1. THE NERVOUS SYSTEM

2. Learning Outcomes C11 – analyse the transmission of nerve impulses
Describe the structure of a neuron
Identify the function of dendrite, axon, cell body, axoplasm, axomembrane
Differentiate between sensory, motor and interneurons

3. Consists of the brain, spinal cord and nerves throughout the body

4. Central Nervous System
CNS consists of the brain and spinal cord

5. Peripheral Nervous System
PNS consists of nerves throughout the body
Carries messages to and from the CNS

6. Neurons
Neurons are nerve cells
Neurons have 3 main parts

8. Cell body contains the nucleus and organelles
Axon transmits an impulse away from the cell body to the next cell
Dendrite receives an impulse and transmits it to the cell body

9. Axoplasm refers to the cytoplasm within the axon
Axomembrane refers to the plasma membrane of the axon

10. Long axons are covered in a myelin sheath
Nodes of Ranvier are intermittent gaps in the sheath

11. Schwann cells wrapped around the axon contain myelin (a specialized phospholipid) in their plasma membranes

12. Types of Neurons
Sensory neurons carry impulses from sensory receptors to the CNS
Have long dendrites
Motor neurons carry impulses from the CNS to an effector (muscle or gland)
Have long axons
Interneurons connect other neurons to the CNS

13. Fig. 17.2

14. Transmission of Nerve Impulses
Nerve impulses travel along neurons by means of electrochemical changes in the neuron membranes
The space between neurons is called the synapse
Neurotransmitters carry impulses across the synapse