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