Physiology Of Olfaction And Gustation

Question 1

What are Ordorants?

Answer 1

They are airborne molecules and they give off vapor they reach the olfactory breceptors by being inhaled through the nose and through mouth the vapors circulate the throat

Question 2

What is Olfaction?

Answer 2

It is the sense of smell and involves olfactory receptors responding to chemical stimuli
Made possible by the olfactory bulbs and olfactory membrane

Question 3

What two layers make up the olfactory membrane?

Answer 3

Olfactory epithelium and Lamina propria

Question 4

What is the olfactory epithelium?

Answer 4

Yellowish pigmented epithelium in the roof of the nasal cavity near the septum smell is detected by the olfactory chemoreceptors which are specialized endings of bipolar neurons that convert olfactory stimuli into nerve impulses

Question 5

What does the olfactory epithelium contain?

Answer 5

Olfactory sensory neurons
Supporting cells
Basal stem cells

Question 6

What does the olfactory epithelium cover?

Answer 6

Cribriform plate
Superior portion of the perpendicular plate
Superior nasal conchae of ethmoid bone

Question 7

What does the lamina propria contain?

Answer 7

Areolar tissue
Blood vessels
Nerves
Olfactory glands

Question 8

What are the purpose of the secretions of the olfactory glands?

Answer 8

They absorb water and form an think pigmented mucus that coats surface if the olfactory organs

Question 9

What is the description of the olfactory sensory neurons?

Answer 9

The Cillian is unmyelenated and they contain olfactory receptors
A single axon passes through cribriform plate of the ethmoid bone and enter the olfactory bulbs

Question 10

What is olfactory discrimination?

Answer 10

Can distinguish thousands of chemical stimuli and cns interprets smells by pattern of receptor activity

Question 11

Where does olfactory reception occur?

Answer 11

On the surface membranes of the olfactory cilia

Question 12

How does odorant discrimination occur?

Answer 12

Oforants interact with odorant binding proteins on the membrane surface and adenylyl cyclase activates and this is an enzyme that converts ATP to cAMP

CAMP will open sodium channels in the Plasma membrane which will depolarize
Sufficient depolarization occurs an action potential is triggered in the axon and information is relayed to CNS

Question 13

How many odorant can activate olfactory receptors?

Answer 13

4 odorants

Question 14

What do the axons leaving the olfactory epithelium do?

Answer 14

Collect into 20 or more bundles
Penetrate the cribriform plate of ethmoid bone and will reach the olfactory bulbs of the cerebrum where it will synapse in the Golmeruli

Question 15

How does transmission of olfactory signal to olfactory bulb occur?

Answer 15

The axons of the receptors cells penetrate the cribriform plate and form the olfactory nerve
They synapse on Mitral cells in the olfactory bulb which is superior to cribriform plate
The axons of Mitral cells travel the olfactory tract to reach olfactory cortex and the limbic system

Question 16

What are the olfactory pathways ?

Answer 16

They travel along the olfactory tract to reach olfactory cortex,hypothalamus and portions of limbic system
Arriving information reaches information centers without first synapsing the thalmus

Question 17

What is Gustation?

Answer 17

It is the sense of taste
It has Gustatory Receptors which are distributed on tongue and potions of pharynx and larynx

Question 18

What are taste buds?

Answer 18

They are taste receptors and specialized epithelial cells

Question 19

What is the lingual papillae?

Answer 19

The superior surface of the tongue which are special projections

Question 20

What are the 4 types of the lingual papillae?

Answer 20

Filliform-Provides friction that helps move objects around and dors not contain taste buds
Fungiform-contains 5 taste buds
Foliate
Circumvallate -contains 100 taste buds each

Question 21

What do the taste buds contain?

Answer 21

Basal cells
Gustatory cells

Question 22

What is Gustatory discrimination?

Answer 22

Where dissolved chemicals contact taste hairs and bind to receptir proteins of the Gustatory cell and diffrent tastes involves different receptor mechanisms

Question 23

What do the sweet and sour receptors involve?

Answer 23

Chemically gated ion channels and stimulation produces depolarization of cell(Receptor potential)
These receptor potentials are graded

Question 24

What do the bitter,sweet, and umami stimuli involve?

Answer 24

G proteins which are called gustucins protein complexes and use second messengers to produce their effects

Question 25

What is the end results of taste receptors stimulation?

Answer 25

Release of NT by receptor cells and dendrites of sensory affarents wrapped by receptor membrane and they generate AP in affarent fiber and the Aps obey all or none

Question 26

What is signal transduction?

Answer 26

Binding a tastant with a receptor cell and alters cells ionic channels to produce depolarizing receptor potential and the potential releases an NT and initiates AP with terminal endings of affarent nerve fibers with which receptor cells synapse
Signals conveyed via synaptic stops in brain stem and thalamus to cortical gustatory area

Question 27

What are the Gustatory pathways?

Answer 27

The taste buds are innervated by the facial,glossophryngeal,vagus nerves
Sensory affarent fibers carried by these cranial nerves synapse in solitary nucleus of medulla oblongata and axons of postsynaptic neurons enter medial lemniscus
Where neurons join axons that carry somatic sensory information on touch pressure and proprioception after synapse in thalamus the information is projected on the Gustatory cortex and perception of taste is produced
Neurons in the trigeminal cranial nerve provides information about texture of food and taste related information