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11/02/14 5 th Year Biology

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Recall that the nervous system can be broken down into the Central Nervous System (CNS) & the Peripheral Nervous System (PNS) Explain what is meant by a Neuron Draw the structure of a motor neuron labelling all key structure and give their function. List the three types of Neurons.

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Just to start, work with your partner for two minutes and write down anything you already know about Nervous System!

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The Human nervous system is divided into two parts: 1. Central Nervous System (CNS) consisting of the brain and spinal cord. 2. Peripheral Nervous System (PNS) Consisting of nerves.

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A Nerve is a bundle of neurons connecting one part of the nervous system with another. Structure of a Neuron

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A Neuron is a nerve cell. Impulses (electrical messages) are carried along by neurons. Functions of Parts of Neuron: Cell body: Produces neurotransmitter chemicals. Axon: Conducts impulses away from cell body. Schwann cells: Produces the Myelin Sheath.

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Myelin Sheath: Insulates neurons from each other and speeds impulses. Dendron: is a short fibre that receives information and carries to the cell body. Dendrites: are small branches of a Dendron.

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Dendrites carry nerve impulses to the cell body where they are transported the Axon to the Neurotransmitter vesicles. Here they either cause a new impulse to start up or cause a muscle to move.

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1. Sensory Neuron(Afferent): These carry messages towards the CNS from receptors (stimuli). 2. Motor Neuron(Efferent): These carry messages away from the CNS to effectors (muscles). 3. Interneuron: These link sensory and motor neurons. 4. http://www.youtube.com/watch?v=cUGuWh 2UeMk http://www.youtube.com/watch?v=cUGuWh 2UeMk

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Recall that the nervous system can be broken down into the & the . Explain what is meant by a Neuron Draw the structure of a motor neuron labelling all key structure and give their function. List the three types of Neurons

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5 th Year Biology

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Draw the structure of a Neuron labelling all key structures and give their function Explain what is meant by a Synapse Draw a diagram explaining the transfer of a message at a Synapse Explain the transmission of impulses across a Synapse

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From last class what can we remember about the Nervous System? Work for 2 minutes with your partner and write down what you can remember.

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What kind of obstacles exist for the transmission of electrical messages along neurons? Think about the structure of a neuron!

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The area where two neurons come into close contact is called the Synapse. The gap between the neurons is called the Synaptic cleft.

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Neurotransmitters carry impulses across a synaptic cleft and trigger an impulse in the next neuron. Transmission of Impulses across a Synapse An impulse arrives at a Synapse and cannot cross. Synaptic Vesicles at the end of the exon secretes neurotransmitter substances into the cleft, transmitting the impulse to the next neuron. An enzyme breaks down the neurotransmitter and clears the synapse for the next transmission.

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1. They transmit messages from one neuron to another. 2. They control the direction of the impulses (vesicles) found on one side of the synapse only. 3. The impulse can be blocked by certain chemicals (drugs). This is important in controlling pain.

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Do some independent research where you research any Neurological disorder/disease Name the disorder/disease Give a detailed explanation of its cause Detailed description of the condition i.e. its symptoms, effects, where it occurs etc. Prevention Available treatments-explain them! You will have to explain/teach all of the above to the rest of the class next week!

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The human brain is divided into three sections. Forebrain: Cerebrum, Thalamus, Hypothalamus, Pituitary gland. Mid brain: Activates the forebrain, visual and auditory reflexes occur here. Hindbrain: Cerebellum, Medulla Oblongata.

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The brain and spinal cord are covered by three protective membranes. The Meninges (outer, middle, inner). What disease do we associate with the Meninges? Fluid found between the middle and inner meninges cushions the brain = Cerebrospinal fluid (CSF).

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Cerebrum: Location: Forebrain Function: 2 Hemispheres controls intelligence, personality, memory, sight, language & hearing Hypothalamus: Location: underneath the Cerebrum Function: Controls homeostasis (body temp, thirst etc) also releases TRH

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Pituitary gland: Location: underneath the Hypothalamus. Function: Secretes hormones. Cerebellum: Location: Hindbrain. Function: Controls balance and muscular co- ordination of voluntary muscles. Medulla Oblongata: Location: at the bottom of the brain stem. Function: Controls involuntary muscles i.e. breathing, heartbeat, swallowing and sneezing.

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Thalamus: Location: Above the hypothalamus and below the Cerebrum. Function: Relays messages to the cerebrum.

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Definition: The loss of voluntary muscle power. Cause: Spinal injury, stroke or tumour. Symptom: Loss of voluntary muscle power, an inability to move. Treatment: Physical therapy, there is no known cure for Paralysis.

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Central Canal: Filled with Cerebrospinal fluid supplying nutrients and oxygen to the spinal cord. White Matter: Contains nerve fibres carrying impulses away from cell body i.e. axons. Grey Matter: Contains cell bodies & dendrites. Doral Root: These project from the spinal cord and contain sensory neurons bringing nerve impulses into the spinal cord. Ventral Root: These also project from the spinal cord and contain motor neurons bringing nerve impulses away form the spinal cord.

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This is an automatic response to a stimulus that does not involve the brain i.e. blinking, pulling a hand away from a hot object.

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Tapping below the knee stimulates sensory receptors to send a message into the spinal cord (via the dorsal root). Motor neurons relay the message to the leg muscle (via ventral root) causing the leg to jerk outwards. A message also reaches the brain at the same time as the reflex action occurs. The message is relayed from the sensory neuron to the motor neuron via an interneuron.