Bio 12

NEUR

ONS

Joke of the day:

Wouldn’t that be great!

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 neurons2. Interneurons3. Motor neurons

Parts of a neuron:Label diagram together

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.

3. Axonextension 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:

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.

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:

Message flow in a nerve cell:

Dendrites Cell body axon

dendrites etc of next neuron

effector (muscle or gland)

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

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

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

Arc Reflex WSPage 417

Questions 1-5

Arc Reflex Lab Activity

TO DO: