BIO 360 - Exam 2 - Chapter 10 Review Questions

Question 1

What is the role of the afferent division of the nervous system?

Answer 1

Carry information from sensory receptors to the CNS.

Question 2

Define proprioception.

Answer 2

The ability to tell where our body is in space and to sense the relative locations of different body parts.

Question 3

What are the common elements of all sensory pathways?

Answer 3

A sensor and a sensory neuron. Could be one cell or two.

Question 4

List and briefly describe the four major types of somatic receptors based on the type of stimulus to which they are most sensitive.

Answer 4

Mechanoreceptors—pressure, sound, stretch, etc. Chemoreceptors—specific chemicals.
Photoreceptors–photons of light.
Thermoreceptors—heat and cold.

Question 5

The receptors of each primary sensory neuron pick up information from a specific area, known as the .

Answer 5

receptive field

Question 6

Match the brain area with the sensory information processed there:

(a) sounds
(b) odors
(c) visual information
(d) taste
(e) equilibrium

(1) midbrain
(2) cerebrum
(3) medulla
(4) cerebellum
(5) none of the above

Answer 6

(a) 3; (b) 2; (c) 1, 2; (d) 2, 3; (e) 4

Question 7

The conversion of stimulus energy into a change in membrane potential is called ______. The form of energy to which a receptor responds is called its ______. The minimum stimulus required to activate a receptor is known as the ______.

Answer 7

transduction, adequate stimulus, threshold

Question 8

When a sensory receptor membrane depolarizes (or hyperpolarizes in a few cases), the change in membrane potential is called the ______ potential. Is this a graded potential or an all-or-none potential?

Answer 8

Receptor potentials are graded potentials.

Question 9

Explain what is meant by adequate stimulus to a receptor.

Answer 9

Adequate stimulus—form of energy to which a receptor is most sensitive.

Question 10

The organization of sensory regions in the ______ of the brain preserves the topographical organization of receptors on the skin, eye, or other regions. However, there are exceptions to this rule. In which sense(s) does the brain rely on the timing of receptor activation to determine the location of the initial stimulus?

Answer 10

cortex. Exception—hearing.

Question 11

What is lateral inhibition?

Answer 11

Sensory neurons surrounding a receptive field are inhibited, which enhances contrast between the stimulus and surrounding areas.

Question 12

Define tonic receptors and list some examples. Define phasic receptors and give some examples. Which type adapts?

Answer 12

Tonic receptors, such as for heat, adapt slowly and respond to stimuli that need to be constantly monitored. Phasic receptors adapt rapidly and stop responding unless the stimulus changes. An example is smell.

Question 13

Heart pain perceived as coming from the neck and down the left arm is an example of ______ pain.

Answer 13

referred

Question 14

What are the five basic tastes? What is the adaptive significance of each taste sensation?

Answer 14

Sweet and umami indicate nutritious foods, and bitter may contain toxins. Salty (Na+) and sour (H+) ions are related to body osmolarity and pH, respectively.

Question 15

The unit of sound wave measurement is______, which is a measure of the frequency of sound waves per second. The loudness, or intensity, of a sound is a function of the ______ of the sound waves and is measured in ______. The range of hearing for the average human ear is from ______ to ______ [units], with the most acute hearing in the range of to ______ [units].

Answer 15

Sound waves per second—hertz (Hz). Loudness—a function of the wave amplitude and measured in decibels (dB). Range of hearing: 20–20,000Hz. Most acute hearing: 1000–3000Hz.

Question 16

Which structure of the inner ear codes sound for pitch? Define spatial coding.

Answer 16

Basilar membrane. Spatial coding—association of wave frequencies with different areas of the membrane.

Question 17

Loud noises cause action potentials to: (choose all correct answers)
(a) fire more frequently.
(b) have higher amplitudes.
(c) have longer refractory periods.

Answer 17

(a) fire more frequently.

Question 18

Once sound waves have been transformed into electrical signals in the cochlea, sensory neurons transfer information to the ______, from which collaterals then take the information to the ______ and ______. The main auditory pathway synapses in the ______ and ______ before finally projecting to the ______ in the ______. .

