CH. 8: The Chemical Senses Taste & Smell

True or False: Animals depend on the chemical senses to identify nourishment, poison, or a potential mate.

TRUE!

True or False: Odorants activate the transduction process.

TRUE!

True or False: Smell and taste are both primarily ipsilateral processing.

TRUE!

True or False: Sweet receptors (T1R2+T1R3) and bitter receptors (T2R) can be found on the same taste bud but different taste cell.

TRUE.

True or False: Most receptor cells respond to just one basic taste.

TRUE.

Humans have ____-_____ identified types of olfactory receptors.

Humans have 100-400 identified types of olfactory receptors.

If you dry out your tongue, you'll have a temporary case of ____________.

If you dry out your tongue, you'll have a temporary case of AGEUSIA. Ageusia is a disorder where you lack taste.

In terms of taste chemicals moving into taste cell, they first go through the __________ ends, then pass through the _______________ then pass through the ____________, then it finally reaches the taste cells.

In terms of taste chemicals moving into taste cell, they first go through the APICAL ends, then pass through the MICROVILLI, then pass through the TASTE PORE, then it finally reaches the taste cells.

In the Olfactory BULB: The axons from the olfactory nerves enter the olfactory bulb and synapse onto _____________ neurons via spherical attachments called ____________. Each ______________ receives input from receptor cells expressing a __________ receptors protein. It ORGANIZES all of the info to send to the CNS.

In the Olfactory BULB: The axons from the olfactory nerves enter the olfactory bulb and synapse onto SECOND-ORDER neurons via spherical attachments called GLOMERULI. Each GLOMERULUS receives input from the receptor cells expressing a SINGLE receptor protein. It ORGANIZES all of the info to send to the CNS.

Tastants (tast stimuli) in General: - Pass directly through _______ channels. - Bind to and block _______ channels. - Bind to ________________ receptors and activate __________ messengers. Which 3 tastes are coupled to GPCR?

Tastants (taste stimuli): - Pass directly through ION channels. -Bind to and block ION channels. -Bind to G-Protein Coupled receptors and activate SECONDARY messengers. GPCR Coupled: Bitter, Sweet, Umami

Taste Cell Mechanism for SALTINESS: It contains ____ selective channels at the top of the cell. As the ion ____ enters the taste cell and conducts membrane _______-polarization down the cell, it will then activate ____ & ____ voltage-gated channels. This will result in a(n) _____-flux of the ___ & ___ ions. This will signal for the release of vesicles packed with the NT _____________, which is then sent to the gustatory afferent axon for perceiving the taste. The _____ selective channels at the top of the cell can be blocked by the drug _________ (which also treats __________).

Taste Cell Mechanism for SALTINESS: It contains Na+ selective channels at the top of the cell. As the ion Na+ enters the taste cell and conducts membrane DEPOLARIZATION down the cel, it will then activate Na+ & Ca2+ voltage-gated channels. This will result in an INFLUX of the Na+ & Ca2+ ions. This will signal for the release of vesicles packed the the NT 5-HT (serotonin), which is then sent to the gustatory afferent axon for perceiving the taste. The Na+ selective channels at the top of the cell can be blocked by the drug AMILORIDE (which also treats HIGH BLOOD PRESSURE. IRONIC!!)

Taste Cell Mechanism for SOURNESS: ____ ions in acidic foods block the _____ leak channels. This results in a ___ charge build up. This results in the cell becoming _____-poalrized throughout the cell. It will then activate ___ & ____ voltage gated channels. This will then signal for the release of vesicles that house the NT _________ to the gustatory afferent axon for perception. - Is this receptor going to be ionotropic or metabotropic?

Taste Cell Mechanism for SOURNESS: H+ ions in acidic foods block the K+ leak channels. This results in a + charge build up. This results in cell becoming DEPOLARIZED throughout the cell. It will then activate Na+ & Ca2+ voltage gated channels. This will then signal for the release of vesicles that house the NT 5-HT (serotonin) to the gustatory afferent icon for perception. - Sour receptors are going to be IONOTROPIC!!

Taste buds regenerate every ___ weeks. Quinine is a tastant that stimulates ___________ taste cells. HCl is a tastant that stimulates __________ taste cells.

