Peripheral Nervous System (PNS): Sensory Functions

Sensation

Activation of sensory receptors cells at the level of the stimulus. Information received from the 5 senses

Perception

Processing of sensory stimuli into a meaningful pattern centrally; dependent on sensation. Interpretation of information received form 5 senses

Sensory Receptors

Cells or structures that detect sensations

Stimuli

Sensory receptors are changed directly by...???

Transmembrane Protein Receptors

These types of receptors are activated by ligands and results in opening of ion channels to lead to changes inside cell.

1. free nerve endings
2. encapsulated nerve endings
3. specialized receptor cells

What are 3 general cell types for sensory receptors in the PNS?

ACTION and LOCATION of STIMULUS

The location and function of a sensory receptor in the PNS is dependent on the...

position

Sensor receptor distribution is dependent on....

Free Nerve Endings

Dendrites that are receptive to pain and temperature are examples of which PNS cell type?

Sensitivity to pressure or touch

Sensory receptors with encapsulated endings provide enhanced...

Specialized

??? PNS cell types have a distinct structure to certain stimuli

Specialized Cell Type

Photoreceptors are an example of which PNS sensory cell type?

1. Exteroreceptors
2. Interoreceptors
3. Proprioceptors

What are the 3 categories PNS cell types can be organized into based on location (relative to stimuli)?

Exteroceptor

These types of receptors receive stimuli from the environment. They respond to touch, pain, temperature, or pressure

Interoceptor

These types of receptors receive stimuli from the internal environment (organs, tissues, viscera, vessels)

Proprioceptor

These types of receptors receive stimuli from moving tissues (detect stretch).

1. General
2. Specific

Sensory receptors can be categorized based on function (modality). The 2 categories are...

Specific: Sight, Hearing, Taste, or Smell

Are sensory receptors general or specific if they respond to sight, hearing, taste, or smell?

General: Touch, Proprioception, Kinesthesia, Visceral Sense, Temperature, Pain, and Balance

Are sensory receptors general or specific if they respond to touch, proprioception, kinesthesia, visceral sense, temperature, pain, or balance?

1. sweet
2. sour
3. salty
4. bitter
5. umami
6. fat

Gustation sensory is meant to distinguish which 6 types of taste?

Papillae

???? are the site of gustatory transduction via taste buds

Chemical

Papillae will release NTs based on ?? in food.

1. Facial
2. Glossopharyngeal
3. Vagus

In Taste/Gustation, NTs are released to interact with sensory neurons of which three nerves?

Papillae (taste buds) of the tongue

Determining if you are a "taster" vs. "non-taster" is based on the density of....

bitterness

Non-tasters are thought to be less sensitive to...

Na+ ions
(salt's ionic bond weak with water/saliva)

Salty taste is based on sensitivity to the ??? ions.

H+ ions (acid perception)

H+ ions enter cell --> trigger depolarization--> saliva pH is lowered

Sour taste is based on the sensitivity to ??? ion concentration.

Sweet, Umami, or Bitter

Which taste receptors rely on G-protein coupled receptors to stimulate and activate signal transduction within cell leading to depolarization?

Sweetness

Sensitivity to glucose or fructose will help determine which taste sense?

Umami (Savory)

???? taste is often perceived while eating a protein rich meal.

Bitter
(hence why these papillae may be mostly located at the back of tongue)

??? taste may be related to stimulating the gag reflex to avoid tasting "poisonous foods"

Cranial nerve

Gustation (Taste)

Gustatory cells activated --> NTs released @ dendritic cells --> neurons to ??? nerves activated

Olfactory bulb

Olfaction (Smell)

Olfactory receptor cells --> olfactory nerves --> ???

400

It is believed we have approximately ??? different types of receptors to sense a trillion different smells

Pheromones

??? are sensed via olfaction and thought to have a role in reproduction and attraction

Audition (hearing)

The transduction of sound waves into a neural signal

tympanic membrane

A sound wave will cause the ??? membrane to vibrate.

Amplified

Sound waves are ??? as they move across the malleus, incus, and stapes (the ossicles).

Scala vestibuli

Sound waves are received by the oval window causing pressure waves in the fluid of the ??? ???? and tympani

stereocilia

hair-like cells that bend in response to movement of basilar membrane; attached to the organ of Corti

ion channels

The bending of Stereocilia will open ??? channels to cause depolarization.

Frequency

The standing sound wave generated in the cochlea by the movement of the oval window deflects the basilar membrane on the basis of the ??? of sound.

HIGH

Hair cells at the BASE of the COCHLEA are activated only by ??? frequencies

LOW

Hair cells at the APEX of the COCHLEA are activated by ??? frequencies

linear acceleration by the maculae of hair cells

Equilibrium (Proprioception)

Head position (tilting) is detected by...

Stereocilia

The difference in inertia between the hair cell stereocilia and the otolithic membrane leads to the ??? to bend in the direction of that linear acceleration.

Proprioception

???? is considered a sensory input function; not categorized as either somatic or autonomic

semicircular canals

Rotation movement of the head is encoded by the ????

Opposite

During head movement, as one of the semicircular canals moves with the head, the internal fluid moves in the ??? direction, causing the cupula and stereocilia to bend.

Vision

This sense is based on the transduction of light stimuli received through the eyes.

Red, Green, and Blue

Which color wavelengths of light are detected through vision?

Rods --> Rhodopsin

Cones --> Opsins

Which photoreceptors contain rhodopsin (Vit A) pigment and which contain opsins?

Green (Med.) and Blue (Short)

Rods are sensitive to which wavelengths of light?

Rods --> Low Light

Cones --> Bright Light

Which photoreceptors are more sensitive to bright light and which to low light?

ALL Colors

Long --> Red
Med. --> Green
Short --> Blue

Cones are receptive to which wave lengths/colors?

Isomerization

Light stimulus triggers shape change in visual pigment rhodopsin in rods. Comparing the peak sensitivity and absorbance spectra of the four photopigments suggests that they are most sensitive to particular wavelengths.

Signal Transduction

Photoreceptor --> change in cell membrane potential --> electrical signal --> G-protein coupled receptors amplification

How does signal transduction occur in Vision?

Bleached

Bleaching refers to the refractory period in muscles of the eyes

When rods & cones are ???, they cannot process incoming light.

preganglionic parasympathetic fibers

Which type of fiber coils are considered the longest?

Acetylcholine

Which signaling molecule is most likely responsible for an increase in digestive activity?

Proprioception

Which of the sensory inputs are considered neither entirely somatic nor autonomic?

Nicotinic

Which NT, found in both divisions of the ANS, could be affected by a drug made to bind to or block it?