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Biology 2312 > Chapter 44 > Flashcards

Chapter 44 Flashcards

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1
Q

What are exteroceptors?

A

receptors that sense stimuli that arise in the external environment

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2
Q

Evolutionarily speaking, where did vertebrate sense evolve?

A

first in water before the invasion of land

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3
Q

What are the consequences of the fact that vertebrate sensory systems evolved in water before land?

A

may senses of terrestrial vertebrates emphasize stimuli that travel well in water

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4
Q

What are interoceptors?

A

receptors that sense stimuli that raise from within the body

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5
Q

Which are typically more complex, exteroceptors or interoceptors?

A

exteroceptors

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6
Q

Which bear more of a resemblance to primitive sensory receptors, exteroceptors or interoceptors?

A

interoceptors?

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7
Q

What are the three broad classes of receptors?

A

mechanoreceptors, chemoreceptors, electromagnetic receptors

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8
Q

What are mechanoreceptors? (2)

A

stimulated by mechanical forces such as pressure; include receptors for touch, hearing, and balance

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9
Q

What are chemoreceptors? (2)

A

detect chemicals or chemical changes; includes receptors for smell and taste

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10
Q

What are electromagnetic receptors? (2)

A

react to heat and light energy; includes eye photoreceptors

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11
Q

What is the four-step process for the conveying of sensory information?

A

stimulation, transduction, transmission, interpretation

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12
Q

Describe stimulation in the four-step process for the conveying of sensory information.

A

a physical stimulus impinges on a sensory neuron or associated/separate sensory receptor

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13
Q

Describe transduction in the four-step process for the conveying of sensory information.

A

stimulus energy is transformed into graded potentials in the dendrites of the sensory neuron

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14
Q

Describe transmission in the four-step process for the conveying of sensory information.

A

action potentials develop in the axon of the sensory neuron and are conducted to the CNS along an afferent nerve pathway

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15
Q

Describe interpretation in the four-step process for the conveying of sensory information.

A

brain creates sensory perception from the electrochemical events produced by afferent stimulation.

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16
Q

Why do sensory cells respond to stimuli?

A

because they possess stimulus-gated ion channels in their membranes

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17
Q

In most causes, the sensory stimulus causes what event in the receptor cell?

A

causes a depolarization f the receptor cell, analogous to an EPSP

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18
Q

What is a receptor potential?

A

a depolarization that occurs in a sensory receptor on stimulation

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19
Q

What type of potential is a receptor potential?

A

a graded potential

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20
Q

What is the relationship between the size of the sensory stimulus and the degree of polarization?

A

the larger the sensory stimulus, the greater the degree of polarization

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21
Q

What is responsible for conveying the intensity of a stimulus?

A

the frequency of action potentials, NOT their summation

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22
Q

What is the relationship between stimulus intensity and action potential frequency?

A

a logarithmic relationship

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23
Q

What is the name for the receptors of the skin?

A

cutaneous receptor

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24
Q

Cutaneous receptors are classified as

A

interoceptors

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25
Q

What are nociceptors?

A

the receptors that transmit impulses perceived as pain

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26
Q

Most nociceptors consist of

A

free nerve endings located throughout the body, especially near surfaces where damage is most likely to occur

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27
Q

What is transient receptor potential (TRP) ion channel?

A

a class of ion channel proteins found in nociceptors

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28
Q

The TRP ion channel is stimulated by

A

temperature to produce an inward flow of cations of Na+ and Ca2+

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29
Q

The inward flow of Na+ and Ca2+ through the TRP ion channel causes

A

a depolarizing current which further causes the sensor neuron to fire, leading to the release of glutamate and an EPSP in neurons in the spinal cord, ultimately producing the pain response.

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30
Q

The first identified TRP channel responds to

A

the chemical capsaicin, which is found in chili peppers, and also responds to heat

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31
Q

A cold-responsive TRP receptor responds to

A

the chemical menthol

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32
Q

How do TRP channels reduce the body’s pain response?

