13: General and Special Senses

Two classes of Senses

General and Special

General Sense

Distributed throughout the body with receptor cells in the structures of other organs - temperature, pain, touch, stretch, and pressure

Special Sense

has a specific organ devoted to it - gustation, olfaction, vision, equilibrium and audition

Types of Receptors

Chemoreceptors, thermoreceptors, photoreceptors, mechanoreceptors, and nociceptors

General: Skin Receptors

Somatosensation pressure, and vibration; thermoreceptors detect temperature; and nocireceptors detect tissue damage

Heat Receptor/nociceptor

first arrow on left

Cold receptor/nociceptor

middle arrrow

Merkel cell-axon complex

arrow on far right

Pacinan Corpuscle

arrow bottom right - Deep pressure and vibration is transduced

Meissner Corpuscles

Top arrow on sode - Light touch is transduced

Ruffini corpuscles

middle arrow on side - Stretching of the skin is transduced

Hair follicle receptor - wrapped in a plexus of nerve endings that detect the movement of hair at the surface of the skin

General: Proprioceptors

found in the joints and muscles - They monitor the stretching of tendons, muscles, and the components of joints. 

In skeletal muscle tissue, stretch receptors are called…

Muscle spindles

In tendons, stretch receptors are called…

golgi tendon organs

What nerves innervate the tounge and gustation

Facial nerve (anterior 2/3) and Glossopharyngeal nerve (posterior 1/3)

Filiform papillae are not involved in the sense of taste and contain no taste buds, but help with texture and friction when licking or tasting food

Fungiform Papillae - containing few taste buds that are scattered

Foliate Papillae - contain taste buds that are only important during infancy

Circumvallate papillae - contain many taste buds

Taste Buds composition

barrel-shaped collections of cells that contain Gustatory Cells, supporting cells, and basal cells

Gustatory Cells

white part - Chemoreceptors that respond to the five basic tastes: salty, sour, sweet, bitter, and umami (replaced 7-10 days)

Basal Cells

the blobs - Immature cells, replace other two cell types

Olfactory receptor neurons

Made of chemoreceptors and bipolar neurons - supporting cells and basal cells

Where are Olfactory receptor neurons located?

Olfactory epithelium and contains bipolar sensory neurons

What can be recognized by olfactory receptor cells?

thousands of chemical stimuli

arrow on bottom

olfactory epithelium - contains bipolar sensory neurons - pass over the olfactory epithelial region and dissolve into the mucus and bind to proteins that keep them dissolved

arrow on top -

Olfactory Bulb - axons carry information to several brain regions

How many muscles are in the eyes?

6

eyebrows, eyelids, and eyelashes help what?

to protect the eye from abrasions by blocking particles that may land on the surface of the eye

superior rectus, medial rectus, inferior rectus, and lateral rectus

When each of these muscles contracts, the eye moves toward the contracting muscle. Ex- when the superior rectus contracts, the eye looks up.

superior oblique

contraction of the superior oblique rotates the eye medially

inferior oblique

When it contracts, it laterally rotates the eye

levator palpebrae superioris

elevating and retracting the upper eyelid

Conjunctiva

top arrow - Covers eyes anterior surface and internal eyelid surface

conjunctivitis

"pink eye" -  The eye appears pink because of the dilation of the blood vessels that are found in the conjunctiva

Lacrimal System

lacrimal glands, canaliculi, lacrimal sac, and nasolacrimal duct (bottom arrow is the duct)

Tarsal glands

sebaceous gland found within the eyelids that produce an oily secretion to keep tears in the eye and help prevent tear evaporation.

outermost layer is called and contents

fibrous tunic - Sclera and Cornea

Cornea

allows light to enter

middle layer is called and contents

Vascular Tunic - choroid, ciliary body, suspensory ligaments, and iris

Choroid

highly vascularized connective tissue that provides a blood supply to the eye

What do the Ciliary body and suspensory ligaments do?

bend the lens, allowing it to focus light on the back of the eye

Iris

the colored part of the eye that is a smooth muscle that opens or closes the pupil

pupil

hole at the center of the eye that allows light to enter

innermost layer is called and contents

Retina

retina

contains the nervous tissue responsible for photoreception

What part of the eye is filled with Aqueous humor?

