Senses Flashcards
Sense organs bring information about the external environment….
To the CNS so that the appropriate response can be taken.
What 4 parts of the eye are involved in vision?
- Eyelashes - prevent foreign material entering the eye
- Eyelids - Blinking keeps eye lubricated.
- Iris - coloured region that surrounds pupil.
- Pupil - centre of the eye through which light passes.
What is the conjunctiva?
Epithelial layer that lines inner surface of eyelid and covers the outer surface of the eye.
What are the lacrimal glands?
They continually produce tears to keep the conjunctiva moist and clean.
What is conjunctivitis?
Inflammation of the conjunctiva due to infection or abrasion.
What are the 2 fluid filled cavities of the eyeball called?
The anterior and posterior cavities.
What are the 3 layers of the eyeball wall called?
Fibrous, vascular and neural.
What is the fibrous layer of the eyeball?
Surface layer of the eyeball - Provides protection for the eye and attachment for muscles that move the eye.
What is the vascular layer of the eyeball?
Contains blood vessels and smooth muscle - consists of the iris, ciliary body and choroid.
What is the neural layer of the eyeball?
Contains photoreceptors called rods and cones which respond to light.
What is the optic chiasma?
A part of the brain where the optic nerves partially cross.
The ear is an organ of…
Hearing and balance.
What parts is the ear divided into?
External, Middle ear and inner ear.
What 3 parts is the external ear divided into?
- Auricle
- External acoustic meatus
- Tympanic membrane
The middle ear is connected to the nasopharynx by the…
Auditory tube
What are the 4 part that the inner ear is connected to?
- Semicircular canals
- Vestibulocochlear nerve
- Vestibule
- Cochlea
List the 5 steps of sound transmission…
- Sound waves are collected by the auricle
- Sound waves hit the tympanic membrane causing it to vibrate.
- Vibration is amplified through the ossicles.
- Vibration of stapes on oval window causes fluid in cochlea to vibrate.
- Vibration stimulate the spiral organ which triggers action potentials in the vestibularcochlear nerve.
The sense of smell is the response to…
Airbourne molecules that enter the nasal cavity.
What term are airborne molecules also known by…
Odorants
Where is the olfactory epithelium located?
The upper region of the nasal cavity.
What are the 4 steps in smell detection?
- Odorants enter the nasal cavity and dissolve in the mucus.
- Presented to receptor proteins on olfactory epithelium
- Olfactory nerve is stimulated
- Information transmitted to olfactory cortex.
Where are taste buds located?
On the tongue, soft plate, pharynx and epiglottis.
What is the epiglottis?
Flap made of elastic cartilage covered with a mucous membrane, attached to the entrance of the larynx
How many taste cells does each taste bud contain?
40 taste cells
Sensory axons leave the base of each taste bud…
In the cranial nerve.
What are the 4 steps of taste detection?
- Tastants bind to receptors on hair cells.
- Action potential initiated in sensory neurone
- Sensory axons for taste are contained in the facial, glossopharyngeal and vagus nerves.
- Information transmitted to taste cortex in the parietal lobe.
List the 3 types of taste loss…
- Ageusia - Total loss of taste
- Hypogeusia - Partial taste loss
- Dysgeusia - Distortion of taste.