A

chemical stimulation of the TRP channels reduces the body’s pain response by desensitizing the sensory neurons

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33
Q

What are thermoreceptors?

A

naked dendritic endings of sensory neurons that are sensitive to changes in temperature

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34
Q

How are nociceptors and thermoreceptors similar?

A

nociceptors also contain free nerve endings

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35
Q

Thermoreceptors contain

A

TRP ion channels that are responsive to both hot and cold

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36
Q

Where are cold receptors located?

A

immediately below the epidermis

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37
Q

Which are more numerous, cold or warm receptors?

A

cold receptors are 3-4 x more numerous than warm receptors

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38
Q

Where are warm receptors located?

A

slightly deeper in the dermis, below the cold receptors

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39
Q

Where are thermoreceptors found in the brain?

A

in the hypothalamus, where they monitor the temperature of circulating blood and provide the CNS with info on the body’s core temp

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40
Q

What are four main types of mechanoreceptors in the skin?

A

merkle cell, meissner corpuscle, ruffini corpuscle, pacinian corpuscle

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41
Q

What are Merkle cells?

A

tonic receptors located near the surface of the skin that are sensitive to touch pressure and duration

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42
Q

What are Meissner corpuscles?

A

phasic receptors sensitive to fine touch, concentrated in hairless skin

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43
Q

What are Ruffini corpuscles?

A

tonic receptors located near the surface of the skin that are sensitive to touch pressure and duration

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44
Q

What are Pacinian corpuscles?

A

pressure-sensitive phasic receptors deep below the skin and in the subcutaneous tissue

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45
Q

What are the two tonic receptors?

A

Merkle cells and Ruffini corpuscles

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46
Q

What are the three phasic receptors?

A

Meissner corpuscles, hair follicle receptors, and Pacinian corpuscles

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47
Q

The four mechanoreceptors in the skin contain

A

sensory cells with ion channels that open in response to mechanical distortion of the membrane

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48
Q

What does it mean to be phasic?

A

intermittently activated

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49
Q

What does it mean to be tonic?

A

continuously activated

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50
Q

Phasic receptors are found on surfaces

A

that do not contain hair, like fingers/palms/nipples

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51
Q

Pacinian corpuscles consist of

A

the end of an afferent axon surrounded by a capsule of alternating layers of connective tissue cells and extracellular fluid

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52
Q

What happens when sustained pressure is applied to a Pacinian corpuscle?

A

the elastic capsule absorbs much of the pressure and axon ceases to produce impulses

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53
Q

Muscle length and tension are monitored by

A

proprioceptors

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54
Q

What are muscle spindles?

A

sensory stretch receptors that lie in parallel with the rest of the fibers in the muscle

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55
Q

Each muscle spliced consists of

A

several thin muscle fibers wrapped together and innervated by a sensory neuron, which becomes activated when the muscle/spindle is stretched

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56
Q

What are proprioceptors?

A

sensory receptors that provide information about the relative position or movement of the animal’s body parts

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57
Q

What are Golgi tendon organs?

A

a proprioceptor that monitors the tension exerted on tendons when an associated muscle contracts

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58
Q

What do baroreceptors do?

A

detect blood pressure

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59
Q

Blood pressure is monitored at what two main sites in the body?

A

the carotid sinus and the aortic arch

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60
Q

What is the carotid sinus?

A

an enlargement of the left and right internal carotid arteries that supply blood to the brain

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61
Q

What is the aortic arch?

A

the portion of the aorta very close to its emergence from the heart

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62
Q

What exactly do baroreceptors detect?

A

they detect tension or a stretch in the walls

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63
Q

Describe what happens when blood pressure decreases. (2)

A

the frequency of impulses produced by the baroreceptors decreases; CNS responds by stimulating sympathetic division which increases heart rate and causes vasoconstriction

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64
Q

Describe what happens when blood pressure increases. (2)

A

baroreceptor impulses increase; reduces sympathetic activity and instead stimulates parasympathetic division which lowers heart rate

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65
Q

What is hearing?

