Stereocilia
For the general and special senses:
- Where are they located?
- Are their sense organs simple or complex?
General: all throughout the body, relatively simple sense organs
Special: only in the head, complex sense organs
What does a transducer do? Give an example of a transducer in the body
Converts one form of energy into another; sensory receptors
What do nociceptors detect?
pain
What nerves make up CN VIII?
Vestibular nerve, cochlear nerve
What are the ossicles connected to? What do they do?
Tympanic membrane (ear drum) and oval window
Vibrations on the tympanic membrane cause ossicles to push on oval window, which creates waves in the cochlear fluid
Describe large and small receptive fields. In which one is it hard to discriminate exactly where a stimulus is coming from?
Large: one neuron serves a large area, making it hard to determine exactly where a stimulus originates
Small: many neurons serve an area
What are examples of stimuli that the body is not consciously aware of?
pH, blood pressure, body temperature
Where in the cochlea are high and low frequencies detected?
high frequencies detected at the proximal end of the cochlea
low frequencies detected at the distal end of the cochlea
What is the function of the cornea?
Refraction (bending) of light
Describe hyperopia and myopia
Hyperopia: Farsightedness (can see far things, can't focus on close things)
Myopia: Nearsightedness (can see close things, can't focus on far things)
What causes olfaction?
A chemical binds to receptors on the cilia of olfactory cells
What membranes are present in the organ of corti? Where are stereocilia embedded?
Basilar membrane, tectorial membrane
Stereocilia are embedded in the tectorial membrane
How are endolymph and perilymph different? Where are they found?
Perilymph: similar to extracellular fluid, high in Na+, found in the scala vestibuli and scala tympani
Endolymph: similar to intracellular fluid, high in K+, found in the cochlear duct and semicircular duct
What is the function of the eustachian tubes?
Equalize the pressure between the middle ear and outside
What sensory information is sent to the brain when the cupula in semicircular canals is deformed?
Angular acceleration/rotation
In which lingual papillae are the highest number of taste buds found?
circumvallate papillae
How does vibrating the fluid in the cochlea lead to an action potential?
Vibrations cause stereocilia to bend, tip link pulls open K+ channels, endolymph depolarizes cells, causes an action potential
What are the characteristics of slow pain and fast pain?
slow: dull, widespread, travels along unmyelinated fibers at 0.5-2 m/s
fast: sharp, localized, travels along myelinated fibers at 12-30 m/s
What is referred pain? Give an example of it in the body
Pain in one area of the body (usually viscera) that is perceived as being from somewhere else (usually somewhere superficial)
A heart attack can manifest as left arm pain
What chemicals bind to nocicptors of the trigeminal nerve?
Capsaicin of hot peppers, chlorine, ammonia, menthol
Do the following chemicals trigger the secondary messenger system or cause direct depolarization of taste cells?
- sugar
- sodium
- alkaloids
- glutamate
Sugar: secondary messenger system
Sodium: direct depolarization
Alkaloids: secondary messenger system
Glutamate: secondary messenger system
What does modality refer to in relation to sensory receptors?
The type of stimulus that is sensed (temperature, light, pain --> thermoreceptors, photoreceptors, nociceptors)
Are the following receptors encapsulated or unencapsulated?
- free nerve endings
- krause end bulbs
- tactile discs
Free nerve endings: unencapsulated
Krause end bulbs: encapsulated
Tactile discs: unencapsulated
What needs to happen for molecules to be tasted?
Molecules must be dissolved in saliva and the saliva floods the taste pore
What are the only neurons exposed to the external environment?
Olfactory neurons