module 7 Flashcards
whats the five special senses
smell (olfaction) Taste (gustation) Hearing (audition) Balance (equilibrium) Vision
whats the hearing and balance receptors
mechanoreceptors respond to stretch, bend or deformation
whats the vision receptors
photoreceptors- contrain molecules that respond to light
whats the taste and smell receptors
chemoreceptors- response to chemicals
what must happen to experience the sensations of olfaction
smell molecules (odourants) must be volatile (or gaseous) and dissolved in fluid to activate olfactory receptors.
where are olfacotry neurons located
olfactory epithelium at the roof of the nasal cavity
what do cila do in the nose
branch from the dendrite of each olfactory neurone and contain proteins that function as chemoreceptors.
cila provide a large surface area to increase the chances of coming into contact with an odourant, and are surrounded by mucus, which capture and dissolve odourants.
Binding of dissolved odourants to the receptor proteins triggers the opening of ion channels to generate a graded potential
what will happen is the stimuli is strong enough (smell)
o reach threshold an acton potential is generated and travels along the olfactory nerve to reach the olfactory cortex of the temporal lobe.
whats the olfactory pathway
receptor proteins of olfactory sensory neurons
Olfactory nerve cranial nerve I
Olfactory cortex to the temporal lobe
Olfactory cortex to:
1. The frontal lobe where smell is consciously interpreted and identified.
2. To hypothalamus and other regions of limbic system where an emotional response to the odour is elected.
whats the role of smell
- Noicrecptors and thermoreceptors are also found in the nasal cavity and detect pain and temperature respectively. They are activated by irritants such as ammonia and chilli peppers.
Smells can also signal danger such as smoke or gas and trigger a flight or fight response. - —-
Appetising smells can stimulate salvation.
Smell can offer protection by triggering sneezing and choking in response to unpleasant odours.
what the receptor cells for taste called and where are they located
Gustattory epithelial cells located within the taste buds , soft palate, cheeks, epiglottis and pharynx.
whats the function of saliva
is to allow food to dissolve and penetrate into the taste bud and bind to receptors of gustatory hair cell.
This triggers an action potential conducted along cranial nerves VII, IX and X to the thalamus and the gustatory cortex.
whats the pathway of taste
Gustatory hair cell receptors of the gustatory epithelial cells
facila (VII), glossopharyngeal (IX) and Vagus (X) nerves to thalamus gustatory cortex of the insula.
Hypothalamus and limbic system where an emotional response to the taste is elicited.
whats the 5 basic taste sensations and how their function
- Sweet, guides food rich carbohydrates, important for energy
- Sour, indicates unripe fruits or spoiled fruit.
- Salty, important fr mineral and water balance
- Bitter, warning signal because many toxic plants contain bitter tasting substances.
- Umami (beef flavour), indicates protein rich foods.
whats the role of taste
triggers reflexes such as increased secretions of saliva and gastric juices important for digestion. Taste also imitate protective reflexes such as gagging and vomiting.
The tough also has thermoreceptros, mechanoreceptors, noicreceptors that influences tastes and provide protective information.
whats the three major areas of the ear
- External (outer) ear- hearing only
- Middle ear (typanic cavity)- hearing only
- Internal (inner) ear- hearing and balance
receptors for hearing and balance response to seperate stimuli
Are activated independently
structure and function of parts of the external ear
Auricle (pinna)
elastic cartilage
Auricle funnels sound waves into the external acoustic meatus.
External acoustic meatus
auditory canal extends to the typanic membrane ( eardrum)
Sound waves entering external acoustic meatus travel to and vibrate tympanic membrane
Earwax secreting glands traps foreign particles
Tympanic membrane
thin translucent membrane
Looks liike flattend cone
Vibrates in response to sound waves which then transfer sound energy to bones of middle ear.
whats the structure and function of the middle ear
air filled cavity in the temporal bone
Located between the tympanic membrane laterally and medial by bony wall containing
Ovaral window and round window
Contrains auditory ossicles
Contains pharyngotympanic tube
Pharynotoympanic tube
connects middle ear to nasopharynx
Equalises air pressure in the middle ear cavity with external air pressure
Opens when you swallow or yarn
Auditory Ossicles;
Malleus- hammer
Incus- anvil
Stapes- stirrup (smallest bones in the body)
the role of auditory ossicles is to transmit and amplify the vibratory motion of the tympanic membrane to the oval window.
Movement of the oval widow creates pressure waves in perilymph of cochlea.
whats the regions if the internal ear
located in the temporal bone
two major divisors of internal ear
1. Bony labyrinth- tunnels in the temporal bone subdivided into vestibule, semicircular canals, cochlea filled with perilymph.
2. Membranous labyrinth- series of interconnecting ascs and ducts within the bony labyrinth filled with endolymph.
whats the cochlea
spiral, bony chamber
Extends from the vestibule
Colds around like a snail shell
Contains cochlear duct that houses spiral organ (of corti)
Divided into three chambers, middle chamber Calle cochlear duct
whats the spiral organ
organ for hearing Cochlear hair cells, mechanoreceptors Pressure waves (involves fluid) travel through the perilymph of the cochlea creating movement of the basilar membrane. This movement causes the cilia of the hair cells to move or bend against the tectorial membrane, initiating depolarisation Action potentials generated in hair cells are transmitted along the vestibulcochlear nerve (CN VIII)
whats the pathway of sound from the Pina to the auditory cortex
pinna external auditory miatis (canal) tympanic membrane auditory ossicles (amplifies sound) oval window cochlea perilymph spiral organ basilar membrane vestibularcochlear nerve
what do the auditory ossicles do
amplify sound
what creates pressure waves
movement of stapes against oval window
whats the difference between the oval and round window
Oval window: opening in the bone that partitions middle ear to the start of the cochlear duct. Movement causes pressure waves within the perilymph.
