Special S

Question 1

The middle ear is an air filled cavity which is in the _____

Answer 1

Temporal bone

Question 2

What are the content of the middle ear
The muscles in the middle ear are innervated by?

Answer 2

Bone– mallate, incus, stapes
Nerves– facial, chorda tympani
Muscles tensor tympani and stapedius innervated by beaches of trigeminal nerves and branches of facial nerves respectively
2 Foramen which are ovale(stapes attach) & Rotundum no attach

Question 3

Inner ear consists of

Answer 3

Cochlea & vestibular apparatus

Question 4

Immer ear consists of 3 coiled ducts seperated by ___ namely
Both alae vestibuli and tympani contain perilymph and communicate with each other at the _____ of the cochlea through a small opening
called the ______.

Answer 4

2 membrane
Vestibuli (Vestibular Duct):
Scala Media (Cochlear Duct)
Scala Tympani (Tympanic Duct)

Apex of the cochlea,
helicotrema

Question 5

Scala vestibuli characteristics
Air sound transmission increase with increase in temp. And altitude

Answer 5

Scala Vestibuli (Vestibular Duct):
o Begins @ the Oval Window
o Ends @ the apex of the Cochlea
o Filled with Perilymph.
o Separated from the Scala Media by the Vestibular Membrane

Question 6

Scala media characteristics

Answer 6

Scala Media (Cochlear Duct):
o Runs through the middle of the Cochlea.
o Separates the Vestibular Duct & Tympanic Duct.
o Filled with Endolymph.
o Separated from the Scala Tympani by the Basilar Membrane.

Question 7

Characteristics of Scala tympani

Answer 7

Scala Tympani (Tympanic Duct):
o Begins @ the apex of the Cochlea
o Ends @ the Round Window
o Filled with Perilymph.

Question 8

In the cochlear
The spiral organ of corti is located @

Answer 8

Sits inside the Scala Media & runs along the Basilar Membrane.

Question 9

The Spiral Organ of Corti: is composed of

Answer 9

The Tectorial Membrane (Overlying the Hair Cells)
Hair cells ʹAssociated with cochlear nerve fibres:
Supporting cells
Basilar membrane

Question 10

The ear functions as a transducer , because

Cochlear Branch of the Vestibulocochlear Nerve Originates Here
i.e The Spiral Organ of Corti:

Answer 10

it transforms
the pressure energy of the sound waves into nerve impulses, and the auditory cortex converts these impulses into the sensation of sound

Question 11

ƒ
The Spiral Organ of Corti: contain 2 types of hair cells
With the inner having____cells
And outer one having ____ cells

Answer 11

3500 & 20000

Question 12

What’s the function of the pinna
EAM, Tympanic membrane

Answer 12

EAM -A narrow canal of 25mm long, allow passage of sound wave, secretes wax to lubricate the drum
Tympanic membrane- acts as reasonance that produces vibrations of sound source & amplitude

Question 13

Amplitude of the vibration is directly proportional to intensity of the sound

Contraction of the tensor tympani and stapedius causes

Answer 13

Tensor tympani contraction causes the pulling of the malleus and tympanicmembrane inwards excessively stretching the membrane

Contraction of the tensor stapedius causes the outward movement of the stapes bone from the oval window

Question 14

Function of middle ear

Answer 14

Bony ossicles are vibrated by transmiting vibration from the tympanic membrane, to the bone oscicle then to head of stapes, therefore swinging the foot plate to & from causing opening & closing of the oval window

Question 15

Function of the previous movement in the middle ear

Answer 15

Sound is created through the resonance vibration of a drum.
The movement of the stapes bone against the perilymph in the Scala vestibuli helps transmit sound vibrations to the inner ear.
The malleus bone in the middle ear amplifies the movement of the stapes by about 5 to 3 times due to its inertia.
The tympanic membrane (eardrum) has a surface area that is 17 times larger than the oval window membrane.
The oval window membrane amplifies the sound pressure by about 22 times.
The amplification of sound pressure at the oval window ensures stronger vibrations reach the inner ear.

