PT 505 Chemical Sensations

Perception

The conscious awareness of our sensations

Sensation

The detection of external stimuli by receptors

specific

Receptors detect a _____________ stimuli

Sense organs

groups of receptor cells responding to specific stimuli

transduction

When proteins convert environmental stimuli to nervous system activity

sodium

What specific molecule plays a large role in transduction

electrical

Transduction turns a stimulus in _____________ activity

long-axon receptors, ganglion cells

types of transduction

long-axon receptors

sensory receptors on the neurons axon

ganglion cells

sensory receptors on other cells, not on the direct axon

long-axon receptors

What type of transduction is olfaction?

ganglion cells

What type of transduction is taste??

modality

type of stimulus is the:

Targeted CNS region

What determines the modality of information transmitted?

receptive field

What determines the location of the information transmitted?

receptive field

Area that stimulates receptive neurons

periphery

More receptors converge onto neurons in the _____________ of the retina

visual acuity

Neurons in the center of the retina have greater ________________ than neurons in the periphery.

two point discrimination

ability to distinguish the separation of two simultaneous pinpricks on the skin

decrease

Larger receptive fields would decrease or increases two point discrimination?

Lateral inhibition

antagonistic neural interaction between adjacent regions of the retina

amplitude

Intensity describes the _________________ of a stimulus

firing rate, number of neurons, types of neurotransmitters released

What is the intensity of a stimulus encoded by?

adaptation

decreases response to stimulus over time

phasic receptors

what type of receptors adapt rapidly?

tonic receptors

what type of receptors adapt slowly?

temperature

thermoreceptors respond to:

light

photoreceptors respond to:

odors, taste, body fluid composition

chemoreceptors respond to:

pain

nociceptors respond to:

pressure, stretch

mechanoreceptors respond to:

modality

The difference between thermoreceptors, photoreceptors, chemoreceptors, etc., describes what characteristic of a receptor?

somatosensation

Example of general body distributed reception

vision, hearing, balance, taste, smell

Example of special body distributed reception

visceral

Describes everything other than skin, tendons, and striated muscle

5

How many different tastes are detected?

cells

the 5 different tastes are detected through five different taste _______

7, 9, 10

What cranial nerves are influence through taste?

fungiform

lingual papillae concentrated at the tip and sides of tongue

3

How many taste buds make up fungiform papillae?

vallate

Lingual papillae at the back of the tongue

7-12

how many vallate papillae do our tongues have?

50% (250 buds each)

% of taste buds from vallate papillae

taste cells

Taste buds are made of:

gustation

chemical sensation of taste

taste cells

what is responsible for gustation?

taste hairs

microvilli in the taste pore

receptors

Taste hairs contain the taste _________

ATP

Taste cells release _______ onto sensory nerves 7, 9, and 10

ganglion

What type of cells (in terms of transduction) could taste cells be?

False (contain basal stem cells)

Taste buds are not regenerative. True or false?

1

How many taste receptors are expressed on a taste cell?

true

All types of taste cells are in one taste bud. True or False?

Sour

taste sensed from hydrogen ion sensing cation channels

bitter, umami, sweet

taste sensed from GPCRs

Gq

What type of GCPRs do sweet, umami, and bitter tastes associate with?

calcium

Gq receptors increase intracellular ____________ and release neurotransmitters

glutamate (amino acids)

Umami taste is produced from what?

saccharides (sugars)

Sweet taste is produced from what?

alkaloids

Bitter taste is produced from what?

non-existent

Describe the taste map of the tongue:

3

Number of taste pathways for taste

CN7, CN9, CN10

What are the primary afferent taste pathways?

CN7

cranial nerve responsible for the anterior 2/3 of the tongue

CN9

cranial nerve responsible for the posterior 1/3 of the tongue

epiglottis

cranial nerve 10 is responsible for the

solitary tract nucleus

What is the secondary afferent taste pathway?

limbic

What system does the solitary tract nucleus (2º afferent pathway) in the taste pathway connect with?

ventral posterior medial thalamus

Where is the 3º afferent taste pathway located

primary gustatory cortex

Where does the 3º afferent taste pathway project?

False

Different tastes stimulate the same region of the primary gustatory cortex. True or False?

taste + smell

Flavor =

CN1

What cranial nerves detect odors?

odorant receptors

A few hundred of these live on the cranial nerve 1 to detect odors

True

Odors directly influence the limbic system. True or false?

respiratory, olfactory

What type of epithelium lines the nasal cavity?

olfactory sensory neurons

What does the olfactory epithelium contain?

olfactory nerve

Olfactory sensory neurons form what?

olfactory nerve

what is considered the 1º olfactory afferent?

olfactory bulb

Connects the olfactory nerve to olfactory tracts

olfactory bulb

what is considered the 2º olfactory afferent?

olfactory cilia

Increases surface area for olfaction

one

How many types of odorant receptors are expressed on olfactory cilia?

1-12 months

How often are olfactory bulbs replaced?

air damage

Why do olfactory bulbs need to be replaced?

CN1, olfactory bulbs

What two olfactory structures synapse after one pierces through the cribriform plate?

G-protein

odorant molecules activate these after binding one (or a few) odorants

cAMP-gated cation channels

GPCRs in the odorant pathway activate what?

False (DEPOLARIZE)

cAMP-gated cation channels repolarize OSNs to fire APs and spit our neurotransmitters. True or false?

mitral cells

the main projective output neurons in the olfactory bulbs, known as the 2º neurons

Glomeruli

Collection of OSN axons and mitral cell dendrites

one

Glomeruli correspond to how many specific odorant receptors?

periglomerular cells

What controls lateral inhibition of olfaction?

granule cells

These cells are stimulated by what we WANT to smell (Ex: if we are hungry and are searching for food)

mitral cells, piriform cortex (brain)

What specifically stimulates granule cells?

temporal lobe (primary olfactory cortex)

Where are the 3º neurons located for olfaction?

2º

Which olfactory afferent project to the piriform lobe and limbic system?

orbitofrontal cortex, hippocampus, hypothalamus

Where do the 3º olfactory afferents project to?