Chapter 17 Flashcards
Olfaction
Sense of smell
located in epithelium of the nose
total area of 5 cm²
Olfactory epithelium
Occupies the superior part of the nasal cavity, inferior surface of the cribriform plate, and extending along the superior nasal concha
What are the three cells of the olfactory epithelium?
- Olfactory receptor cells
- Supporting cells
- Basal cells
Olfactory receptor cells
First order neurons of the olfactory pathway
bipolar neuron with an expose knob shaped dendrite
axon projecting through the cribriform plate that ends in the olfactory bulb
Olfactory cilia
Extends from the dendride of an olfactory receptor cell and is the site of olfactory transduction
Olfactory receptor
Located in the plasma membranes of the olfactory cilia
proteins that detect inhaled chemicals
Odorants
The chemicals that stimulate the olfactory receptors in the olfactory cilia
Supporting cells
Columnar epithelial cells of the mucus membrane lining the nose
provide physical support, nourishment, and electrical insulation for the old factory receptor cells
detoxify chemicals that come in contact with the olfactory epithelium
Basal cells
Stem cells located between the bases of the supporting cells
continually undergo cell division to produce new old factory receptor cells which live for two months
Olfactory glands or Bowmans glands
Produce mucus that is carried to the surface of the epithelium by ducts
moistening the surface of the olfactory epithelium
dissolves odorants so that transduction can occur
Olfactory transduction
When a receptor potential (depolarization) develops and triggers one or more nerve impulses
Gustation
Taste
What are the five primary taste?
- Salty
- Sour
- Sweet
- Bitter
- Umami
What is the taste salty caused by?
Sodium
What is the taste sour caused by?
Hydrogen ions
What is the taste sweet caused by?
Glucose, fructose, sucrose, aspartame, Saccharin, and sucralose
What is bitter taste caused by?
Wide variety of substances including caffeine, morphine, quinine, and many poisons
What is umami taste caused by?
Meaty or savoury caused by amino acids
What is the shape of a taste bud and what three cells are they consisted of?
Oval body containing supporting cells, gustatory receptor cells, and basal cells
In each taste bud how How many gustatory receptors cells are surrounded by a supporting cell?
50 Gustatory receptor cells
What and where are the gustatory microvilli?
Project from each gustatory receptor cell to the external surface through the taste poor
Taste pore
An opening in the taste bad
Basal cell of taste bud
Stem cells found at the perphery of the Tastebud near the connective tissue layer
produce supporting cells which develop into gustatory receptors cells every 10 days
Papillae of tastebuds
Taste buds are found in elevations on the tongue called papillae
They increase surface area and provide a rough texture to the upper surface of the tongue
What are the three papillae types that contain taste buds?
- Vallate papillae
- Fungiform papillae
- Foliate papillae
Vallate papillae
12 very large circular papillae form an inverted V shape row at the back of the tongue
housing 100 to 300 taste buds
Fungiform papillae
Mushroom shaped elevation scattered over the entire surface of the tongue
contain about five taste buds each
Foliate papillae
Located in small trenches on the lateral margins of the tongue
most of their taste buds degenerate in early childhood
Filiform papillae
Entire surface of the tongue
pointed thread like structures contain tactile receptors but no taste buds
increase friction between the tongue and food making it easier for the tongue to move food in the oral cavity
Tastants
Chemicals that stimulate gustatory receptors cells
Are all Receptor potential’s the same for different tastant?
No
How do you receptor potential’s arise for tastant other than salty and sour?
G proteins activate enzymes that produce the second messenger Inositol triphosphate which intern ultimately causes depolarization of the gustatory receptor cell and release of neural transmitter
Ophthalmology
The science that deals with the eyes and their disorders
Electromagnetic radiation
Energy in the form of waves that radiates from the sun
Electromagnetic spectrum
The range of electromagnetic radiation
Visible light
Part of the electromagnetic spectrum with wave length ranging from about 400 to 700 nm
Visible light exhibits colours depending on its wavelength
What are the accessory structures of the eye?
Eyelids, eyelashes, eyebrows, lacrimal apparatus, extrinsic eye muscles
What is the superior region of the upper eyelid?
Levatorpalpebrae superioris
What is the space between the upper and lower eyelid that exposes the eyeball?
Palpebral fissure
What are the angles of the palpebral fissure known as?
Lateral commisure
Medial commisure
What is contained in the lacrimal caruncle of the medial Commisure?
Sebaceous oil glands and sudoriferous sweat glands
What is the tarsal plate of the eyelid?
A thick fold of connective tissue that gives form and support to the eyelids
What is the embedded role of elongated, modified sebaceous glands on each tarsal plate known as?
