Download A.P. Biology Chapter 40

A.P. Biology
Sense Organs
Sensory Reception
Type of Sensory
Receptor
Stimulus
Mechanoreceptor
Pressure, position,
acceleration (balance)
Heat
Tissue damage
Chemicals (taste, smell)
Light (vision)
Thermoreceptor
Pain Receptor
Chemoreceptor
Photoreceptor
Brain’s assessment of a stimulus depends
on:
1.
2.
3.
Which nerve pathway is carrying the stimulus
(i.e. optic nerve—assessed as vision)
Frequency of action potentials (receptors “fire”
more frequently for a “stronger” stimulus)
Number of axons stimulated (stronger stimulus
recruits more receptors)
Sense Organs
= concentrations of sensory receptors
 Examples: Eye, Ear, Nose etc.

Taste—Chemoreceptors in
taste buds on the tongue

Chemicals bind to receptors on taste
cells, generating nerve impulses in
sensory neurons
Smell—Chemoreceptors in the nose
(olfactory cells) detect chemicals (odors)
Two types of Photoreceptors—
Located in the Retina
Rod Cells—B/W
vision
Cone Cells –
Color vision
Stimulation of the photoreceptors
generates nerve impulses  optic
nerve  brain
Lens
focuses
images onto
the retina
 Muscles/
ligaments
change the
shape of the
lens

Vision
Problems
and their
Corrections
Hearing & Balance

Hearing
Sound waves enter auditory canal
 Vibrate the Tympanic Membrane
 Malleus, Incus, Stapes
 Vibrates Oval Window
 Moves fluid in the Cochlea
 Hair cells move, stimulating nerve
cells in the auditory nerve
(mechanoreceptors)


Balance/Movement

Fluid movement in the Semi-circular
Canals