The Nervous System Part 3: Special Senses

Question 1

Elements of the central neural auditory pathway

• Transmits ..?.. information from ..?.. receptors (the inner ..?.. cells) to the ..?.. cortex
• Impulses pass through ..?.. (containing auditory ..?..) and along the ..?.. fibers of the ..?.. nerve to the cochlear ..?.. of the ..?..
• Neurons project to ..?.. nucleus (at junction of ..?.. and ..?..)
• Axons ascend in ..?.. (..?.. tract) to the ..?.. (auditory ..?.. center in the midbrain)
• This projects to ..?.. nucleus of the ..?..
• Axons of the ..?.. neurons project to the ..?.. cortex which provides ..?.. awareness of ..?..
• The auditory pathway is unusual because not all of the ..?.. from each ear ..?.. to the ..?.. side of the ..?… For this reason each ..?.. receives ..?.. from ..?.. ears.

Answer 1

• auditory; cochlear; hair; cochlear
• spiral ganglion; bipolar cells; afferent; cochlear; nuclei; medulla
• superior olivary; medulla; pons
• lateral lemniscus; fibre; inferior colliculus; reflex; midbrain
• medial geniculate; thalamus
• thalamic; primary auditory; conscious; sound
• fibres; cross over; other; brain; auditory cortex; impulses; both

Question 2

The pathway of sound waves and resonance of the basilar membrane

1. ..?.. vibrate the ..?..
2. Auditory ..?.. vibrate and ..?.. is amplified
3. ..?.. waves created by the ..?.. pushing on the ..?.. move through ..?.. in the ..?..
   4a. Sounds with frequencies ..?.. hearing travel through the ..?.. and do not ..?.. hair cells
   4b. Sounds in the ..?.. range go through the ..?.., vibrating the ..?.. and deflecting ..?.. on ..?.. cells

Answer 2

1. Sound waves; tympanic membrane
2. Ossicles; pressure
3. Pressure; stapes; oval window; fluid; scale vestibuli
   4a. Below; helicotrema; excite
   4b. Hearing; cochlear duct; basilar membrane; hairs; inner hair

Question 3

Mechanism responsible for sound transduction
- Sound waves vibrate the ..?..
- Transferred to ..?.. bones of ..?.. ear (auditory ..?..; ..?.. sound)
- ..?.. is attached to the ..?.., vibrations become ..?.. waves within the ..?..
- Fluid ..?.. push on the flexible ..?.. of the ..?..
- ..?.. from the waves transfers across the ..?.. into the ..?.. and is ..?.. back into the ..?.. ear at the ..?..
- ..?.. cells within the ..?.. create ..?.. in the ..?.. neurons of the ..?..

Answer 3

• tympanic membrane
• 3; middle; ossicles; amplify
• stapes; oval window; fluid; cochlear
• waves; basilar membrane; cochlear duct
• energy; cochlear duct; tympanic duct; dissipated; middle; round window
• hair; cochlear duct; action potentials; sensory; cochlear nerve

Question 4

Mechanism responsible for sound localisation

• Several ..?.. nuclei, especially the ..?.. nuclei help ..?.. sound’s ..?.. in space by means of two cues: according to relative ..?.. and relative ..?.. of ..?.. reaching the two ears.
• If the sound source is directly in ..?.., ..?.. or behind, ..?.. and ..?.. cues are the ..?.. for ..?.. ears.
• When the sound comes from ..?.. side, it activates receptors of the ..?.. ear slightly ..?.. and more ..?…

Answer 4

• brain stem; superior olivary; localise; source; space; intensity; timing; sound waves
• front; overhead; intensity; times; same; both
• one; nearer; earlier; vigorously

Question 5

Mechanism responsible for detection of sound intensity (loudness)

