1. The Nervous System
Chapter 36

2. Basic Structure
Neurons
Composed of 3 parts
Cell body
Dendrites
Axon

4. DENDRITES
Branchlike extensions that receive impulses and carry them to the cell body

5. AXON
Single extension of neuron that carries impulses away from the cell body and toward other neurons, muscles, and glands

6. CELL BODY
Contains nucleus of nerve cell

7. How are neurons connected?
SYNAPSES!
Junction between neurons
Impulses must cross synaptic space to reach the brain and other destinations

8. What’s the Matter? White and Gray Matter
Axons are covered with a white substance called the MYELIN SHEATH
This white covering gives this part of the brain its “white” appearance.
The MYELIN SHEATH is formed from SCHWANN cells
SCHWANN cells insulate the axon and increase the speed of the impulse

9. WHITE MATTER

10. GRAY MATTER
Absence of myelin sheaths in neurons accounts for gray matter in the brain.

11. MOVEMENT OF A SIGNAL The “Electric Slide” in the body!
Neurons send electrical signals/impulses in the body!
Where is the signal going?
Sensory organs
Brain
Muscles

12. 3 Types of Neurons Sensory neurons Interneuron Motor neurons
carry signals from outside and inside the body to the brain and spinal cord
Interneuron
found in brain and spinal cord
process sensory impulses and send the message on the motor neuron
Motor neurons
carry impulses away from the brain and spinal cord

14. LOOK AT PICTURE ON NOTES
How do neurons work?
Reception-stimulus from outside is detected
Transmission-message is sent to brain
Interpretation-brain interprets message and formulates response
Transmission-message is sent to muscle
Response-muscle responds to stimulus
LOOK AT PICTURE ON NOTES

15. ANATOMY OF THE BRAIN CEREBRUM - 2 hemispheres
controls conscious activities, intelligence, memory, language, skeletal muscle movements, and senses
gray matter
surface area increased by folds (more surface area = greater intelligence)

16. ANATOMY OF THE BRAIN CEREBELLUM-located at back of brain
controls balance, posture, and coordination

17. ANATOMY OF THE BRAIN MEDULLA OBLONGATA - brain stem
controls involuntary activities (ex: breathing and heart rate)

18. CENTRAL VS PERIPHERAL Brain and spinal cord Control center Nerves
Outside informers
Somatic system
Autonomic system
Sympathetic system
Parasympathetic system

19. PERIPHERAL SOMATIC SYSTEM
-Relays info to and from skin, skeletal muscles, and CNS
-Voluntary
-Exceptions: reflexes are involuntary p. 981
AUTONOMIC SYSTEM
-Sympathetic
-Parasympathetic
-Relays info to and from internal organs and CNS
-Involuntary
SYMPATHETIC
-controls in times of stress
PARASYMPATHETIC
-controls when body is at rest

22. REFLEX ARC