chapter 38: sense organs

Question 1

what are sensory receptors

Answer 1

Structure that receives either external or internal environmental stimuli and is a part of a sensory neuron or transmits signals to a sensory neuron

Question 2

what is sensory transduction

Answer 2

conversion of a stimulus into a nerve impulse by using a receptor

Question 3

what is perception

Answer 3

sensory stimulation we are aware of

Question 4

what are the four main kinds of sensory receptors

Answer 4

-chemoreceptors
-photoreceptors
-mechanoreceptors
-thermoreceptors

Question 5

what is a chemoreceptor

Answer 5

sensitive to chemical stimulation (taste & smell)

Question 6

what are photoreceptors

Answer 6

respond to light (vision)

Question 7

what are mechanoreceptors

Answer 7

respond to mechanical stimuli (pressure, sound waves, & gravity)

Question 8

what are thermoreceptors

Answer 8

receptor that detects heat

Question 9

how do sensory receptors in animals work

Answer 9

-Perceive very different ways
-Snakes detect infrared energy
-Bats, dolphins, whale echolocation
-Dogs sense of smell is incredibly strong

Question 10

characteristics of chemoreceptors

Answer 10

-Chemoreceptors are universally found in animals
-Most primitive sensory receptors to have developed in animals - evolved the longest - huge variety

Question 11

examples of chemoreceptors locations in animals

Answer 11

-Planarians: concentrated on the auricles of the head in planaria
-Arthopods: found on antennae and mouthparts in insects and other arthropods
-Fish: scattered across skin
-Snakes: Jacobson’s organs

Question 12

how does human sense of taste work

Answer 12

-10,000 taste buds located primarily tongue along walls of papillae (small elevations)
-Taste receptors are located within taste buds in humans
-Taste buds: structure in vertebrate mouth containing sensory receptors for taste
-Generate nerve impulses in associated sensory nerve fibers

Question 13

how does sense of smell in humans work

Answer 13

-Olfactory cells: modified neuron that is a sensory receptor for smell
-Each cell ends in a tuft of cilia
-1 out of 1,000 different types of receptor proteins
-Odor can contain many odor molecules
-Olfactory bulb direct connections with limbic system
-Emotions & vivid memories
-Smell & taste work together

Question 14

how does the sense of vision work

Answer 14

-Photoreceptors differ in complexity in different kinds of animals
-Simplest only recognize presence & intensity of light
-Eyespots in planaria allow the direction of light to be determined
-Compound eye (Arthropods) many different visual units called ommatidia

Question 15

how do animals detect light

Answer 15

-Some fish, reptiles, & most birds color vision
-Camera-type eyes: Type of eye found in vertebrates and certain mollusks; a single lens focuses an image on closely packed photoreceptors

Question 16

what kind of animals have stereoscopic vision and why

Answer 16

predator, allows to lock onto target
very good at perceiving objects at different angles

Question 17

what kind of animals have panoramic vision and why

Answer 17

prey - seeing predators with large field of visionq

Question 18

how does focusing of the eye work

Answer 18

-Light rays pass through pupil & focused on retina
-Brain processes image in correct orientation
-Shape of lens is controlled by ciliary muscle: muscle that controls shape of lens

Question 19

two kinds of photoreceptors

Answer 19

rods and cones

Question 20

characteristics of rods

Answer 20

-Night vision
-Peripherial vision & motion
-sensitive to light
-100s of rods are connected to one cell, so the brain cant distinguish between individual cells and the images are not very detailed

Question 21

characteristics of cones

Answer 21

-Primarily in fovea centralis
-Fine detail & color
-B (blue), G (green), & R (red) pigments
-each cone is attached to one cell, providing a detailed image to the brain

Question 22

how do impulses get from the retina to the visual cortex

Answer 22

-Fibers synapse with neurons in nuclei within thalamus
-Take nerve impulses to visual area within occipital lobe
-Image inverted & reversed
-Corrected in visual regions of the brain

Question 23

how does the sense of hearing and equilibrium work

Answer 23

-Mechanoreception sensing physical contact or movement in environment
-Receive information at distance
-Avoid danger, detect prey, find mates, ect

Question 24

how does sense of hearing in insects work

Answer 24

Tympanum – a thin membrane stimulated to vibrate by sound waves that directly activates nerve impulses in attached receptor cells

Question 25

how does sense of hearing in fish work

Answer 25

Lateral line system – detects water currents & pressure waves from nearby objects

Question 26

what are the three parts of the human inner ear

Answer 26

semicircular canals, vestibule, cochlea

Question 27

what are semicircular canals

Answer 27

Half-circle shaped canals; contains receptors for rotational equilibrium

Question 28

what are vestibules

Answer 28

cavity that lies between the semicircular canals & cochlea

Question 29

what is the cochlea

Answer 29

spiral-shaped structure containing sensory receptors for hearing

Question 30

characteristics of the auditory canal and the middle ear

Answer 30

-Sound waves enter the auditory canal
-Strike tympanic membrane
-Malleus takes pressure from the inner surface of tympanic membrane & passes it to by means of the incus to staples
-Stapes strikes membrane of oval window & vibrate

Question 31

what are statocysts

Answer 31

-Gravitational equilibrium organs
-Provide information about the position of the head
-statolith hair cells
-ball rolls to let animals know their location
-mollusks, crustaceans

Question 32

what is rotational equilibrium

Answer 32

-Semicircular canals
-Base of each three canals (ampulla) is enlarged
-Head rotates cupula is displaced
-generates nerve impulse and sends to head
-Uses information to maintain equilibrium

Question 33

what is gravitational equilibrium

Answer 33

-Utricle & saccule
-Contain hair cells whose stereocilia embedded within a gelatinous material called otolithic membrane
-Heads moves otoliths are displaced & otolithic membrane sags
-base of cochlea, “ocean”, up and down movements

Question 34

what are proprioceptors (somatic senses)

Answer 34

Reflex actions that maintain muscle tone
Equilibrium & posture

-Ex: muscle spindles are embedded in muscle fibers
-If muscle relaxes too much; muscle spindle stretches; generates nerve impulses that cause it to contract slightly
-twitch in sleep
-Stretched excessively Golgi tendon organ causes muscle relaxation

Question 35

what are cutaneous receptors (somatic senses)

Answer 35

-Dermis layer contains many cutaneous receptors
-Skin sensitive to touch, pressure, pain, and temperature

Question 36

what are pain receptors (somatic senses)

Answer 36

-Also called nociceptors
-Damaged cells release chemicals that cause pain receptors to generate nerve impulses
-Alert us to potential danger

Question 37

what are the parts of the human ear?

Answer 37

-outer ear, pinna - gathers sound waves
-auditory canal - catches debris
-tympanic membrane - amplifies sound waves
-3 bones, stapes, incus, malleus - amplifies
-cochlear and canals