Sensory and Motor Mechanisms - Fundametnals of Biology - Lecture Slides, Slides of Biology

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Chapter 49

Sensory and Motor Mechanisms

• Bats use sonar to detect their prey
• Moths, a common prey for bats can detect the bat’s sonar and attempt to flee

Receptors …in and out

• Exteroreceptors
  • Detect stimuli coming from the outside of the body
• Interoreceptors
  • Detect internal stimuli

Functions Performed by Sensory

Receptors

• All stimuli represent forms of energy
• Sensation involves converting this energy
  • Into a change in the membrane potential of sensory receptors
• Sensory receptors perform four functions in this process - transduction - amplification - transmission - integration

• Some small-scale studies of dogs’ ability to detect the chemical markers of cancer, specifically melanoma, have shown promising results.

Amplification

• Amplification is the strengthening of stimulus energy by cells in sensory pathways

Integration

• The integration of sensory information
  • Begins as soon as the information is received
  • Occurs at all levels of the nervous system
• Some receptor potentials are integrated through summation - In spatial summation , several presynaptic neurons converge at a synapse with a single post synaptic neurone. In temporal summation there is only one presynaptic and one postsynaptic neuron but the frequency of impulses reaching the synapse is important.
• Another type of integration is sensory adaptation - A decrease in responsiveness during continued stimulation