Chapter 15

Question 1

Sensory receptors

Answer 1

• sense organs
• receptors that make it possible for the body to response to changed in the external and internal environment

Question 2

Sensation

Answer 2

• a physical feeling or perception resulting from changes in or the contact with the body
• occurs when receptor potential is reached
  - graded response, to the strength of a stimulus

Question 3

Define special sense

Answer 3

• smell, taste, vision, hearing and equilibrium
• locally distributes in the body (tightly grouped)

Question 4

Define general sense

Answer 4

• touch, pain, pressure, temperature
• widely distributed throughout the body

Question 5

Receptors can be classified according to?

Answer 5

Location
Stimulus detection
Structure

Question 6

Exteroceptors

Answer 6

Located on or very near the surface of the body
- respond to external changes

Question 7

Visceroceptors (interceptors)

Answer 7

• located internally, within the bodily organs
  - respond to internal environments (heat, stretch, chemicals)

Question 8

Proprioceptors

Answer 8

• specialized visceroceptor
• located in skeletal muscle

Question 9

Classifications of receptors

Answer 9

Mechanoreceptors - “deform” or change position of the receptor
Chemoreceptors - amount of the changed concentration of certain chemicals
Thermoreceptors - change in temperature
Nociceptors - any stimulus that rebuts in pain or tissue damage
Photoreceptors - light stimuli

Question 10

The somatic sensations that arise form receptors

Answer 10

• detect touch, pressure, vibration, pain and body position and movements
• send impulses to the primary somatosensory area of parietal lobe of cerebral cortex
• somatosensory area processes the information and send it to the primary motor areas in the frontal lobe.

Question 11

The 5 sensory receptors in the skin

Answer 11

Unencapsulated dendrites: detect pain, light, pressure, changes in temperature
Merkel disks: detect light, touch, and pressure
Meissner’s corpuscles: detect beginning and end of light touch and pressure
Ruffini endings: respond to ongoing pressure
Pacinian corpuscles: detect deep pressure and high-frequency vibration

Question 12

Mechanoreceptors

Answer 12

1) in joints: detect joint position
2) in skeletal muscles: muscle spindles, specialized Mechanoreceptors for monitoring muscle length, which relay information about limb position
3) in tendons: detect tension

Question 13

Proprioception

Answer 13

• the unconscious perception of movement and spatial orientation arising from stimuli within the body itself
  - specialized Mechanoreceptors
  
  • “muscle sense”
  • tells us the level of contraction and stretch in each skeletal muscles

Question 14

The two types of proprioception stretch receptors

Answer 14

• muscle spindles
• Golgi tendon receptors

Question 15

Themoreceptors detecting temperature

Answer 15

• themoreceptors near skin surface provide information about external environment
  
  • surface themoreceptors adapt quickly
• themoreceptors in thoracic and abdominal organs monitor core temperature.
  
  • core temperature receptors do not adapt quickly

Question 16

Pain receptors signal?

Answer 16

• unencapsulated nerve endings respond to injury from excessive pressure, heat, light, or chemicals
• fast paint (acute, sharp)
  
  • occurs very quickly
  • informs us of stimuli to be avoided
• slow pain
  
  • occurs more slowly
  • originates in muscles or internal organs
  • referred pain may be perceive as originating in a different area of the body

Question 17

Olfaction

Answer 17

Sense of smell
- olfactory epithelium consists of yellow-colored epithelial support cells, basal cells, and bipolar type of olfactory sensory neurons
- chemoreceptors

Question 18

Taste buds

Answer 18

• sense organs that respond to
  - taste stimuli
• most taste buds are associated with papillae
  - small, elevated projection on the tongue

Question 19

Types of tongue papillae

Answer 19

Fungiform: large mushroom-shaped bumps found int he anterior two thirds of the tongue surface
Circumvallate: huge, dome-shaped bumps that for a transverse row near the back of the tongue
Foliate: red, leaf-like ridge of mucosa on the lateral edges of the posterior tongue surface
Filiform: bumps with tiny, thread-like projections, scattered among the fungiform papillae

Question 20

Gustatory cells

Answer 20

• chemoreceptors found in taste buds that are responsible for taste
• stimulated by chemicals called tastants that dissolve in saliva

Question 21

The five primary taste sensations

Answer 21

Bitter
Salty
Sweet
Savory
Sour

Question 22

The sense of hearing and balance

Answer 22

• The ear serves as a duel sensory organ
  
  • hearing and equilibrium (balance)
• stimulation for both is the activation of Mechanoreceptors called hair cells
  
  • which are triggered by the displacement of fluid

Question 23

Middle ear

Answer 23

• also called the tympanic cavity
• a tiny epithelial-line cavity hollowed out of the temporal bone

Contains:
- tympanic membrane (eardrum)
- auditory ossicles:
Malleus (hammer)
Incus (anvil)
Stapes (stirrups)

Question 24

Inner ear

Answer 24

Called the labyrinth
Bony labyrinth:
Vestibule
Cochlea
Semicircular canals
Membranous labyrinth:
Utricle
Saccule

Question 25

Main structure of the eye

Answer 25

Sclera Iris Pupil Lens Iris Cornea

Question 26

Accessory structure of the eye

Answer 26

Eyebrows Eyelashes Eyelids Lacrimal apparatus

Question 27

The layers of the eye

Answer 27

Fibrous layer: sclera, cornea Vascular layer: choroid, ciliary body, iris Inner layer: retina, optic nerve, retinal blood vessels

Question 28

Muscles of the eye

Answer 28

Extrinsic: - skeletal muscle, that voluntarily moves the eyeball Includes: superior, inferior, medial, and lateral rectus muscles. Superior an inferior oblique muscles Intrinsic: - smooth muscles, located within the eye itself - iris; ciliary muscles

Question 29

Regulating the amount of light

Answer 29

- the iris (smooth muscle) causes pupils to constrict or dilate to control the amount of light entering the eye

Question 30

Focusing the image

Answer 30

- involves bending of light by cornea and lens - accommodation - adjustment of lens curvature to enable focusing on near and far objects - made possible by ciliary muscles - ability to accommodate deteriorates with age

Question 31

Retina

Answer 31

- allows us to see in color, adapt to varying light intensities, and perceive images

Question 32

The four layers of the retina

Answer 32

1) outermost: pigmented cells, absorb excess light 2) photoreceptors: rods and cones 3) bipolar cells: synapse with rods and cones 4) innermost: ganglion cells, axons become the optic nerve

Question 33

Photoreceptors

Answer 33

- rods and cones - response to light: photopigment (protein) changes shape - Rods: approximately 120 million - cones: approximately 6 million - one million ganglion cells - significant amount of convergence and summation

Question 34

Rhodopsin

Answer 34

Rhodopsin: photopigment within the rods - more sensitive to light than photopigment in cones - in dim light, vision primarily depends on rods - rods do note enable color vision - rods and cones are not evenly distributed on the retina - regions of the retina farthest from the fovea have the highest ratio of rods to cones

Question 35

The cones providing color vision and accurate images

Answer 35

- three types of cones enable color vision: red, green, and blue - brain interprets ratios of impulses combined from ganglion cells connected to the three kinds of cones - cones require stronger light to be activates - in dim light, we primarily use rods and don’t see color - cones responsible for visual acuity

Question 36

Visual receptors adjust how

Answer 36

Depends on: - adjustment of pupil size by iris - adaptation by the rods Adaptation takes longer when going from light to dim light - bright light “uses up” the rhodopsin temporarily - takes several minutes to resynthesize rhodopsin