Answer 18

Signals from cochlea to medulla, with collaterals to reticular formation and cerebellum. Synapses in midbrain and thalamus before projecting to auditory cortex in the cerebrum.

Question 19

The parts of the vestibular apparatus that tell our brain about our movements through space are the ______, which sense rotation, and the ______ organs, which respond to linear forces.

Answer 19

semicircular canals—rotation; otolith organs—linear forces

Question 20

List the following structures in the sequence in which a beam of light entering the eye will encounter them: (a) aqueous humor, (b) cornea, (c) lens, (d) pupil, (e) retina.

Answer 20

(b), (a), (d), (c), (e)

Question 21

The three primary colors of vision are ______, ______, and ______. White light containing these colors stimulates photoreceptors called ______. Lack of the ability to distinguish some colors is called ______.

Answer 21

red, blue, and green; cones; color-blindness

Question 22

List six types of cells found in the retina, and briefly describe their functions.

Answer 22

Rods and cones (photoreceptors), bipolar cells, ganglion cells, horizontal cells, and amacrine cells. Photoreceptors transduce light energy. Remaining cells carry out signal processing.

Question 23

Compare and contrast the following:

(a) the special senses with the somatic senses
(b) different types of touch receptors with respect to structure, size, and location
(c) transmission of sharp localized pain with transmission of dull and diffuse pain (include the particular fiber types involved as well as the presence or absence of myelin in your discussion)
(d) the forms of hearing loss
(e) convergence of retinal neurons with convergence of primary somatic sensory neurons

Answer 23

(a) Special senses have receptors localized in the head. Somatic senses have receptors located all over the body. (b) See Fig. 10.10. (c) Sharp (fast) pain—small, myelinated Aδ fibers. Dull (slow) pain—small, unmyelinated C fibers. (d) Conductive loss: sound cannot be transmitted through the external or middle ear. Sensorineural loss: inner ear is damaged. Central hearing loss: auditory pathways are damaged. (e) Minimal convergence of retinal neurons in the fovea results in the sharpest vision. Minimal convergence of primary somatic sensory neurons creates smaller receptive fields, and two-point discrimination is better. Regions with more convergence have less acute vision or poor two-point discrimination.

Question 24

Draw three touch receptors having overlapping receptive fields (see Fig. 10.2) and number the fields 1–3. Draw a primary and secondary sensory neuron for each receptor so they have separate ascending pathways to the cortex. Use the information in your drawing to answer this question: How many different regions of the skin can the brain distinguish using input from these three receptors?

Answer 24

seven distinct areas: 1, 2, 3, 1+2, 1+3, 2+3, and 1+2+3

Question 25

Describe the neural pathways that link pain with emotional distress, nausea, and vomiting.

Answer 25

Ascending pathways for pain go to the limbic system (emotional distress) and hypothalamus (nausea and vomiting).

Question 26

Trace the neural pathways involved in olfaction. What is Golf?

Answer 26

Olfactory receptors—olfactory bulb—secondary sensory neuron—higher-order neurons—olfactory cortex, with parallel pathways to amygdala and hippocampus. Golf—G protein of olfactory receptors.

Question 27

Compare the current models of signal transduction in taste buds for salty/sour ligands and sweet/bitter/umami ligands.

Answer 27

Bitter, sweet, and umami: membrane receptors on type II receptor cells, with different G protein-linked receptors and signal transduction pathways for each ligand. Pathways end with release of ATP. Salt ions (Na+) apparently enter type 1 support cells through ion channels. H+ enters type III presynaptic cells through channels. Pathway ends with serotonin release.

Question 28

Put the following structures in the order in which a sound wave would encounter them: (a) pinna, (b) cochlear duct, (c) stapes, (d) ion channels, (e) oval window, (f) hair cells/stereocilia, (g) tympanic membrane, (h) incus, (i) vestibular duct, (j) malleus

Answer 28

(a), (g), (j), (h), (c), (e), (i), (b), (f), (d)

Question 29

Draw the structures and receptors of the vestibular apparatus for equilibrium. Label the components. Briefly describe how they function to notify the brain of movement.

Answer 29

See Fig. 10.22.

