sense organs Flashcards
What is the fundamental purpose of sensory receptors?
transduction - conversion of stimulus energy
What is receptor potential
the small local electrical change on a receptor cell (local potential/depolarization).
what are the two main types of sensory receptors?
afferent: propagate signal to integrating centre via AP
epithelial cells: sends signal to afferent neuron which propagates via AP or integrating centres.
the sensory receptors transmit 4 kinds of information
Modality (type of stimulus)
location (receptive field)
intensity (as intensity rises firing frequency rises)
duration (how long)
what are unencapsulated nerve endings?
Free nerve endings: pain and temp
Merkel Discs: light touch and texture
hair receptors: dendrites around a hair follicle, monitor movement of hair
what are encapsulated nerve endings?
Meissner corpuscles: light touch and texture
krause end bulbs: tactile
Bulbous corpuscles: heavy touch, pressure, joint movement, and skin stretching.
Lamellar corpuscles: deep pressure, stretch, tickle, vibration.
what are the chemical senses
taste (gustation): chemical stimulants on taste buds
smell (olfaction): response to odorants.
what are the taste sensations?
salty: metal ions
sweet: carbs and high caloric value
sour: acids such as citrus fruit
bitter: spoiled and poisonous foods
umami: meaty taste.
how does hearing occur
this is in response to vibrating air molecules where equilibrium of the sense of motion, body, orientation, and balance happens causing fluid in the ear.
what are light absorbing cells called? and what are the categories?
photoreceptors: rod cells which are in charge of night vision, cone cells for day vision, outer segments of rod cells are to absorb light.
what are the types of cells in the retina?
Photoreceptor cells: absorb light and generate chemical or electrical signals
bipolar cells: dendrites with rods and cones and axon synapses with ganglion cells
ganglion cells: form optic nerve.
what is the macula lutea
put in the centre of the eye that produces finely detailed images.
what is the optic disc
convergence of nerve fibres from retina no photoreceptor cells and is the blind spot.
what are rods?
retinal from a vitamin A derivative called retinal, made with opsin which is a protein embedded in disc (opsin) membrane but rods cannot distinguish colour.
what are cones
day vision and colour vision
