Transcript Sensory Mechanisms - Bio Resource Site

Sensory
Mechanisms
Sensory receptors and the brain
Sensation
Perception
• Action potentials transmitted by
sensory receptors to the brain
• Sensory receptors
▫ Specialized
neurons/epithelial cells
▫ Extero- and interoreceptors
▫ Convert energy to changes in
membrane potentials and
transmit to brain
▫ Four functions: transduction,
amplification, transmission,
and integration
• Interpretation of the stimuli by
the brain
• Ex. colors, taste, sound, smell
1. Follow the
movement of the
rotating pink dot with
your eyes.
2. Stare at the cross
in the center.
3. Concentrate on the
cross at the center for
a long period of time.
Is the blue
side in the
front or back
of the cube?
Types of sensory receptors
Mechanoreceptors
 Physical deformation
 Stretch receptors in
muscles and hair cells
Pain receptors
 Excess heat, pressure,
presence of chemicals,
prostaglandins
 Naked dendrites called
nociceptors
Chemoreceptors
 Presence and
concentrations of
chemicals in the
environment
 Osmoreceptors in
brain, gustatory and
olfactory receptors,
pheromone receptors in
moth antennae
Thermoreceptors
 Heat or cold
 Skin receptors and
interoreceptors in the
hypothalamus
EM receptors
 EM energy
 photoreceptors:
infrared in snakes,
electroreceptors in
eels, rods and
cones in humans
Vision and photoreceptors
* All have pigment molecules that absorb light
Eye cup of planarians
Compound eyes of insects, crustaceans,
polychaetes
Ommatidia are sensitive to movement!
Single lens eyes of jellyfish,
polychaetes, spiders, mollusks
Single lens eyes of vertebrates
Sclera
Choroid
Retina with rods and cones
Ciliary body
Fovea (center
of visual field,
most cones)
Suspensory
ligament
Cornea
Iris
Optic
nerve
Pupil
Aqueous
humor
Lens
Vitreous humor
Optic disk
(blind spot)
Structure of the human eye
Central artery and
vein of the retina
Hearing and equilibrium in invertebrates
Ciliated
receptor cells
Statolith
Cilia
Sensory nerve fibers
Statocysts in invertebrates
Tympanic
membrane
1 mm
Hearing and equilibrium in mammals
1 Overview of ear structure
2 The middle ear and inner ear
Incus
Middle
ear Inner ear
Outer ear
Stapes
Skull
bones
Semicircular
canals
Malleus
Auditory nerve,
to brain
Pinna
Tympanic
membrane
Hair cells
Cochlea
Eustachian
tube
Auditory
canal
Tectorial
membrane
Tympanic
membrane
Oval
window
Eustachian
tube
Round
window
Cochlear duct
Bone
Vestibular canal
Auditory nerve
Basilar
membrane
Axons of
sensory neurons
4 The organ of Corti
To auditory
nerve
Tympanic canal
3 The cochlea
Organ of Corti
Chemoreceptors and taste
Taste buds in mammals
Sensilla in insects
Chemoreceptors and smell
Brain
Action potentials
Odorant
Olfactory bulb
Nasal cavity
Bone
Epithelial cell
Odorant
receptors
Plasma
membrane
Odorant
Chemoreceptor
Cilia
Mucus