• ..?.. sounds create larger vibrations of the ..?.., auditory ..?.. and ..?..; creating ..?.. waves with greater ..?.. in the ..?…
• This creates large ..?.. of the ..?.., ..?.. deflections of the ..?.., and larger ..?…
• They release more ..?.. and recruit more ..?.. to participate in the ..?.. and so generate more ..?..
• The brain interprets more ..?.. action potentials as greater ..?…

Answer 5

• larger; tympanic membrane; ossicles; oval window; pressure; amplitude; cochlear fluid
• movements; basilar membrane; larger; hair cells; graded potentials
• neurotransmitter; bipolar neurons; impulse; action potential
• frequent; loudness

Question 6

Mechanism responsible for direction (perception) of sound pitch

• Sound waves of different ..?.. activate ..?.. in different ..?.. along the ..?… Impulses from specific ..?.. are interpreted as specific ..?…
• When sound consists of several ..?.. of many ..?.., it activates several populations of cochlear ..?.. simultaneously and we perceive ..?.. tones.

Answer 6

• frequencies; hair cells; positions; basilar membrane; hair cells; pitches
• tones; frequencies; hair cells; multiple

Question 7

Where do high frequency sounds displace the basilar membrane?

Answer 7

Near the base

Question 8

Where do medium- frequency sound displace the basilar membrane?

Answer 8

Near the middle

Question 9

Where do low- frequency sounds displace the basilar membrane?

Answer 9

Near the apex

Question 10

What are the components of the vestibular apparatus?

Answer 10

• semi circular canals
• vestibule

Question 11

What do the semi- circular canals monitor?

Answer 11

Dynamic equilibrium from movements of the head

Question 12

What does the vestibule monitor?

Answer 12

Static equilibrium from linear acceleration and position of the head with respect to gravity

Question 13

• Maculae monitor ..?.. of head and play role in controlling ..?..; respond to ..?.. acceleration but not ..?…
• Inertia causes ..?.. to slide ..?.. or ..?.. when ..?.. moving over the ..?.., bending them and creating ..?… When ..?.. or bend head, otoliths ..?.., ..?.. the hair cells.

Answer 13

• Position; head; posture; linear; rotation
• otolith membrane; backward; forward; stop; hair cells; stimulus; nod; roll; bending.

Question 14

• Cristae ampullas monitor ..?.. acceleration in all ..?.. planes due to positions of ..?…
• ..?.. within the semi-circular canals will deform the ..?.. in the ..?., ..?.. the hairs, ..?.. creates impulse.

Answer 14

• Rotational; 3; semi-circular canals
• endolymph; cupula; duct; bending; depolarisation

Question 15

What structures are responsible for equilibrium and balance?

Answer 15

• vestibular apparatus: semi-circular canals; vestibule
• maculae
• Cristae ampullae

Question 16

Effect of gravitation pull on the macula receptor in the utricle: depolarisation

• when hairs bend ..?.. the ..?.., the ..?.. cell ..?.. which excites the ..?… This generates more frequent ..?..

Answer 16

• towards; kinocilium; hair; depolarises; nerve fibre; AP’s

Question 17

Effect of gravitation pull on the macula receptor in the utricle: hyperpolarisation

• when hairs bend ..?.. from the ..?.., the ..?.. cell ..?.. which ..?.. the nerve fibre and ..?.. the ..?.. frequency

Answer 17

• away; kinocilium; hair; hyperpolarises; inhibiting; decreasing; AP

Question 18

When does the cupula stand upright?