A

the detection of sound waves

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66
Q

Why does hearing work better in water than in air?

A

because water transmits pressure waves more efficiently

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67
Q

What system in fish provides a sense of “distant touch?”

A

lateral line system

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68
Q

The lateral line system enables fish to

A

sense objects that reflect pressure waves and low-frequency vibrations

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69
Q

Is the lateral line system found in amphibians?

A

found in amphibian larvae but is lost at metamorphosis

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70
Q

Is the lateral line system found in terrestrial vertebrates?

A

no

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71
Q

How does the lateral line system interact with the fish’s hearing?

A

the lateral line system supplements the fish’s sense of hearing

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72
Q

What does the lateral line system consist of?

A

hair cells within a longitudinal canal in the fish’s skin that extends along each side of the body and within several canals in the head

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73
Q

(lateral line system) The hair cells’ surface processes project into

A

a gelatinous membrane called a cupula

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74
Q

(lateral line system) hair cells have hairlike processes called

A

stereocilia

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75
Q

What is a kinocilium?

A

longer hairlike process present on hair cells in the lateral line system

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76
Q

Describe sterecilia. (2)

A

actually microvilli; contain actin fibers

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77
Q

Describe a kinocilium. (2)

A

true cilium; contains microtubules

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78
Q

If the stereocilia are bent in the direction of the kinocilium, what happens?

A

associated sensory neurons are stimulated and generate a receptor potential

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79
Q

If the stereocilia are bent in the opposite direction of the kinocilium, what happens?

A

activity of the sensory neuron is inhibited

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80
Q

Otoliths are composed of

A

calcium carbonate crystals

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81
Q

Where are otoliths located?

A

otolith organs of the membranous labyrinth, a system of fluid-filled chambers and tubes also present in other vertebrates

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82
Q

What structure in the fish is primarily responsible for detecting sound?

A

otoliths

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83
Q

What structures make up the outer ear? (2)

A

ear canal; ear drum (tympanic membrane)

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84
Q

Vibrations of the tympanic membrane cause movement of

A

one or more small bones that are located in a bony cavity known as the middle ear

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85
Q

Amphibians/reptiles have what single middle ear bone?

A

stapes (stirrup)

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86
Q

Mammals have what three middle ear bones?

A

stapes (stirrup); malleus (hammer); incus (anvil)

87
Q

What connects the middle ear to the throat?

A

Eustachian tube

88
Q

What is another name for the Eustachian tube?

A

auditory tube

89
Q

The stapes vibrates against

A

a flexible membrane called the oval window

90
Q

The oval window leads to

A

the inner ear

91
Q

What transmits sound into the inner ear?

A

the oval window, because it’s smaller in diameter than the tympanic membrane and thus vibrations against it produce more force per unit area

92
Q

What does the inner ear consist of?

A

cochlea

93
Q

What is the cochlea?

A

bony structure containing part of the membranous labyrinth called the cochlear duct

94
Q

Where is the cochlear duct located?

A

center of the cochlea

95
Q

The area above the cochlear duct is called the

A

vestibular canal

96
Q

The area below the cochlear duct is called the

A

tympanic canal

97
Q

The cochlear duct, vestibular canal, and tympanic canal are all

A

filled with fluid

98
Q

The oval window opens into the

A

upper vestibular canal, so that when the stapes causes it to vibrate, it produces pressure waves of fluid

99
Q

The pressure waves produced by the upper vestibular canal travel to

A

the tympanic canal, which pushes the round window and transmits the pressure back into the middle ear cavity

100
Q

As pressure waves are transmitted through the cochlea to the round window, what happens?

A

the cochlear duct vibrates, which causes the basilar membrane (bottom of cochlear duct) to vibrate

101
Q

The surface of the cochlear duct’s basilar membrane contains

A

sensory hair cells

102
Q

What is the tectorial membrane?

