Sensory Systems Practice Questions

Q: Which sense organ is primarily associated with an efferent nerve supply?

Organ of Corti. ***Organ of Corti*** - The **organ of Corti** receives efferent innervation via the **olivocochlear bundle**, which modulates the sensitivity of outer hair cells. - This efferent input helps to sharpen frequency tuning and protect the inner ear from excessive noise. *Golgi tendon organ* - The **Golgi tendon organ** is a **proprioceptor** that senses muscle tension and is supplied by afferent (sensory) fibers, not efferent. - Its primary role is to provide feedback on muscle force to the central nervous system. *Retina* - The retina is primarily a **sensory organ** containing photoreceptors that transmit visual information through afferent pathways to the brain. - While there are some interneurons, its main nerve supply is **afferent** for visual processing. *Taste bud* - Taste buds are **chemoreceptors** that detect taste stimuli and transmit signals via afferent nerve fibers to the brain. - They are not characterized by a prominent efferent nerve supply controlling their primary sensory function.

Q: Which motor protein is primarily involved in the function of the organ of Corti in the inner ear?

Myosin. ***Myosin*** - **Myosin** is crucial for the **mechanotransduction** process in the hair cells of the organ of Corti, specifically the **outer hair cells**. - It facilitates **electromotility**, allowing outer hair cells to change length in response to sound, amplifying vibrations and enhancing hearing sensitivity. *Kinesin* - **Kinesin** is primarily involved in **anterograde axonal transport** of vesicles and organelles along **microtubules** in neurons. - While present in various cell types, its main role is not directly in the sound transduction mechanism of the organ of Corti. *Actin* - **Actin** is a fundamental component of the **cytoskeleton** and forms the core of the stereocilia in hair cells. - Although essential for the structural integrity and mechanical properties of stereocilia, **actin itself is not a motor protein**; rather, it interacts with motor proteins like myosin. *Dynein* - **Dynein** is primarily responsible for **retrograde axonal transport** along microtubules and the movement of **cilia and flagella**. - It plays a role in cellular transport, but not directly in the active sound amplification or mechanotransduction within the organ of Corti.

Q: Umami taste is evoked by?

Glutamic acid. ***Glutamic acid*** - Umami is known as the **fifth basic taste** alongside sweet, sour, salty, and bitter. - It is primarily elicited by **L-glutamate**, an amino acid found in many protein-rich foods and fermented products. *Glucose* - **Glucose** is a simple sugar and is responsible for the **sweet taste**. - It does not directly evoke the umami sensation. *Quinine* - **Quinine** is a compound known for its intense **bitter taste**. - It is often used as a reference substance for bitterness perception studies. *Sodium chloride* - **Sodium chloride**, commonly known as table salt, is responsible for the **salty taste**. - It plays no direct role in eliciting the umami taste sensation.

Q: Which Brodmann's areas are primarily associated with somatosensory perception?

1, 2, 3. ***1, 2, 3*** - **Brodmann areas 1, 2, and 3** comprise the **primary somatosensory cortex**, responsible for processing sensory input from the body, such as **touch, temperature, pain, and proprioception**. - These areas are located in the **postcentral gyrus** of the parietal lobe. *4, 6* - **Brodmann area 4** is the **primary motor cortex**, critical for executing voluntary movements. - **Brodmann area 6** is the **premotor and supplementary motor cortex**, involved in planning and coordinating movements. *44, 45* - **Brodmann areas 44 and 45** constitute **Broca's area**, which is primarily involved in **speech production and language processing**. - Damage to this area can result in expressive aphasia. *41, 42* - **Brodmann areas 41 and 42** are the **primary auditory cortex**, responsible for processing auditory information and sound perception. - They are located in the temporal lobe.

Q: What is the SI unit of luminous intensity?

Candela. ***Candela*** - The **candela (cd)** is the **SI base unit** used to measure **luminous intensity**. - **Luminous intensity** quantifies the power emitted by a light source in a particular direction per unit solid angle. *Lumen* - The **lumen (lm)** is the **SI derived unit** for **luminous flux**, which measures the total perceived power of light. - It describes the total amount of visible light emitted by a source in all directions, not its intensity in a specific direction. *Lux* - The **lux (lx)** is the **SI derived unit** for **illuminance**, which measures how much luminous flux is spread over a given area. - It indicates the perceived brightness of a surface, rather than the intensity of the light source itself. *Coulomb* - The **coulomb (C)** is the **SI derived unit** for **electric charge**. - It is completely unrelated to light or luminous intensity.

Q: What is the intensity in decibel of normal conversation in humans?