Answer 18

When at rest

Question 19

Describe the flow of endolymph during rotational acceleration

Answer 19

Endolymph moves inside the semi-circular canal in the opposite direction of the rotation- it lags behind due to inertia. Endolymph flow bends the cupula and excites the hair cells

Question 20

Pathways of the balance and orientation system of the body, from receptors to effector organs

• Hair cells in the ..?.. apparatus are stimulated
• Impulse travel to

o ..?.. nuclei (major integrative centre for ..?..) in the ..?..
- Also receives information from ..?.. and ..?.. receptors (..?.. in the ..?.. muscles)
- The nuclei integrates this information and sends commands to ..?.. motor centres that control ..?.. muscles and ..?.. movements of the ..?.., limb and ..?.. muscles via the ..?.. tracts
- The ensuing reflex movements of the ..?.. and ..?.. allow us to remain ..?.. on the visual ..?.. and quickly adjust our ..?.. to ..?.. or regain ..?…

o Cerebellum
- Also receives information from ..?.. and ..?.. receptors (..?.. in the ..?.. muscles) as well as from the ..?..
- Coordinates ..?.. muscle activity, regulates ..?.. to maintain head ..?.., ..?.. and ..?.., often in the face of ..?.. changing ..?..
- ..?.. is ..?.. control of delicate ..?.. movements and ..?..

Answer 20

• vestibule
  o vestibular; balance; brainstem
• visual; somatic; proprioceptors; neck
• brain stem; extrinsic eye; reflex; neck; trunk; vestibulospinal
• eyes; body; focused; field; body position; maintain; balance
• visual; somatic receptors; proprioceptors; neck; cerebrum
• skeletal; muscle tone; position; posture; balance; rapidly; inputs
• specialty; fine; postural; timing

Question 21

What are the main sources of the body’s position in space?

Answer 21

• vestibular receptors
• visual receptors
• somatic receptors (skin, muscle and joints)

Question 22

What are the main processing areas where information about the body’s position in space is processed?

Answer 22

• cerebellum
• vestibular nuclei (brain stem)

Question 23

What is the output response by the CNS once information about the body’s position in space is processed?

Answer 23

• occulomotor control: cranial nerve nuclei III, IV, VI (eye movments)
• spinal motor control: cranial nerve XI nuclei and vestibulospinal tracts (neck, limb and trunk movments)

Question 24

Vomiting centre of the brain stem monitors the blood for ..?..

Answer 24

poisonous substances

Question 25

Visual accommodation, its purpose and the process

*Visual accommodation: the process that increases ..?.. of the ..?.. to maintain a ..?.. or ..?.. on an object as its ..?.. varies. Accommodation acts like a ..?.., but can also be ..?.. controlled.

• ..?.. muscles ..?.. pulling the ..?.. body ..?.. toward the ..?.. and ..?.. releasing ..?.. in the ..?.. ligaments/ciliary ..?..
• The elastic lens ..?.. and ..?.. since it is no longer ..?.. providing ..?.. needed to focus on a ..?.. object on the ..?..
• ..?.. fibres of the ..?.. nerve control ..?.. muscles
• Gradual ..?.. of ..?.. with ..?.. reflects lens’s decreasing ..?..

Answer 25

• refractory power; lens; clear image; focus; distance; reflex; consciously
• ciliary; contract; ciliary; anteriorly; pupil; inward; tension; suspensory; zonules
• recoils; bulges; stretched; shorter focal length; focus; close; retina
• parasympathetic; occulomotor; ciliary
• loss; accommodation; age; elasticity

Question 26

Visual acuity: ..?.. or ..?.. of vision, measured by the ability to discern ..?.. or ..?.. at a given ..?.. according to a ..?.. standard.

Answer 26

Sharpness; resolution; vision; letters; numbers; distance; fixed

Question 27

How many layers does the retina consist of?

Answer 27

2

Question 28

What are the layers of retina?

Answer 28

1. Pigmented layer
2. Neural layer

Question 29

What does the neural layer of the retina consist of posteriorly to anteriorly?

Answer 29

• photoreceptors
• bipolar cells
• ganglion cells

Question 30

Where is the focal point in someone with myopia?

Answer 30

In front of the retina

Question 31

What type of lens is required to correct myopia?

Answer 31

A concave lens moves the focal point further back.

Question 32

Where is the focal point in someone with hyperopia?