Question 16

The middle ear is
separated from external auditory meatus by

Answer 16

tympanic
membrane.

Question 16

The middle ear is
separated from external auditory meatus by

Answer 16

tympanic
membrane.

Question 17

What’s the function of the middle ear muscles

Answer 17

Tensor tympani if the vibration is too high the tensor tympani pulls away the malleus from incus to prevent damage
Stapedius muscle: pulls the stapes to prevent sound transmission

Question 18

Functions of the eustachian tune

Answer 18

Its main function is to equalize the pressure on both sides of the eardrum.

Question 19

Normally, the Eustachian tube is closed at one end, preventing anything from entering the middle ear. This closure is important because it keeps things like saliva, food particles, and air from reaching the sensitive middle ear. These substances could potentially cause infections or damage.

However, the Eustachian tube can temporarily open during certain actions like swallowing, chewing, or yawning. When it opens, it allows for a brief communication or connection between the middle ear and the nasopharynx. This opening helps equalize the pressure on both sides of the eardrum. When you experience a change in altitude, such as when you’re on an airplane or traveling to higher elevations, the pressure in the middle ear can become imbalanced. By opening the Eustachian tube, you can equalize the pressure and relieve any discomfort or popping sensations you may feel in your ears.

Question 20

What’s the function of the inner ear

Answer 20

It contains the sense organ of hearing the organ of cordi
When it’s stimulated by sound vibration it generates nerve impulses in the organ of cordi that’s transmitted to the auditary area in the cerebral cortex through the cochlear of auditary nerve CN8

Question 21

Major part of the
auditory pathway lies in medulla oblongata, midbrain
and thalamic region.

Question 22

Higher center for hearing is in temporal lobe of
cerebral cortex, where the fibers of auditory pathway
finally terminate

Question 23

What are the receptors of auditary sensation

Answer 23

Hair cells in organ of Corti are the receptors of the
auditory sensation.

Question 24

Auditary pathways
Features of first order neurons

Answer 24

Is bipolar
They are afferent fibres in cochlear nerve
They are spiral in nature
They transmit impulses to organ of corti
This cochlear nerve enter the brain @ upper medulla and divided into 2 branches

Question 25

This cochlear nerve enter the brain @ upper medulla and divided into 2 branches
1st order neurons terminate@ in the
Movements of the basilar membrane are maintained by changes in the
______ window.

Answer 25

central cochlear nucleus
Dorsal cochlear nucleus

round

Question 26

First-order neurons: These are special cells called hair cells located in your inner ear, specifically in a spiral-shaped structure called the cochlea. When sound waves enter your ear, they cause vibrations that stimulate these hair cells. The first-order neurons convert these vibrations into electrical signals.

Second-order neurons: The electrical signals generated by the first-order neurons travel along the auditory nerve, which is a bundle of nerve fibers. These signals reach a structure in the brainstem called the cochlear nucleus. Here, the second-order neurons receive and process the electrical signals.

Third-order neurons: The processed signals from the cochlear nucleus are then relayed to another structure called the inferior colliculus, which is located in the midbrain. The third-order neurons receive the signals and further refine them.

Fourth-order neurons: Finally, the refined signals reach the auditory cortex, which is a part of the brain responsible for processing sound. The fourth-order neurons in the auditory cortex receive and interpret the signals, allowing you to perceive and make sense of the sound you hear.

Question 27

In what direction does the second order neuron run

Answer 27

rst group of fibers cross the midline and run to the
opposite side, to form trapezoid body. Fibers from
trapezoid body go to the superior olivary nucleus

Second group of fibers terminate at superior olivary
nucleus of same side via trapezoid body of the
same side

Third group of fibers run in lateral lemniscus of
the same side and terminate in nucleus of lateral
lemniscus of same side

Fourth group of fibers run into reticular formation,
cross the midline as intermediate trapezoid fibers
and finally join the nucleus of lateral lemniscus of
opposite side.

