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Presentation on theme: "THE NERVOUS SYSTEM."— Presentation transcript:


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

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