Vertebrates 18 - Receptors Flashcards Preview

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Flashcards in Vertebrates 18 - Receptors Deck (34)
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Merkel disks

Skin surface, slow adapting ie they stay active as long as stimulus is there (light touch, grip). Found in bottom of feet and hands, lips of fish (for pressure)


Meissner’s corpuscles

Skin surface, rapid adapting ie shut off when stimulus isn’t changing (texture). Found in bottom of feet and hands, lips of fish (for pressure)


Free nerve endings

Pain, touch, itching; they can wrap around vibrissae (sensitive!)


Pacinian corpuscles

Deep in skin for pressure (harder touch), vibrations. Rapid adapting. Layers of membrane around them. Elephants have lots in the trunk and toes.



Elephants have lots of Pacinian corpuscles in the trunk and toes, so very sensitive to vibrations; Possible use in communicating/knowing of presence of other elephants in area (far away)


Lateral line receptors

In fish, larval amphibians, not amniotes. Used in schooling, navigation. Have neuromast cells along the body, support cells.


Neuromast organ

Have sensory hair cells which respond to pressure (water pressure). Covered in cupula (gelatin bulb) which contains the kinocilia (tall) and sterocilia (short) “hairs”.


Hair cells

Tonic receptors (always sending signal). Output by cilia movement (stretch ion channels). More/less NT released so more/less depolarizations depending on direction of bending.


Schooling behaviour

Hangout close together. Protection from predation: look huge, hard to see individual fish. Hard to swim close together and bumping together would remove mucous layer (bad). Facilitated by lateral line


Vertebrate outer ear

Pinna (outside shape), auditory canal, tympanum. Pinna funnels in sound, in some animals can be moved (directionality).


Vertebrate middle ear

Air-filled cavity (eustachian tube). Malleus, incus and stapes. Stapes causes oval window to vibrate


Role of eustachian tube

Connects to the pharynx, used to balance pressure which helps tympanum vibrating. Can get blocked by mucous or infection which prevents tympanum from vibrating, can even rupture.


Where did the middle ear bones come from?

Malleus was articular bone, incus was quadrate, and stapes came from a bone in skull.


Vertebrate inner ear

Semicircular canals, and cochlea (in mammals), to auditory nerve


Lizard, amphibians, bird ear

No real outer ear, the disk is the tympanum (birds have very shallow canal). No pinna



Connects from tympanum to the inner ear in lizards, amphibians, birds. Analogous to the stapes in mammals


Sound in water

Travels faster and with more power. Fish are about same density as water so sound travels to swim bladder easily.


Fish hearing

Inner ear receives the sound “directly”. Osteichthyes have weberian apparatus and have better hearing.


Weberian apparatus

Amplifies sound. Air in swim bladder vibrates in response to sound, causes bones to vibrate and connect to inner ear. Hearing is better



Has the organ of corti. Made of several cells and tissues. Basilar membrane and tectorial membrane with receptors between. Filled with endolymphatic fluid.


Basilar membrane and Range of frequency

Thinner and stiffer at proximal end, so highest frequency (16kHz) at the proximal end. More loose so lowest frequency (500Hz) vibrates at distal end


Different ranges across vertebrates

Mammals have larger range (cochlea is long). Bats and porpoises are very high for echolocation. Blue whale can hear 10Hz, long distance communication.


Utriculus and sacculus

For equilibrium. Part of inner ear. Filled with endolymphatic fluid



For static equilibrium, for orientation to reference to gravity. Contain otoliths (CaCO3) which are on gelatinous material above hair cells. Get stimulated based on movement.



For dynamic equilibrium. Attached to 3 perpendicular semi-circular canals (x, y, z). Help determine where you are going, how fast. Helps orient in 3D space. Fluid pushes against the cupula which activates the hair cells.


Reading: aging and hair cells

Outer and inner hair cells in basilar membrane. Cilia on air cells can be damaged by frequency and by amplitude (loudness) of sound. They also die naturally and are not replaced.


Reading: Precautions for studying hair cells

Hair cells are sensitive to vibrations in a building. Basement pool filled with concrete and table on a cushion of air (pneumatic pistons).


Reading: how does hair cell work?

Tonic, always sending impulse. Cilia move in response to membranes moving in the fluid. Turn them on and off (i.e. 16kHz) in response to vibration. Most sensitive receptor ever.



In only some fish, sharks, monotremes. Like a 6th sense.


Ampulla of Lorenzini

Most common electroreceptor. Canals with mucous/jelly that conducts electricity (salts), electrosensory cells at end and depolarizes with stimulus. Mostly found in head and in lateral line.