Chp 54 (The Chemical Senses: Taste & Smell) Flashcards
Taste receptor cells occur on the tonque in groups of how many?
in groupd of 50-150 and each of these groups forms a taste bud which is grouped together with other taste buds into taste papillae.
The taste buds are embedded in the epithelium of the tonque and make contsct with the outside enviroment through a ______ ______.
What is the average life of a taste bud?
Taste Pore
10 Days
Taste receptor capillaries have been grouped into 5 general categories called?
Primary Sensations of Taste
Neme the 5 primary senstations of taste?
- Sour
- Salty
- Sweet
- Bitter
- Umami
“Sour Taste” is caused by what ?
and
What is the intensity of this “sour taste” sensation proportional to?
Acids-by the Hydrogen Ion concentration
logarithm of the hydrogen ion concentrations
Meaning:** the more acidic the food the stronger the sour sensations becomes
The Salty Taste is elicited by _____ _____. Mainly by the ____ ____ concentration.
- Ionized Salts*
- Sodium Ions*
T or F
The Sweet Taste is not caused by any single class of chemicals
True
What are some of Chemicals that cause the sweet tase ?
- Sugars
- glycols
- alcohol
- aldehydes
- ketones
- amides esters
- some AA’s
- some small proteins
- sulfonic acids
- halogenated acids
- inorganic salts of lead
- beryllium
Most of teh substances that cause a sweet taste are _____ chemicals.
Organic Chemicals
The bitter taste (similar to Sweet) is not caused by any single type of chemical agent.
2 Particular classes of substances are especially cause bitter taste sensations are:
- Long-Chain organic substances that contain nitrogen
- Alkaloids
Umami is a Japanese word meaning “delicious” , which qualitatevly differs form Sour, sweet, salty and bitter…..
“Umami” is the dominant taste of food containing what?
I-Glutamate such as:
meat extracts and aging cheese
Define Taste Blindness:
inability to appreciate gustatory stimuli
unable to taste cetain substances such as Thiourea coumpunds
The receptor cells for the smell sensation are
called _____ cells, which are actually ______ _____ cells, derived originally from the CNS itself.
Olfactory Cells
Bipolar nerve cells
How many olfactory cells are found in the Olfactory Epithelium?
100 Million interspersed among Sustentacular Cells
The Sense of Smell known as ______ is carried out by the _______ nerve or CN 1.
Olfaction
Olfactory Nerve
The nasal cavity is made up of three regions.
Name the 3 regions:
- first, is the nasal vestibule which is the area just inside the nostrils.
- second is the respiratory region, which is just above the nasal vestibule and is separated by three shelf-like bony structures; the superior, middle and inferior nasal conchae.
- third, is the olfactory region which is at the top of the nasal cavity and is involved in smelling.
The Lining in the respiratory region is a layer of ____ ______ that create mucus to moisten the air and trap pathogens.
Epithelial Cells
Lining the olfactory region is a layer of special _____ ______ which form the olfactory epithelium.
special epithelial cells
The olfactory epithelium consists of olfactory receptor cells which are ______that respond to molecules, called ______.
chemoreceptors
odorants
T or F
The olfactory epithelium also contains cuboidal epithelial cells which support those olfactory receptor cells.
False
The olfactory epithelium also contains columnar epithelial cells which support those olfactory receptor cells.
Below the olfactory epithelium is a layer of connective tissue called the______ ______.
lamina propria
The lamina propria contains olfactory glands also known as _____ _____ which produce nasal mucus that protects the surface of the olfactory epithelium.
Bowman’s glands
Below the lamina propria is the roof of the olfactory region which is formed by the ____ _____ of the ethmoid bone.
cribriform plate
The olfactory receptor cells are _____ neurons, meaning that they have ____ _____outside the olfactory epithelium.
bipolar neurons
two projections
Bipolar neurons have 2 projections outside the olfactory epithelium:
Name them and what are they responsible for?
- One projection carries their dendrites to the bottom of the epithelium and gives off hair-like structures called the olfactory hairs, or cilia.
