Blood pressure receptors in the aorta and carotid sinus are classified by location as which type of receptor?
Interoceptor
✓
Exteroceptor
Proprioceptor
Nociceptor
Correct Answer
Interoceptor
Interoceptors monitor conditions inside the body, such as stretch of the walls of major arteries, so the baroreceptors of the aorta and carotid sinus belong here. Exteroceptor is wrong because exteroceptors, such as skin receptors, respond to stimuli from outside the body. Proprioceptor is wrong because proprioceptors sense the position of muscles, tendons and joints. Nociceptor is a classification by stimulus, pain or tissue damage, not by location.
Category: Receptor Types
Question 2
Pain and temperature receptors in the dermis that consist only of dendrites embedded in tissue, with no surrounding capsule, are classified structurally as which type?
Encapsulated endings
Free nerve endings
✓
Specialized receptor cells
Lamellated corpuscles
Correct Answer
Free nerve endings
Free nerve endings are bare dendrites that sit directly in the tissue, and they are the typical structure of pain and temperature receptors. Encapsulated endings are wrong because their dendrites are wrapped in connective tissue. Specialized receptor cells are wrong because these are distinct cells, such as photoreceptors, rather than dendrites. Lamellated corpuscles are wrong because they are a type of encapsulated ending surrounded by layers of connective tissue.
Category: Receptor Types
Question 3
Which receptor, located deep in the dermis and subcutaneous tissue, responds to deep pressure and high-frequency vibration?
Tactile (Meissner) corpuscle
Merkel disc
Lamellated (Pacinian) corpuscle
✓
Bulbous (Ruffini) corpuscle
Correct Answer
Lamellated (Pacinian) corpuscle
Lamellated corpuscles are large, onion-like encapsulated receptors deep in the skin that detect deep pressure and rapid vibration. Tactile (Meissner) corpuscle is wrong because it sits in the papillary dermis and responds to light touch and lower-frequency vibration. Merkel disc is wrong because it lies at the epidermal-dermal junction and responds to sustained light touch and low-frequency vibration. Bulbous (Ruffini) corpuscle is wrong because it responds mainly to stretch of the skin and joint capsules.
Category: Receptor Types
Question 4
Which proprioceptor lies among skeletal muscle fibers, detects stretch of the muscle, and triggers the knee-jerk reflex?
Golgi tendon organ
Merkel disc
Hair follicle plexus
Muscle spindle
✓
Correct Answer
Muscle spindle
Muscle spindles are stretch receptors within skeletal muscle, and tapping the patellar tendon stretches the quadriceps spindles to start the knee-jerk reflex. Golgi tendon organ is wrong because it lies in tendons and senses tendon tension rather than muscle stretch. Merkel disc is wrong because it is a skin receptor for light touch. Hair follicle plexus is wrong because it detects movement of hairs.
Category: Receptor Types
Question 5
Salty taste results when which ion enters gustatory receptor cells and depolarizes them?
Sodium
✓
Hydrogen
Potassium
Calcium
Correct Answer
Sodium
Salty taste is produced when sodium ions from dissolved salt flow into gustatory cells, depolarizing them. Hydrogen is wrong because hydrogen ion entry produces sour taste. Potassium is wrong because it is not the ion that signals saltiness. Calcium is wrong because it is not the ion that enters to produce salty taste.
Category: Taste and Smell
Question 6
The umami taste, often described as savory, is produced by which substance?
Glucose
Glutamate
✓
Hydrogen ions
Alkaloids
Correct Answer
Glutamate
Umami receptors respond to the amino acid L-glutamate, which gives foods such as broth and aged cheese a savory taste. Glucose is wrong because it stimulates sweet receptors. Hydrogen ions are wrong because they produce sour taste. Alkaloids are wrong because they are detected as bitter.
Category: Taste and Smell
Question 7
Which cranial nerve carries taste information from the posterior one third of the tongue?
