1. A System for Communication & Regulation of Life Process
The Nervous System
A System for Communication & Regulation of Life Process

2. What Does the Nervous System Do?

3. It Helps Maintain Homeostasis

4. How?

5. It brings messages from one place to another.
By Using Special Cells

6. are the basic functional unit of the nervous system.
Neurons
(Nerve cells)
are the basic functional unit of the nervous system.

7. receive, conduct, and send impulses.
Neurons
receive, conduct, and send impulses.

8. A Typical Neuron Cyton Dendrite Terminal Bulbs Terminal Branches Axon

9. How Do Impulses Start?

10. They Need a Stimulus

11. Stimulus
(plural = stimuli)
a change in the external or internal environment that an organism responds to.

12. Light, Sound, Pressure, Cold, Hot, etc..
Examples
External
Light, Sound, Pressure, Cold, Hot, etc..

13. Chemicals Changes, Temperature Changes, etc...
Examples
Internal
Chemicals Changes, Temperature Changes, etc...

14. Different Types of Neurons next slide

15. Inter-neuron
Sensory Neuron
Motor neuron
???

16. Parts of the Neuron Explained

18. The Dendrite Dendrites
receive stimuli from sense organs or from other neurons in the form of a neurotransmitter.

19. Cell Body Cell Body conducts impulses from the dendrites toward
the axon

20. Axon Axon conducts impulses from the cyton toward the
terminal branches

21. Myelin Sheath
Myelin Sheath - an arrangement of cells around the axon. It helps protect the axon and speed up impulses.

22. Terminal Branches
Terminal Branches
a fork in the axon.

23. Synaptic Knobs Synaptic Knobs- Releases chemicals called
Neurotransmitters, which allow the message to be received by the next neuron, or a muscle, gland, organ etc…
Terminal (Synaptic) Knobs

24. Neurotransmitters
Impulse Direction
Neurotransmitters
Synapse

25. How Neurotransmitters Work
Neurotransmitters diffuse from the end of one neuron to receptors on the next
neuron. When they land on the specific receptor they allow gates to open that
allow sodium to enter - this ignites the electro-chemical impulse to begin in the
the next neuron.

26. Impulses

27. What are impulses?

28. The cell membrane of a neuron conducts electrical signals from on end to another - in one direction.

29. The inside of a neuron has an overall negative charge, and the outside has an overall positive charge.
Outside Neuron
Channels
Inside neuron

30. The outside of a neuron has sodium ions (Na+)
The outside of a neuron has sodium ions (Na+). The inside has negatively charged proteins.

31. Neither of these chemicals can pass through the cell membrane
Neither of these chemicals can pass through the cell membrane. They are attracted to each other because of their opposite charge.

32. There are many protein channels along the membrane where sodium (Na+) can enter, but only when the gate is open.
Stimuli cause the gates to open

33. The flow of charge (negatives or positives)across the membrane is electricity. This is why the impulse of a neuron is said to have an electrico-chemical nature.

34. Steps in making an impulse

35. Steps in making an impulse
A stimulus occurs
Either an external (sound, light, etc..) source or an internal source (such as a neurotransmitter).

36. Steps in making an impulse
Gates Open
This allows the sodium to enter the cell.

37. Steps in making an impulse
Adjacent Gates Open
The opening of one gate cause the next gate to open - like dominos

38. Steps in making an impulse
The Impulse Travels to the End of the Neuron

39. Steps in making an impulse
Neurotransmitters are released when the impulse reaches the Terminal Knobs

40. The Reflex Arc
A special pathway

41. The Advantage of a Reflex
The advantage of a reflex is that we can respond quickly to a stimulus.
A reflex pathway does not involve the brain which is an advantage because the reflex is quicker.

42. Pathway of a Reflex Stimulus Sensory Neuron Sensory Organ Interneuron
Effector
(Muscle or Gland)
Motor Neuron

43. Diseases of the Nervous System

44. Cerebral Palsy
Results from brain damage, usually at birth. It is a term used to describe a group of diseases that affect the ability to control movement.

45. Multiple Sclerosis (MS)
Results from damage to the Myelin Sheath.
Symptoms vary but may include: shaking, blurred vision, slurred speech, and weakness.

46. Parkinson’s Disease
Involves a particular group of brain cells in the brain.
Symptoms: Tremors, poor balance, stiffening of the muscles.
* The thinking functions is usually OK.

47. Alzheimer's Disease
Degenerative disease of the brain. The person usually loses the ability to remember, think correctly and speak.
The condition usually gets worse over time once it starts. It may take years to notice.

48. Notes
This slide presentation is a work in progress. Please feel free to notify the author of any mistakes or suggestion for improvement.