Chapter 9: Sensory Systems Flashcards
1
Q
What is sensation?
A
The process of detecting physical stimuli from the environment (like light, sound, heat, or pressure) and sending this information to the brain.
Involves: Sensory organs (eyes, ears, skin, etc.)
2
Q
What is perception?
A
The process by which the brain selects, organizes, and interprets sensory information to make it meaningful.
Involves: The brain’s interpretation and understanding of the raw sensory input
3
Q
What are the four major events involved in sensation?
A
- Stimulation of sensory receptors
- Transduction of the stimulus
- Generation of action potentials
- Integration of sensory input
4
Q
What is an adequate stimulus?
A
The kind of stimulus to which a sensory receptor responds best.
5
Q
List the five major groups of sensory receptors.
A
- Mechanoreceptors
- Thermoreceptors
- Photoreceptors
- Chemoreceptors
- Nociceptors
6
Q
What do mechanoreceptors respond to?
A
Mechanical stimuli/forces such as deformation, stretching, or touch, vibration
7
Q
What do nociceptors respond to?
A
Painful stimuli resulting from physical or chemical damage to tissues.
8
Q
What is a receptor potential?
A
A graded potential that forms in a sensory receptor during transduction.
9
Q
What is the receptive field?
A
The stimulated physical area or specific set of conditions that causes a response in a sensory neuron.
10
Q
What does sensory coding represent?
A
Specific details about a stimulus using organizational and functional features of the nervous system.
11
Q
What are the four attributes encoded by sensory systems?
A
- Modality
- Location
- Intensity
- Duration
12
Q
What is modality in the context of sensory systems?
A
Each unique type of sensation, such as touch, pain, vision, taste, or hearing.
13
Q
What is labeled line coding?
A
The association of a modality with the activation of a particular labeled line.
- each type of sensory receptor sends a signal along a specific neural pathway
14
Q
What is acuity in sensory perception?
A
Sharpness of perception; the ability to precisely locate and distinguish one stimulus from another.
15
Q
What factors affect acuity?
A
- Size of the receptive field
- Density of sensory receptors
16
Q
What is two-point discrimination?
A
The ability to perceive two points applied to the skin as two separate points.
17
Q
What encodes stimulus intensity?
A
- Frequency of action potentials generated
- Number of sensory receptors activated
18
Q
What is adaptation in sensory receptors?
A
Adaptation is the process where a sensory receptor becomes less responsive to a constant or unchanging stimulus over time.
Your senses “get used to” a stimulus if it stays the same.
19
Q
What are the two types of receptors based on adaptation speed?
A
- Slowly adapting receptors
- Rapidly adapting receptors
20
Q
What is the function of first-order neurons in sensory pathways?
A
Detect stimuli and send signals to the spinal cord or brain stem.
21
Q
What is the role of second-order neurons?
A
Transmit signals to the thalamus, usually crossing sides.
22
Q
What is hyperalgesia?
A
Increased sensitivity to painful stimuli.
23
Q
What are the four modalities of somatic sensations?
A
- Tactile
- Thermal
- Pain
- Proprioceptive
24
Q
What is the primary role of Meissner corpuscles?
A
Detect light touch and generate action potentials mainly at the onset of touch.
25
What do thermal sensations detect?
How hot or cold the skin is.
26
What type of nociceptors respond to intense mechanical stimuli?
Mechanical nociceptors.
27
What is the difference between fast pain and slow pain?
* Fast pain: sharp, well-localized sensation
* Slow pain: dull, poorly localized sensation
28
What are the two types of pathways activated by nociceptors?
* Spinal reflex pathways
* Ascending pathways to the brain
29
Fill in the blank: The process where a sensory receptor converts a physical stimulus into an electrical signal is called _______.
[transduction]
30
True or False: The thalamus processes and refines perception.
False
31
What do rapidly adapting receptors respond to?
They respond when the stimulus is first applied and then cease to respond while the stimulus is maintained.
32
What type of fibers transmit signals for fast pain?
A-delta fibres
## Footnote
A-delta fibres are small myelinated axons with conduction velocities ranging from 12 to 30 m/sec.
33
What type of fibers transmit signals for slow pain?
C fibers
## Footnote
C fibers are responsible for dull aching sensations that are poorly localized.
34
What are the two types of pain pathways activated by nociceptors?
* Spinal reflex pathways
* Ascending pathways to the brain
35
What is the role of spinal reflex pathways?
Provide unconscious protective responses when a noxious stimulus begins to damage the body
36
What neurotransmitters are released from first-order pain neurons?
* Glutamate
* Neuropeptide substance
37
Define somatic pain.
Arises from stimulation of nociceptors in skin, skeletal muscles, and joints
38
Define visceral pain.
Results from stimulation of nociceptors in visceral organs
39
What is referred pain?
