Sensory Nervous System - Detecing the enviroment Flashcards
3 types of sensory neuron (receptor) structure
- sensory receptor with free nerve endings
- sensory receptors with specialized structure
- sensory receptor with a receptor cell
sensory neuron with free nerve-endings
regular neuron
the sensory receptor is the neuron itself
dendrites take in stimuli - afferent neuron
sense organ
sensory receptor involving one dendrite
in a specialized structure - non neural
connective - tissue layer
pressure on skin
sensory receptor with afferent neuron
sensory receptor formed by a cell that synapses with an afferent neuron
presynaptic receptor
sensory receptor (attached to afferent neuron)
can function as single cells (or with accesory cells - recieves info that neuron needs)
can be grouped in a complex sensory organ - collection in the eye
modality
type of sensory info needed
mechanoreceptors
respond to mechanical deformation
thermoreceptor
respond to cold and heat
nocioreceptors
respond to pain - tissue damage
electromagnetic receptors
respond to electrical + magnetic fiekd - infared and ultraviolent light
photoreceptors
respond to visible light
chemoreceptors
respond to various chemicals
receptor potential
stimuli causes ion movements across membrane - alters rate at which AP is generated - increases frequency e.g bio lab + inner ear hair cells
inner ear cells as AP firing rate
bending of hair cells increase frequency of APs
bending the other way is non-preferred - decreases frequency - no bend will create stable frequency
example of mechanoreceptors
stretch receptors
hair cells
stretch receptors
in inverts and verts
detect relative position of body structures
has mechaincally gated sodium channels
deforming stimulus depolarizes membrane
perform a variety of roles in animals
stretch receptors in the knee-jerk reaction
hitting the knee in that specific spot with stretch receptors moves the extensor muscles which deform the stretch receptors which sends signals to motor neurons to move the leg
stretch receptors in wings of insects
wings elevate - connector tissue between body and wing is stretched - deformd the membrane of neurons - leads onto other things
neuronal mechanreceptors
stretch receptors
non neuronal mechanoreceptors
hair cells
process of hair cells working as mechanoreceptors
hair cell with sterocilia detects fluid movements and currents
opens mechanic gated - K+ channels
depolarizes
triggers voltage gated calcium channels which send neurotransmutter into sensory neuron and CNS
hair cells as balance in crabs
statolith - calcarious core that will move which then moves hair cells which then triggers k+ channels and sensory neurons
orientation is detected by types of hair cells triggered
hair cells as balance in fishes
water goes into the pores of the fish
bends the hair cells
depending on how much water is spread over the surface area of the fish and the amount of hair cells bent - the fish can detect if it’s going straight or turning
hair cells as balance in humans
fluid will move the cupula which moves hair cells which triggers K+ channels then sensory neurons
hair cells as organs of sound in insects
organs on legs (tympanum) vibrate from pressure which moves hair cells
hair cells as organ of sound in humans
eardrum vibrates due to pressure - fluid moves in cochlea - moves basiliar membrane - which moves hair cells - tectorial membrane is not moved - leads to auditory nerve
3 types of photoreceptor arrangements
- eye spots (cups)
- compound eyes
- camera eyes
eye spots
pigment cups prevent light from one direction of the eye spot - which is why animals need two
light reaches photoreceptor cells and is transduced
can only see light and dark - no details
where are eye spots found
invertebrates - flatworms
where are compound eyes
arthropods and some annelides
insects, lobsters, segmented worms
compound eyes
multiple little eyes
each one is a ommatidium
which has a lens and focuses the light
has accessory cells (light blocking pigment cells)
axon leads onto CNS
detects complex images which produces evolved brain function
Camera eyes are found in
cephlapod molluscs, all vertebrates
camera eyes
normal human eyes with retina, cornea, lens, pupil, and iris - also allows for complex images and evolved brain function
commonality between all three types of photoreceptors
photopigment
photopigment
transduces light energy into a biolelectric signal
absorbing energy from light and transducing it
rods
in the retina and detect low intensity - gray shades - white and black
higher sensitivity - need fewer photons
cones
detect high intensity photons - colour
photopigments
retinal and an opsin
photopigments in rods
rhodopsin
photopigments in cones
several kinds of opsins in cones
how we see in humans
light comes in from the lens - it’s focused - goes to cones and rodes - receptor potentials - goes to horizontal cells - biopolar cells - amacrine cells - ganglion cells - optic nerve
retina is
outgrowth of brain - comes from ectoderm
what do interneurons do in the retina
assist inr etinal intergration
phototransduction in rods and cones (dark)
NA channels are open
which depolarizes the plasma membrane
glutamate is released in the cell
keeps gates open
phototransductin in rodes and cones (light)
NA channels close
hyperpolarizes plasma membrane
glutamate is not released
cis retinal is converted to trans retinal
which triggers metabolic process
cGMP is converted into GMP
keeps sodium channels closed
example of receptor potential in retina
when photon enters cones and rods and NA closes and hyperpolarization occurs
examples of action potentials in retina
when ganglion cells send signals up to brain with the optic nerve
retinal intergration by interneurons
modify original signal from receptor cells
assist in defining boundaries, changing retinal sensitivity
identifying object movement
colour of object
allows for well-developed sensory system
example of chemoreception
taste and olfaction
taste in flies
each leg has chemoreceptor cells with dendrites that reach the tip of the leg with a pore - eeach taste receptor responds to a diff stimulus
neuronal!!
taste in humans
non-neuronal receptor cells grouped into taste buds
each receptor has a preferred chemical sensitivity
salt and sour are simple compounds - bound by ionotropic receptors
sweet, umami, and bitter - complex compounds bound by metabotropic receptors
mouth olfaction
binding of odorant leads to membrane depolarization - involves less concentrated molecules
thermoreception in vampire bats
noseleaf creates an infared image of
crotalid snakes
pit organs form infared image of rat
electroreception in electric fish
produces electric field and if it is distrubed, they know