Question 30

Map the following terms related to vision. Add terms if you wish. Map 1 accommodation reflex binocular vision blind spot ciliary muscle cornea cranial nerve III pupillary reflex retina depth of field field of vision focal point fovea iris lateral geniculate visual cortex visual field lens macula optic chiasm optic disk optic nerve phototransduction zonules Map 2: The Retina amacrine cells bipolar cells bleaching cGMP cones ganglion horizontal melanin melanopsin opsin pigment epithelium retinal rhodopsin rods transducin

Answer 30

Start with Fig. 10.25 and the basic components of vision. Work in details and related terms from the text.

Question 31

Explain how accommodation by the eye occurs. What is the loss of accommodation called?

Answer 31

The lens changes shape due to contraction/relaxation of the ciliary muscles. Loss of this reflex—presbyopia.

Question 32

List four common visual problems, and explain how they occur.

Answer 32

Presbyopia—loss of accommodation due to stiffening of the lens with age. Myopia or near-sightedness—longer-than-normal distance between lens and retina; hyperopia or far-sightedness—shorter-than-normal distance. Color-blindness—defective cones.

Question 33

Explain how the intensity and duration of a stimulus are coded so that the stimulus can be interpreted by the brain. (Remember, action potentials are all-or-none phenomena.)

Answer 33

Intensity—action potential frequency. Duration—duration of a train of action potentials.

Question 34

Make a table of the special senses. In the first row, write these stimuli: sound, standing on the deck of a rocking boat, light, a taste, an aroma. In row 2, describe the location of the receptor for each sense. In row 3, describe the structure or properties of each receptor. In a final row, name the cranial nerve(s) that convey(s) each sensation to the brain. 

Answer 34

See Tbl. 10.1 and the section for each special sense.

Question 35

You are prodding your blindfolded lab partner’s arm with two needle probes (with her permission). Sometimes she can tell you are using two probes. But when you probe less sensitive areas, she thinks there is just one probe. Which sense are you testing? Which receptors are being stimulated? Explain why she sometimes feels only one probe.

Answer 35

Testing touch-pressure, mediated through free nerve endings and Merkel receptors. Feeling only one probe means both needles are within the same receptive field.

Question 36

Consuming alcohol depresses the nervous system and vestibular apparatus. In a sobriety check, police officers use this information to determine if an individual is intoxicated. What kinds of tests can you suggest that would show evidence of this inhibition?

Answer 36

Walk a straight line, stand on one leg with the eyes closed, count backward by 3s.

Question 37

Often, children are brought to medical attention because of speech difficulties. If you were a clinician, which sense would you test first in such patients, and why?

Answer 37

Test hearing first. If children cannot hear well, they cannot imitate speech.

Question 38

A clinician shines a light into a patient’s left eye, and neither pupil constricts. Shining the light into the right eye elicits a normal consensual reflex. What problem in the reflex pathway could explain these observations?

Answer 38

Absence of the consensual reflex upon stimulating the left eye suggests damage to the left retina and/or to the left optic nerve.

Question 39

An optometrist wishes to examine a patient’s retina. Which of the following classes of drugs might dilate the pupil? Explain why you did or did not select each choice. a sympathomimetic a muscarinic antagonist a cholinergic agonist an anticholinesterase a nicotinic agonist

Answer 39

To dilate: a sympathetic agonist (a) or something that blocks muscarinic receptors (b). To constrict: a cholinergic agonist (c), a nicotinic agonist (e), or an anticholinesterase (d), which prevents breakdown of ACh.

Question 40

The iris of the eye has two sets of antagonistic muscles, one for dilation and one for constriction. One set of muscles is radial (radiating from the center of the pupil), and the other set is circular. Draw an iris and pupil, and arrange the muscles so that contraction of one set causes pupillary constriction and contraction of the other set causes dilation.

Answer 40

Circular muscles form a ring on the inner part of the iris, surrounding the pupil. When these muscles contract, the pupil gets smaller. The radial muscles extend from the outer edge of the iris to the circular muscles. When the radial muscles contract, they pull on the relaxed circular muscles and expand the diameter of the pupil (dilation).

Question 41

As people age, their ability to see at night decreases. What changes in the retina might explain this?

Answer 41

Loss of rods explains loss of night vision.