Tarsal glands or meibomian glands
Conjunctiva
A thin protective mucous membrane composed of nonkeratinized stratified squamous epithelium with numerous goblet cells that is supported by areolar connective tissue
Palpebral conjunctiva
Lines the inner aspect of the eyelids
Bulbar conjunctiva
Passes from the eyelids onto the surface of the eyeball where it covers the sclera but not the cornea
over the sclera the conjunctiva is vascular
Sebaceous ciliary glands
Found at the base of the hair follicles of the eyelashes
release a lubricating fluid into the follicles
infection can cause a sty
Lacrimal apparatus
Group of structures that produce and drain Lacrimal fluids or tears in a process called lacramation
Lacrimal glands
The size and shape of an almond
secrete Lacrimal fluid and drains into 6 to 12 excretory lacrimal ducts
that empty tears onto the surface of the conjunctiva of the upper lid then pass over the eye and enter two small openings called lacrimal puncta
What’s an infection of the lacrimal sacs called?
Dacryocystitis
What is the lacrimal fluid contain?
Watery solution containing salts mucus and lysozyme
Periorbital fat
Located in the boney orbit around extrinsic eye muscles
What do the six extrinsic eye muscles do?
Move the eye in almost every direction
Adult eyeball
Measures 2.5 cm in diameter
only anterior 1/6 is exposed
consists of three layers
What are the three layers of the wall of the eyeball?
- Fibrous tunic
- Vascular tunic
- Retina (inner tunic)
Fibrous tunic
Superficial layer of the eyeball
consist of the anterior cornea and posterior sclera
Cornea
A transparent coat that covers the coloured iris
because it’s curved the cornea helps focus light onto the retina
the outer surface consist of nonkeratinized stratified squamous epithelium
the middle coat consists of collagen fibres and fibroblasts
inner surface is simple squamous epithelium
Sclera
White of the eye
a layer of dense connective tissue made up of mostly collagen fibres and fibroblast
covers the entire eyeball except the cornea
gives shape to the eyeball, makes it more rigid, protects its inner parts and serves as a side of attachment for the extrinsic eye muscles
Sclera venous sinus or canal of schlemm
Located at the junction of the sclera and cornea an opening filled with aqueous humour fluid
Vascular tunic
Middle layer of the eyeball composed of choroid, ciliary body, and Iris
Choroid
Highly vascularized posterior portion of the vascular tunic
lines most of the internal surface of the sclera
provides nutrients to the posterior surface of the retina and also contains melanocytes which absorbs stray light rays; preventing reflection and scattering of light within the eyeball
Ciliary body
Anterior portion of the vascular tunic
extends from the ora serrata to a point posterior to the junction of the sclera and cornea
appears dark brown in colour
consists of ciliary processes and ciliary muscle
Culinary processes
Protrusions or folds on the internal surface of the ciliary body
contain blood capillaries that secrete aqueous humour
Zonular fibers of eyeball
Extend from the ciliary process also called suspensory ligament
attach to the lens
fibres consist of thin Hollow fibres that resemble elastic connective tissue fibres
Ciliary muscle of eyeball
Circular band of smooth muscle changes the tightness of the zonular fibres which alters the shape of the lens
Iris
Coloured portion of the eyeball shaped like a flatten doughnut
suspended between the cornea and the lens and is attached at its outer margin to the ciliary process
consisting of melanocytes and circular and radial smooth muscle fibres
Regulates the amount of light going through the pupil
Pupil
Whole in the centre of the iris, autonomic reflexes regulate pupil diameter in response to light levels
Circular muscles of pupil
Or sphincter papillae, When bright lights stimulates the eye the iris contracts causing a decrease in the size of the pupil
Radial muscles of pupil
Dilator papillae, In dim light sympathetic neurons stimulate the iris to contract causing an increase in pupil size
Retina
Inner layer of the eyeball lines the posterior 3/4 of the eyeball and is the beginning of the visual pathway
What are the different layers of the retina?
Optic disc - where the optic nerve exits the eyeball
central retinal artery
central retinal vein
pigmented layer
neural (sensory) layer - which processes visual data before sending nerve impulses into axons
What are the three distinct layers of the retinal neurons?
Photo receptor cell layer, bipolar cell layer, and ganglion cell layer which are separated by two zones the outer and inner synaptic layers
What are the other two types of cells present in the bipolar cell layer of the retina?
