BRAINCAKE

Neuronal Communication

OCR A-level BiologyTopic 2 of 1238 lessons

Revision notes for Neuronal Communication in OCR Biology A (H420). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.

  1. Co-ordinationCells are specialised to carry out particular functions.
  2. HomeostasisHomeostasis is the maintenance of a constant internal environment despite internal and external environmental changes.
  3. Cell SignallingAt a cellular level, communication takes place through cell signalling.
  4. The Nervous SystemThe nervous system is responsible for detecting stimuli (changes to the internal and external environment), processing the information and carrying…
  5. NeuronesThere are three types of neurones: sensory neurones motor neurones relay neurones All neurones have a cell body, dendrons and axons.
  6. Sensory NeuronesSensory neurones carry electrical impulses from sensory receptors to the central nervous system (CNS), which is the brain and spinal cord.
  7. Motor NeuronesMotor neurones carry electrical impulses from the central nervous system (CNS) to effectors.
  8. Myelinated NeuronesSpecial cells called Schwann cells grow and wrap around some axons many times laying down two phospholipid bilayers each time.
  9. Sensory ReceptorsSensory receptors are usually found in sense organs such as the skin, ear and eye.
  10. Pacinian CorpusclesPacinian corpuscles are located deep within the skin and detect mechanical pressure.
  11. Generator PotentialNormally, the sensory neurone is at its resting potential.
  12. Resting PotentialNormally, a neurone is not transmitting an impulse and the membrane is at a resting potential of -70mV.
  13. DepolarisationA generator potential causes sodium ions to enter the neurone through the (stretch-mediated) sodium channels in the membrane.
  14. RepolarisationAfter depolarisation the inside of the axon membrane is at about +40 mV.
  15. HyperpolarisationWhen the potassium voltage-gated channels open, lots of potassium ions diffuse out of the axon down their electrochemical gradient.
  16. The Action PotentialThe temporary reversal of the charge across the axon membrane is called the action potential.
  17. Nerve ImpulseA nerve impulse is an action potential that starts at one end of the neurone and is propagated along the axon to the other end of the neurone.
  18. Saltatory ConductionMyelinated neurones propagate nerve impulses about 100x faster than non-myelinated neurones.
  19. SynapsesThe junction between two neurones or a neurone and a muscle or gland cell is called a synapse.
  20. NeurotransmittersVesicles containing neurotransmitters are found in the swollen end of the presynaptic neurone - the synaptic knob.
  21. Transmission of Impulse across SynapseWhen an action potential reaches the pre-synaptic bulb, calcium ion channels open.
  22. The Role of SynapsesSynapses ensure impulses can travel in only one direction.
  23. SummationEach action potential triggers the release of the same amount of neurotransmitter into the synaptic cleft.
  24. Structural Organisation of the Nervous SystemThe mammalian nervous system is organised structurally into the central nervous system (CNS) and the peripheral nervous system (PNS).
  25. Functional Organisation of the Nervous SystemThe nervous system is functionally organised into two systems: The Somatic Nervous System and the Autonomic Nervous System.
  26. The Autonomic Nervous SystemThe autonomic nervous system can further be subdivided into the sympathetic and parasympathetic nervous systems.
  27. Comparison of NeuronesThe somatic nervous system has heavily myelinated neurones connecting the CNS to receptor and effector organs.
  28. The BrainThe brain receives information about the environment from receptor cells and processes this information to bring about a co-ordinated response.
  29. Structure of the BrainThere are 5 main areas:Cerebrum-controls voluntary actions, learning and conscious thought Cerebellum - posture, balance and non-voluntary movement…
  30. CerebrumThe cerebrum receives sensory information from receptors, processes it and send impulses via motor neurones to effectors to carry out the…
  31. Association Areassensory area - receives information from receptor cells.
  32. CerebellumThe cerebellum controls and co-ordinates muscular movement and muscle tone, posture and balance Damage to this part of the brain leads to…
  33. Medulla OblongataThe medulla oblongata is the part of the brain at the base of the brainstem, where the brain joins the spinal cord.
  34. HypothalamusThe hypothalamus controls some metabolic processes and autonomic responses via its sympathetic and parasympathetic centres.
  35. Pituitary GlandThe pituitary is a pea-sized gland located at the base of the hypothalamus.
  36. Reflex ActionsThe body can respond to dangerous situations without conscious thought.
  37. Knee-jerk ReflexThe spinal cord is a column of nervous tissue protected by the spine and running up the back.
  38. Blinking ReflexThe involuntary blinking of the eyelids (the optical reflex) e.g. in reaction to bright light is a cranial reflex.

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