Auditory Sense

· Physical energy – Sound wave

· Sense organ – Ear

· Ear can transduce three characteristics

o Frequency – pitch (Hz)

o Amplitude – Loudness (db)

o Timber – complexity of the wave (how rich the sound is)

How?

· Structure

o Outer

o Middle

o Inner

o Pinna- for outer

o Eardrum – membrane vibrates as compressed air comes in connected to hammer, anvil, stirrup translated into area called oval window

o Cochlea - has membrane known as basil membrane

§ Tiny hair called go back and forth as sound wave brushes over surface and translates wave into actual potential.

Controversy

· How to sense different pitch?

o Place principle – Different frequency sounds stimulate different place in basilar membrane.

o Frequency principle – Different frequency sounds produce different rate of nerve firing.

· Which one is correct? – both

Skin senses

· Somatisensory system

o Spread throughout the body

o Not in one particular organ

Four types of sensation

· Warm

· Cold

· Pressure

· Pain

Pain

· Two fibers

o C – fiber – dull pain

o A-delta – sharp pain

· Both send impulse to spinal cord. Impulse then goes to brain.

· Pain messenger – Substance P

o Neurotransmitter

· Different degrees of pain activate different pain neurons.

Gate-control

· Pain could be modulated.

· “Gate” could be shut?

· Other input from the skin could take over the pathways in spinal cord. (Dentist hitting Hajmay because of nova cane)

Two natural analgesics

· Serotonin

· Endorphins

o Could be activated in many situations.

Interesting substance

· Capsaicin – stimulate receptors that respond to pain associated with heat

· Induce substance P’s release

· But, capsaicin release substance P faster than the neuron can resynthesize.

Gustatory sense

· Physical energy – Chemical

· Sense organ – Papillae on tongue (tastebuds inside the tongue)

· Only few tastes can be detected

o Sweet, sour, bitter, and salty

Olfactory sense

· Physical energy – Chemical molecules

· Sense organ – nose

· Receptors – olfactory bulbs

Controversy

· Pheromones

o Odors that sexually arouse opposite sex

o Used by many animals – vomeronasal organ

o For human – unknown