BSI Lecture 64 Special Senses Flashcards
What type of light are the photoreceptors of the eye only sensitive to?
electromagnetic radiation (EM)
The eye is sensitive to only wavelengths between ___ and ___ light.
Blue (400nm just before ultraviolet)/ red (700nm just after infrared)
What are the 3 layers of the eye?
Fibrous (Sclera (connective tissue), cornea)
Vascular
Inner
What part of the lens focuses/refracts lights
Cornea (more so than the lens) / Lens
What is the function of the pigmentation in the choroid?
To absorb light and prevent reflection
When the ciliary muscles contract (decrease tension on zonular fibers) what is the shape of the lens?
Convex, this is to focus more light for near vision
What part of the eye has the greatest number of photoreceptors?
Fovea centralis
What is the “blind spot” part of the eye?
optic disc (this is where the optic nerve (CNII) and blood vessels enter/leave the eye)
What are the fluid parts of the eyes and where are they found in the eye?
Aqueous Humor (between iris and cornea), Vitreous humor (posterior part of eye)
What does the lacrimal gland produce?
Lacrimal apparatus (tears, which contains mucus antibodies and antibacterial enzyme lysozyme)
What are the tarsal glands (meibomian glands)?
Modified sebaceous skin oil gland (oily secretions slows evaporation of the tears)
What is the shape of the lens when the SNS is active?
Flat ( optimizing it for far vision in poor light)
What mechanism do photoreceptors use for light?
Mechanism 2 (GPRs), activates phosphodiesterase to convert cGMP to GMP
What is the name of the ligand/chromophore in photoreceptors that when light energy is received, changes conformation?
Retinal
What are the name of the GPR and G-protein in photoreceptors?
GPRs (opsin), G-protein (Gt)
What are the 2 types of photoreceptors and their function?
Rods (light)
Cones (colors, red, blue, green)
What part of the thalamus do optic fibers go to?
Lateral geniculate nucleus (LGN), they then go to the visual cortices in the occipital lobe.
The 6 skeletal muscles that control the eye produce 2 types of eye movements, what are they?
Small/fast movements (saccades, help search the image for the most important features and to prevent bleaching)
Slow movements are used to track moving objects and require interaction with the vestibular system
_____ is due to excessive intraocular pressure and causes blindness by destroying the optic nerve.
Glaucoma
What are the 3 tiny bones of the ear?
Malleus, Incus, Stapes
What is the eardrum called?
Tympanic membrane
What inside the ear limits the over-amplification of the bones?
2 small muscles attached to the bones
The stapes moves the _____ ____ of the inner ear at the start of the spiral cochlear where hair cells respond to vibrations.
oval window.
The ___ ____ sets up sympathetic pressure changes in the fluid inside the cochlea.
Oval window
The cochlea is divided into the what parts?
Scala vestibuli, scala tympani, chochlear duct
____ of ______ contains the mechanoreceptors which respond to vibrations.
Organ of Corti
The mechanoreceptors or the organ of Corti has so-called _____ which are anchored in the overlying tectorial membrane.
stereocilia
T or F? The “hair” cells respond by bending the cilia which open the K+ cation channels.
True, This depolarizes the cell (yes with K+) and opens voltage-gated channels to let Ca2+ in.
What are the types of NTs released in the cochlear?
Glutamate
Which area of the cochlear responds to high frequencies?
Region of the cochlear closest to the start of the oval window
T or F? The signal from the cochlear goes directly to the auditory cortices in the temporal lobe.
False, go via the thalamus then to the auditory cortices.
______ is caused by excessive bone growth which can fuse to the stapes and oval window.
Otosclerosis
The ______ system is necessary for maintaining equilibrium (balance) and is important component of proprioception
vestibular
The _____ _______ detect angular acceleration during rotation of the head along 3 perpendicular axes.
semicircular canals
The cilia of the semicircular canals are embedded in a gelatinous mass called the _______
cupula
The ______ and ______ provide information about linear acceleration with respect to gravity.
utricle (vertically oriented) / saccule (oriented at right angles)
Name 3 important functions of the vestibular system.
- Control and coordinate the eyes so despite moving, the eyes remain fixed on the same object
- Helps maintain posture
- allows conscious awareness of position and acceleration of the body
What is the fluid in the semicircle canals and cochlear called?
Endolymph (note it is interlinked and continuous with CSF (loss in CSF fluid could affect balance and cause nausea)
What sense is considered our most primitive sense?
Olfaction
Where does the olfactory information go?
Directly to the limbic system where it can elicit very basic emotional response
Olfaction begins at the _____ _____ in the upper part of the nasal cavity which contains receptor neurons.
olfactory epithelium
T or F Olfaction receptors use G-olf receptors which in turn activates AC, (increase cAMP), and PLC (increase DAG and IP3)
True
T or F? Information is sent to the glomeruli in the brain extension known as the olfactory bulb
True
Information from the olfactory tract primarily goes to the limbic system but also sends information to the ___ of the temporal lobe for conscious perception and the frontal cortices for an association.
True
Does adaption occur in the sense of smell?
Yes, possibly by GPR phosphorylation
Taste buds are found in the ______ of the tongue.
papilla
Describe “Salty” taste gustation
Na+ ions entering the cells directly, depolarizing the taste buds.
Describe “Sour” taste gustation
H+ ions physically block certain K+ channels that would normally hyperpolarize the cell.
Describe “Sweet” taste gustation
GPRs recognizing certain sugar molecules and activate specific G-protein found only in these receptors call Gust
Describe “Bitter” taste gustation
GPRs but they all act via Gust G-proteins
Describe “Umami” taste gustation
Thought to recognize glutamate (also thought to act via GPRS and Gust)
Absence of a sense of smell is called ____________
anosmia