Answer 32

Behind the retina

Question 33

What type of lens is required to correct hyperopia?

Answer 33

A convex lens moves the focal point forward

Question 34

In what kind of light are rods activated?

Answer 34

Dark vision; dim light

Question 35

Rods

• ..?..-light, low-..?.. and ..?.. vision receptors
• ..?.. numerous and more ..?.. to light
• Cells contain only ..?.. pigment
• Many rods ..?.. onto a ..?.. ganglion, so gives low ..?..

Answer 35

• dim; resolution; peripheral
• more; sensitive
• 1
• converge; single; visual acuity

Question 36

What are the 3 phases in phototransduction in rods?

Answer 36

• pigment synthesis
• pigment bleaching
• pigment regeneration

Question 37

Phototransduction in rods:

• Pigment synthesis
o ..?.. (visual pigment) forms and accumulates in the ..?..
o Vitamin ..?.. is ..?.. to the ..?..l and added to ..?.. = ..?..
o ..?.. bind to ..?.. channels keeping the channels ..?..
o Allows ..?.. and ..?.. to enter, ..?.. the cell to its ..?.. potential

• Pigment bleaching
o When ..?.. absorbs ..?.., ..?.. changes to ..?..
o This leads to ..?.. of ..?.. to ..?.. and ..?.. (..?..)
o Activated ..?.. activates ..?.. called ..?.., which activates ..?.., an enzyme that breaks down ..?.., which ..?.. the cation channels
o ..?.. and ..?.. stop ..?.. the cell and it ..?..

• Pigment regeneration
o Enzymes in ..?.. layer covert ..?.. back to ..?..

Answer 37

• rhodopsin; dark
• A; oxidised; 11-cis-retinal; opsin; rhodopsin
• cAMP; cation; open
• Na+; Ca2+; depolarising; dark
• rhodopsin; light; retinal; all-trans-retinal
• breakdown; rhodopsin; retinal; opsin; bleaching
• rhodopsin; G protein; transducin; phosphodiesterase; cAMP; closes
• Na+; Ca2+; entering; hyperpolarises
• pigmented; all-trans-retinal; 11-cis-retinal

Question 38

Cones in ..?.. vision and ..?.. (light) vision
- ..?.., high ..?.. and ..?.. receptors
- Cells contain ..?.. different pigments
- One ..?.. cell per ..?.. neuron and ..?.. giving ..?.., high ..?.. of small areas of the ..?..

Answer 38

Colour; photo topic; light
- colour; resolution; bright-light
- 3
- cone; bipolar; ganglion; detailed; visual acuity; visual field

Question 39

Phototransduction in cones: Essentially the same as for ..?.., but ..?.. are ..?.. times less ..?.. to ..?.., which means it takes ..?..-intensity (..?..) light to ..?.. cones.

Answer 39

Rhodopsin; cones; hundred; sensitive; light; higher; brighter; activate

Question 40

Light and dark adaptation
- Rhodopsin is incredibly ..?.., even starlight ..?.. some of the molecules. As long as light is ..?..-intensity, relatively little ..?.. bleaches and ..?.. continues to respond to ..?..
- In ..?..-intensity light, rhodopsin is bleached as ..?.. as it can ..?.., making the rods ..?.. but ..?.. still respond

Answer 40

• sensitive; bleaches; low; rhodopsin; retina; stimuli
• high; fast; regenerate; non-functional; cones

Question 41

Cones are ..?.. acuity and have ..?.. cone per ..?.. cell in the ..?..

Answer 41

High; one; ganglion; fovea

Question 42

Where are rods mostly located?

Answer 42

In the peripheral retina

Question 43

Where are cones mostly located?

Answer 43

In the central retina

Question 44

What is phototransduction?

Answer 44

Process by which light energy is converted into a graded receptor potential.