These cilia protrude beyond the nasal mucosa so that they can come into contact with odorants trapped by the mucus.
- The other projection is an axon that joins up with axons of other receptors to form tiny olfactory nerves - collectively called cranial nerve 1.
Tiny olfactory nerves pass through small openings of the _____ _____of the ethmoid bone, called the _____ ______, to enter inside the olfactory bulb.
cribriform plate
olfactory foramina
The olfactory bulb contains ____ ____ neurons in the olfactory pathway, and it sends information through the _____ _____ to the ______ _____in the temporal lobe.
second order neurons
olfactory tract
olfactory cortex
What is found within the membrane of the cilia?
olfactory receptor proteins : called G-protein coupled receptors and the odorants bind to them.
What happens after an odorant binds to a receptor?
signal transduction occurs - meaning that it activates a G protein inside the cell called the G-olfactory protein.
Signal transduction activates the G-Protein, triggering the G-protein _____ ______ pathway, which ultimately opens up ____ and ____channels - allowing those ions to flow into the cell.
G-protein coupled receptor pathway
calcium and sodium
What happens as calcium ions flows into the cell?
- causes Ca++-activated chloride channels to open up.
Note: Since there’s a higher concentration of Cl- ions inside the receptor cell relative to outside the cell, the Cl- ions flow out of the cell.
In the G-Protein coupled receptor pathway….The combination of positive ions coming in and negative ions going out causes the receptor cell membrane to _______, or become____ _____. This causes the neuron to _____ and _____ the sensory information up the ______ _____towards the ______ bulb.
Once the signal reaches the olfactory bulb, the ____ ____ that make up the olfactory nerve synapse with second order neurons called ____ ____.
depolarize
less negative
fire and transmit
Olfactory nerver
olfactory bulb
receptor cells
mitral cells
- When second order neuron* ______ cells are activated “receptor cells” release neurotransmitters, like _____ which causes _____ of the mitral cells. This signal then travels through the mitral cell axons which form the _____ _____.
- The olfactory tract splits into a lateral and medial tract.
Mitral Cells
glutamate
depolarization
olfactory tract
The olfactory tract splits into ____ and _____ track.
Explain Lateral tract:
lateral and medial tract
- The lateral tract runs to an area deep within the ipsilateral (same side), temporal lobe, called the piriform cortex which is the primary center for olfaction.
From there some fibers can also go to the limbic system, which is composed of the thalamus, hippocampus and amygdala, which are the centers for emotion and memory. And this is why certain odors can trigger emotions or memories from the past, like the smell of the ocean might remind you of family vacations to the beach.
The olfactory tract splits into ____ and _____ track.
Explain Medial tract:
Lateral and Medial Tract
medial tract crosses over to the contralateral (opposite side) piriform cortex meaning that smell from one olfactory receptor can reach both sides of the brain.
Note: so, if you have a cold and the right nasal cavity is completely clogged, some signals can still pass to the right side of the brain from the left nasal cavity.
When smell molecules enter the nose they get trapped by what?
1. mucus at the roof of the nasal cavity
Once smell molecules are trapped in Nasal Cavity and bind to (1)____ _____ ______ receptors found on the cell membrane of specialized sensory neurons, called (2)______ ______.
This triggers a(3) ____ _____, which travels through the axons of the (4)______ _____to reach the olfactory bulb that sits on the (5)_____ _____ of the ethmoid bone.
1. G-protein coupled receptors
2. olfactory receptors
3. nerve signal
4. olfactory receptors
5. cribriform plate
Nerve signal travels through the axons of the olfactory receptors to reach the 1)_____ _____ that sits on the cribriform plate of the (2)_____ bone.
From there the signal travels through the(3)____ _____ to reach the piriform cortex in both temporal lobes, which are the (4)____ _____ for olfaction, and the limbic system where smell is associated with (5)______ and (6)______.
- olfactory bulb
- ethmoid bone
- olfactory tract
- primary centers
- memory
- emotions