Question 28

___&___ forms the 2nd order neuron

Answer 28

Neurons of dorsal and ventral cochlear nuclei in the
medulla oblongata form the second order neurons of
auditory pathway.

Question 29

The crossing fibres of both ventral & dorsal crosses in front of the stria acoustica & trapezoid body

Question 30

Third order neurons are in the ___&___

Answer 30

superior olivary nuclei & trapezoid body
Acends via nucleus of lateral lemniscus
To relay @ inferior colliculus

Question 31

The 3rd order arise from the neuron superior olivary nuclei
and nucleus of lateral lemniscus and asends in the lat. Lamniscus and relay in nucleus of lateral
lemniscus (inferior colliculus) however

Answer 31

Some fibers doesn’t relay it asends directly to superior colliculus and trapezoid nucleus

Question 32

The lat. Lemniscus contains___ order neuron

Answer 32

The 2nd from cochlear
& 3rd from superior olivary & trapezoid nucleus

Question 33

What are 4th order neuron

Answer 33

Are fibres of inferior colliculus and they relay in the medial geniculate body of the thalamus
Some relay & some don’t

Question 34

5th oder neuron

Answer 34

Fibers from medial geniculate body go to the temporal cortex, via internal capsule as auditory radiation
The control area of the temporal lobe

Question 35

The control area of the temporal lobe includes

Answer 35

41,42– responds to low & high pitched sounds

Question 36

Where’s the auditory psychic area and it’s function

Answer 36

Areas that perceive sound but can’t be determined area 22

Question 37

To determine nerve deafness & conductive deafness

Answer 37

Rinnes test
Weber
Audiometer

Question 38

Partial deafness is always associated with

Answer 38

Increased auditory threshold

Question 39

Sound is a sensation produced when sound wave strikes the tympanic membrane
Hearing is the ability to perceive & interprete the sound wave
Ear functions as transducers

Question 40

Ear functions as transducers means

Answer 40

the case of the ear, its primary function as a transducer is to convert sound waves, which are mechanical energy, into electrical signals that can be interpreted by the brain.

Question 41

Outer Ear: The outer ear collects sound waves and directs them into the ear canal.

Middle Ear: Sound waves reach the eardrum, causing it to vibrate. These vibrations are then transmitted through a chain of tiny bones called the ossicles: the malleus (hammer), incus (anvil), and stapes (stirrup). The ossicles amplify the vibrations as they pass from the eardrum to the inner ear.

Inner Ear: The amplified vibrations from the ossicles enter the cochlea, a snail-shaped structure in the inner ear. Within the cochlea, there are specialized cells called hair cells that line the basilar membrane.

Hair Cells: The vibrations in the fluid of the cochlea cause the basilar membrane to move, which, in turn, causes the hair cells to bend. This bending of hair cells generates electrical signals.

Auditory Nerve: The electrical signals produced by the hair cells are transmitted via the auditory nerve to the brain.

Question 42

What’s Frequency is

Answer 42

Is the rate at which air wave oscillate per unit time

Question 43

Normal human frequency is 20-2000
For male is ___
Female____

Answer 43

Male 120hz
Female 250hz

Question 44

Amplitude of sound is the intensity or volume of sound
Measured in Bels

Question 45

Standard sound has a frequency of 1000 hz

Question 46

The threshold of hearing is typically around 0 dB SPL, but it may vary among individuals.

Question 47

The theory proposes that high-frequency sounds cause maximum stimulation near the base of the cochlea, while low-frequency sounds stimulate the apex or the far end of the cochlea

Resonance theory, also known as frequency or temporal theory, suggests that we perceive pitch based on the rate at which the auditory nerve fibers fire action potentials in response to sound waves

Question 48

traveling wave theory explains how sound waves travel through the ear, starting from the outer ear, passing through the middle ear, and ultimately reaching the inner ear.

