Sensation Flashcards
What is the difference between sensation and perception?
Sensation is the process of encoding events and stimuli by the nervous system. It depends on low level physical, biochemical and neutral events.
Perception is the process by which the brain interprets sensory information.
Are all neurons spiking- generate action potential?
No, some neurons are non-spiking. Typically in these, rate of neurotransmistter release is proportional to membrane potential. This works for small neurons.
What are the five sensations that the tongue has receptors for?
Salty, sweet, sour, bitter and umami.
How are sour sensations perceived?
Hydrogen ions fron acidic foods close hydrogen ion gated potassium channels, slightly increasing the membrane potential.
How are sweet, bitter and umami sensations perceived?
Through coupled G proteins
True or false, the neurons in a particular sensory cortex are significantly different from neurons in another cortex.
False, the quality of perception depends on the receptors, not on the neurons. For example, in blind people the visual cortex can take over the functions of the auditory cortex, demonstrating the similarity between neurons, regardless of their cortex.
Explain the difference between the temporal coding theory and the rate coding theory.
Rate coding theory: the precise timing of action potentials doesn’t matter, only the number of action potentials in a particular time window is important.
Temporal coding theory: precise timing and the relative time difference between action potentials is informative.
Both are used.
Receptor potentials differ from action potentials in that:
a. only APs depend on movement of Na+ ions into the cell. Incorrect
b. only APs are produced by receptor cells.
c. only APs involve the opening of voltage-gated ion channels.
d. only APs involve a depolarization of the cell membrane.
e. RPs are always produced by closing of open ion channels.
Only APs involve the opening of voltage-gated ion channels.
The properties of the receptor potential that allow receptors to code stimulus timing and duration are:
Select one:
a. summation and adaptation.
b. summation, adaptation and grading.
c. adaptation, grading and range fractionation. Incorrect
d. slow, intermediate and fast adaptation.
e. slow adaptation, fast adaptation and grading.
Summation and adaptation
Which of the following statements is CORRECT?
Select one:
a. All sensory systems have specialized receptor cells. Incorrect
b. Receptor cells always communicate directly with afferent nerve fibres.
c. Receptor cells use chemical transmitters to communicate with relay cells or afferent nerve fibres.
d. In nerve fibres specialized to detect a sensory stimulus, the nodes of Ranvier are the specialized receptive zones.
e. Receptor zones of nerve fibres generate action potentials for transmission by the nerve.
Receptor cells use chemical transmitters to communicate with relay cells or afferent nerve fibres.