Question 45

Photopigments are embedded in free-floating ..?… Discs in cone cells are ..?.. with the ..?.., and thus ..?.. between discs link to ..?…

Answer 45

Membrane discs; continuous; plasma membrane; spaces; ECF

Question 46

• Retinal combines with different ..?.. to form ..?.. types of ..?… Depending on the type of opsin bound, retinal absorbs different ..?.. of the ..?.. spectrum.
• There is only ..?.. kind of ..?.. for all ..?.. cells.
  There are ..?.. different opsins for ..?.. cells, but only one per cell, you get ..?.. cones, ..?.. cones and ..?.. cones.

Answer 46

• opsin proteins; four; visual pigments; wavelengths; visible
• one; opsin; rod; 3; cone; one; red; blue; green

Question 47

What happens when all cones are stimulated equally?

Answer 47

We see white

Question 48

What is retinal made from?

Answer 48

Vitamin A

Question 49

What are the 2 isomer forms of retinal?

Answer 49

1. Kinked/bent form: 11-cis-retinal= inactivated form
2. All-trans-retinal: when the pigment absorbs a photon= activated form

Question 50

Generating an impulse (vision)

• Photoreceptors do not generate ..?.., but only create ..?.. (either as ..?.. or ..?..). Retinal cells are ..?.. and lie ..?.. together.
• Graded potentials are sufficient to serve as ..?.. that directly regulate ..?.. release at the ..?.. by ..?.. or ..?.. voltage gated ..?.. channels.
  -In the light, photoreceptors are ..?.., which stops them releasing their ..?.. neurotransmitter. No longer inhibited, ..?.. cells ..?.. and release ..?.. into ..?.. cells.
• Only here is an ..?.. created. This action potential is transmitted to the ..?.. along ..?.. cell axons that make up the ..?.. nerve

Answer 50

• AP’s; graded potentials; EPSPs; IPSPs; small; close
• signals; neurotransmitter; synapse; opening; closing; Ca2+
• hyperpolarised; inhibitory glutamate; bipolar; depolarise; neurotransmitter; ganglion
• AP; brain; ganglion; optic

Question 51

Events of phototransduction

1. ..?.. absorbs ..?.. and changes ..?.. and ..?.. is activated
2. ..?.. pigment activates ..?.. (..?..)
3. ..?.. activates ..?.. (PDE)
4. PDE converts ..?.. into ..?.., causing ..?.. levels to ..?..
5. As ..?.. levels fall, ..?.. cation channels ..?.., resulting in ..?..

Answer 51

1. Retinal; light; shape; visual pigment
2. Visual; transducin; G protein
3. Transducin; phosphodiesterase
4. CGMP; GMP; cGMP; fall
5. CGMP; cGMP-gated; close; hyperpolarisation

Question 52

Signal transmission in the retina in the dark

1. ..?..- gated channels ..?.., allowing cation ..?.. therefore the photoreceptor ..?..
2. Voltage gated ..?.. channels ..?.. in ..?..
3. ..?.. is released ..?..
4. Neurotransmitter causes ..?.. in ..?.. cell. ..?.. results.
5. ..?.. closes voltage-gated ..?.. channels, ..?.. neurotransmitter release
6. No ..?.. occur in the ..?.. cell
7. No ..?.. occur along the ..?.. nerve

Answer 52

1. CGMP; open; influx; depolarises
2. Ca2+; open; synaptic terminals
3. Neurotransmitter; continuously
4. IPSPs; bipolar; hyperpolarisation
5. Hyperpolarisation; Ca2+; inhibiting
6. EPSPs; ganglion
7. APs; optic

Question 53

Signal transmission in the retina in the light

1. ..?..- gated channels ..?.., so cation influx ..?… Photoreceptor ..?..
2. Voltage- gated ..?.. channels ..?.. in ..?..
3. ..?.. neurotransmitter is ..?..
4. Lack of ..?.. in ..?.. cells results in ..?..
5. ..?.. opens voltage-gated ..?.. channels and ..?.. is released
6. ..?.. occur in the ..?.. cell
7. ..?.. propagate along the ..?.. nerve