Question 49

____ receptors is responsible for odorsell & it’s located in

Answer 49

Olfactory receptors
In nassl mucosa called olfactory mucosa membrane
Yellow in color & occupies 5cm2 @ the roof of the nasal cavity

Question 50

___ secrets me cosa to cover the olfactory mucosa membrane

Answer 50

Bowman’s gland

Question 51

Olfactory mucosa membrane contains ___ types of cells namely

Answer 51

3
Supporting
Olfactory receptors cella
Neuroblastic progenitor cells

Question 52

Features of olfactory receptors cells

Answer 52

They are bipolar
They have thin dendrite with expanded hard called olfactory rods
Their axons pierces the cribiform plate of the ethmoid bone and enter the olfactory bulb

Question 53

Neural elements of the olfactory bulb are

Answer 53

Mitral cells
Tuft cells
Granular cells or progenitor cells
Recurrent collateral cells from mitral cell axons

Question 54

Therefore,odoriferous substances (odorants) should be

Answer 54

Volatile
(b) Relatively highly water and lipid-soluble .

Question 55

The mucus that covers the olfactory receptors contains odorant-binding proteins (OBPs). These OBPs help to concentrate the odorants and transfer them to the olfactory receptors, which are responsible for detecting smells.

When the odorants reach the olfactory receptors, they activate a G protein, which in turn activates the adenyl cyclase enzyme. This activation leads to the increased production of cyclic AMP (cAMP).

The cAMP molecule binds to and opens sodium (Na+) channels, causing depolarization.which generates a receptor potential and is transmitted by nerve cells. These action potentials carry the information about the odorant to the brain, allowing us to perceive the smell.

Question 56

In some cases, certain odorants may be coupled to an enzyme called ______ which produces inositol phosphates, which also open the sodium channels, leading to depolarization and the initiation of action potentials.

Answer 56

phospholipase C which

Question 57

Explain olfactory nervous pathways

Answer 57

Olfactory receptor neurons have axons that pass through the cribriform plate and enter the olfactory bulb

The axons of these neurons connect with the dendrites of three types of cells: mitral cells, tufted cells, and periglomerular short axon cells.

These connections form specialized synapses called olfactory glomeruli.

Additional cells in the olfactory bulb include granule cells (with an inhibitory role) and deep short axon cells (whose function is unknown).

The output fibers (efferent fibers) that leave the olfactory bulb mainly consist of axons from mitral cells

These axons pass through the intermediate and lateral olfactory striae.
The axons terminate on the dendrites of pyramidal cells in the olfactory cortex.
The olfactory cortex includes brain structures associated with the limbic system, which is involved in emotions and memory.

Question 58

Unlike other sensations, the olfactory pathway doesn’t pass through the thalamus as it travels to higher brain areas. Olfaction is the only sense that doesn’t go through the thalamus.

Question 59

The inhibitory feedback pathway involving the granule cells helps in

Answer 59

enhance the ability to distinguish different odors by sharpening the excitation within the olfactory bulb. It also plays a role in central olfactory adaptation, where our sensitivity to certain smells decreases over time.

Question 60

The olfactory bulb receives input from various sources, including the

Answer 60

nucleus of the diagonal band (centrifugal fibers), the ipsilateral (same side) anterior olfactory nucleus, and the contralateral (opposite side) anterior olfactory nucleus via the anterior commissure.

Question 61

What are the The centrifugal fibers

Answer 61

and the other afferent inputs travel backward from certain brain areas to the olfactory bulb. These inputs mostly terminate at the granule cells. These cells, in turn, inhibit other cells in the olfactory bulb, particularly the mitral and tufted cells.

Question 62

What’s The anterior olfactory nucleus:

Answer 62

This region helps coordinate input from the opposite (contralateral) olfactory cortex and may transfer olfactory memories from one side to the other.

Question 63

What’s the piriform cortex:

Answer 63

This area is responsible for distinguishing different odors and is likely involved in our conscious perception of smell (the main olfactory area).

