exam deck 8

Question 1

What do ascending sensory pathways do?

Answer 1

They transmit sensory information from the skin, joints, muscles, and viscera to the brain for processing.

Question 2

What sensory inputs do the specific ascending pathways convey?

Answer 2

Tactile discrimination, vibratory sense, and position sense.

Question 3

Describe the path of 1st order neurons in specific ascending pathways.

Answer 3

They receive input from receptors, travel ipsilaterally in the spinal cord to the medulla oblongata, and synapse with 2nd order neurons.

Question 4

What do 2nd order neurons do in specific ascending pathways?

Answer 4

Their axons cross to the contralateral side of the spinal cord and project to the thalamus.

Question 5

What is the role of 3rd order neurons?

Answer 5

They relay sensory signals from the thalamus to the primary somatosensory cortex for integration.

Question 6

How do non-specific ascending pathways differ from specific ones?

Answer 6

They lose modality specificity and primarily serve alerting and arousal functions.

Question 7

How is sensory information represented in the somatosensory cortex?

Answer 7

Input from one side of the body projects to the opposite cortex, with areas proportional to sensory discrimination.

Question 8

What role does the thalamus play in sensory pathways?

Answer 8

It acts as a relay center for sensory input before signals are sent to the cortex.

Question 9

What determines spatial discrimination of sensory input?

Answer 9

The size of receptive fields and overlap between adjacent fields.

Question 10

What is referred pain?

Answer 10

Pain perceived at a location other than the stimulus origin, due to shared pathways in the somatosensory system.

Question 11

How is the somatosensory cortex organized?

Answer 11

It is topographically organized, with larger areas devoted to parts of the body with higher sensitivity.

Question 12

What are modality-specific receptors, and what do they do?

Answer 12

These receptors respond to specific stimuli and have discrete receptive fields that contribute to spatial discrimination.

Question 13

How does the thalamus contribute to sensory pathways?

Answer 13

It integrates sensory input from different modalities and relays it to the somatosensory cortex.

Question 14

How was knowledge about sensory pathways derived?

Answer 14

From cortical stimulation in conscious subjects, revealing the topographical representation of sensory inputs.

Question 15

What is the primary function of non-specific ascending pathways?

Answer 15

To contribute to arousal and alerting responses by integrating mixed modalities.

Question 16

How do hair cell afferents respond to bending?

Answer 16

The discharge rate changes depending on the direction in which the hair bundles are bent.

Question 17

What happens to endolymph during head rotation?

Answer 17

Endolymph displacement bends hair cells in the semicircular canals.

Question 18

How does head rotation affect firing frequencies in the semicircular canals?

Answer 18

Rotation increases firing on one side and decreases it on the opposite side.

Question 19

What do otolith organs detect?

Answer 19

They detect linear acceleration and gravitational forces.

Question 20

How do otolith organ hair cells respond to gravity?

Answer 20

They respond to shifts caused by gravity or head tilts, indicating orientation.

Question 21

What is the role of CNS vestibular pathways?

Answer 21

To process signals for balance, spatial orientation, and postural control.

Question 22

What do blue, pink, and green circles represent in taste receptor distribution?

Answer 22

Blue: Common AAs in receptor families. Pink: Variable AAs. Green: AAs in ‘taster’ mice.

Question 23

What type of receptors do bitter and sweet ligands use?

Answer 23

G-protein-coupled receptors.

Question 24

How do bitter ligands transduce signals?

Answer 24

By activating transducin, which releases Ca²⁺ from intracellular stores.

Question 25

How do sweet ligands transduce signals?

Answer 25

By activating gustducin, using a cAMP pathway to close K⁺ channels and depolarize the cell.

Question 26

How do sour and salt ligands transduce signals?

Answer 26

They alter ion channels, causing depolarization and triggering extracellular Ca²⁺ entry.

Question 27

What triggers neurotransmitter release in taste transduction?

Answer 27

Increased intracellular Ca²⁺.

Question 28

What is gustatory processing?

Answer 28

The sensory processing of input from taste receptors to produce taste perception.

Question 29

What stimuli do T1R receptors detect?

Answer 29

T1Rs sense sweet stimuli.

Question 30

What stimuli do T2R receptors detect?

Answer 30

T2Rs sense bitter stimuli.

Question 31

What is the candidate receptor for umami taste, and what does it detect?

Answer 31

The t-mGluR4 receptor is the candidate umami receptor and detects glutamate.

Question 32

Which receptors are implicated in sodium salt and acid sensation?

Answer 32

MDEG/ENaC receptors, part of a superfamily of ion channels.