1. Nervous System
NERVOUS SYSTEM

2. Background and Development

3. Neuron Cell of the nervous system
Structural and functional unit of nervous system
React to physical and chemical changes in surroundings

4. Nerve impulse
Transmission of information by electrochemical changes

5. Nerve Fibers
Highways for impulses to travel

6. Central Nervous system (CNS)
Brain and spinal cord

7. Peripheral nervous system (PNS)
Made of the nerves that connect the CNS to other body parts

8. Draw a neuron Draw and label a neuron in your notes Regular: p. 216
Honors: p. 359

9. Parts of a neuron
Cell Body- contains the nucleus, cytoplasm, cell membrane, mitochondria, and other organelles

10. Parts of a neuron Dendrite- type of branched nerve fiber
The “fingers” of the neuron, or main receptor sites

11. Parts of a neuron
Axon- nerve fiber that conducts impulses away from the cell body

12. Parts of a Neuron Axon Terminal-
The “end” of one neuron, a connection is made with another neuron

13. Model it!- Neuron Dance

14. Parts of a neuron
Myelin sheath (Schwann cells)- cells wrapped around the axon like a bandage
Nodes of Ranvier- narrow gaps in the myelin sheath

15. Grey vs. White Matter Grey matter- unmyelinated nerve tissue
Appears grey, slower transmission of nerve impulses
White matter- Myelinated nerve tissue
- Appears white, faster transmission of nerve impulses

16. Lets Practice!
The Myelin Race

17. Example Drawing Regular: p. 228 or p. 229 Honors: p. 394 or p.395
Draw and label with: stimulus, receptor, sensory neuron, interneuron, motor neuron, effector, and response

18. Reflex arc

20. Testing Reflexes Reflex investigation
Create this data table in your notes:
Reflex Test
Receptor site
Response
Knee-jerk
Middle finger
Babinski
Other tendon
Pupillary

21. Other Reflexes Stimulus Response The aroma of your favorite food
Salivation
A nasty odor
Nausea
A bright light shining in your eye
Pupils get smaller
An insect flying towards your eye
Blinking

22. Types of Receptors
Chemoreceptors- sensitive to chemical concentrations
Pain Receptors- sensitive to tissue damage
Thermoreceptors- sensitive to temperature
Mechanoreceptors- changes in pressure or movement
Photoreceptors- light energy

23. Testing Mechanoreceptors
Homunculus Man

24. Key Chemical Players
Potassium (K+): pass through cell membranes more easily than sodium
Sodium (Na+)
Calcium (Ca2+)

25. Cell membrane potential
The surface of a cell (the cell membrane) is usually electrically charged
Has pumps to keep chemicals in balance (sodium/potassium pumps)
Outside cell: Overall more +
Cell membrane (bilayer)
Inside cell membrane: overall more -
Inside cell: overall more +

26. Resting potential
When the cell membrane is undisturbed there is a difference in electrical charge
More sodium is outside than potassium
More potassium inside than out
More Na+ = ( +)
Cell membrane
More K+ = ( -)

27. Steps of action potential
1) threshold reached (stimulated)
2) Channels open for sodium to rush in (they are attracted to the negative inside)
3) membrane becomes depolarized, or looses its negative charge
4) Channels open for potassium to flow out of the membrane
5) membrane becomes repolarized, or is negative again

28. Parts of the brain

29. Exit Ticket
With someone near you, discuss the importance of having reflexes in the body.
Write a one paragraph summary of your conversation. Why are reflexes important?