A

gelatinous membrane into which stereocilia from hair cells from the cochlear duct’s basilar membrane project

103
Q

What is the organ of Corti? (3)

A

apparatus consisting of basilar membrane, hair cells + sensory neurons, tectorial membrane

104
Q

The basilar membrane of the cochlea is made up of

A

elastic fibers of varying length and stiffness

105
Q

Describe the basilar membrane fibers at the far end of the cochlea and at the base of the cochlea.

A

At the base of the cochlea, the fibers are short and stiff; at the far end, they’re 5 times longer and 100 times more flexible

106
Q

Which parts of the cochlea respond to higher and lower pitches?

A

base responds to higher pitches, apex responds to lower pitches

107
Q

When a wave of sound energy enters the cochlea from the oval window, what happens?

A

it initiates an up-and-down motion that travels the length of the basilar membrane

108
Q

What causes hair cell depolarization in the basilar membrane?

A

bending of stereocilia

109
Q

The hair cell depolarization in the basilar membrane results in

A

action potentials sent to the brain

110
Q

What is the frequency range of human hearing?

A

20 to 20,000 Hz in children

111
Q

What is echolocation?

A

when mammals emit sounds and determine the time it takes for the sounds to bounce back

112
Q

What is a statocyst?

A

sensory structure that consists of ciliated hair cells with the cilia embedded in a gelatinous membrane containing crystals of calcium carbonate

113
Q

Give four examples of animals that make use of echolocation.

A

bats, shrews, whales, dolphins

114
Q

What is another name for the calcium carbonate crystals in the statocyst?

A

statoliths

115
Q

What do statoliths do?

A

increase the mass of the gelatinous membrane so that it can bend the cilia when the animal’s position changes

116
Q

Perilymph fluid is similar in composition to

A

interstitial fluid

117
Q

Endolymph fluid is similar in composition to

A

intracellular fluid

118
Q

The receptors for gravity in most vertebrates consist of

A

two chambers of the membranous labyrinth called the utricle and the saccule

119
Q

What is contained with the utricle and saccule?

A

stereocilia and a kinocilium

120
Q

The hairlike processes in the utricle and saccule are embedded within

A

the otolith membrane which contains calcium carbonate crystals

121
Q

The utricle is more sensitive to

A

horizontal acceleration

122
Q

The saccule is more sensitive to

A

vertical acceleration

123
Q

The membranous labyrinth of the utricle and saccule is continuous with

A

three semicircular canals which are oriented in different directions so as to pick up any angle of acceleration

124
Q

Accelerations of the utricle and saccule cause

A

cilia to bend, which produces an action potential in an associated sensory neuron

125
Q

What are ampullae?

A

swollen ends of the semicircular canals into which protrude the cilia of another group of hair cells

126
Q

The cilia that protrude into the ampullae are embedded within

A

a sail-like wedge of gelatinous material called a cupula

127
Q

The cupula that contain the cilia that protrude into the ampullae itself protrudes into

A

the endolymph fluid of each semicircular canal

128
Q

When the head rotates, what happens inside the cupula?

A

fluid inside semicircular canals pushes against the cupula and causes cilia to bend

129
Q

What is the vestibular apparatus?

A

term that collectively refers to the saccule, utricle, and semicircular canals

130
Q

What is another name for taste?

A

gustation

131
Q

What are the five tastes?

A

sweet, sour, salty, bitter, umami

132
Q

What are taste buds?

A

collections of chemosensitive epithelial cells associated with afferent neurons

133
Q

In fish, where are taste buds located?

A

scattered over the surface of the body

134
Q

The most sensitive vertebrate chemoreceptors can be found in

A

fish

135
Q

The taste buds of all terrestrial vertebrates occur in the

A

epithelium of the tongue and oral cavity, within raised areas called papillae

136
Q

Taste buds are shaped like

A

onions

137
Q

How many taste cells does each taste bud have?

A

between 50 and 100

138
Q

What are taste pores?