Taste buds regenerate every 3 weeks. Quinine is a tastant that stimulates BITTER taste cells. HCl is a tastant that stimulates SOUR taste cells.

__________ is the inability to smell. __________ epithelium = _________ receptors.

ANOSMIA is the inability to smell. MORE epithelium = MORE receptors.

Additional Olfactory System Pathway: Vomeronasal Organ (VNO): - It's located near the __________________. - It then gets routed to the _________ and ______________. Who has this pathway? Do humans have it? This results the flehmen response. What is it? How about snakes?

Additional Olfactory System Pathway: Vomeronasal Organ (VNO): - It's located near the OLFACTORY EPITHELIUM. - It then gets routed to the AMYGDALA and HYPOTHALAMUS. Most animals. Humans do show to have it, but it's VERY SMALL and there are no receptors. SO INACTIVE? Flehmen response: Animals open mouth and inhales to draw ruin pheromones towards VNO. ie. Snakes "hiss" to bring odorants from tongue and stick it to their VNO.

True or False: You don't start interpreting the texture and taste of the food until it lasses the medulla.

FALSE. It needs to pass through the THALAMUS and get to the insular cortex (to tell you the taste) and the parietal cortex (to tell you the texture).

True or False: The olfactory tract for humans gets sent to the pyriform cortex.

FALSE. The olfactory tract for humans gets sent to the TEMPORAL LOBE. Humans DO NOT HAVE a pyriform cortex.

Areas of Sensitivity on the Tongue: 1) Tip of the tongue has many ______________ receptors. 2) Back of the tongue has many ___________ receptors. 3) Sides of the tongue has many ____________ & __________ receptors. - Are they only in these regions? -Why do you think the bitter receptor is in that region?

Areas of Sensitivity on the Tongue: 1) Tip of the tongue has many SWEET receptor. 2) Back of the tongue has many BITTER receptors. 3) Sides of the tongue has many SOUR & SALTY receptors. - NO. They're distributed throughout the tongue, but these regions are HIGHLY concentrated. - Bitter receptors are at the BACK of the tongue so you can THROW IT UP. "Poison Detector"

SSRI's is known for a depression drug. It can also affect the perception of how salty and sour things are. Why?

Because the NT that gets released to send to the gustatory afferent axon is 5-HT (SEROTONIN!!)

Central Olfactory Pathways (Neocortex): From the Olfactory tract, the information gets routed to the ________________ nucleus of the ____________.

Central Olfactory Pathways (Neocortex): From the olfactory tract, the information gets routed to the MEDIAL DORSAL nucleus of the THALAMUS. YES BITCH. There is a pathway where smell gets routed through the thalamus.

True or False: Chemical senses is the newest evolutionary sensory system.

FALSE. CHEMICAL senses is the newest evolutionary sensory system.

Central Olfactory Pathways (Olfactory Tract. The one that DOESN'T pass through the thalamus): From olfactory tract, it gets sent to the __________ cortex (it's the ________ lobe in humans). The anterior portion of the cortex interprets for ____________________. The poster portion of the cortex interprets for _____________________.

Central Olfactory Pathways (Olfactory Tract. The one that DOESN'T pass through the thalamus): From olfactory tract, it gets sent to the PYRIFORM cortex (it's the TEMPORAL lobe in humans). The anterior portion of the cortex interprets for CHEMICAL STRUCTURES. The poster portion of the cortex interprets for QUALITIES OF ODORANTS. (do you like the smell of it? Is it pungent? etc.)

True or False: Only one receptor type allows the brain to identify odorant.

FALSE!!! COMBINED activity of several receptor types allows brain to identify odorant!!!

True or False: Bitter, umami, and sour taste cells all have the same type of mechanism.

FALSE. BITTER, UMAMI, and SWEET all have the same type of GPCR mechanism. Sour works on H+ and blocking of K+ channels.

From tongue to the brain: The cranial nerves ___,___,___ will send signal from the ___________________ nucleus to the ___________ nucleus of the ___________. It will then send it to the ___________________ cortex (aka: Taste cortex).