Horizontal cells and amacrine cells, Which form laterally directed neural circuits that modify the signals being transmitted along the pathway from photo receptors to bipolar cells to ganglion cells
Rods of eyeballs
Allow us to see in dim light such as moonlight, do not provide colour vision
Cones of eyeball
Brighter light stimulate these which produce colour vision
three types of cones are present in the retina: blue cones, green cones, red cones
Blind spot of eyeball
Optic disc, Contains no rods or cones we cannot see images that strikes the Blindspot
Macula lutea of eyeball
Yellow spot, is in the exact centre of the posterior portion of the retina at the visual axis of the
Fovea centralis
A small depression in the centre of the macula lutea contains only cones
The layers of bipolar and ganglion cells which scatter light do not cover the cones here
area of highest visual acuity
Lens
Behind the pupil and Iris within the cavity of the eyeball contains proteins called Crystallins
Helps focus images on the retina to facilitate clear vision
Crystallins
Within the cells of the lens
proteins arranged like the layers of an onion make up the refractive media of the lens
normally perfectly transparent and lacks blood vessels
The lens divides the interior of the eyeball into what two cavities?
Anterior cavity and vitreous chamber
Anterior cavity of eyeball
Consists of two chambers
anterior chamber between the cornea and Iris
posterior chamber lies behind the Iris and in front of the Zonular fibres and lens
both are filled with aqueous humour
Vitreous chamber
Largest posterior cavity of the eyeball
lies between the lens and the retina
contains the vitreous body and hyaloid canal
Vitreous body of the eyeball
A transparent jelly like substance that holds the retina flush against the cordoid giving the retina an even surface for the reception of clear images
Hyaloid canal
A narrow channel that is inconspicuous in adults and runs through the vitreous body from the optic disc to the posterior aspect of the lens occupied by the hyaloid artery
Refraction
When light rays travelling through transparent substance pass into a second transparent substance with a different density they bend at the junction between the two substances
Images focussed on the retina or what?
Inverted (upside down)
Accommodation
The increase in curvature of the lens for near vision
Nearpoint of vision
The minimum distance from either an object can be clearly focussed with maximum accommodation
Convex
A surface that curves outward, like the surface of a ball
Concave
Surface the curves inward, like the hollow of a ball
Myopia
Nearsightedness, occurs when the eyeball is too long relative to the focussing power of the cornea and lens or when the lenses thicker
Hyperopia
Farsightedness or hypermetropia, The eyeball length is short relative to the focussing power of the cornea and lens or the lenses thinner can see distant objects clearly but not close ones
Astigmatism
Either the cornea or the lens has an irregular curvature as a result parts of the image are out of focus or vision is blurred or distorted
Constriction of the pupil
Narrowing of the diameter of the hole through which light enters the eye due to the contraction of the circular muscles of the iris
Convergence
Refers to medial movement of the two eyeballs so that both are directed towards the object being viewed
Binocular vision
When both eyes focus on only one set of objects
How are rods and cones named?
Due to the different appearances of the outer segment
Does the transduction of light energy into receptor potential occurs in the outer segment of both rods and cones?
Yes
What does the inner segment of photo receptors (rods and cones) contain?
Cell nucleus, Golgi complex, and many mitochondria
at the proximal end photo receptors expand into bulblike synaptic terminals filled with synaptic vesicles
Photo pigment
The coloured protein that undergoes structural changes when it absorbs light in the outer segment of a photo receptor
Rhodopsin
The single type of photo pigment in rods
What are the three different cone photo pigments that are present in the retina?
Blue cones, green cones, and red cones
Photo pigments associated with vision contain what two parts?
Glycolprotein known as opsin and a
derivative of vitamin A called retinal
What are the four ways photo pigments respond to light?
- Isomerization
- Bleaching
- Conversion
- Regeneration
Isomerization
When cis retinal absorbs a photon of light it straightens out to a shape called trans retinal
Bleaching
In about a minute trans retinal completely separate from opsin. retinal is responsible for the colour of the photo pigment so the separation of trans retinal from opsin causes opsin to look colourless because of the colour change this is part of the cycle is term bleaching
Conversion
An enzyme called retinal isomerase converts trans retinal back to sis retinal
Regeneration
The cod-retinal then combine to opsin, reforming a functional photo pigment
Photo transduction
The process by which light energy is converted into a receptor potential in the outer segment of a photo receptor
Otorhinolaryngology
The science that deals with the ears, nose, pharynx, and larynx and their disorders
What are the three main regions of the ear?
- External ear, which collect sound waves and channels them in word
- Middle ear, which convey sound vibrations to the oval window
- Internal ear, which houses the receptors for hearing and equilibrium
What are the different parts of the external ear?
Auricle, external auditory canal, and eardrum
Auricle or pinna
Flap of elastic cartilage shaped like the flared end of a trumpet and covered by skin
the rim of the oracle is the helix the inferior portion is the lobule
External auditory canal of the outer ear
A curved tube about 2.5 cm long that lies on the temporal bone and leads to the eardrum
Tympanic membrane or eardrum
A thin semi transparent partition between the external auditory canal and middle ear covered by epidermidis and lined by simple cuboidal epithelium
tearing of the tympanic membrane is called a perforated eardrum
Ceruminous glands
Specialized sweat glands that secrete earwax or cerumen
Middle ear
A small air filled cavity in the petrous portion of the temporal bone that is line by epithelium
separated from the external ear by the tympanic membrane and from the internal ear by a boney partition that contains two small openings the oval window and the round window
attached to it is the auditory ossicles
What are the auditory ossicles?
