Nervous System Physiology Part 7

Question 1

Describe rods in vision

Answer 1

• Rods are our dim-light and peripheral vision receptors.
• They are more numerous and far more sensitive to light than cones are.
• They do not provide sharp images or color vision.
• Colors disappear and the edges of objects appear fuzzy in dim light and at the edges of our visual field.

Question 2

Describe cones in vision

Answer 2

• Cones, by contrast, are our vision receptors for bright light and provide high-resolution color vision.

Question 3

Compare the location in the retina for rod cells and cone cells.

Answer 3

• Rod Cells: Found around the periphery
• Cone Cells: Found around the central fovea

Question 4

Compare the optimal light conditions for rod cells and cone cells.

Answer 4

• Rod Cells: Dim light (“night” vision)
• Cone Cells: Bright light (“day” vision)

Question 5

Compare the visual acuity provided by rod cells and cone cells.

Answer 5

• Rod Cells: Low resolution (many rods converge onto one bipolar cell)
• Cone Cells: High resolution (one cone synapses with one bipolar cell)

Question 6

Compare the color sensitivity of rod cells and cone cells.

Answer 6

• Rod Cells: All wavelengths (achromatic, black and white)
• Cone Cells: Certain wavelengths (red, green, blue)

Question 7

Compare the type of vision provided by rod cells and cone cells.

Answer 7

• Rod Cells: Non-color
• Cone Cells: Color

Question 8

Compare the number of types of photopigments in rod cells and cone cells.

Answer 8

• Rod Cells: One (all contain rhodopsin)
• Cone Cells: Three different iodopsin pigments

Question 9

Compare the relative abundance of rod cells and cone cells.

Answer 9

• Rod Cells: Many
• Cone Cells: Fewer

Question 10

Describe the optic pathways starting from the retinal ganglion cells.

Answer 10

Axons from retinal ganglion cells form the optic nerves and optic tracts, synapse in the lateral geniculate body of the thalamus, and ascend to the visual cortex in the geniculocalcarine tract.

Question 13

How do hear stuff?

Answer 13

Sound waves enter the external auditory canal and the sound energy is transmitted from the tympanic membrane to the inner ear (cochlea) by the malleus, incus, and stapes in the middle ear.

Question 14

What structures transmit sound energy from the tympanic membrane to the inner ear?

Answer 14

The malleus, incus, and stapes.

Question 15

Through which canal do sound waves enter the ear?

Answer 15

The external auditory canal.

Question 16

What is the cochlea almost completely divided by?

Answer 16

A membranous tube called the cochlear duct

Question 17

What does the cochlear duct contain?

Answer 17

Sensory receptors of the auditory system.

Question 18

What are the receptor cells in the organ of Corti called?

Answer 18

Hair cells

Question 19

What type of receptors are hair cells?

Answer 19

Mechanoreceptors

Question 20

What protrudes from one end of hair cells?

Answer 20

Hairlike stereocilia.

Question 21

What membrane lies above the hair cells in the organ of Corti?

Answer 21

The tectorial membrane.

Question 22

What is the function of stereocilia on hair cells?

Answer 22

They detect mechanical changes (vibrations) and convert them into neural signals.

Question 25

Neural Pathways in Hearing

Answer 25

ongitudinal • Cochlear nerve fibers enter the brainstem and synapse with Lateral Portary auditory cus (halamus) Inferior colliculus interneurons there. Fibers from both ears often converge on the same neuron. • From the brainstem, the - Lateral lemniscus information is transmitted via a polysynaptic pathway to the thalamus and on to the auditory cortex in the temporal lobe.

Question 26

Where do cochlear nerve fibers synapse after entering the brainstem?

Answer 26

They synapse with interneurons in the brainstem

Question 27

Where do auditory signals travel after the brainstem?

Answer 27

To the thalamus via a polysynaptic pathway, then to the auditory cortex in the temporal lobe.

Question 28

What part of the brain is responsible for processing auditory signals?

Answer 28

A combination of involuntary reflexes (spinal cord) and voluntary actions (higher brain centers).

Question 29

What does posture and movement depend on?

Answer 29

A combination of involuntary reflexes (spinal cord) and voluntary actions (higher brain centers).

Question 30

Name the five components involved in motor control.

Answer 30

Spinal Cord, Brain Stem, Cerebellum, Basal Ganglia, Motor Cortex.

Question 32

What is the function of the higher centers in the motor control hierarchy?

Answer 32

Form complex plans based on intention and communicate with the middle level.

Question 33

What brain areas are associated with the higher centers?

Answer 33

Areas involved with memory, emotions, motivation, and the sensorimotor cortex.

Question 34

What is the function of the middle level in motor control?

Answer 34

Converts plans from higher centers into programs for patterns of neural activation.

Question 35

Which structures are part of the middle level?

Answer 35

Sensorimotor cortex, cerebellum, parts of basal nuclei, and some brainstem nuclei.

Question 36

What is the role of the local level in motor control?

Answer 36

Specifies muscle tension and joint angles to execute movement.

Question 37

Which structures are included in the local level?

Answer 37

Brainstem or spinal cord interneurons, afferent neurons, motor neurons.