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Flashcards in Mechanoreceptors Deck (31):

What are Mechanoreceptors?

Sensory receptors that detect mechanical stimuli; changes in touch and pressure.


What are Free Nerve Endings?

Mechanoreceptors that respond to light touch, phasic.


What are Pacinian Corpuscles?

Mechanoreceptors that respond to deep pressure and vibrations, located in the nerve endings of the skin, consist of a concentric layer of connective tissue wrapped around the peripheral terminal of an afferent neuron, phasic.


What are Ruffini Endings?

Mechanoreceptors that respond to deep pressure, wide receptive field, phasic.


What are Meissner's Corpuscle?

Mechanoreceptors that respond to light touch and pressure, lie just beneath the skin with a small receptive field, phasic.


What are Stretch Receptors?

A tonic receptor commonly found in the walls of tissues/organs that can be distended (muscle, stomach); stretching deforms them and they depolarize [Stretching in stomach is interpreted as fullness].


What are Hair Cells?

Modified epithelial cells that are used for equilibrium and hearing (sense of movements of internal fluid) and in the lateral line system - sense movements of external fluid.


What are common features of Hair Cells?

1. Receptor cells do not have axons
2. Afferents project to CNS
3. Receptor cells release neurotransmitter (glutamate)
4. Cells bath in endolymph
5. Depolarized by inward movement of potassium
6. Hair cells are always firing (continuous secretion of some kind of neurotransmitter)


What is Endolymph?

A liquid high in potassium concentration (meaning extracellular fluid is low in potassium)


True or False: In humans, the hair cell only synapses onto afferent neurons.

False, hair cells in humans can form synapses with efferent neurons.


What are neuromasts? (Lateral Line System)

A mechanoreceptive organ that allows the sensing of mechanical changes in water (consists of cupula and stereocilli), set in pits and canals along the side of the body; the lateral line system consists of a row of them.


What kind of ion channels does the Lateral Line System (in Fish) have?

Mechanically gated ion channels in hair cell membrane that cause depolarization or hyperpolarization.


What are Proprioceptors?

(Example: Hair cells) Maintains body balance and position.


What is a Statocyst?

An organ of equilibrium (orientation of gravity) found in invertebrates (mollusks) that is important for life in water. A simple system like lobsters deals only with gravity while a more complex, like squids and octopus, deals with gravity and acceleration.


What are hairs in the inner ear embedded in?

The gelantinous cupula; which is embedded in enodlymph.


What do 3 Semicircular canals provide?

3D sensitivity; angular motion of the head.


What direction does the endolymph move in?

The opposite direction of the head. The movement of the endolymph deflects hairs.


What are Otolith Organs?

Located between the semicircular canals and the cochlea, made up of calcium carbonate, they deal with gravity (tilting of the head) and forward/backward motion.


What is the Vestibular System?

The Semicircular Canals and the Otolith Organs; the system that maintains body balance and allows a sense of the position of the body in relation to gravity.


What is hearing?

The detection of very small changes in air pressure (sound waves).


What is pitch?

The frequency of pressure change.


What does sound vibrate?

Tympanic Membrane (ear drum).


What constituents the middle ear?

The stapes, incus, and malleus. Transports the sound from the outer ear to the inner ear.


How much does sound energy get amplified in the ear?

24x (sound gets to the oval window).


What is the inner ear?

A continuous tube (upper part = vestibular canal, lower part = tympanic canal) filled with perilymph (similar to extracellular fluid)


What is the Cochlear duct filled with?

Endolymph. Sound is detected by hair cells in the Cochlea.


What does the Basilar membrane contain?

The hair cells involved with sound.


What does stretching of the stereocillia open?

Mechanically gated potassium channels. Inward flow of potassium concentration depolarizes receptive potential.


How do we differentiate between high pitch and low pitch sound?

The vestibular membrane portion close to the oval window is narrow and stiff, and high pitch sound causes this to vibrate. The other end is very flexible, and low pitch sounds will cause it to vibrate.


True or False: All the hair cells in the human cochlea vibrate in response to sound.

False. Depending on the pitch of the sound, only some of the hair will vibrate.


Do terrestrial animals or aquatic animals have more efficient amplification mechanisms?

Terrestrial animals because fish do not have an outer or middle ear and therefore a more simple amplification system.