From Tongue to the Brain:

From Tongue to the Brain: The cranial nerves ___,___,___ will send signal to the _____________ (gustatory nucleus). This is where it will then send the signal into 2 different pathways. First Pathway... -Will then send to the ___________ (aka: Vomiting center). Here, the Blood Brain Barrier is __________. -This region is also linked to the _____________ & ________________ (where you associate the food with emotion. Emotional response to taste). - This region is also linked to the _______________ (where it regulates your hunger). Second Pathway... -Will then send to the _____________ (where most of our senses are going to be rooted through). - This region will then be processed to the _____________ cortex (to interpret "What am I actually tasting") & the ____________ cortex ( to interpret "what texture is on my tongue").

From Tongue to the Brain: The cranial nerves 10, 9, 7, wil lenend singel to the MEDULLA (gustatory nucleus). This is where it will then send the signal into 2 different pathways. First Pathway... - Will then send to the PONS (aka: Vomiting center). Here, the Blood Brain Barrier is WEAK (Allowing for small molecules to pass through). -This region is also linked to the AMYGDALA & HIPPOCAMPUS (where you associate the food with emotion. Emotional response to taste). - This region is also linked to the HYPOTHALAMUS (where it regulates your hunger). Second Pathway... -Will then send to the THALAMUS (where most of our senses are going to be rooted through). - this region will then be processed to the INSULA cortex (to interpret" what am I actually tasting") * the PARIETAL cortex (to interpret "what texture is on my tongue").

Anatomy of Tongue.... Describe where these types of papillae are most concentrated on the tongue: Fungiform Foliate Filiform Circumvallate Which one is more common?

Fungiform: TIP OF TONGUE Foliate: SIDES OF TONGUE FILIFORM: ALL OVER Circumvallate: Back of tongue Most common: FILIFORM!

General Taste Cell Mechanism For Bitter, Umami, and Sweet: ___________ receptors are on the apical region of the taste cell. It will then activate the molecule _________ that's located intracellularly. This protein will then activate ____ ion storage. These intracellularly free floating ___ ions will then activate ____ ion channels and ____ permeable channels. The release of the NT _____ will then signal the gustatory afferent axon for perception. GPCR Receptor families: _____ is the GPCR for BITTERNESS ____________ is the GPCR for SWEETNESS _____________ is the GPCR for UMAMI There are ____ types of bitter receptors comprised of the ____ protein!

General Taste Cell Mechanism for Bitter, Umami, and Sweet: G PROTEIN COUPLED receptors are on the apical region of the taste cell. It will then activate the molecule PHOSPHOLIPASE C that's located intracellularly. This protein will then activate the Ca2+ ion storage. These intracellularly free floating Ca2+ ions will then activate Na+ ion channels and ATP permeable channels. The release of the NT ATP will then single the gustatory afferent axon for perception. GPCR Receptor families: T2R is the GPCR for BITTERNESS. T1R2+T1R3 is the GPCR for SWEETNESS T1R1+T1R3 UMAMI. There are 25 types of bitter receptors comprised of the T2R protein!

Generally, when we interpret sensory information, it's going to be in the __________________ cortex (in the _________ lobe).

Generally, when we interpret sensory information, it's going to the in the ORBITOFRONTAL CORTEX (in the FRONTAL lobe).

Molecular Mechanism of OLFACTORY RECEPTOR CELLS: The odorants will attach to the _________ receptor (SPECIFIC ONLY TO OLFACTORY CELLS). This will then cause the activation of the intracellular __________ molecule to open additional channels such as ____ & _____ channels, allowing these ions to flow _____ to the cell. This will then open voltage gated _____ channels to flow _______ of the cell. This cascade will result in a ___-polarization of the membrane, and sub sequentially an activation.

Molecular Mechanism of Olfactory Receptor Cells: The odorants will attach to the Golf receptor (SPECIFIC ONYL TO OLFACTORY CELLS). This will then cause the activation of the intracellular cAMP molecule to open additional channels such as Ca2+ & Na+ channels, allow these ions to flow INTO the cell. This will then open voltage gated Cl- channels to flow OUT of the cell. This cascade will result in a DEPOLARIZATION of the membrane. and sub sequentially an activation.

Which of the following is not a function of pheromones? a) Reproductive behaviors b) Territorial boundaries c) Identification d) Signal agression or submission

NONE. They're ALL functions.

