The Nervous System

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By Po-Han ChenThe Nervous SystemWhat good does it make?Creatures on the world can feel the surrounding in order to adapt the environment for survival. Animals relies on…
By Po-Han ChenThe Nervous SystemWhat good does it make?Creatures on the world can feel the surrounding in order to adapt the environment for survival. Animals relies on Endocrine system and Nervous system to adjust itself. Nervous system controls muscle contraction and coordinate the organs within a short time in order to protect itself.3% of overall mass, but it is the most complicated system in bodyNervous System
  • The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body
  • PartsYour Nervous system is mainly made up ofThe NervesSpinal cordThe BrainNerve CellsThe nervous system is made up of Neurones.Each neurone consists of a cell body and extending nerve fibreNeurons can be divided into 3 types SensoryMotorInterneuronsNeurons and SynapsesSensory NeuronsINPUT Fromsensory organs to the brain and spinal cord.I.e., from Nose, eyes to brainMotor NeuronsOUTPUTFrom the brain and spinal cord To the muscles and glands.Interneurons (Relay Neurons)Interneurons carry information between other neurons only found in the brain and spinal cord.The Neuron can be separated into 4 parts :The cell bodyDendritesAxonMyelin sheathStructure of NeuronThe cell bodyRound structure Contains DNADose Protein manufacturing Directs metabolismNo role in neural signalingContains the Cell’s NucleusDendritesInformation collectorsReceive inputs from neighboring neuronsIf enough inputs the cell’s AXON may generate an outputAxonOutput structureOne axon per cell, 2 distinct partsThe tube branches at the end and attaches to other cells.YouTube Video
  • How neurons communicate
  • Neurons communicate by electrical signal called the Action Potential.
  • it is based on movements of ions between cells.
  • When an Action Potential occurs a molecular message is sent to neighboring neurons
  • The Big BossBrain is the organ that controls everything in your body, including your thought and reaction.Nervous SystemThe nervous system is divided into two sections:Central Nervous System+Outer Nervous SystemCentral Nervous SystemThe Central Nervous System is made up of Brain and Spinal cordElectrical Signals are carried from the Brain to the receptors through Spinal cordThe Path
  • Betweenthe receptors and the effectors, the Central Nervous system coordinates the action potentials passing through the nervous system.
  • Outer Nervous SystemThe Outer Nervous System is made of the nerves and the sense organsSense Organs includes Skin - Touch Nose - Smell Tongue - TasteNerve ImpulseElectrical signals are carried through nerve impulse which is widely spread in the bodyAction PotentialAn action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a stereotyped trajectoryPolarisation
  • Resting neurons have Potential Difference
  • Outer surface-> Positively chargedInner surface -> Negatively charged
  • Resting potential (-65mV), therefore said Polarised
  • How does it work?
  • Resting potential is generated by Sodium-potassium pump and a potassium channel
  • The pump moves three sodium ions out by active transport for every two potassium ions brings in.
  • The facilitated diffusion allowed to let potassium ions back out.
  • More positive ions move out than move in.
  • Depolarise when Stimulated
  • Sodium potassium pumps work all the time, but Channel protein can be opened or closed.
  • Depolarisation requires another protein channel, which is Sodium Channel.
  • When Stimulated, sodium channel opens and then ions diffuses in. This increases the positive charge inside the cell. Charge is now Reversed. With a potential difference of +40mV, This is Action Potential and membrane is depolarised.Makes it much easier
  • Practice Questions
  • Q: What do sensory, relay and motor neurons do in the nervous system?
  • Answer:
  • Sensory – INPUT Fromsensory organs to the brain and spinal cord.Relay – Interneurons carry information between other neurons only found in the brain and spinal cord.Motor – OUTPUTFrom the brain and spinal cord To the muscles and glands.Practice Questions
  • Q: Give two factors that increases the speed of conduction of action potentials
  • Answer:
  • Bigger axon diametersIncrease in temperatureBibliography
  • Notes from Richard
  • Thank you for your attentionTHE END
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