Sensory Systems Practice Questions

Q: Parvocellular pathway carries signals for the detection of

Color contrast. ***Color contrast*** - The **parvocellular pathway** is specialized for processing **fine spatial details** and **color information**. - It receives input primarily from **red and green cones**, contributing to the perception of hue and saturation. *Luminous contrast* - The detection of **luminosity** or **brightness contrast** is primarily mediated by the **magnocellular pathway**. - The magnocellular pathway is more sensitive to **changes in light intensity** and achromatic contrasts. *Temporal frequency* - **Temporal frequency** (motion detection and flicker) is predominantly handled by the **magnocellular pathway**. - This pathway has a faster response and is better suited for perceiving rapid changes in visual stimuli. *Saccadic eye movements* - While related to vision, **saccadic eye movements** are controlled by motor systems in the brainstem and frontal eye fields, not directly by the parvocellular pathway itself. - The parvocellular pathway processes **visual input** that informs these movements but does not generate them.

Q: What is the range of sonic frequencies that can be heard by humans?

20-20,000 Hz. **20-20,000 Hz** - This is the standard **audible frequency range** for human hearing, also known as the audible spectrum - Frequencies below 20 Hz are **infrasound** (inaudible to humans) - Frequencies above 20,000 Hz are **ultrasound** (inaudible to humans) - This range represents the full capacity of the human cochlea and auditory system *1500-6000 Hz* - This represents only the **speech frequency range**, critical for understanding human conversation - This is a narrow subset within the full audible spectrum - Excludes perception of both very low-pitched sounds (bass) and very high-pitched sounds (treble) *10,000-15,000 Hz* - This covers only a **small portion of high frequencies** within human hearing - Omits all low and mid-frequency sounds as well as the highest audible frequencies - Does not represent the complete audible range *20,000-25,000 Hz* - This range consists primarily of **ultrasound frequencies** above human hearing threshold - While some young individuals may detect sounds slightly above 20,000 Hz, this is exceptional and not the standard audible range - Most of this range is completely inaudible to humans

Q: Which sensory receptor is primarily responsible for mediating slow vibration sensation?

Meissner corpuscles. ***Meissner corpuscles*** - These are **rapidly adapting mechanoreceptors** located in the dermal papillae, particularly abundant in glabrous (hairless) skin of fingertips, palms, and soles. - They are highly sensitive to **low-frequency vibration (10-50 Hz)**, which corresponds to **slow vibration sensation**. - They respond to **light touch** and **dynamic skin deformation**, making them ideal for detecting flutter and slow vibratory stimuli. *Ruffini's endings* - These are **slowly adapting mechanoreceptors** (Type II) located deep in the dermis and subcutaneous tissue. - They primarily detect **sustained pressure**, **skin stretch**, and **joint position**, contributing to proprioception. - They are NOT primarily involved in vibration sensation but rather in detecting continuous mechanical deformation. *Pacinian capsule* - These are **rapidly adapting mechanoreceptors** located deep in the dermis, subcutaneous tissue, and periosteum. - They are highly sensitive to **high-frequency vibration (200-300 Hz)**, which corresponds to **fast vibration sensation**. - They detect rapid changes in pressure and are the most sensitive mechanoreceptors to high-frequency stimuli. *Merkel's disc* - These are **slowly adapting mechanoreceptors** (Type I) found at the epidermal-dermal junction. - They are responsible for **sustained touch**, **pressure**, and **fine tactile discrimination** (texture, edges, shapes). - They do not detect vibration but rather respond to continuous indentation of the skin.

Q: Which of the following is true during far accommodation of the eyes?

The ciliary muscles are relaxed. ***The ciliary muscles are relaxed*** - During **far accommodation**, the eye is set to focus on distant objects, which requires the **lens** to be as thin and flat as possible. - This flattening of the lens is achieved when the **ciliary muscles relax**, increasing tension on the suspensory ligaments. *The lens becomes more curved due to ciliary muscle contraction* - This statement describes **near accommodation**, where the **ciliary muscles contract** to decrease the tension on the suspensory ligaments, allowing the lens to become more spherical and curved. - A more curved lens has greater refractive power, necessary for focusing on close objects. *The focal length of the lens is decreased to focus on distant objects* - A **decreased focal length** means the lens is more powerful and curved, which is needed for **near vision**, not distant vision. - For **distant vision**, the lens flattens, increasing its **focal length** to match the parallel light rays coming from far away. *The zonula fibers become slack to allow lens flattening* - When the **ciliary muscles relax** during far accommodation, they move away from the lens, which **increases the tension** on the zonula fibers (suspensory ligaments). - This increased tension pulls on the lens, causing it to flatten and become thinner.

Q: Impulses generated in the taste buds of the tongue reach the cerebral cortex via the

Thalamus. ***Thalamus*** - The **thalamus** acts as a crucial relay station for almost all sensory information, including taste, before it reaches the **cerebral cortex** for conscious perception. - Taste signals from the cranial nerves (facial, glossopharyngeal, vagus) travel to the **nucleus of the solitary tract** in the brainstem, then to the **ventral posteromedial (VPM) nucleus of the thalamus**, and finally to the **gustatory cortex**. *Dorsal roots of the first cervical spinal nerve* - The dorsal roots of cervical spinal nerves are involved in transmitting **somatosensory information** (touch, pain, temperature, proprioception) from the neck and head region, not taste. - These nerves carry signals from the spinal cord to the brain, whereas taste pathways originate from cranial nerves in the head. *Hypoglossal nerve* - The **hypoglossal nerve (CN XII)** is primarily a **motor nerve** responsible for controlling the muscles of the tongue, essential for speech and swallowing. - It has no direct role in transmitting taste sensations to the cerebral cortex. *Lingual nerve* - The **lingual nerve** is a branch of the **trigeminal nerve (CN V)** and carries **general sensation** (touch, pain, temperature) from the anterior two-thirds of the tongue. - While it runs with the **chorda tympani** (a branch of the facial nerve that carries taste), the lingual nerve itself does not transmit taste signals to the brain.

Q: Retinal cells which secrete acetylcholine are:

Amacrine cells. ***Amacrine cells*** - A subpopulation of **amacrine cells** in the retina is known to be **cholinergic**, meaning they synthesize and release **acetylcholine**. - These cholinergic amacrine cells play a role in **directional selectivity** and spatial processing within the retina. *Bipolar cells* - **Bipolar cells** primarily act as interneurons that transmit signals from photoreceptors to ganglion cells in the retina. - They typically release **glutamate** as their neurotransmitter, not acetylcholine. *Ganglion cells* - **Ganglion cells** are the output neurons of the retina, whose axons form the **optic nerve**. - While they receive input from cholinergic amacrine cells, ganglion cells themselves do not secrete acetylcholine; they are primarily glutamatergic. *Horizontal cells* - **Horizontal cells** are interneurons that provide lateral inhibition in the outer plexiform layer of the retina. - They primarily release **GABA** (gamma-aminobutyric acid) as their neurotransmitter, not acetylcholine.

Q: Which type of photoreceptor is primarily responsible for color vision?

Cones. ***Correct Answer: Cones*** - **Cones** are specialized photoreceptor cells in the retina responsible for **color vision** and **high-acuity vision**. - There are **three types of cones**, each sensitive to different wavelengths of light: **L-cones (red)**, **M-cones (green)**, and **S-cones (blue)**. - This trichromatic system allows for the perception of a wide range of colors through photopic (daylight) vision. *Incorrect: Rods* - **Rods** are photoreceptor cells primarily responsible for **scotopic vision** (vision in low light conditions) and **peripheral vision**. - They contain rhodopsin and do not contribute to color perception, instead detecting differences in light intensity. - Rods are more numerous (~120 million) than cones (~6 million) in the human retina. *Incorrect: Bipolar cells* - **Bipolar cells** are second-order interneurons in the retina that transmit signals from photoreceptors (rods and cones) to ganglion cells. - They play a role in the initial processing of visual information but are **not photoreceptors themselves**. - They do not directly detect light or color. *Incorrect: Occipital cortex* - The **occipital cortex** (visual cortex, area V1-V5) is the brain region responsible for processing visual information, including color perception. - It is **not a photoreceptor** but rather the cortical destination for visual signals. - It receives processed input from the retina via the lateral geniculate nucleus of the thalamus.

Question 1

Parvocellular pathway carries signals for the detection of

Accepted Answer

Color contrast

Answer

Luminous contrast

Answer

Temporal frequency

Answer

Saccadic eye movements

Question 2

What is the range of sonic frequencies that can be heard by humans?

Accepted Answer

20-20,000 Hz

Answer

1500-6000 Hz

Answer

10,000-15,000 Hz

Answer

20,000-25,000 Hz

Question 3

During the process of accommodation, there is a change in the shape of the lens. This change involves:

Accepted Answer

an increase principally in the anterior curvature of the lens

Answer

decrease in the synthesis of rhodopsin

Answer

contraction of ciliary muscle

Answer

an increase principally in the posterior curvature of the lens

Question 4

Which sensory receptor is primarily responsible for mediating slow vibration sensation?

Accepted Answer

Meissner corpuscles

Answer

Pacinian capsule

Answer

Merkel's disc

Answer

Ruffini's endings

Question 5

Which of the following is true during far accommodation of the eyes?

Accepted Answer

The ciliary muscles are relaxed

Answer

The focal length of the lens is decreased to focus on distant objects

Answer

The lens becomes more curved due to ciliary muscle contraction

Answer

The zonula fibers become slack to allow lens flattening

Question 6

Which of the following best describes the permeability to sodium and potassium in rod cells in response to light?

Accepted Answer

Decreased sodium permeability, unchanged potassium permeability

Answer

Decreased sodium permeability, decreased potassium permeability

Answer

Decreased sodium permeability, increased potassium permeability

Answer

Increased sodium permeability, decreased potassium permeability

Question 7

Impulses generated in the taste buds of the tongue reach the cerebral cortex via the

Accepted Answer

Thalamus

Answer

Dorsal roots of the first cervical spinal nerve

Answer

Hypoglossal nerve

Answer

Lingual nerve

Question 8

Function of the ossicles in the middle ear is to

Accepted Answer

Conduct and amplify sound energy from the tympanic membrane to the oval window

Answer

None of the options is correct

Answer

Only amplify sound without conducting it

Answer

Protect from loud sound

Question 9

Retinal cells which secrete acetylcholine are:

Accepted Answer

Amacrine cells

Answer

Bipolar cells

Answer

Ganglion cells

Answer

Horizontal cells

Question 10

Which type of photoreceptor is primarily responsible for color vision?

Accepted Answer

Cones

Answer

Bipolar cells

Answer

Rods

Answer

Occipital cortex

Sensory Systems — MCQs

Sensory Systems — MCQs

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