Answer 53

1. CGMP; close; stops; hyperpolarises
2. Ca2+; close; synaptic terminals
3. No; released
4. IPSPs; bipolar; depolarisation
5. Depolarisation; Ca2+; neurotransmitter
6. EPSPs; ganglion
7. APs; optic

Question 54

• Pupillary reflex: response of ..?.. when a ..?.. is shone in the ..?.. or ..?.. eye ..?.. muscles of the iris enhance the effect of ..?.. by ..?.. the ..?.. of the pupil toward ..?…
• This accommodation pupillary reflex prevents most ..?.. light rays from ..?.. the eye. Such rays would pass through the extreme ..?.. of the ..?.. and would not ..?.. properly, causing ..?.. vision.

Answer 54

• Iris; light; same; opposite; Sphincter pupillae; accommodation; reducing; size; pupil; 2mm
• divergent; entering; edge; lens; focus; blurred

Question 55

What are the afferent and efferent components of the pupillary reflex?

Answer 55

• Afferent component: optic nerve (CN II) fibres to pretectal nucleus in the midbrain
• Efferent component = parasympathetic fibres in oculomotor (CN III) nerve

Question 56

Explain how the left and right visual fields are projected onto the visual cortex

• Visual information on your ..?.. hand side is captured by the ..?.. sides of each eye ball. This is because the ..?.. is ..?.. and ..?.. images when projecting onto your ..?..
• At the optic chiasm: ..?.. fibres stay on the ..?.. side; ..?.. fibres ..?.. to the ..?.. side
• Impulses continue via the ..?..
  o These sweep ..?.. around the ..?..
  o Synapse with neurons in the ..?.. (within ..?.. bodies of the ..?..)
  o Some branch to the ..?.. and ends in the ..?.. (visual ..?.. centres that control ..?.. of the eye), and ..?.. nuclei (which mediate ..?..)
• Axons from ..?.. project through the ..?.. to form the ..?.. fibres in the cerebral ..?..
• These fibres project to the ..?.. in the ..?..
  o ..?.. perceptions of ..?.. occurs
• A tumour pushing on the optic chiasm would result in ..?.. since ..?.. fibres would be ..?.., which gain ../.. from the ..?…

Answer 56

• right; left; lens; concave; inverts; retina
• temporal; same; nasal; cross over; opposite
• optic tracts
  o posteriorly; hypothalamus
  o lateral geniculate nuclei; lateral geniculate; thalamus
  o midbrain; superior colliculi; reflex; extrinsic muscles; pretectal; pupillary reflexes
• thalamic neurons; internal capsule; optic radiation; white matter
• primary visual cortex; occipital lobe
  o conscious; visual images
• tunnel vision; nasal; affected; stimuli; outer visual field

Question 57

Describe the role of the lateral geniculate nucleus in vision
- LGM is the ..?.. part of the ..?..
- Serves as the primary ..?.. for ..?.. by the ..?…
- The ..?.. LGN receives information from the ..?.. visual field, and visa verse for the ..?.. LGN.
- Maintains fibre ..?.. established at the ..?… The LGM has ..?.. layers, and ..?.. from the two eyes is maintained in ..?.. layers (cells with imput from the ..?.. eye are in layers ..?.., ..?.. and ..?..; cells with input for the ..?.. side eye are located in layers ..?.., ..?.. and ..?..)
- Axons from the LGN form ..?.. that ..?.. at the ..?..
o The topographical order of information is maintained in the ..?..

Answer 57

• visual; thalamus
• relay nucleus; visual processing; cerebral cortex
• left; right; right
• separation; chiasm; 6; input; separate; opposite; 1; 4; 6; same; 2; 3; 5
• optic radiations; terminate; visual cortex
  o cortex