Question 64

______: This region is probably involved in emotional responses to smells.

Answer 64

The corticomedial part of the amygdaloid nucleus

Question 65

_______ This area is likely involved in the formation and storage of olfactory memories.

Answer 65

The entorhinal cortex:

Question 66

Both smell & taste use external chemo receptors

Question 67

Write a note on taste bud receptors

Answer 67

Taste buds are oval-shaped structures consisting of four types of cells: basal cells, type 1 cells, type 2 cells, and type 3 cells
Type 1 and type 2 cells are sustentacular cells, while type 3 cells are gustatory receptor cells that connect to sensory nerve fibers.
Basal cells differentiate into receptor cells. Receptor cells are continuously replaced every approximately 10 days.

If a sensory nerve is severed, the corresponding taste buds degenerate. However, if the nerve regenerates, neighboring cells can form new taste buds.
Each taste bud is innervated by around 50 nerve fibers.

Taste buds are found in the mucosa of the tongue, palate, pharynx, as well as in the fungiform contain approximately 5 taste buds each and circumvallate papillae of the tongue.contain approximately 100 taste buds each.
Filiform papillae do not typically contain taste buds.

Question 68

Short note on the stimulation of taste buds

Answer 68

Taste buds are chemoreceptors that respond to dissolved substances in oral fluids, such as saliva.
The strength of taste depends on the solubility of a substance. The more soluble a substance is, the more it stimulates the taste buds, leading to a greater number of impulses transmitted to the brain’s cerebral cortex.
However, the binding of substances to taste buds is weak, and even a small amount of water or saliva can diminish the taste sensation.
Taste buds can be stimulated by substances within the body as well. For example, the bitter taste experienced during jaundice is caused by circulating bile salts.

Question 69

Olfaction (sense of smell) is more powerful than taste in determining the flavor of food.

Question 70

When a person has a common cold, they may complain of a loss of taste, but it is actually a loss of smell that affects their perception of flavor.

Question 71

When food passes through the mouth, its volatile (gaseous) components are inhaled into the nasal cavities, where they are smelled.

Question 72

Short note on mechanism of taste buds stimulation

Answer 72

Taste substances act on the tiny structures called microvilli in the taste pores of our tongue
These substances create generator potentials

Generator potentials then trigger action potentials in the sensory neurons, which send signals to the brain.

Ebner’s glands, located on the back of the tongue, secrete a protein that helps bind, concentrate, and transmit taste substances to the receptor cells.

Contd

Question 73

The mechanism of producing the generator potential varies depending on the type of taste

Answer 73

Sweet substances increase the level of a molecule called cyclic AMP inside the receptor cells. This reduces the flow of potassium ions (K+) and leads to the generation of the generator potential.

Bitter substances trigger the release of calcium ions (Ca++) from a cellular structure called the endoplasmic reticulum, which produces the generator potential

Salty substances induce the entry of sodium ions (Na+) through open channels in the receptor’s membrane, resulting in the generation of the generator potential.

Sour substances block the potassium channels in the receptor’s membrane, causing the generator potential to form.

Question 74

Short note on food preferences

Answer 74

Food preference refers to the tendency of animals to choose certain types of food over others.
For example, if an animal’s adrenal glands are removed (adrenalectomized), it will automatically choose to drink water with a high concentration of sodium chloride (NaCl) over pure water.
Similarly, if an animal’s parathyroid glands are removed (parathyroidectomized), it will prefer drinking water with a high concentration of calcium ions (Ca++).
Hypoglycemic animals, which have low blood sugar levels, tend to select the sweetest food among various options.

Question 75

Short note on nervous pathways of taste

Answer 75

Sensory nerve fibers from taste buds are myelinated but conduct signals slowly. And constitute the 1st order neuron
Nerves from the front two-thirds of the tongue travel through the chorda tympani (a branch of the 7th cranial nerve).

Nerves from the back one-third of the tongue travel via the glossopharyngeal nerve (9th cranial nerve).

Sensory taste fibers from the pharynx and epiglottis are transmitted through the vagus nerve (10th cranial nerve).

All these sensory fibers come together in the medulla oblongata and form the tractus solitarius

The tractus solitarius relays signals in the nucleus of the tractus solitarius.

