Bioknowledgy
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    • 1. Cell biology >
      • 1.1 Introduction to cells
      • 1.2 Ultrastructure of cells
      • 1.3 Membrane structure
      • 1.4 Membrane transport
      • 1.5 The origin of cells
      • 1.6 Cell division
    • 2. Molecular biology >
      • 2.1 Molecules to metabolism
      • 2.2 Water
      • 2.3 Carbohydrates and lipids
      • 2.4 Proteins
      • 2.5 Enzymes
      • 2.6 Structure of DNA and RNA
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    • 3. Genetics >
      • 3.1 Genes
      • 3.2 Chromosomes
      • 3.3 Meiosis
      • 3.4 Inheritance
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      • 4.1 Species, communities and ecosystems
      • 4.2 Energy flow
      • 4.3 Carbon cycling
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    • 5. Evolution and biodiversity >
      • 5.1 Evidence for evolution
      • 5.2 Natural selection
      • 5.3 Classification of biodiversity
      • 5.4 Cladistics
    • 6. Human physiology >
      • 6.1 Digestion and absorption
      • 6.2 The blood system
      • 6.3 Defence against infectious disease
      • 6.4 Gas exchange
      • 6.5 Neurons and synapses
      • 6.6 Hormones, homeostasis and reproduction
  • Additional higher level (AHL)
    • 7. Nucleic acids >
      • 7.1 DNA structure and replication
      • 7.2 Transcription and gene expression
      • 7.3 Translation
    • 8. Metabolism, cell respiration and photosynthesis >
      • 8.1 Metabolism
      • 8.2 Cell respiration
      • 8.3 Photosynthesis
    • 9. Plant biology >
      • 9.1 Transport in the xylem of plants
      • 9.2 Transport in the phloem of plants
      • 9.3 Growth in plants
      • 9.4 Reproduction in plants
    • 10. Genetics and evolution >
      • 10.1 Meiosis
      • 10.2 Inheritance
      • 10.3 Gene pools and speciation
    • 11. Animal physiology >
      • 11.1 Antibody production and vaccination
      • 11.2 Movement
      • 11.3 The kidney and osmoregulation
      • 11.4 Sexual reproduction
  • Options
    • A. Neurobiology and behaviour >
      • A.1 Neural development
      • A.2 The human brain
      • A.3 Perception of stimuli
      • A.4 Innate and learned behaviour (AHL)
      • A.5 Neuropharmacology (AHL)
      • A.6 Ethology (AHL)
    • B. Biotechnology and bioinformatics
    • C. Ecology and conservation >
      • C.1 Species and communities
      • C.2 Communities and ecosystems
      • C.3 Impacts of humans on ecosystems
      • C.4 Conservation of biodiversity
      • C.5 Population ecology (AHL)
      • C.6 Nitrogen and phosphorus cycles (AHL)
    • D. Human physiology
  • Giving back - BioKQQAnswers

Essential idea: Neurons transmit the message, synapses modulate the message.

The image above shows a tiny segment of a model of a mouse brain the lines show neurons and the dots show synapses. The image is intended to illustrate both the how complex even a small mammal's brain is and additionally how important the synapses between neurons are; it is the synapses that drive communication and conscious thought. With the exception of the memory centre the number of cells in the human brain does not increase after birth, what increase is the number of connections and hence synapses between neurons.

Understandings, applications and skills

6.5.U1 Neurons transmit electrical impulses. [The details of structure of different types of neuron are not needed.]
6.5.U2 The myelination of nerve fibres allows for saltatory conduction.
6.5.U3 Neurons pump sodium and potassium ions across their membranes to generate a resting potential.
6.5.U4 An action potential consists of depolarization and repolarization of the neuron.
6.5.U5 Nerve impulses are action potentials propagated along the axons of neurons.
6.5.U6 Propagation of nerve impulses is the result of local currents that cause each successive part of the axon to reach the threshold potential.
6.5.U7 Synapses are junctions between neurons and between neurons and receptor or effector cells. [Only chemical synapses are required, not electrical, and they can simply be referred to as synapses.]
6.5.U8 When presynaptic neurons are depolarized they release a neurotransmitter into the synapse.
6.5.U9 A nerve impulse is only initiated if the threshold potential is reached.
6.5.A1 Secretion and reabsorption of acetylcholine by neurons at synapses.
6.5.A2 Blocking of synaptic transmission at cholinergic synapses in insects by binding of neonicotinoid pesticides to acetylcholine receptors.
6.5.S1 Analysis of oscilloscope traces showing resting potentials and action potentials.
[Text in square brackets indicates guidance notes]

Starters

What would the world be like if you could feel no pain?
Would it be like having a superpower? In a very rare condition Congenital insensitivity to pain with anhidrosis (CIPA) some people cannot sense pain. Watch the video to learn more.

How do nerves work?
A TED-Ed lesson introducing nerve impulses by Elliot Krane

Presentation and Notes

The presentation is designed to help your understanding.
Download presentation


Vocabulary

Correct use of terminology is a key skill in Biology. It is essential to use key terms correctly when communicating your understanding, particularly in assessments. Use the quizlet flashcards or other tools such as learn, scatter, space race, speller and test to help you master the vocabulary.
The 6.5 Neurons and synapses notes - the bottom line template can be used as a note construction template in itself or as a checklist if you are using your own or another template such as the Cornell style template.


Quick quiz

Quick quiz Use the BioK Quick Quiz on 6.5 Neurons and synapses (as directed) to check your understanding of the topic.

Structure of a neuron

You are not required to draw and label a neuron, but never-the-less you need to understand it's fascinating structure to appreciate it's function.
Picture
Source: http://upload.wikimedia.org/wikipedia/commons/a/a9/Complete_neuron_cell_diagram_en.svg

Weblinks

Synapses
6.5 Transmission across a synapse by Stephanie Castle (IB Biology Review)

Nature of science

Cooperation and collaboration between groups of scientists—biologists are contributing to research into memory and learning. (4.3)

Higher functions of the brain including memory and learning are only partly understood at present and are being researched very actively. They have traditionally been investigated by psychologists but increasingly the techniques of molecular biology and biochemistry are being used to unravel the mechanisms at work. Other branches of science are also making important contributions, including biophysics, medicine, pharmacology and computer science.

The Centre for Neural Circuits and Behaviour at Oxford University is an excellent example of collaboration between scientists with different areas of expertise. The four group leaders of the research team and the area of science that they originally studied are:
  • Professor Gero Miesenböck – medicine and physiology
  • Dr Martin Booth – engineering and optical microscopy
  • Dr Korneel Hens – chemistry and biochemistry
  • Professor Scott Waddell – genetics, molecular biology and neurobiology.

source: Oxford University Press IB Course Companion

Theory of knowledge

Watch the TED video to find out how neurons shaped civilization by V S Ramachandran.
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