A

the top of the taste bud through which microvilli poke through

139
Q

The prototypical salty taste is due to (2)

A

Na+ ions which diffuse through Na+ channels into cells in receptor cells in the taste bud; Na+ influx depolarizes membrane and causes receptor cell to release neurotransmitter and activate sensory neuron that sends impulse to brain

140
Q

The prototypical sour taste is due to (2)

A

H+ ions; increased concentration of H+ ions depolarize the membrane when they diffuse through ion channels

141
Q

Sweet, bitter, and umami substances bind to

A

G-protein coupled receptors specific for each category

142
Q

What is another name for smell?

A

olfaction

143
Q

Where are olfaction chemoreceptors located?

A

upper portion of the nasal passages

144
Q

The olfaction chemoreceptors project into

A

the nasal mucosa

145
Q

The axons of olfaction chemoreceptors project

A

directly into the cerebral cortex

146
Q

What needs to happen to an odorant particle before it can be detected?

A

particle must dissolve in extracellular fluid before they can activate the olfactory receptor

147
Q

What are peripheral chemoreceptors? (2)

A

located in the aortic and carotid bodies; sensitive to plasma pH

148
Q

What are the central chemoreceptors?

A

located in the medulla oblongata; sensitive to the pH of cerebrospinal fluid

149
Q

Which two chemoreceptors monitor pH?

A

peripheral chemoreceptors and central chemoreceptors

150
Q

What happens to the pH when the breathing rate is too low?

A

concentration of plasma CO2 increases which lowers both blood pH and cerebrospinal fluid pH

151
Q

What do photoreceptors do?

A

capture light energy

152
Q

Invertebrates have what kind of vision systems?

A

simple visual systems with photoreceptors clustered in eyespots

153
Q

What is a limitation of eyespots?

A

eyespots can perceive the direction of light, but cannot be used to construct a visual image

154
Q

What are the four phyla?

A

annelids, mollusks, arthropods, chordates

155
Q

How did the visual systems of the four phyla evolve?

A

evolved independently - an example of convergent evolution

156
Q

What is the sclera?

A

the “white of the eye”; formed of tough connective tissue

157
Q

Light enters the eye through

A

a transparent cornea, which begins to focus the light

158
Q

Why does light focusing occur?

A

light is refracted when it travels into a medium of different density

159
Q

What is the iris?

A

colored portion of the eye

160
Q

The contraction of iris muscles in bright light results in

A

the decreasing of the size of its opening, the pupil

161
Q

What is the opening of the iris?

A

pupil

162
Q

What is the lens?

A

transparent structure that completes the focusing of light onto the retina @ back of eye

163
Q

How is the lens attached to ciliary muscles?

A

lens is attached by the suspensory ligament to the ciliary muscle

164
Q

The shape of the lens is influenced by

A

the amount of tension in the suspensory ligament

165
Q

What is the fovea? (2)

A

center of retina; point where eye forms sharpest image

166
Q

The suspensory ligament surrounds the lens and connects it to which ciliary muscle?

A

the circular ciliary muscle

167
Q

What happens when the ciliary muscle contracts?

A

pulls slack in the suspensory ligament which makes the lens more rounded and bends light more strongly (close vision)

168
Q

What happens when the ciliary muscle relaxes?

A

ciliary muscle moves away from lens and tightens the suspensory ligament; lens becomes more flattened and bends light less (distance vision)

169
Q

People who are nearsighted or farsighted

A

do not properly focus the image on the retina

170
Q

The lens in amphibians and fish

A

does not change; they focus images by zooming in and out

171
Q

Rods are

A

visual photoreceptors responsible for black-and-white vision

172
Q

Cones are (2)

A

response for high visual acuity (sharpness) and color vision

173
Q

How many rods and cones are in each retina?

A

100 million rods + 3 millian cones

174
Q

Where are most cones concentrated?

A

in the fovea

175
Q

Are rods in the fovea?

A

No, rods are almost completely absent from the fovea

176
Q

What is the basic common cellular structure of rods and cones?

A

inner segment rich in mitochondria contains numerous vesicles filled with neurotransmitter molecules; connected by narrow stalk to outer segment, which is packed photopigments

177
Q

What is rhodopsin?

A

photopigment in rods

178
Q

Rhodopsin consists of

A

opsin bound to a molecule of cis-retinal (derived from vitamin A)

179
Q

Where is Vitamin A derived from?

A

carotene, a photosynthetic pigment in plants

180
Q

What is photopsin?

A

photopigment of cones

181
Q

How many different types of cones do humans have?

A

3

182
Q

Photopsin consists of

A

cis-retinal bound to a different protein

183
Q

How many layers are in the retina?

A

3 layers of cells

184
Q

The layer closest to the external surface of the eyeball consists of

A

rods and cones

185
Q

The next layer after the one containing rods and cones contains

A

bipolar cells

186
Q

The layer closest to the cavity of the eye contains

A

ganglion cells

187
Q

In order to reach the photoreceptors, light must first

A

pass through the ganglion cells and bipolar cels

188
Q

The ganglion cells in the eye function as

A

neurons that send action potentials to the brain

189
Q

The ganglion sends information to the brain via what structure?

A

optic nerve

190
Q

The retina contains two additional types of neurons called

A

horizontal cells and amacrine cels

191
Q

In the dark, photoreceptor cells (2)

A

release an inhibitory neurotransmitter that hyper polarizes the bipolar neurons; this prevents the bipolar neurons from releasing excitatory neurotransmitters to the ganglion cells that signal to the brain

192
Q

In the light, photoreceptor cells

A

stop releasing inhibitory neurotransmitters which stimulates bipolar neurons; bipolar cells in turn stimulate ganglion cells which sends info to the brain

193
Q

What are lateral geniculate nuclei?

A

structures of the thalamus that project into the occipital lobe and transmit action potentials from ganglion cells

194
Q

What is the relationship between cones and bipolar cells in the fovea?

A

in the fovea, each cone makes a one-to-one connection with a bipolar cell

195
Q

What is the relationship between bipolar cells and ganglion cells in the fovea?

A

in the fovea, each bipolar cell synapses with one ganglion cell

196
Q

Why is the point-to-point relationship important in the fovea?

A

responsible for the high acuity of foveal vision

197
Q

Outside of the fovea, what is the relationship between rods, bipolar cells, and ganglion cells? (2)

A

many rods can converge on a single bipolar cell, many bipolar cells can converge on a single ganglion cell

198
Q

What is the consequence of the multiple relationships outside the fovea?

A

permits the summation of neural activity, making the area of the retina outside the fovea more sensitive to dim light than the fovea, but at the expense of acuity and color vision

199
Q

Color blindness results from

A

the inherited lack of one or more types of cones

200
Q

People with normal color vision are called

A

trichromats (have all three cones)

201
Q

People with only two types of cones are called

A

dichromats

202
Q

What is parallax?

A

slight displacement of images because of binocular vision

203
Q

What is binocular vision?

A

the ability to perceive 3D images and to sense depth

204
Q

Most birds have what placement of eyes?

A

laterally placed eyes

205
Q

How many foveas do birds have in each retina?

A

2; one fovea provides sharp frontal vision; the other provides sharper lateral vision

206
Q

What are the only vertebrates that can sense infrared radiation?

A

snakes

207
Q

Pit vipers have what specialized structure to detect heat? (2)

A

pit organs located on either side of the head; each pit organ is composed of 2 chambers separated by a membrane

208
Q

All aquatic animals generate

A

electrical currents from contractions of their muscles

209
Q

Give three examples of elasmobranchs.

A

sharks, rays, and skates

210
Q

Elasmobranchs have electroreceptors calle

A

the ampullae of Lorenzini

211
Q

Where are Lorenzini receptors located?

A

in sacs that open through the jelly-filled canals to pores on the body surface

212
Q

Why are ampullae of Lorenzini useful?

A

can sense electrical currents generated by the muscle contractions of their prey

213
Q

Give four examples of animals that navigate along the magnetic field lines of the earth.

A

eels, sharks, bees, some birds

Biology 2312 (11 decks)

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