Somatic Sensation Flashcards
What senses do we have?
Fine touch, vibration, proprioception, temperature, pain, pressure and special senses so smell, taste, vision, hearing and balance
Define sensation
Conscious or subconscious awareness to either external or internal stimulus
What kind of sensory receptors do first order neurones of the sensory system have?
Free nerve endings, encapsulated nerve endings or specialised cells
What are the sensory modalities of a nerve?
Light touch, temperature and chemical changes
What are the qualities of a sensory nerve?
Sweet, sour, salt for example and this would be taste
They are subdivisions of modalities
What are proprioceptors responsible for?
Providing information on body position in space
Explain the process of sensory transduction
A stimulus evokes a change in permeability of ions in a receptor membrane
There is movement of ions across the membrane
There is a generator potential
Then an action potential
What is the strength of the signal determined by?
The rate of action potential
A stronger stimulus also activates neighbouring cells
What are the two types of adaptation?
Slowly adapting tonic receptors which keep firing until the stimulus is removed
Rapidly adapting phasic receptors which respond maximally and briefly to a stimulus such as clothes
Define acuity and what is it determined by?
The precision by which a stimulus can be located
It is determined by lateral inhibition, two point discrimination and synaptic to convergence and divergence
What is lateral inhibition?
Inhibition from neighbouring inhibitory neurones
What does two-point discrimination depend upon?
The receptive field and the density of receptors
Define two-point discrimination
The minimal distance required to perceive two stimuli
What is convergence?
This is a decrease in acuity
It is like the function of the tympanic membrane lots signals come in and converge into one
What is divergence?
This is an amplification in signal
A signal produces lots of signal
A bit like the radiation from a firework
