1. Nervous System

2. Nervous System
Purpose: The Nervous System controls and coordinates functions throughout the body and responds to internal and external stimuli

3. Parts of the Nervous System
Central Nervous System:
Brain and Spinal Cord
Peripheral Nervous System: The rest of the nerves in the body

4. How do they work together?
Peripheral nerves connect the central nervous system to the rest of the body

5. Central Nervous System
Consists of the brain and spinal cord
Relays messages, processes and analyzes information

6. The Brain
Cerebrum - largest part of the brain. Thinking, language, motor function, touch
Cerebellum - “little brain”. Controls coordination, balance, movement.
Thalamus - located just above brain stem. Motor function,
sensory perception
Hypothalamus - size of pearl. Controls autonomic and endocrine function, food and water intake

7. Peripheral Nervous System
Consists of all of the nerves that are not a part of the brain or spinal cord
Includes sensory and motor nerves

8. Peripheral Nervous System
Somatic Nervous Sys:
Controls voluntary movement of skeletal muscle
Autonomic Nervous Sys:
Controls involuntary movement such as respiration and heart beat

9. Cells of the Nervous System
The cells that carry the messages throughout the nervous system are called neurons

10. Parts of a Neuron

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12. Parts of a Neuron - Dendrites
Branched projections of a neuron that receives signals from other neurons. Sends signals to the cell body.

13. Parts of a Neuron - Cell Body
The cell body contains the nucleus and other organelles. Dendrites branch off of the cell body.

14. Parts of a Neuron - Axon
The axon is a long, projection of the neuron that conducts the electrical impulse away from the cell body

15. Parts of a Neuron - Myelin Sheath
Myelin forms a layer around the axon and functions to increase the speed of electrical impulses along axon

16. Parts of a Neuron - Schwann Cells
Schwann cells form myelin, which help conduct nerve impulses along the axon

17. Parts of a Neuron - Nodes of Ranvier
Nodes of Ranvier are gaps between the myelin sheaths. Electrical impulses jump from node to node, which helps to increase the speed of conduction.

18. Parts of a Neuron - Axon Terminals
Axon terminals are the end branches of a neuron. Chemicals called neurotransmitters are transferred from one neuron to the next at the axon terminals.

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20. How does the electrical signal travel along the axon?
YouTube The Schwann Cell and Action Potential
Action Potential

21. Action Potential
Neuron is stimulated by another neuron or by the environment.
Positively charged sodium ions flood in and the inside becomes temporarily more positive.
As the impulse passes, potassium ions flood out restoring the resting potential.

22. What happens when the impulse reaches the end of the neuron?
The axon terminal ends at the synapse

23. Synapse
A structure that permits a neuron to pass a electo-chemical signal to an adjacent neuron.

24. What happens at the Synapse?
The electrical activity is converted into the release of a chemical (neurotransmitter), which binds to receptors

25. Propagation of the Nerve Impulse1 2 3
Dendrites Cell Body Axon (Action Potential)
Axon
Terminal 4 7 6 5
Receptor Neurotransmitter Synapse

26. YouTube Nerve Impulse Animation

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28. 3 Types of Neurons
Sensory
Interneuron
Motor

29. Sensory Neuron
Sensory neurons carry impulses from the senses to the brain and spinal cord

30. Interneuron
Interneurons connect sensory and motor neurons and carry impulses between them

31. Motor Neuron
Motor neurons carry impulses from the brain and spinal cord to muscles and glands

32. An involuntary and instantaneous movement in response to a stimulus
Examples: Blinking, Knee-jerk reflex, Shivering, Sneeze, Yawn, Cough

33. Reflex Arc Stimulus to sensory neuron to interneuron to motor neuron
Occurs quickly by activating spinal motor neurons without going through the brain

34. YouTube Video
Reflex Arc

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