Anterior and Posterior Chamber

What part of the eye is filled with Vitreous humor?

Vitreous Chamber

What are the cells responsible for detecting light?

photoreceptors (rods and cones)

Rods

green things - function in dim light - don’t provide sharp vision or color vision, more numerous than cones

Cones

blue things - Operate best in bright light, provide high acuity color vision

Optic Disc

Contains no rods or cones; axons exit the eye - blind spot

fovea centralis

divit - The exact center of the retina that contains only cones; maximal visual acuity

Macular Degeneration - Area around fovea degenerates

Cataracts - cloudy lens

Glaucoma - high pressure in eye hurts optic nerve

External Ear f

Auricle (pinna), External auditory canal, Ceremonious glands, and tympanic membrane

ceruminous glands

produce cerumen or earwax that cleans and waterproofs the canal, impeeding microorganism growth

tympanic membrane

or ear drum, which vibrates after it is struck by sound waves

Middle Ear Structures

Malleus, Incus, Stapes, Auditory tube, Stapedius muscle, roound and oval windows, tympanic cavity, and Tensor tympani muscle

Name the Ossicles in order from left to right

Malleus, Incus, and Stapes

auditory tube 

Connects air-filled middle ear to the nasoppharynx to equilibrate air pressure across the tympanic membrane - normally closed but will open during swallowing or yawning

Otitis Media

Infection of the middle ear - trapped fluid and mucus behind the eardrum

stapedius and tensor tympani

(Tensor - red ~ Stap - Gray) contract by reflex during loud sounds. Their action stiffens the ossicle chain, preventing overstimulation and damage of the delicate cells of the inner ear

Inner Ear Structures

Vestibule, Semicircular Canals, Cochlea, and Vestibular and Cochlear Nerves

Vestibule

Has two parts called the utricle and saccule, which detect linear acceleration and head position - helps sense equilibrium

Semicircular Canals

Detect rotational movements and help sense equilibrium

Cochlea

Detects sound waves

Oval Window (Middle Ear)

located at the beginning of a fluid-filled tube within the cochlea called the scala vestibuli

scala vestibuli

top space - containing perilymph (Cushions and protects inner-ear structures and transmit sound)

cochlear duct

middle scala - contains the sound-transducing neurons and Endolymph (clear fluid that helps w hearing and balance)

scala tympani

bottom scala - containing perilymph (Cushions and protects inner-ear structures and transmit sound)

round window

Where the scala tympani ends, which is covered by a membrane that contains the fluid within the scala

basilar membrane

middle bar - As the fluid waves move through the scala vestibuli and scala tympani,it moves depending on the frequency of the waves. Higher frequency waves move closer to the base of the cochlea. Lower frequency waves move near the tip of the cochlea.

hair cells and tectorial membrana

The stereocilia extend up from the hair cells to the overlying tectorial membrane. When the pressure waves move the basilar membrane, the tectorial membrane slides across the stereocilia. This bends the stereocilia, causing hair cells to send messages to sensory neurons within the vestibulocochlear nerve, which in turn, relays the information to the brain.

Gustation - Sensory Cell, Type of Receptor, and Cranial Nerves

Gustatory Cell, Chemoreceptor, and CN VII and CN IX (7 and 9)

Olfaction - Sensory Cell, Type of Receptor, and Cranial Nerves

Olfactory Neuron, Chemoreceptor, and CN I (1)

Vision - Sensory Cell, Type of Receptor, and Cranial Nerves

Rods and Cones, Photoreceptor, and CN II (2)

Audition - Sensory Cell, Type of Receptor, and Cranial Nerves

Cochlear Hair Cells, Mechanoreceptor, and CN VIII (8)

Equilibrium - Sensory Cell, Type of Receptor, and Cranial Nerves

Hair Cells, Mechanoreceptor, and VIII (CN 8)