Senses Flashcards
What does the iris do?!
Contract and relax to allow different amounts of light in and out
What does the lens do?!
Refract light onto the fovea
Where is the origin of blood vessels?!
The optic disk
What is the macula involved in?!
Central vision
What are the two components of the retina?!
Nasal retina and the temporal retina
What are the two types of photoreceptors in the eye?!
Rods and cones
Which out of the two photoreceptors is involved with colour vision?!
Cones
What do the photoreceptors do?!
Convert light energy to neural activity
Which photoreceptor is more sensitive to light?!
Rods
What happens to light that isn’t absorbed by the photoreceptors?!
Absorbed by the black cell layer
What do bipolar cells do?!
Create the direct pathway from photoreceptors to ganglion cells
What is the direct pathway in the eye?!
Photoreceptors - bipolar cells - retinal ganglion cells
What is involved with the indirect pathway in the eye?!
Horizontal cells and amacrine cells
What is the signal transduction pathway in photoreceptors in the dark?!
Constantly depolarised and therefore constantly releasing neurotransmitters
What is the signal transduction pathway for photoreceptors in the light?!
The photo pigment GPCR, is activated
This means GMP’s are made which reduces cGMP’s and therefore Na+ channels close = no neurotransmitter is released
Does light stimulate or inhibit the release of neurotransmitters?!
Inhibit
What is the primary visual cortex arranged into?!
The cortical module
What do the blobs in the cortical module do?!
Process colour
Where does information go from the retinal ganglion?!
To the optic nerve followed by the optic chiasm
What is the main nucleus called that is involved with the retinofugal projection?!
Lateral geniculate
Where are rod receptors mainly located?!
In the periphery
What does the fovea contain a large number of?!
Cone photoreceptors
Are rods or comes convergent?!
Rods - small signals are pooled together to make a response
Do rods or cones produce a image with a single photon of light?!
Rods
Do rods or cones have higher spatial acuity?!
Cones
In what form is sound?!
Pressure waves?!
What makes up the outer ear?!
Pinna
Concha
Auditory meatus
What does the external ear do?!
Gathers sound energy and focuses it onto the tympanic membrane
What does the middle ear do?!
Focuses the energy from the tympanic membrane onto the oval window
What do the ossicles connect?!
The tympanic membrane and the oval window
What increases the efficiency of sound transmission to the inner ear?!
Two small muscles called the tensor tympani and the stapedius
Flexion of these muscles stiffens the ossicles and reduces the amount of sound energy transmitted to the cochlea
What does the cochlea do?!
Amplifies sound waves and converts them into neural signals
What are the fluid filled chambers of the cochlea called?!
Scalar media
Scala tympani
Scala vestibule
What does the motion of the travelling wave do?!
Displaces the hair on the basilar membrane
This bends the sterocilla causing the potassium ion channels to open and potassium moves in
How does information from the cochlea reach the brainstem?!
Auditory nerve enters the brainstem and then branches to innervate the three divisions of the cochlea nucleus
What happens when the sterocilla are disturbed?!
You get mechanoelectrical transduction
Which nerve converts auditory information to the brain?!
Cranial nerve VIII
Where are the ossicles located?!
The middle ear
What are chemical stimuli called?!
Odourants
How are the olfactory bulb and receptors connected?!
Via the olfactory nerve
Which cortex is involved with smell?!
The pyriform cortex in the temporal lobe - relayed to the thalamus
Where does transduction of olfactory information occur?!
In the olfactory epithelium
Describe the olfactory receptor neurones.
Small diameter
Bipolar
Unmyelinated
How can olfactory receptors get damaged?!
They have direct access to odourants including airborne pollutants etc.
What do olfactory receptor neurones express?!
Olfactory specific G-protein
What does the olfactory specific G protein activate?!
Agenylate cyclase which produced cAMP, this opens cyclic nucleotide-gated channels which allows sodium and calcium to enter, chloride channels also open causing depolarisation - action potential
What do the axons that leave the epithelium form?!
Make up the olfactory nerve (cranial nerve I)
Where is the auditory complex located?!
Superior temporal gyrus in the temporal lobe of the brain
What does the olfactory epithelium line?!
Nasal cavity below the cribform plate
What are the three types of taste buds?!
Circumvallate papillae
Foliate papillae
Fungiform papillae
What are the circumvillate papillae?!
The largest taste buds, contain thousands of taste buds and are located at the posterior
What are the foliate papillae?!
Elongated structure
Posterior lateral edge
What are the fungiform papillae?!
Smallest
Widespread across the anterior
Tip of the tongue
What are the basic tastes?!
Salty, sweet, bitter, sour and urmani
Located across all areas of the tongue
Where do the first order neurones for taste project to?!
Medulla
Where do 2nd order neurones for taste project to?!
Thalamus
Where do third order neurones for taste project to?!
Gustatory cortex
Where are taste buds found?!
Palate, pharynx and larynx
What is urmani the taste of?!
Monosodium glutamate
Where is the fovea located?!
Central region of the retina
What is the endolymph rich in?!
Potassium ions (ions move from the endolymph into the cell)
Where is the auditory complex located?!
The superior temporal gyrus
What does the production of cAMP in the olfactory pathway do?!
Opens the cationic channels = move in
Opens chloride ions = move out
Causes depolarisation
Where do olfactory signals go?!
Orbitofrontal cortex Thalamus Hypothalamus Hippocampal formation (All above are indirect) Amygdala
What connects the olfactory bulb to its targets?!
Olfactory tract
What connects the olfactory receptors to the olfactory bulb?!
Olfactory nerve (cranial nerve I)
