Sensory nervous system detecting the environment Flashcards
why is it important for animals to detect there environment
in context of homeostasis
how can sensory receptors function in terms of the kind of cell it is
can function as single cell or with accessory cells
what is an example of how sensory receptors can be grouped in a complex sensory organ
the eyes of an insect
mechanoreceptors
respond to mechanical deformation
thermoreceptors
respond to cold and heat
nocioreceptors
respond to pain (tissue damage)
electromagnetic receptors
respond to electrical and magnetic fields; infrared and ultra violet light
photoreceptors
respond to visible light
chemoreceptors
respond to various chemicals
how does a sensory respond work with a change in AP firing rate
-stimuli alter ion movements across membranes
-produce a graded receptor potential
-alters rate at which AP is generated in axon hillock
-change in firing rate interpreted by CNS
what are stretch receptors
-common in invertebrates and vertebrates
-detect relative position of body structures
-membrane has a mechanically-gated Na+ channels
-deforming stimulus depolarization membrane
-preform a variety of roles in animals
what are mechanoreceptor examples
stretch receptors
hair cells
what are stretch receptors
-common in both (in)vertebrates
-detect relative positions of body structure
-membrane has mechanically gated Na+ channels
-deforming stimulus depolarizes the membrane
(hitting your knee reflex)
what are hair cells
-receptor cells with sterocillia to detect fluid currents
how do hair cells work
-they have mechanically gated ion channels in membrane
-can depolarize or hyperpolarize hair cells
-voltage regulated ca+ channels regulate neurotransmitters
-hair cells synapses with the sensory neuron that projects to CNS
what is the function of hair cells
-in organs of balance
-provides into on gravity, acceleration and water currents
-provide about sound frequency, amplitude, and loaction
where are hair cells found
in organs of sound
what are the three photoreceptors
-eye spots (found in many invertebrates)
-compound eye (arthropods, some annelids)
-camera eye (cephlapod molluscs, all vertebrates)
what do all photoreceptors have in common
all use photopigment to transduce light energy into bioelectrical signals
what do compund eyes and camera eyes have incommon that eye spots dont
lends to focus light and form images; complex central nervous system to interpret sensory info
how does phototransduction work in the vertabrate retina
-rods: detect low intensity light, grey shades, white to black
-cones: detect high intensity photons, colour
what can be found for photopigments in rods and cones
rods-rhodopsin
cones-several kinds of opsins
the retina is an…
an outgrowth of the brain
what does the retina do
The retina is a layer of photoreceptors cells and glial cells within the eye that captures incoming photons and transmits them along neuronal pathways as both electrical and chemical signals for the brain to perceive a visual picture
what is an opsin
a protein which forms part of the visual pigment rhodopsin and is released by the action of light.
what do photons inhibit
retinal receptor cells
what is cis-retinal
inactive visual pigments
what is trans-retinal
active visual pigment
photoreceptors cause…
initial polarization
what is an example of chemoreceptors
taste
what does each taste receptor cell respond to
-a different stimulus; water, salt, sugar
-which convays info about taste and conc
for chemoreceptors what are non-neuronal recepotor cells group into
taste buds
in chemoreceptors what does each receptor have
a preferred chemical sensitivity
how does salty and sour taste transactions work
they are simple- cation inflow depolarizes the cell, neuro transmitter releases
how does sweet, bitter and umami taste transductions work
complex, 2nd messanger pathway
what is olfaction
relies on distance chemoreception
what does taste rely on
contact chemoreception
how does olfaction work
binding of odorant leads to membrane depolarization
how many olfaction neurons do humans have
107
dogs: 20x more
moths 1000x more then dogs
hoe many genes encode for different olfactory receptors
at least 1000
how do olfactory receptors compare in vert and inverts
they are very simular
what are thermoreceptors
temperature infrared
what is electroreception
-electric field
-electroreceptors detect distortions of electric fields
-also produce large fields (up to 600v) for prey capture