60dB. ***60dB*** - The sound intensity of **normal human conversation** is typically around **60 decibels (dB)**. - This level is considered **moderate** and is comfortably audible without causing discomfort or hearing damage. *30dB* - A sound intensity of **30dB** is characteristic of a **quiet whisper** or a **soft rustle of leaves**. - This level is much **quieter** than a normal conversation and would require closer proximity to be clearly heard. *90dB* - **90dB** represents a significantly **louder sound**, comparable to that of a **lawnmower** or a **heavy truck** passing by. - Prolonged exposure to sounds at this intensity can start to cause **hearing damage**. *150dB* - **150dB** is an **extremely loud** and potentially **painful** sound level, similar to a **jet engine at takeoff** or a **firecracker** exploding nearby. - Exposure to sounds this intense can cause **immediate and permanent hearing loss**.

Q: Miracle fruit is used to change the taste from?

Sour to Sweet. ***Sour to Sweet*** - The **miracle fruit** (Synsepalum dulcificum) contains a glycoprotein called **miraculin**. - Miraculin binds to taste receptors on the tongue and modifies their perception, making **sour foods taste sweet**. *Sour to Bitter* - The primary effect of miracle fruit is to convert **sour tastes into sweet tastes**, not bitter ones. - No known natural compound consistently changes sour perception to bitter. *Bitter to Sweet* - While miraculin makes sour foods sweet, it does not typically convert **bitter tastes into sweet sensations**. - Bitter taste perception involves different receptor pathways that are not significantly altered by miraculin. *Salty to Sweet* - Miracle fruit primarily targets **sour taste receptors**. - It does not have a significant effect on altering the perception of **salty tastes to sweet**.

Q: Which of the following receptors is stimulated by sustained pressure?

Ruffini's end organ. ***Ruffini's end organ*** - These are **slowly adapting mechanoreceptors** located deep in the dermis and subcutaneous tissue. - They are responsible for detecting **sustained pressure**, stretch, and position sense. *Merkel's disc* - These are **slowly adapting mechanoreceptors** found in the basal epidermis. - They are crucial for sensing **light touch** and **two-point discrimination**. *Hair cells* - These are **mechanoreceptors** primarily found in the inner ear, responsible for hearing and balance. - They are not involved in the perception of somatosensory stimuli like pressure on the skin. *Meissner Corpuscles* - These are **rapidly adapting mechanoreceptors** located in the dermal papillae, close to the skin surface. - They are primarily involved in detecting **light touch** and **discriminative touch**, especially changes in texture.

Q: Vibrations are detected by which types of receptors?

Rapidly adapting. ***Rapidly adapting*** - **Rapidly adapting mechanoreceptors**, such as **Pacinian corpuscles** and **Meissner's corpuscles**, are highly sensitive to changes in pressure and movement. - They fire at the **onset and offset of a stimulus**, making them ideal for detecting vibrations, which are rhythmic changes in pressure. *Slowly adapting* - **Slowly adapting mechanoreceptors**, such as **Merkel cells** and **Ruffini endings**, are responsible for sustained pressure and touch. - They continue to fire as long as the stimulus is present, making them less suited for detecting transient vibratory stimuli. *Non-adapting* - The human body does not typically have **truly non-adapting** sensory receptors; most receptors show some form of adaptation to continuous stimuli. - This term is not standard in the classification of mechanoreceptors based on their adaptation rates. *None of the above* - This option is incorrect because rapidly adapting receptors are indeed responsible for detecting vibrations.

Question 1

Which sense organ is primarily associated with an efferent nerve supply?

Accepted Answer

Organ of Corti

Answer

Golgi tendon organ

Answer

Retina

Answer

Taste bud

Question 2

Weber Fechner law is related to?

Accepted Answer

Relationship between intensity of stimulus and sensation felt

Answer

Phantom limb

Answer

Force of contraction in heart

Answer

Cortical plasticity

Question 3

Which motor protein is primarily involved in the function of the organ of Corti in the inner ear?

Accepted Answer

Myosin

Answer

Kinesin

Answer

Dynein

Answer

Actin

Question 4

Umami taste is evoked by?

Accepted Answer

Glutamic acid

Answer

Glucose

Answer

Quinine

Answer

Sodium chloride

Question 5

Which Brodmann's areas are primarily associated with somatosensory perception?

Accepted Answer

1, 2, 3

Answer

4, 6

Answer

44, 45

Answer

41, 42

Question 6

What is the SI unit of luminous intensity?

Accepted Answer

Candela

Answer

Lumen

Answer

Lux

Answer

Coulomb

Question 7

What is the intensity in decibel of normal conversation in humans?

Accepted Answer

60dB

Answer

30dB

Answer

90dB

Answer

150dB

Question 8

Miracle fruit is used to change the taste from?

Accepted Answer

Sour to Sweet

Answer

Sour to Bitter

Answer

Bitter to Sweet

Answer

Salty to Sweet

Question 9

Which of the following receptors is stimulated by sustained pressure?

Accepted Answer

Ruffini's end organ

Answer

Merkel's disc

Answer

Hair cells

Answer

Meissner Corpuscles

Question 10

Vibrations are detected by which types of receptors?

Accepted Answer

Rapidly adapting

Answer

Slowly adapting

Answer

Non-adapting

Answer

None of the above

Sensory Systems — MCQs

Sensory Systems — MCQs

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