Facial nerve
Trigeminal nerve
Glossopharyngeal nerve
✓
Hypoglossal nerve
Correct Answer
Glossopharyngeal nerve
The glossopharyngeal nerve, cranial nerve IX, carries taste from the posterior third of the tongue. Facial nerve is wrong because it carries taste from the anterior two thirds of the tongue. Trigeminal nerve is wrong because it carries general touch, pain and temperature from the face and mouth rather than taste. Hypoglossal nerve is wrong because it is a motor nerve to the tongue muscles.
Category: Taste and Smell
Question 8
Axons of olfactory receptor neurons pass through the cribriform plate of which bone to reach the olfactory bulb?
Sphenoid
Frontal
Temporal
Ethmoid
✓
Correct Answer
Ethmoid
The cribriform plate is part of the ethmoid bone, and its small foramina let olfactory axons pass from the nasal cavity to the olfactory bulb. Sphenoid is wrong because it forms the middle of the cranial floor and holds the pituitary gland. Frontal is wrong because it forms the forehead and the roofs of the orbits. Temporal is wrong because it houses the middle and inner ear.
Category: Taste and Smell
Question 9
Which middle ear structure presses against the oval window and transmits vibrations into the cochlea?
Stapes
✓
Malleus
Incus
Tympanic membrane
Correct Answer
Stapes
The stapes is the last of the three ossicles, and its footplate sits in the oval window, pushing vibrations into the fluid of the cochlea. Malleus is wrong because it is attached to the tympanic membrane. Incus is wrong because it is the middle ossicle linking the malleus to the stapes. Tympanic membrane is wrong because it separates the external ear from the middle ear and first receives sound waves.
Category: Hearing and Balance
Question 10
High-frequency sounds most strongly stimulate hair cells at which location?
Apex of the cochlea
Base of the cochlea
✓
Ampulla of a semicircular canal
Macula of the utricle
Correct Answer
Base of the cochlea
The basilar membrane is narrow and stiff near the base of the cochlea, close to the oval and round windows, so high frequencies vibrate it most there. Apex of the cochlea is wrong because the wide, flexible apex responds best to low frequencies. Ampulla of a semicircular canal is wrong because its hair cells detect head rotation, not sound. Macula of the utricle is wrong because it detects head position and linear acceleration.
Category: Hearing and Balance
Question 11
Which inner ear structures detect rotation of the head?
Utricle
Saccule
Semicircular canals
✓
Cochlear duct
Correct Answer
Semicircular canals
The three semicircular canals each have an ampulla whose hair cells extend into a gelatinous cupula that bends when fluid lags during head rotation. Utricle is wrong because it senses head tilt and horizontal linear acceleration. Saccule is wrong because it senses head position and vertical linear acceleration. Cochlear duct is wrong because it contains the receptors for hearing.
Category: Hearing and Balance
Question 12
In the corneal (blink) reflex, which cranial nerve carries the motor command that closes the eyelids?
Trigeminal nerve
Oculomotor nerve
Optic nerve
Facial nerve
✓
Correct Answer
Facial nerve
The facial nerve, cranial nerve VII, stimulates the orbicularis oculi muscles on both sides to close the eyes during the corneal reflex. Trigeminal nerve is wrong because it carries the sensory signal from touch on the cornea. Oculomotor nerve is wrong because it controls most extraocular muscles and raises the upper eyelid. Optic nerve is wrong because it is a sensory nerve that can only bring in the light stimulus.
Category: Reflexes
Question 13
Which region of the retina provides the sharpest visual acuity?
Fovea
✓
Optic disc
Ora serrata
Peripheral retina
Correct Answer
Fovea
The fovea at the center of the retina is packed with cones, each connected to its own ganglion cell, which gives the highest acuity. Optic disc is wrong because it has no photoreceptors and forms the blind spot. Ora serrata is wrong because it is the jagged front edge of the retina with little visual function. Peripheral retina is wrong because many photoreceptors converge on each ganglion cell there, lowering acuity.
Category: Vision
Question 14
Which photopigment allows rods to function in dim light?
