of myelin sheath along an axon.  nerve impulses jump from one node to another which speeds up the movement of the nerve impulses. Parts of a neuron:

9. Message flow in a nerve cell: DendritesCell bodyaxon dendrites etc of next neuron effector (muscle or gland)

10.  There is a microscopic gap between the terminal end of the axon and the membrane of another neuron or effector cell.  Nerve impulses must cross this gap as part of the transmission of the impulse.  The synapse must be bridged by a chemical called a neurotransmitter. SYNAPSE

11.  Reflexes are involuntary and often unconscious, they are fast because they do not go through the brain.  The reflex arc is the simplest nerve pathway, which occurs without brain coordination. REFLEX ARC

12.  Synapse: http://www.youtube.com/watch?v=FR4S1BqdFG4  Arc Reflex: http://www.youtube.com/watch?v=wLrhYzdbbpE http://www.youtube.com/watch?v=wK3VUQTRIBg VIDEO CLIPS

13.  Arc Reflex WS  Page 417  Questions 1-5  Arc Reflex Lab Activity TO DO: