Transcript chapter30_Sections 6

Cecie Starr
Christine Evers
Lisa Starr
www.cengage.com/biology/starr
Chapter 30
Sensory Perception
(Sections 30.6 - 30.9)
Albia Dugger • Miami Dade College
30.6 Visual Disorders
• Vision is impaired when light is not focused properly, when
photoreceptors do not respond as they should, or when some
aspect of visual processing breaks down
• Common vision disorders result from defective or
degenerating photoreceptors, misshapen eyes, a clouded
lens, or excess aqueous humor
Color Blindness
• Sometimes one or more types of cones fail to develop or
function improperly
• Red-green color blindness is an X-linked recessive trait in
which a person has trouble distinguishing reds from greens
• As in other X-linked traits, it shows up more often in males
Lack of Focus
• Disorders in which light rays do not converge as they should
cause focus problems
• Astigmatism results from an unevenly curved cornea, which
cannot properly focus incoming light on the lens
• Nearsightedness or farsightedness occurs when the distance
from the front to the back of the eye is longer or shorter than
normal
Nearsighted and Farsighted
• In nearsightedness, light rays converge in front of the retina;
in farsightedness, light rays are focused behind the retina
Nearsighted
distant
object
Fig 30.10a, p. 495
Farsighted
close
object
Fig 30.10b, p. 495
Age-Related Disorders
• A cataract is a clouding of the lens
• In age-related macular degeneration (AMD), photoreceptors
in the macula are destroyed, which clouds the center of the
visual field more than the periphery
• Glaucoma results when too much aqueous humor builds up
inside the eyeball
Age-Related Disorders
• Vision with cataracts
• Vision with AMD
ABC Video: Restoring Sight
30.7 The Chemical Senses
• The senses of taste and smell involve chemoreceptors
• taste receptors
• Chemoreceptors involved in taste
• olfactory receptors
• Chemoreceptors involved in sense of smell
Sense of Smell
• In humans, olfactory receptors line the nasal passages
• Olfactory receptors detect water-soluble or volatile (easily
vaporized) chemicals
• Receptor axons carry signals to olfactory bulbs in the brain
• Many animals use olfactory cues to navigate, find food, and
communicate, as with pheromones
Pheromones
• Pheromones are chemical signals that act as social cues
among many animals that have the means to detect them
• Example: Olfactory receptors on antennae of a male silk moth
help him find a pheromone-secreting female
• In the nasal cavity of reptiles and most mammals, a cluster of
sensory neurons forms a vomeronasal organ that responds
to pheromones
Key Terms
• pheromones
• Signaling molecules that affect another member of the
same species
• vomeronasal organ
• Pheromone-detecting organ of vertebrates
Olfactory Receptors
Olfactory Receptors
olfactory tract
from receptors
to the brain
olfactory
bulb
bony
plate
ciliated
endings of
olfactory
receptor
that project
into mucus
inside nose
Fig 30.12, p. 496
Sense of Taste
• Taste receptors help animals locate food and avoid poisons
• In humans, taste buds are located in specialized epithelial
structures (papillae) on the tongue’s upper surface
• Tastes are combinations of five main sensations:
• sweet (glucose and the other simple sugars)
• sour (acids)
• salty (sodium chloride or other salts)
• bitter (plant toxins, including alkaloids)
• umami (amino acids such as glutamate)
Taste Receptors
Taste Receptors
taste
bud
hairlike
ending
of taste
receptor
section through
circular papilla
sensory nerve
Fig 30.13, p. 496
Key Concepts
• Chemical Senses
• Binding of specific chemicals activates chemoreceptors in
the lining of the nose and mouth
• Many animals also have organs that detect pheromones:
chemicals that one member of a species uses to
communicate with another member of the same species
30.8 Keeping the Body Balanced
• The vestibular apparatus, a system of fluid-filled sacs and
canals in the inner ear, houses organs essential to
maintaining posture and sense of balance
• These organs of equilibrium detect gravity, acceleration,
and other forces that related to the body’s position and motion
• They include hair cells, mechanoreceptors with specialized
pressure sensitive cilia
Key Terms
• organs of equilibirum
• Sensory organs that respond to body position and motion
• vestibular apparatus
• System of fluid-filled sacs and canals in the inner ear;
contains organs of equilibrium
• hair cell
• Mechanoreceptor that is activated when movement of
overlying membrane causes its hairlike cilia to bend
Organs of Equilibrium
• Organs of equilibrium are located in three semicircular canals
and two sacs, the saccule and utricle
• Rotation of the head in any combination of directions moves
fluid inside the canals and sacs
• Fluid pressure makes cilia bend, which deforms hair cells in
the plasma membrane enough to stimulate an action potential
• A vestibular nerve carries the sensory input to the brain
Sense of Balance
• The brain senses dynamic equilibrium (angular movement
and rotation of the head) by comparing signals from
semicircular canals on both sides of the head
• The saccule and utricle help the brain monitor head position,
how fast the head is moving in a straight line, and maintain
posture (static equilibrium)
Vestibular Apparatus
Vestibular
Apparatus
semicircular
canals
vestibular
nerve
saccule
utricle
gelatinous membrane
in a semicircular canal
hair cells with their cilia
embedded in membrane
sensory neurons
Fig 30.14, p. 497
Vestibular
Apparatus
semicircular
canals
vestibular
nerve
saccule
utricle
Fig 30.14a, p. 497
Vestibular Apparatus
gelatinous membrane
in a semicircular canal
hair cells with their cilia
embedded in membrane
sensory neurons
Fig 30.14b, p. 497
Vestibular Apparatus
semicircular
canals
vestibular
nerve
saccule
utricle
gelatinous membrane
in a semicircular canal
hair cells with their cilia
embedded in membrane
sensory neurons
Stepped Art
Fig 30.14, p. 497
ANIMATION: Dynamic equilibrium
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30.9 Detecting Sounds
• Many arthropods and most vertebrates can hear sounds
• In land vertebrates, ear flaps capture sounds traveling
through air, and internal parts of the ear sort them out
Properties of Sound
• Sound is a form of mechanical energy
• Sounds arise when a vibrating object causes pressure waves
in air, water, or some other medium
• Amplitude (wave height) determines how loud a sound is
• Frequency (number of waves per second) determines pitch
Wave Properties of Sound
Wave Properties of Sound
Soft
Low
note
Loud
High
note
A Same frequency,
different amplitude
B Same amplitude,
different frequency
Fig 30.15, p. 498
Wave Properties of Sound
Soft
Low
note
Loud
High
note
A Same frequency,
different amplitude
B Same amplitude,
different frequency
Stepped Art
Fig 30.15, p. 498
Animation: Properties of Sound
Vertebrate Hearing (1)
• Human ears have three regions:
• The outer ear collects sound waves
• The middle ear amplifies sound waves and transmits
them to the inner ear
• The inner ear includes the vestibular apparatus and the
cochlea: a coiled, fluid-filled structure with three ducts
Key Terms
• outer ear
• External ear and the air-filled auditory canal
• middle ear
• Eardrum and the tiny bones that transfer sound to the
inner ear
• inner ear
• Fluid-filled vestibular apparatus and cochlea
• cochlea
• Coiled, fluid-filled structure in the inner ear that holds the
sound-detecting organ of Corti
Anatomy of the Ear (1)
Anatomy of the Ear (1)
inner ear
vestibular
apparatus,
cochlea
outer ear
middle ear
pinna,
auditory
canal
eardrum,
ear bones
The outer ear’s
flap and canal collect
sound waves.
1
Fig 30.16.1, p. 498
Vertebrate Hearing (2)
• In the middle ear, sound waves are transmitted from the
eardrum, through three tiny bones (hammer, anvil, and
stirrup), onto the surface of the oval window, an elastic
membrane that is the boundary between the middle and inner
ear
• The inner ear contains the vestibular apparatus and the
cochlea
Anatomy of the Ear (2)
Anatomy of the Ear (2)
oval window
(behind stirrup)
middle ear bones:
stirrup
anvil
auditory nerve
hammer
auditory
canal
2
eardrum
round
window
cochlea
The eardrum and middle ear bones amplify sound.
Fig 30.16.2, p. 498
ANIMATION: Ear structure and function
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Vertebrate Hearing (3)
• Membranes divide the interior of the cochlea into three fluidfilled ducts
• Pressure waves from the oval window travel through fluid in
the cochlea and bend hair cells embedded in one of the
cochlear membranes
Anatomy of the Ear (3)
Anatomy of the Ear (3)
fluid-filled
duct
fluidfilled
duct
organ of Corti
sensory
neurons (to
the auditory
nerve)
fluid-filled duct
One coil of the cochlea in cross-section. The organ of Corti
detects pressure waves in fluid-filled ducts inside the cochlea.
3
Fig 30.16.3, p. 499
Vertebrate Hearing (4)
• The organ of Corti, the organ responsible for hearing, sits on
the base of the membrane in the middle duct
• In the organ of Corti, arrays of hair cells with specialized cilia
extend into an overlying membrane
• When pressure waves cause the membrane to move, hair
cells undergo action potentials that travel along an auditory
nerve to the brain
Anatomy of the Ear (4)
Anatomy of the Ear (4)
hair cells of organ of Corti
overlying membrane
basilar membrane
4
Pressure waves cause the basilar membrane beneath the
organ of Corti to move upward. The movement pushes hair
cells against an overlying membrane. The resulting action
potentials travel along the auditory nerve to the brain.
Fig 30.16.4, p. 499
Hearing Loss
• Repeated exposure to a specific loud sound can kill hair cells
that respond to that sound
• Hearing loss can also result from damage to the auditory
nerve, loss of fluid in the inner ear, damage to the small
bones of the middle ear, or even an excess amount of earwax
Sound-Induced Damage to Hair Cells
Key Concepts
• Balance and Hearing
• The ear functions in the senses of balance and hearing
• In both cases, movements stimulate mechanoreceptors
• In balance, body movements are the source of the
stimulation
• In hearing, pressure from sound waves causes movement
that stimulates mechanoreceptors
A Whale of a Dilemma (revisited)
• Our technology has dramatically altered the sensory
landscape for animals and us
• Sound pollution harms animals by disorienting them,
interfering with ability to find prey, or disrupting courtship
• In humans, environmental noise impairs concentration,
interferes with sleep patterns, raises anxiety and increases
risk of high blood pressure and other cardiovascular problems
Animation: Sound Detection