Second-order neurons start at this nucleus, cross the midline, join the medial lemniscus, and ascend to the posterior central nucleus of the thalamus.

Third-order neurons arise from the thalamus, pass through the sensory radiation (via the posterior limb of the internal capsule), and terminate in the taste projection area of the cerebral cortex in the lower part of the postcentral gyrus.

Question 76

Short note on taste modalities or types of taste

Answer 76

Bitter: Tasted at the back of the tongue, mostly sensed by the circumvallate papillae. Examples of substances that produce a bitter taste include quinine sulfate, strychnine hydrochloride, morphine, nicotine, caffeine, urea, and certain inorganic salts like magnesium, ammonium, and calcium.

Sour: Tasted along the edges of the tongue. The sour taste is caused by the presence of H+ ions in acids. Organic acids generally create a stronger sour taste compared to inorganic acids because they penetrate cells more rapidly.

Sweet: Tasted at the tip of the tongue. Examples of substances that produce a sweet taste include sucrose, maltose, lactose, glucose, certain ketones, polysaccharides, some alcohols, chloroform, saccharin, and even lead salts

Salt: Tasted at the front part of the tongue’s dorsum, primarily by certain cations of inorganic salts, especially Na+. Some organic compounds can also taste salty.

The four taste modalities (bitter, sour, sweet, and salt) can also be sensed in the pharynx, epiglottis, and palate. Sour and bitter tastes are particularly noticeable in the palate.

Question 77

Write a short note on taste abnormalities & discrimination of taste

Answer 77

There are three types of taste abnormalities:

Ageusia: Absence of the sense of taste.
Hypogeusia: Diminished taste sensitivity.
Dysgeusia: Disturbed sense of taste.
These abnormalities can occur in certain diseases and can also be caused by certain drugs. For example, captopril can cause a temporary and unexplained loss of taste sensation.

humans have difficulty detecting small differences in the intensity of tastes. Just like how our sense of smell struggles to perceive slight changes in odor, our ability to notice slight changes in taste intensity is also limited. It takes about a 30% change in the concentration of a substance we taste before we can actually perceive a noticeable difference in its intensity.

Question 78

Write a short note on olfactory adaptation

Answer 78

olfactory adaptation refers to the gradual decrease and disappearance of our perception of a specific odor when we are continuously exposed to it. This adaptation occurs primarily in the brain rather than the receptors themselves, and it involves feedback inhibition of smell signals, leading to reduced activity in the olfactory bulb.

This reduction in activity is likely caused by the stimulation of certain centrifugal fibers, which leads to feedback inhibition of smell signals in the central nervous system.
As a result, the decreased discharge of smell signals contributes to the adaptation or decreased perception of the odor.

Question 79

Short note on Pain Nerve Endings in the Olfactory Membrane

Answer 79

The olfactory membrane has nerve endings that can sense pain, but they don’t have any protective covering. These nerve endings are connected to the trigeminal nerve, which is responsible for transmitting sensory information from the face. These nerve endings can be stimulated by substances that cause irritation, like ammonia, chlorine, menthol, and pepper. When these nerve endings are activated, they can cause you to sneeze, produce tears, and temporarily slow down your breathing as a response to these irritating substances in your nose.

Question 80

Tests of Smell Sensation

Answer 80

The first test involves sniffing different non-irritating odors and identifying them.
Each nostril is tested separately to evaluate the sense of smell in each.

The second test, called olfactometry, measures the threshold of smell using a special instrument called an olfactometer.

Question 81

What are the Abnormalities of Smell

Answer 81

Anosmia refers to a complete loss of smell, while hyposmia indicates a decreased sense of smell.
Dysosmia refers to distorted perception of smells

Question 82

Detecting source of odor

Answer 82

locating the source of an odor relies on differences in arrival time of odor molecules to the two nostrils.
The nostril closer to the source receives odor molecules slightly earlier and in a slightly higher concentration.
Both nostrils and an intact olfactory nervous pathway are required to accurately determine the source of an odor.

Question 83

Olfactormeter