Chapter 38: The Nervous System - The Sensory System

Question 1

1) ____ step process to get sensory information to the CNS

Answer 1

1) Four

Question 2

Steps for information traveling to CNS

Answer 2

1) Stimulation (sensory information)
2) Transduction (converted to potential)
3) Transmission (carried to CNS)
4) Interpretation (perception)

Question 3

Types of sensory systems depend on the 1) ___________

Classification of receptors based on 2) ___________

Answer 3

1) types of stimuli
2) location
- Exoteroreceptor
- Proprireceptors

Question 4

Types of receptors

Answer 4

Mechanoreceptors
Thermoreceptors
Photoreceptors
Chemoreceptors
Nociceprtors

Question 5

Location of receptors

Answer 5

Exoteroceptors: Sense organs (vision, hearing, smell, taste) that are also responsible for touch, pressure, pain, temperature.

Interoceptors: Viscera and blood vessels

Proprioceptors: Similar to interoreceptors. Occur in skeletal muscle, tendons, joints, ligaments, CT wraps, which monitor the degree of stretch of the organs they occupy.

Question 6

Receptors can be 1) ________ or they can 2) ________

Answer 6

1) afferent neurons, meaning they take signals toward CNS

2) regulate afferent neurons if they are not neurons themselves (i.e. sensory receptor cell)

Question 7

Chemoreception

Answer 7

TASTE & SMELL

• These are not limited to mouth and nose sensations (fish taste via skin, flies taste via feet)
• Human taste -
  * Taste buds are collections of taste receptors. Buds are located on visible papillae.

Question 8

Taste

Answer 8

"Gustation"
Papilla = circuvallate (back of tongue), foliate (side of tongue), and fungiform.
    *****Papilla-----> Taste pore
      -------> taste bud
Receptors: Sweet, sour, salty, umami!

Question 9

1) _______ and 2) ________ act DIRECTLY on ion channels

Answer 9

1) Salty

2) Sour

Question 10

1) ________, 2) _________, and 3) _________ act INDIRECTLY on ion channels via 4) ___________

Answer 10

1) Sweet
2) Bitter
3) Umami
4) G proteins (protein-coupled receptors)

Question 11

Smell -

Answer 11

“Olfaction”
- Stimulus enters nasal epithelium where it becomes a solution (mucus)
- Genes coding for olfactory receptors = 1000
**Humans have 400 of these
genes. 600 are
pseudogenes
**Each receptor only
expresses ONE (OR)
molecule!
- What we perceive as a smell is actually a COMBINATION of responses from some subset of the 400 (OR) receptor molecules. “Profiles!!”

***** Receptor cell (cilia) —->
Olfactory nerve

Question 12

1) _______ sensory information has a relatively 2) _______ route to higher brain centers, so it is very powerful!

Answer 12

1) Odor

2) Unfiltered

Question 13

Gravity and movement: sensation and transduction occur in 1) _________

Answer 13

1) inner ear

Question 14

Gravity and movement

Answer 14

Vestibular apparatus - provides the brain with information about the body’s position in space, and it is used to maintain balance and equilibrium.

Question 15

Transduction in the vestibular apparatus occurs via 1) _______ movement within the structure, which deforms the 2) _________.. Direction of movement will either 3) _________ or 4) ________ the membrane.

Answer 15

1) fluid
2) hair cells
3) depolarize
4) hyperpolarize

Question 16

Vestibular apparatus

Answer 16

Fluid filled structure that provide brain with information regarding the body’s position.

• Utricle : horizontal acceleration, with respect to GRAVITY
• Saccule : vertical acceleration, with respect to GRAVITY
• Semi-circular canals : angular (rotation) acceleration

Question 17

The ear

Answer 17

Outer ear
 - Pinna -----> Auditory canal
Middle ear
 -
Inner ear
 - Cochlea 
 - Semicircular canals (rotation) 
 - Vestibule
        - Utricle (horizontal
          acceleration)
        - Saccule (vertical
          acceleration)
Eustachian tube

Question 18

Pathway of sound

Answer 18

Outer ear —–> tympanic membrane ——> middle ear bones (Malleus, incus, and sales) ——> oval window ——> fluid in inner ear (cochlea = continuous)

Question 19

Inner ear: Cochlea = 1) ______ fluid filled chambers

Answer 19

1) Three
- Vestibular canal (continuous)
- Cochlear duct
- Tympanic canal

Flexibility along the basilar membrane in the organ of Corti (which includes the basilar membrane, hair cells, and the tectorial membrane) varies along its length. Because of this, the position along the membrane which the hair cells are deformed varies with the frequency of sound.

Question 20

Frequency of sound = 1) _________

Answer 20

1) Pitch

HIGH = 20,000 Hz, short waves (stimulate cochlea near beginning of structure) 
MEDIUM = 2,000 Hz, medium waves
LOW = 500 Hz, long waves (stimulate structure further down its length)

Question 21

Visions 5 basic structures

Answer 21

1) Iris
2) Lens
3) Retina
4) Fovea
5) Optic nerve

Question 22

Receptors of the eye are 1) _______, and there are 2) _______ types.

Answer 22

1) Photoreceptors
2) two
- Rods (low light, black/white)
- Cones (illumination, color)

Question 23

Region of the retina with most accurate vision is the 1) ______

Answer 23

1) Fovea
- Mostly cones, which are responsible for detailed vision.
- Very few rods

Question 24

Rods & cones - Pigments respond to light by changing 1) ________ _____

Answer 24

1) Isometric form - CIS to TRANS!
a) Synaptic terminal
b) Inner segments
c) Connecting cilium = modified ciliated cells!!!
d) Outer segments (contain
PIGMENT DISKS)
- Photopigment of rods = rhodopsin
- Photopigments of cones (3) are photopsins (red, blue, and green)/

Question 25

Signals from the eye to the brain!

Answer 25

1) Light enters the eye.
2) Image focused onto the fovea located on the retina.
3) Ganglion, to amacrine, to bipolar, to horizontal, to receptors.
4) Photo pigment receptors change shape, triggering an action potential in membrane, depolarizing it.
5) Receptors transmit signal toward optic nerve, which travels to the brain.

Question 26

Cones

Answer 26

Blue = 420 nm
Green = 530 nm
Red = 560 nm (OPTIMAL)
- Different combinations of these lead to different perceptions of color/images.

Each photoreceptor differs in the wavelength at which they are most sensitive.
** Sex linked color blindness results from the lack of one or more types of cones.

Question 27

1) _______ are more likely to suffer from color blinds because it is a 2) _______ linked disease carries on the 3) _______ chromosome.

Answer 27

1) Males
2) Sex
3) X