Malleus, incus, stapes
Tensor tympani
Women’s movement and increases tension on the eardrum to prevent damage to the inner ear from loud noises
Stapedius
Supplied by the facial nerve
the smallest Skeletal muscle in the human body
Decreases the sensitivity of hearing
Hyperacusia
Abnormally sensitive hearing
Auditory tube or Pharyngotympanic tube
Commonly known as the eustachian tube
consists of both bone and elastic cartilage
connects the middle ear with the nasal pharynx and is normally closed at its medial end
during swallowing and yawning it opens allowing air to enter or leave the middle ear
Internal (inner) ear
Also called the labyrinth
consists of two main divisions outer boney labyrinth an inner membraneous labyrinth
Boney labyrinth
Consists of three areas: the semi circular canals, the vestibule, and the cochlea
lined with Periosteum and contains perilymph
Perilymph
Chemically similar to cerebrospinal fluid surrounds the membraneous labyrinth
Membraneous labyrinth
A series of epithelial sacks and tubes inside the boney labyrinth that have the same general form as the bon labyrinth in house the receptors for hearing an equilibrium and contains endolymph
Vestibule
Ovals central portion of the boney labyrinth
What are the two sacs called in the membraneous labyrinth in the vestibule?
Utricle and saccule
The vestibular branch of the vestibulocochlear nerve consist of what three nerves?
Ampullae, utricular, and saccular nerves
Spiral organ
Coiled sheet of epithelial cells including supporting cells in about 16,000 hair cells which are receptors for hearing
What are the two groups of hair cells?
Inner hair cells are arranged in a single row where is the outer hair cells are arranged in three rows
What is at the apical tip of each hair cell?
Stereocilia That extends into the endolymph of the cochlear duct
Where are the cell bodies of the sensory neurons located in the ear?
Spiral ganglion
Tectorial membrane
A flexible gelatinous membrane covers the hair cells of the spiral organ
ends of the stereocilia are in bedded here
Sound waves
Altering high and low pressure regions travelling in the same direction through some medium originating from a vibrating object in much the same way that ripples arise and travel over water
Pitch
Frequency of a sound vibration
Does this sound get louder or quieter the larger the intensity of the vibration?
Louder
And how is sound intensity measured?
Decibels (dB)
What are the events that are involved in hearing?
- Oracle direct sound waves into the external auditory canal
- Sound waves strike the Tim panic membrane causing it to vibrate back-and-forth
- Central area of the Timpanic membrane connects to the malice which vibrates along the Timpanic membrane transmitting from the malice to the Incas and then to the stapes
- The oval shaped footplate of the stapes which attaches to the circumference of the oval window vibrate in the oval window. The vibrations at the oval window are 20 times more vigourous than those of the tympanic membrane
- Movement of the Stapies at the oval window sets up fluid pressure waves in the PerriLymph of the cochlea as the oval window bulges in word it pushes on the Perilymph of the scala vestibuli
- Pressure waves are transmitted from the scala vestibuli to the scala tympani and eventually to the round window causing it to bulge outward into the middle ear
- pressure waves form the walls of the Scalea vestibuli and scala tympani they also push the vestibular membrane back-and-forth creating pressure waves in the endolymph inside the cochlear duct
- Pressure waves in the endolymph cause the basiliar membrane to vibrate which moves the hair cells of the spiral organ against the tectorial membrane this leads to bending of the stereocilia and ultimately to the generation of nerve impulses in first order neurons in cochlear nerve fibres
Which sound frequency produces max vibrations in the base of the cochlea?
High frequency/high-pitched
What frequency causes maximal vibrations of the basal membrane in the Apex of the cochlea?
Low frequency/ low pitched
What are the receptor organs for equilibrium called? And what do they include?
Vestibular apparatus
Utricle and saccule of vestibule, and Semicircular ducts of the semicircular canals
What are the two otolithic organs?
Utricle and saccule
Macula
A small, thickened region attached to the inner walls of both the utricle and saccule
What are the two types of cells of the maculae?
Hair cells (sensory receptors) and supporting cells
What are Stereocilia and kinocilium collectively known as?
Hair bundle
Otolithic membrane
Thick, gelatinous, glycoprotein layer
Otoliths
Dense calcium carbonate crystals
Ampulla
Dilated portion of each semicircular ducts
Crista
Small elevation in the ampulla
Consists of a group of hair cells and supporting cells
Cupula
A mass of gelatinous material that covers the crista
