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

▫ 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

Vision and photoreceptors* All have pigment molecules that absorb light

Structure of the human eye

Ciliary body

Iris

Suspensoryligament

Cornea

Pupil

Aqueoushumor

Lens

Vitreous humor

Optic disk(blind spot)

Central artery andvein of the retina

Opticnerve

Fovea (centerof visual field, most cones)

Retina with rods and cones

ChoroidSclera

Hearing and equilibrium in invertebrates

Ciliatedreceptor cells

CiliaStatolith

Sensory nerve fibers

Statocysts in invertebrates

1 mm

Tympanicmembrane

Hearing and equilibrium in mammals

Pinna

Auditory canal

Eustachian tube

Tympanicmembrane

Stapes

Incus

Malleus

Skullbones

Semicircularcanals

Auditory nerve,to brain

Cochlea

Tympanicmembrane

Ovalwindow

Eustachian tube

Roundwindow

Vestibular canal

Tympanic canal

Auditory nerve

BoneCochlear duct

Hair cells Tectorialmembrane

Basilarmembrane

To auditorynerve

Axons of sensory neurons

1Overview of ear structure 2The middle ear and inner ear

4 The organ of Corti 3 The cochleaOrgan of Corti

Outer earMiddle

ear Inner ear

• Utricle and saccule tells the position and the fixed position of the body in space or any linear acceleration

Chemoreceptors and tasteSensilla in insects

Taste buds in mammals

Chemoreceptors and smell

Brain

Nasal cavity

Odorant

Odorantreceptors

Plasmamembrane

Odorant

Cilia

Chemoreceptor

Epithelial cell

Bone

Olfactory bulb

Action potentials

Mucus