19 D Special Senses Flashcards
Is the receptor for dynamic equilibrium
Is located in the ampulla of each semicircular canal
Responds to angular movements
crista ampullaris (or crista)
Each crista has support cells and hair cells that extend into a gel-like mass called the
cupula
Three canals that each define two-thirds of a circle and lie in the three planes of space
Membranous semicircular ducts line each canal and communicate with the utricle
The ampulla is the swollen end of each canal and it houses equilibrium receptors in a region called the crista ampullaris
These receptors respond to angular movements of the head
The Semicircular Canals
jellylike mass studded with tiny CaCO3 stones called otoliths
Otolithic membrane
The central egg-shaped cavity of the bony labyrinth
Suspended in its perilymph are two sacs: the saccule and utricle
1. Saccule extends into the cochlea
2. Utricle extends into the semicircular canals
These sacs:
House equilibrium receptors called maculae
Respond to gravity and changes in the position of the head
The Vestibule
A spiral, conical, bony chamber that:
Extends from the anterior vestibule
Coils around a bony pillar called the modiolus
Contains the organ of Corti (hearing receptor)
The Cochlea
The cochlea is divided into three chambers
- Scala vestibuli
- Scala media (cochlear duct)-contains the Organ of Corti
- Scala tympani
Series of membranous sacs within the bony labyrinth
Filled with a potassium-rich fluid
Membranous labyrinth
Tortuous channels worming their way through the temporal bone
Contains:
Cochlea-hearing
Vestibule- head tilt and acceleration motion
Semicircular Canals-rotational and acceleration motion
Filled with perilymph
Bony labyrinth
The tympanic cavity contains three small bones
Malleus
Incus
Stapes
Loud sounds are dampened by two muscle
tensor tympani and stapedius muscles
Thin connective tissue membrane that vibrates in response to sound
Transfers sound energy to the middle ear ossicles
Boundary between outer and middle ears
Tympanic membrane (eardrum)
Short, curved tube filled with ceruminous glands
External auditory canal
The auricle (pinna) is composed of:
The helix (rim)
The lobule (earlobe)
Respond only in bright light
Have high-acuity color vision
Are found in the macula lutea
Are concentrated in the fovea centralis
Cones: (blue, red, green)
Respond best in dim light
Are used for peripheral vision
Allow us to see black/white
Rods:
contains:
Photoreceptors
a. Rods- allow you to see black/white and in dim light.
b. Cones- allow you to see color when you have bright light.( only works when plenty of light)
Neural layer
the outer layer that absorbs light and prevents its scattering
Pigmented layer
The colored part of the eye
Pupil – central opening of the iris
Regulates the amount of light entering the eye during:
Close vision and bright light – pupils constrict
Distant vision and dim light – pupils dilate
Changes in emotional state – pupils dilate when the subject matter is appealing or requires problem-solving skills (sympathetic stimulation)
Iris
A thickened ring of tissue surrounding the lens
Composed of smooth muscle bundles (ciliary muscles)
Anchors the suspensory ligament that holds the lens in place
Ciliary Body
A dark brown membrane that forms the posterior portion of the uvea
Supplies blood to all eye tunics
Choroid region
- Vascular Tunic (Uvea) Has three regions:
- Choroid
- Ciliary body
- Iris
clear(anteriorly)
-lets light enter the eye
Cornea
opaque (posteriorly)
-protects the eye and anchors extrinsic muscles
Sclera
Structure of the Eyeball
A slightly irregular hollow sphere with anterior and posterior poles
The wall is composed of three tunics –
1. Fibrous-outer
2. Vascular -middle
3. Sensory-inner
The internal cavity is filled with fluids called humors (Vitreous and Aqueous)
The lens separates the internal cavity into anterior and posterior segments
a. Enable the eye to follow moving objects
b. Maintain the shape of the eyeball
Six straplike extrinsic eye muscles
secrete tears
Tears
1. Contain mucus, antibodies (defensin), and lysozyme
2. Enter the eye via superolateral excretory ducts
3. Exit the eye medially via the lacrimal punctum
4. Drain into the nasolacrimal duct
Lacrimal glands
Transparent membrane that:
Lines the eyelids as the palpebral conjunctiva
Covers the whites of the eyes as the ocular conjunctiva
Lubricates and protects the eye
Conjunctiva
contains glands that secrete a whitish, oily secretion (Sandman’s eye sand)
Lacrimal caruncle
Protect the eye anteriorly
Palpebral fissure – separates eyelids
Canthi – medial and lateral angles (commissures)
Palpebrae (Eyelids)
move the eyebrows medially (What you talking about Willis?)
Corrugator muscles
depresses the eyebrows (I’m sorry)
Orbicularis muscle
Coarse hairs that overlie the supraorbital margins
Functions include:
1. Shading the eye
2. Preventing perspiration from reaching the eye
Eyebrows
70% of all sensory receptors are in the eye
Most of the eye is protected by a cushion of fat and the bony orbit
Accessory structures include
- Eyebrows
- Eyelids
- Conjunctiva
- Lacrimal apparatus
- Extrinsic eye muscles
send impulses to:
The olfactory cortex just above the orbits.
The hypothalamus, amygdala, and limbic system exhibit emotional response to smell) ex. Smoke , gas, or skunk –stimulate the sympathetic system where as appetizing odors stimulate para sympathetic (salivation)
Mitral cells
Influence of Other Sensations on Taste
Taste is 80% smell
Thermoreceptors, mechanoreceptors, nociceptors also influence tastes
Temperature and texture enhance or detract from taste
We can smell over 1000 different odors
taste sensation elicited by the amino acid glutamate
Umami
taste sensation alkaloids (base) such as quinine and nicotine
Bitter
taste sensation- hydrogen ions (acid)
Sour
taste sensation- metal ions
Salt
taste sensation- sugars, saccharin, alcohol, and some amino acids
Sweet
taste cells
Gustatory cells
dynamic stem cells
Basal cells
insulate the receptor
Supporting cells
Taste buds are found in papillae of the tongue mucosa
Papillae come in three types:
filiform, fungiform, foliate and circumvallate
to substances dissolved in fluids of the nasal membranes
Smell
to substances dissolved in saliva
Taste
Chemical senses
gustation (taste) and olfaction (smell)
