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Neuronal Communication

AQA A-level BiologyTopic 6 of 1338 lessons

Revision notes for Neuronal Communication in AQA Biology (7402). 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. Co-ordination SystemsThere are two main co-ordination systems which interact and work together: The nervous system.
  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 transmit electrical impulses from sensory receptors to a relay neurone, motor neurone or the brain.
  7. Motor NeuronesMotor neurones transmit impulses from either relay neurones or sensory neurones 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 100× faster than non-myelinated neurones.
  19. SynapsesTwo connecting neurones are not in physical contact with each other but there is a gap between the presynaptic knob and the postsynaptic neurone.
  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 carries impulses to glands, smooth muscle and cardiac muscle and is not under voluntary control.
  27. Comparison of NeuronesThe somatic nervous system has heavily myelinated neurones connecting the CNS to receptor and effector organs.
  28. Receptors in the Eye - Rod CellsThe retina of the human eye contains millions of light -sensitive receptors called rod cells and cone cells.
  29. Receptors in the Eye - Cone CellsThere are about 6 million cone cells in the human eye concentrated in the fovea (the part of the retina opposite the pupil) with the numbers…
  30. Sino-Atrial NodeThe heart muscle is called cardiac muscle.
  31. Contraction of the HeartThe sino-atrial node initiates a wave of excitation which spreads out across both atria.
  32. Autonomic Control of the Heart RateDuring exercise, the heart rate needs to increase in response to an increased demand for oxygen.
  33. ChemoreceptorsDuring exercise the heart rate increases to increase the supply of oxygen to respiring cells and to remove CO2.
  34. Pressure ReceptorsWhen blood pressure is higher than normal pressure receptors within the walls of the aorta and carotid arteries detect the change and send impulses…
  35. Reflex ArcThe body can respond to dangerous situations without conscious thought.
  36. TaxesA taxis is a movement in the direction of a stimulus.
  37. KinesisA kinesis is a non-directional random movement that increases in rate when conditions are unfavourable.
  38. TropismsPlants are non-motile and cannot move towards a stimulus.

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