Nervous System IX Flashcards
Examples of chemoreceptors
- blood chemoreceptors
- nociceptors
- hypothalamic glucose sensing neurons
- taste, smell
Examples of stimulus of mechanoreceptors
- touch
- proprioceptors
- nociceptors
- auditory (hair cells)
- balance
What are examples of photoreceptors
Vision (rods and cones)
Examples of thermoreceptors
Thermal receptors
Nociceptors
What do mechanically gated channels do?
Convert mechanical stimulus into electrical signal
- receptor potential or generator potential
What are receptive fields
Sensory neurons are activated by stimuli that fall within a specific physical area
What determines size of receptive fields?
Type of sensory receptor and if there is convergence of multiple primary neurons onto a secondary neuron
How many neurons do somatosensory neurons have?
3 neurons
Primary sensory neuron: converts physical stimulus to electrical signal (in skin or muscle)
Secondary: projection neurons carry info up spinal cord to brain
Tertiary: from thalamus to relevant cerebral cortex area
What creates large receptive fields?
Convergence
Areas where fine touch is less important
Ex) leg or back
- 3 primary sensory neurons with own receptive fields overlap but all synapse on same secondary
- sub threshold stimuli sum and initiate AP at secondary neuron
- two stimuli that fall within same secondary receptive field are perceived as single point
Where are small receptive fields found?
More sensitive areas
- 1 primary sensory neuron communicates with 1 secondary
-ex) fingers
- two stimuli perceived as distinct (two-point discrimination)
Where is visceral info integrated?
Brainstem and spinal cord
Where are special and somatic sensory info routed?
Through thalamus before projection to relevant cortical centres
Where are olfactory pathways routed?
From nose through olfactory bulb to olfactory cortex
Not through thalamus
Where are equilibrium pathways projected to?
Cerebellum
What do all special senses have?
Dedicated cortical regions