Melanopsin
Rhodopsin
✓
Iodopsin
Melanin
Correct Answer
Rhodopsin
Rhodopsin is the light-sensitive pigment of rods, and it is sensitive enough to respond to very dim light. Melanopsin is wrong because it is found in a small group of light-sensitive ganglion cells that help set circadian rhythm. Iodopsin is wrong because it is a term for cone photopigments. Melanin is wrong because it is a dark pigment that absorbs stray light rather than a visual photopigment.
Category: Vision
Question 15
Most fibers of the corticospinal tract cross to the opposite side at which location?
Internal capsule
Cerebral peduncles
Medullary pyramids
✓
Pons
Correct Answer
Medullary pyramids
Most corticospinal fibers decussate at the pyramids of the medulla, near the border with the spinal cord, forming the lateral corticospinal tract. Internal capsule is wrong because it is a band of white matter the tract passes through without crossing. Cerebral peduncles are wrong because they carry the descending fibers through the midbrain on the same side. Pons is wrong because the tract passes through it before reaching the decussation.
Category: Motor Control
Question 16
In the dorsal column system, first-order axons carrying touch from the legs ascend in which structure?
Fasciculus cuneatus
Medial lemniscus
Lateral corticospinal tract
Fasciculus gracilis
✓
Correct Answer
Fasciculus gracilis
The fasciculus gracilis is the medial part of the dorsal column and carries touch and proprioception from the legs and lower body. Fasciculus cuneatus is wrong because it carries input from the upper body and arms. Medial lemniscus is wrong because it is formed by second-order axons after they cross in the medulla. Lateral corticospinal tract is wrong because it is a descending motor pathway.
Category: Sensory Pathways
Question 17
Second-order axons of the spinothalamic tract cross to the opposite side in which region?
Spinal cord
✓
Medulla oblongata
Pons
Thalamus
Correct Answer
Spinal cord
In the spinothalamic tract the second-order neuron's axon crosses in the spinal cord at about the level where the pain or temperature signal entered. Medulla oblongata is wrong because that is where the dorsal column system crosses. Pons is wrong because neither major ascending spinal pathway crosses there. Thalamus is wrong because it holds the third-order neurons, after the crossing has occurred.
Category: Sensory Pathways
Question 18
Auditory information is relayed to the auditory cortex of the temporal lobe by which nucleus?
Lateral geniculate nucleus
Medial geniculate nucleus
✓
Superior colliculus
Solitary nucleus
Correct Answer
Medial geniculate nucleus
The medial geniculate nucleus of the thalamus receives auditory input from the inferior colliculus and relays it to the auditory cortex. Lateral geniculate nucleus is wrong because it relays visual information to the occipital lobe. Superior colliculus is wrong because it is a midbrain center for visual reflexes and orienting the head. Solitary nucleus is wrong because it receives taste information in the medulla.
Category: Sensory Pathways
Question 19
Which brain structure compares descending motor commands with proprioceptive feedback and corrects errors in movement?
Hypothalamus
Prefrontal cortex
Cerebellum
✓
Hippocampus
Correct Answer
Cerebellum
The cerebellum receives copies of motor commands and proprioceptive input, and when they disagree it sends corrections through the red nucleus. Hypothalamus is wrong because it regulates homeostasis and autonomic functions. Prefrontal cortex is wrong because it handles planning, working memory and executive functions rather than moment-to-moment correction. Hippocampus is wrong because it is involved in forming memories.
Category: Motor Control
Question 20
The primary motor cortex is located in which gyrus of the frontal lobe?
Postcentral gyrus
Superior temporal gyrus
Cingulate gyrus
Precentral gyrus
✓
Correct Answer
Precentral gyrus
The precentral gyrus, just in front of the central sulcus, is the primary motor cortex, where neurons send commands down the corticospinal and corticobulbar tracts. Postcentral gyrus is wrong because it is the primary somatosensory cortex in the parietal lobe. Superior temporal gyrus is wrong because it contains the auditory cortex. Cingulate gyrus is wrong because it is part of the limbic system on the medial surface.
Category: Motor Control