SENSORY SYSTEM By: Kelley Tang & Bobbi Westendorf

RECEPTORS & SENSATIONS

Five types of receptors

Chemoreceptors Mechanoreceptors

Nociceptors Thermoreceptors Photoreceptors

RECEPTORS.

1. Must be a stimulus

2. Must detect the stimulus and create action potential

3. Action potential must be conductive to the central nervous system

4. Impulse must be translated into information

5. Must be interpreted in the CNS into an awareness or perception of the stimulus

GENERAL SENSES (SOMATIC SENSES)

- are those that are found throughout the body

* Touch

* Pressure

* Proprioception

* Temperature

* Pain

TOUCH & PRESSURE

Three of the receptors involved:

-Free never endings

-Meissner’s corpuscles

-Pacinian corpuscles

PROPRIOCEPTION

*Sense of position and orientation*

• -Golgi organs found at the junction of a tendon with a

muscle spindles located in the skeletal muscles are important

mechanoreceptors for proprioception

TEMPERATURE

-Thermoceptors are located immediately under the skin and

are widely distributed throughout the body

-10x more cold receptors in a given area than heat

receptors

-initiated by nociceptors which are free nerve endings

- -No pain receptors in the nerve tissue of the brain

PAIN

GUSTATORY SENSE

-one of the special senses

-(Taste buds) are localized in the mouth region, primarily on the surface of the tongue

-Receptors belong in the Chemoreceptor category

*four different taste sensations*• Salty • Sweet • Sour • Bitter

OLFACTORY SYSTEM

- bipolar neurons surrounded by supporting columnar epithelial cells in the olfactory epithelium of nasal cavity

-Chemoreceptors

-stimulated by chemicals dissolved in liquids

- part of what we “taste” is really smell, part of what we “smell” is what we taste

VISUAL SENSE

- - most consider vision to be one of the most important senses

- -photoreceptors

- * Protective features and Accessory structures of the Eye*

- -Eyebrows

- -orbicularis oculi

- -elevator palpebrae superioris

- -Eyelashes

- -sebaceous glands

- -stye

- -lacrimal apparatus, gland, ducts, sac

- -nasolacrimal duct

-

VISUAL SENSE

*structure of the Eyeball*

AUDITORY SENSE

-the ear is the organ of hearing (auditory or acoustic organ)

-mechanoreceptors

-divided into the external, inner, and outer ear

*external ear*

auricle

External auditory meatus

Ends at the tympanic membrane

*middle ear*

Mallaus

Incus

Stapes

*inner ear*

Bony labyrinth

Vestibule

Semicircular canals

cochlea

AUDITORY SENSE

*physiology of hearing*

-initiation of impulses

-pitch and loudness

-auditory pathway

SENSE OF EQUILIBRIUM

*a combination of two different senses*

-static equilibrium : occurs when the head is motionless or moving in a straight line

-dynamic equilibrium: is in response to rotational or angular movement

The receptors for static equilibrium are located in the bony vestibule of the inner ear – this nerve

This nerve transmits the impulses to the cerebral cortex

QUIZ

1. Which of the following is NOT a general sense? A. Taste B. Touch C. Pressure D. Pain

ANSWER

D. Pain Pain is not a general sense because the general senses are touch, taste, smell, site, and sound. The organs that are related to these senses include the skin, tongue, nose, eyes, and ears. Pain is not a sense, it is something that can be felt on these organs using these senses.

QUIZ (CONTINUED)

2. Damage to which cranial nerve will interfere with the sense of taste from the tip of the tongue?

ANSWER

There are three cranial nerves involved in taste, this includes the Facial Nerve, the Glossopharyngeal Nerve, and the Vagus Nerve. These nerves all carry information from the back of the tongue or the front of the tongue.

QUIZ (CONTINUED)

3. In what lobe of the brain is the sense of smell interpreted?

a. Temporal Lobe

b. Frontal Lobe

c. Occipital Lobe

d. Parietal Lobe

ANSWER

A. Temporal Lobe The lobe of the brain that controls smell is the temporal lobe. The temporal lobe receives impulses from the olfactory bulb at the top of the nasal sinus, and then it interprets it as smell.

QUIZ (CONTINUED)

4. Dr. Ike Ular, a ophthalmologist, suspects that his patient might have glaucoma. One of the tests he performed was to pleasure the pressure in the anterior cavity of the eye. The fluid in this cavity is…

a. endolymph

b. vitreous humor

c. aqueous humor

d. perilymph

ANSWER

C. Aqueous Humor

The fluid in this cavity is called “Aqueous Humor”. This is the correct answer because Aqueous Humor is a transparent, gelatinous fluid similar to plasma; it fills the space between the cornea and the iris – in the anterior chamber. Since it is filled in the anterior chamber, this is the correct answer because the doctor involved in the question performed his test in the anterior.