Which of the following regions does not perceive taste (have taste receptors)? a) Palate b) Tongue c) Pharynx d) Epiglottis

NONE. They ALL perceive taste!

Olfactants have to dissolve in ___________ for cilia to take them in.

Olfactants have to dissolve in MUCOUS for cilia to take them in.

Olfactory Cells: Each receptor cell expresses (a) _____________ olfactory receptor protein(s). Receptors respond to different ____________. Responses to all cells allow us to _____________________ the odor.

Olfactory Cells: Each receptor cell expresses a SINGLE olfactory receptor protein. Receptors respond to different ODORS. Responses to all cells allow us to DIFFERENTIATE the odor.

Olfactory Receptor Cell during Stimulation: The _______ of the olfactory receptor cell is the one that generates the ACTION POTENTIAL. The action potential propagates down the _____________ nerve. The _______ of the olfactory receptor cell is a SLOW RECEPTOR POTENTIAL and may or may not lead to an AP. JUST A VOLTAGE SHIFT.

Olfactory Receptor Cell during Stimulation: The SOMA of the olfactory receptor cell is the one that generates the ACTION POTENTIAL. The action potential propagates down the OLFACTORY nerve (cranial nerve 1). the CILIA of the olfactory receptor cell is a SLOW RECEPTOR POTENTIAL and may or many not lead to an AP. JUST A VOLTAGE SHIFT.

____________ are bumps on the tongue that house taste buds. Each taste bud is made up of about _______ taste cells.

PAPILLAE are bumps on the tongue that house taste buds. Each taste bud is made up of about 50 taste cells.

Papillae house ________________ which house ____________. _______________ themselves are what recognize a specific taste.

Papillae house TASTE BUDS which house TASTE CELLS. TASTE CELLS themselves are what recognize a specific taste.

__________ is the most under developed sense in humans.

SMELL is the most under developed sense in humans.

Sensitivity to smell depends on the _________ of receptors not the ________ of receptors. -Humans have ~______ receptors. -Dogs have ~______ receptors.

Sensitivity to smell depends on the NUMBER of receptors not the TYPE of receptors. - Humans have ~10 million receptors. -Dogs have ~1 billion receptors.

What is the shortest nerve ???? Where is it?

Shortest nerve is the CRANIAL NERVE 1. It's the OLFACTORY NERVE that connects the olfactory senses to the OLFACTORY BULB!!!

Taste is going to be processed ______-laterally. This means that the information at the right side of your tongue will be processed on the ________ side of your brain. & This means that the information at the left side of your tongue will be processed on the _______ side of your brain.

Taste is going to be processed IPSILATERALLY. This means that the information at the right side of our tongue will be processed on the RIGHT side of your brain. & This means that the information at the left side of your tongue will be processed the LEFT side of your brain.

What's the difference between taste and flavor?

Taste: Is a specific sensation. Only ONE type of taste receptor. Flavor: Is a combination of BOTH tastes and smells.

The Organs of Smell: The cilia of olfactory cells are branched and immersed in the __________ layer and pass through a thin sheet of bone called ________________. It is then connected to the ___________ nerve (cranial nerve __), then connected to the __________ bulb.

The Organs of Smell: The cilia of olfactory cells are branched and immersed in the MUCOUS layer and pass through a thin sheet of bone called CRIBRIFORM PLATE. It is then connected to the OLFACTORY nerve (cranial nerve 1), then connected to the OLFACTORY BULB.

The ________________ taste is seen in many Asian cultures.

The UMAMI taste is seen in many Asian cultures.

If you eat quickly and then you get a signal for being full, why can you assume that you already ate too much?

This is because the hypothalamus regulates your hunger. The hypothalamus works on the hormonal level, which is generally slower. So by the time you got the signal for being full, you already ate too much.

To taste food, you must have ________. What are the five basic taste receptors?

To taste food, you must have SALIVA. 1) Saltiness 2) Sweetness 3) Bitterness 4) Umami 5) Sourness

In olfactory processing, what happens if you have to much mucous?

Too much mucous won't lead to binding of odorant onto cilia of receptor cell. This means NO ACTION POTENTIAL, and you can't SMELL!

Do humans have pheromones?

We don't know. It's not clear info atm.