Senses: General and Special

Anatomy P110/J.Wiens Porterville College

Senses: General and Special

I. Two Divisions

1. General Senses -

2. Special Senses –

Stimuli – changes in the

Receptors –

Tonic Receptors –

Phasic Receptors – detect stimuli, then can undergo

II. Classification of Receptors

1. Stimulus Origin

Exteroceptors – detect stimulation from

Interoceptors – detect stimuli from

Proprioceptors – detects

(Located in joints, muscles, and tendons)

2. Modality of Stimulus

Chemoreceptors – sensitive to

Thermoreceptors – sensitive to

Photoreceptors – sensitive to

Mechanoreceptors – mechanical stimuli from

Baroreceptors – sensitive to pressure change within

Nociceptors – sensitive to

Phantom Pain – example:

Referred Pain – example:

Pain from internal organs is interpreted elsewhere as superficial pain.

III. General Senses

Tactile Receptors

1. Free nerve endings

touch –

root hair plexus –

pain –

temperature – thermoreceptors for heat -

thermoreceptors for cold -

2. Tactile discs (Merkel)

3. Krause Bulbs (found in mouth, nasal cavity)

4. Pacinian (Lamellated) corpuscle – Located deeper in dermis. Larger structure lamellated with CT.

5. Ruffini Corpuscle –

6. Meissner (Tactile) Corpuscle – Small CT structure in papillary layer of dermis.
Numerous in lips and fingertips.

Special Sense Receptors - Olfactory (smell), Gustatory (taste), Eye (vision), Ear (hearing)

IV. Olfactory Receptors

a) Chemoreceptors stimulated by

b) Located in the

c) Olfactory receptors are neurons with

d) Can be

V. Gustatory Organs

a) Taste buds are on the ________ of papillae. The “onion” has a

b) Five taste sensations:

VI. The Eye

1. Accessory Structures

(A) Eyelid

(B) Conjunctiva – the thin membrane that covers

2. Structure of Eyeball

A. Fibrous tunic

Sclera – ____________ of the eye
Protective covering to which

Optic nerve –

Cornea – ____________ of the eye.

______________light rays. Clear, made of C.T. and few cells.

B. Vascular tunic

Choroid – Brownish-black in color.

Ciliary body – ______________ _______ ___ __________ that helps hold lens

Iris –

Brown eyes -

Blue eyes -

Radial muscle –

Circular muscle -

Lens –

Held in place by suspensory ligaments.

Accommodation

For close-up viewing – When ciliary body _____________, the “ring” becomes ______________, the suspensory ligaments ____________, and the lens naturally ____________. For distance viewing – opposite of above.

Why we need glasses or bifocals as we get older:
Lens thickens with age and becomes less resilient. It is not able to spring out to the more spherical shape needed for close-up vision. So our lens is too ___________ to read clearly and we need to thin it out…How? Hold reading farther away or get reading glasses.

Also see page _____.
Near-sighted means you can only see clearly ___________. This occurs because your eyeball becomes

too __________. Your glasses need to have _____________ lenses to spread the light rays.

Far-sighted means you can only see clearly _______________. This occurs because your eyeball becomes too __________. Your glasses need to have ____________ lenses to focus light rays.

Aqueous humor- _______________________________ that maintains the shape of the eyeball.

C. Neural tunic

Retina contains rods and cones.

Rods Cones

Macula lutea – this area has the ________ ____________. (Area of _____________ _________.) Optic disc – where ________ __________ from rods and cones turns backward and _________ the eye.

X O

Vitreous humor – ________, _____________ ________ in the posterior cavity that helps maintain

the shape of eye

VII. The Ear

1. Outer ear

A. Auricle –

B. External auditory canal – guarded by hairs and has _____________ ________ which help keep out

insects and dust.

C. Tympanic membrane

2. Middle ear

A. Tympanic cavity

B. Ossicles

C. Muscles – attach to ossicles.
Function -

3. Inner ear

The labyrinth includes the

A. Vestibule – organ of ____________ __________________.

Consists of a ______________ and ________________ that each have a _______________

containing ________________ in a _________________ _________________. Tilting of the

head causes membrane to shift on the macula, which causes _________________ of the

stereocilia and kinocilium on the hair cells.

B. Semicircular canals – organ of ___________ _________________.

Three canals – all at right angles to each other.

Each contains an ___________ which contains an elevated _________ ___________ which

contains stereocilia. On top is a gelatinous dome called the ___________. When moving, the

inertia of endolymph causes the cupula to bend, which causes the stereocilia to bend, which

sends ____________ to the brain.

C. Cochlea – organ of __________________

Snail –shaped, fluid-filled structure.

______________ of stapes against the _______ __________ produces pressure waves.

__________________ (also called the Spiral Organ) is the specific organ of ____________.

D. Use the lab and textbook to memorize the anatomy of the cochlea and be able to describe how

sound waves move through the different parts.

E. Look closely at the spiral organ and be able to explain why we hear sound.