Round window: thin membrane that separates the end of the cochlear duct from middle ear. Absorbs pressure waves and prevents perilymph from leaking into middle ear. Allows another one to come through.
whats the role of equilibrium
s to provide information about the location of our head, how rapid the movement and in which direction eg. If head is bent forward or bawards, tilted or rotated.
Equilibrium depends on inputs from the internal ear as well as vision and information from proprioceptors of muscles and tendons.
Mechanoreceptors for equilibrium are found in the semicircular canals and vestibule of inner ear.
whats the two types of equilibriums
static equilibrium
dynamic equilibrium
whats static equilibrium
evaluating the position of the head relative to gravity (up/down) and forward/back. Information supplied when the head is motionless, or moving in a straight line- detected by hair cells in the vestibule. Eg in a lift or moving in a car
whats dynamic equilibrium
evaluates the position of the head while it is rotating, or moving in an angular direction- detected by hair cells in semicircular canals.
what structures are involved in equilibrium (balance)
vestibule
semicircular canals
whats the vestibule
saccule: continuous with cochlear duct
Utricle: continuous with semicircular cancels
Both contain equilibrium receptors
Until and saccule contain hair cells that are embedded in jellylike substance
Tiny stones are embedded in the surface of the jelly. When head position is changed gravity pulls on the stones and distorts the jelly and hair cells.
Distortion of the hair cells is the stimulus for their depolarisation and the transmission of action potentials.
whats the seminal canals
3 fluid filled canals that lie in three planes of space
Equilibrium receptors respond to rotational moment of the head
Dynamic equilibrium contain hair cells surrounded by endolymph, angular movement moves endolymph, hair cells are distorted and are depolarised.
whats the pathway of equilibrium
distortion of the hair cells is the stimulus fro depolarisations and the transmission of action potentials along vestibulocochlear nerve Action potentials travel to: The reflex centres of the brain stem Cerebellum Vestibular cortex of the insula
which is our dominant sense
vision
whats the accessory structures of the eye functions
Eyebrows
protect the eye from perspiration
Shade from direct sunlight
Eyelids
muscular folds of facial skin fringed with hair
Glands secrete oily lubricant that prevent eyelids from sticking together.
Conjunctiva
transparent mucous membrane lining the eyelids and white of the eye.
Produces lubricant fluid to prevent drying out and frictoion
whats the function of the lens
are biconvex, transparent and flexible
Changes shape to focus light on retina
Round and thickened unless an outside force is applied
Held in place by ciliary zones called suspensory ligaments attached to ciliary muscles
whats the cilliary muscles and suspensory muscles do
hold lens in place
when the lens bulges what happens to the cilliary muscles and zonules and give examples of situation
cillary muscles= contract towards lens
ciliary zonules=loosen
refactory power of lens=increased
eg pencil moving closer to eye
when the lens fatten/thinner what happens to the cilliary muscles and zonules and give examples of situation
ciliary mussels= relax
cilliary zonules= tighten
refectory power of lens- decreased
eg pencil move away form eye
what division of the autonomic ns contract ciliary muscle for close vision
parasympathetic
what division of the autonomic system relaxes cilliary muscles for distance vision
sympathetic
function of aqueous humour
supply oxygen and nutrient sot lens and cornea
function of visterous humour
maintains shape of eye and holds retina in place
whats the three layers of the eyeball
fibrous layer (outer layer)
sclera – tough opaque connective tissue, covers most of eye
cornea - transparent region at front of eye
2. Vascular Layer (middle layer), three regions
• choroid – highly vascularised area
• ciliary body – forms ciliary muscle rings around lens
• iris– adjustable diaphragm that controls diameter of pupil
3. Retina (inner layer): nervous layer
photoreceptors (cones & rods)
fovea centralis (visual acuity)
optic disc
whats rods
receptors for dim light and peripheral vision
whats cones
receptors for bright light, colour and visual acuity
whats refraction
bending of light rays as it passes through different mediums (ie: humours, cornea and lens)
light travels in straight lines until they hit a different object
When it hits the object the light rays bends or refract
whats the pathway of light in th eye
cornea aqueous humour pupil lens virtuous humour retina photorecpetors optic nerves optic chiasma thalamus optic radiations visual cortex of occipital lobe
whats accomodation
increasing or decreasing the refractory power of the lens (increase/decrease) the amount of bending of the light rays)
whats happens in distance vision
person wth normal vision, an object 6 meters or more away from the eye reflects light rays that are virtually parallel to each other. These light rays will focus on the retina wit the lens flattened (ciliary muscles relaxed, suspensory ligaments tightened)
Image is inverted
what happens in close vision
objects closer than 6 meters reflect light rays that are on divergent paths (not parallel).
Require refraction to direct them onto the retina.
Hence lens thicken (become more round and fat) to increase refectory power= accommodation
Achieved through contraction of the ciliary muscle and suspensory ligaments loosen.
Image is inverted
whats convergence of eyeballs
turning both eyeballs medially eg looking at the tip of your nose
whats converting light to action potentials
light rays from an object are focussed on the retina where the photoreceptors (rods and cones) are located.
Rods contain rhodpsin, which is very sensitive to light
Light promotes the breakdown of rhodopsin causing the rod cell membrane to depolarise which produces an action potential of the optic nerve.
Cones function in a similar way using a different type of rhodopsin.
the structure that houses the receptors for satic equilibrium
vestibule
the structure that houses the receptors for dynamic equilibrium
semicircular canal
the structure that houses the receptor for hearing
spiral organ of corti
