Lab 13: General Senses & Special Senses

Sensory receptors are either

Specialized cells or dendrites of a sensory neuron

Receptors of the general senses respond to

Chemicals, temperature, & mechanical deformation

Action potentials that reach the cerebral cortex are interpreted as

Sensations (conscious preception)

Action potentials that are interpreted in the spinal cord or brain stem causes a

Reflex response (not conscious perception)

What are the somatic sensations?

Tactile, thermal, pain, proprioception

The somatic sense receptors are located in the

Skin (cutaneous sensations) or in muscles, tendons, or joints

The visceral receptors sense

Stretch, chemicals, & pressure

The visceral sense receptors are found in

The internal organs

What bare dendrites receive somatic sensations?

Free nerve endings & encapsulated

Tactile corpuscles detect

Touch & low vibrations

Hair root plexus detect

Movement that disturb hair

Nonencapsulated sensory corpuscles detect

Pressure & continuous touch

Bulbous corpuscles detect

Stretching & steady pressure

Lamellar corpuscles detect

Steady pressure & high vibrations

Free nerve endings detect

Certain chemicals; itch & tickle

Sensory receptors for olfaction are located in

Olfactory epithelium (chemoreceptors)

How does an odorant molecule be smelled?

Diffuse through air into our nose, dissolve in mucus to stimulate olfactory cilia (dendrites)

The olfactory sensory neurons synapse in the

Olfactory bulbs in the crista galli

Why do you think a cold or allergies affect your sense of smell?

Because colds or allergies can cause congestion in the nose

What are the olfactory tracts/bulbs & what is the function?

Bulbs are the olfactory sensory neurons & tracts extend from the bulbs, they receive input regarding odors

What is the ethmoid bone and what is the function?

Located in the center of the skull, forms nasal cavity & orbital cavity

What is the cribriform plate and what is the function?

Forms roof of nasal cavity, transmits olfactory nerves

What is the nasal cavity and what is the function?

Space above/behind the nose, moistens nose with mucus, filters & blocks substances from entering respiratory tract

What is the olfactory gland & mucus and what is the function?

Supports olfactory epithelium, produce mucus that is carried to the surface of epithelium by ducts; dissolves odorants for transduction

What is an olfactory sensory neuron?

Bipolar neuron, dendrite & axon in cribriform plate

Where are sensory receptors for gustation located?

Taste buds on the tongue. soft palate, pharynx, epiglottis (chemoreceptors)

Where are taste buds located?

On the sides of elevated areas of the tongue; lingual papillae

Taste buds contain around 50…

Gustatatory epithelial cells

Each gustatory epithelial cell has a single hair called

Gustatory microvilli

Where do gustatory microvilli project too?

Taste pores

Name three cranial nerves that transmit sensory information from the taste buds to the brain

Facial nerve, glossopharyngeal nerve, vagus nerve

Which sense, taste or smell, appears to be more important in the proper identification of a strong substance?

Smell; the smell tricks us into thinking that we are tasting that substance because they are connected in the same airway (nasopharynx)

What are the 2 types of receptors in the retina?

Rods & cones

The eye is protected by

Eyelids, eyelashes, eye brows, & tear ducts/glands

What is the lacrimal gland?

Releases fluid that cleanses & protects the eyes surface; lubricates & moistens

What is the lacrimal drain?

Drains the tears from the eyes surface to the nasal cavity

What is the eyelid?

Upper & lower folds of skin that cover the eye

What is the pupil?

The black center of the eye; lets light in and focus on the retina

What is the iris?

Colored part of the eye; controls the amount of light entering the eye by closing/opening the pupil

What is the sclera?

The white part of the eye, protective covering

What is the superior rectus?

Oculomotor (III); moves eyeball superiorly, medially, & rotates medially

What is the inferior rectus?

Oculomotor (III); moves eyeball inferiorly, medially, & rotates laterally

What is the medial rectus?

Oculomotor (III); moves eyeballs medially

What is the lateral rectus?

Abducens (VI); moves eyeballs laterally

What is the superior oblique?

Trochlear (IV); moves eyeball inferiorly, laterally, & rotates medially

What is the inferior oblique?

Oculomotor (III); moves eyeballs superiorly, laterally, & rotates laterally

What is the function of the ciliary muscle?

Changes shape of lens to focus on a near object

What is the function of the ciliary process?

Secrete aqueous fluid

What is aqueous humor?

Water-like fluid in front of the lens

What is the anterior chamber?

Front of eye; cornea & iris

What is the posterior chamber?

Between the iris & lens

What is the cornea?

Transparent part of eye covering iris & pupil allowing light to enter

What is the lens?

Biconvex structure behind the iris; focus light rays onto retina

What is the zonular fibers of lens?

Connects the lens of the eye to the ciliary body

What is the bulbar conjunctiva?

The covering over your eyeball that protects the white of the eye

What is the retina?

Light sensitive layer of tissue at the back of the eyeball; converts images to electric signals

What is the choroid?

Layer of blood vessels and connective tissue between white of the eye and retina

What is the fovea centralis

At the back of the retina, responsible for high-acuity vision

What is the optic disc?

On retina, transfers photoreceptors to the optic nerve; “blind spot”, no light-sensitive cells

What is the optic nerve?

Sends visual messages to your brain from the photoreceptors

What is vitreous humor?

Gel-like substance between lens & retina

Cones are photoreceptors involved in

Visual acuity & color

Rods are photoreceptors involved in

Low light conditions

Visual acuity refers to

The ability to see objects at various distances

How is visual acuity tested

Snellen Eye Chart

Emmetropia is

20/20 vision

Myopic is

20/100 - nearsighted

Hyperopic is

20/15 - farsighted

Color-blindness results from

An absence in a photopigment in the cones

Astigmatism results from

Irregular curvature of the cornea or lens

Where are sound waves funneled into?

External acoustic meatus

The external acoustic meatus causes

Tympanic membrane to vibrate

What are the auditory ossicles & what do they do?

Amplify vibrations; malleus, incus & stapes

After the auditory ossicles, sound is passed on to

Vestibular window

Vestibular window causes pressure waves by fluid inside

Cochlea, perilymph, & endolymph

What causes a receptor potential in the ear?

Pressure waves moving basilar hair cells

Where do nerve impulses regarding hearing travel?

Cochlear branch

How is pressure released?

Cochlear window

In the ear, what houses receptors for equilibrium?

Semi-circular canals

How is information from the semi-circular canals (equilibrium) transferred to the brainstem/cerebellum?

Vestibular branch

What are semicircular canals

Canals in the inner ear to keep your balance

What are semicircular ducts

Contain endolymph & surrounded by perilymph

What is the ampulla?

In each semicircular canal; houses sensory epithelium

What is the macula?

In utricle & saccule, contains receptors for linear de/acceleration & head tilt

What is the scala media?

Cavity in cochlea filled with endolymph

Is there a relationship between the receptor density of an area and the size of the cerebral cortex receiving information from those receptors?

The greater the density of tactile receptors in a body area, the greater the area of cerebral cortex receiving information from these receptors