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( c ) Function of converging, diverging and reverberating pathways

KA 3: The cells of the nervous system and neurotransmitters at synapses. ( a ) Structure and function of neurones. (e) Action of recreational drugs. Key Area 3: Neurones & Neurotransmitters. (b) Neurotransmitters at synapses. ( d ) Neurotransmitters, moods and behaviour.

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( c ) Function of converging, diverging and reverberating pathways

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  1. KA 3: The cells of the nervous system and neurotransmitters at synapses (a) Structure and function of neurones (e) Action of recreational drugs Key Area 3: Neurones & Neurotransmitters (b) Neurotransmitters at synapses (d) Neurotransmitters, moods and behaviour (c) Function of converging, diverging and reverberating pathways

  2. Key Area 3(a) Structure and function of neurones • Be able to identify the following structures in a diagram: • Dendrites • Cell body • Axons • Myelin sheath • State the function of the above structures • State what is what meant by myelination • State the difference in impulse conduction between 2 year olds and adolescents and adults • Describe and explain the effects of destroyed myelin sheaths • State 4 functions of glial cells

  3. NERVE FIBRE (Axon)‏ CELL BODY Revision of Neurones • Our nervous system is made of nerve cells called neurones • Consist of a cell body attached to very long nerve fibre • Electrical impulses carry messages along neurones.

  4. Neurones • There are 3 types of neurones; • Sensory neurones • Inter neurones • Motor Neurones • These neurones allow an electrical impulse to pass along them resulting in a reflex action.

  5. These cells provide the body with a means of rapid communication. • Although they appear very different they all have the same basic structure.

  6. Node Node Direction of Impulse DendritesCell Body Axon

  7. Myelination Young kids (particularly toddlers) are usually very uncoordinated. Why do you think this is?

  8. Myelination • Myelination is the development of myelin around the axon. • This process continues from birth until adolescence. Consequently the speed of impulse conduction in younger children is slower than in older children. • As a result children under 2 are not as coordinated and cannot respond to external stimuli as rapidly as older children.

  9. Glial Cells • Neurones only account for around 50% of the cells in your nervous system • The rest are called Glial cells • They carry out various roles and your nervous system could not function without them! The Nervous System, Part 1: Crash Course A&P #8 – Up to 5:24

  10. Glial Cells

  11. Glial Cells • Glial cells account for around 50% of the cells found in the nervous system and physically support the neurones by carrying out various functions. • Their functions include: • producing the myelin sheath • maintaining a homeostatic (ideal) environmentaround the neurones • removing debris by phagocytosis

  12. Diseases of the Nervous System • Some diseases destroy the myelin sheath causing a loss of coordination. • For example: • Polio • Tay-Sachs disease

  13. Multiple Sclerosis • If someone suffers from MS then their own immune system is damaging the myelin sheaths around axons. • This can result in a lose of coordination • https://www.youtube.com/watch?v=VIoDr8ugbqI (2.11)

  14. Diseases of the Nervous System • Some diseases destroy the myelin sheath causing a loss of coordination. • For example: • Polio • Multiple sclerosis • Tay-Sachs diseases

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