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