Pain felt in a different location from the source due to convergence of sensory neurons
40
What are proprioceptive sensations?
Allow us to know where our limbs are located and how they are moving
41
What is kinesthesia?
Perception of body movements
42
What are proprioceptors?
Embedded in muscles and tendons, informing us about muscle contraction and joint position
43
What is weight discrimination?
Ability to assess the weight of an object
44
Name the three types of proprioceptors.
* Muscle spindles
* Tendon organs
* Joint kinesthetic receptors
45
What do muscle spindles detect?
Static muscle length and changes in muscle length
46
What do tendon organs protect against?
Damage due to excessive tension
47
What is the function of joint kinesthetic receptors?
Help detect joint position, movement, and prevent injury
48
What two major pathways carry touch and pain to the brain?
* Dorsal Column Pathway
* Anterolateral Pathway
49
What is the function of the dorsal column pathway?
Carries touch, pressure, vibration, and proprioception
50
What is the function of the anterolateral pathway?
Carries pain, temperature, itch, and tickle
51
Where does the primary somatosensory cortex receive signals from?
The opposite side of the body
52
What is the sensory homunculus?
Map of the body inside the brain showing sensitivity of body parts
53
What is the role of the somatosensory association area?
Interprets and compares current sensations with previous ones
54
What do visceral sensations provide information about?
Conditions in the visceral organs of the body
55
What are interoceptors?
Sensory receptors that respond to internal stimuli
56
What are extroreceptors?
Sensory receptors that detect stimuli from the external environment
57
What is olfaction?
The sense of smell
58
What types of cells are found in the olfactory epithelium?
* Olfactory receptor cells
* Supporting cells
* Basal cells
59
What is the function of olfactory receptor cells?
Sensory neurons that respond to olfactory stimuli
60
What do supporting cells in the olfactory epithelium do?
Provide physical support and detoxify chemicals
61
What is the role of basal cells in the olfactory epithelium?
Stem cells that produce new olfactory receptor cells
62
What do olfactory glands produce?
Mucus that moistens the olfactory epithelium
63
Outline the olfactory transduction process.
* Odorant binds to receptor
* Activates G protein Golf
* Produces cAMP
* Opens cation channels
* Depolarization occurs
64
What are glomeruli in the olfactory bulb?
Structures that receive input from one type of olfactory receptor
= smell processing
65
What is the function of mitral cells?
Send smell information deeper into the brain
66
How does olfaction adapt to stimuli?
Sensitivity decreases rapidly, adapting about 50% in the first second
67
What are the five primary tastes?
* Salty
* Sour
* Sweet
* Bitter
* Umami
68
What causes the salty taste?
Presence of sodium ions (Na+) in food
69
What is the mechanism for transducing bitter tastants?
Binds to G protein-coupled receptor, activates gustducin and phospholipase C
70
What cranial nerves carry taste signals from taste buds?
* Facial nerve (VII)
* Glossopharyngeal nerve (IX)
* Vagus nerve (X)
71
What is the path of gustatory signals to the brain?
Taste buds → gustatory nucleus in medulla → thalamus → gustatory cortex
72
What is the threshold sensitivity for bitter taste?
Lowest threshold (highest sensitivity)
73
What is adaptation in the context of taste?
Getting used to a taste after continuous exposure
74
What is the significance of the visual system?
Extremely important to human survival
75
What is electromagnetic radiation?
Energy in the form of waves that radiates from the sun
76
What is the visible light range in the electromagnetic spectrum?
Wavelengths ranging from about 400-700 nm
77
What are the accessory structures of the eye?
* Eyebrows and eyelashes
* Eyelids
* Lacrimal apparatus
* Extrinsic eye muscles
78
What is the function of eyebrows and eyelashes?
Protect the eyes from foreign objects, perspiration, and direct rays of the sun.
79
What do eyelids do?
Shade the eyes during sleep and protect from excessive light.
80
What is the lacrimal apparatus?
produce, distribute, and remove tears from the eye
- lubricate, protect, nourish
81
What is the role of lacrimal glands?
Components of the lacrimal apparatus that secrete tears.
82
What is lysozyme?
A bacterial killing enzyme that helps protect the eye from infection.
83
What are extrinsic eye muscles responsible for?
Moving the eye in various directions.
84
What is the cornea?
A transparent structure that admits light into the eye and refracts incoming light rays.
85
How much refraction occurs at the cornea?
About ⅔ of the total refraction of light.
86
What is the sclera?
The white part of the eye, a tough coat of connective tissue that gives shape and protects internal parts.
87
What is the function of the choroid?
Lines most of the inner surface of the sclera and contains blood vessels that provide nutrients to the retina.
88
What does the ciliary body do?
Responsible for secreting a fluid called aqueous humour.
89
What is the iris?
Responsible for eye color and regulates the amount of light that enters the eye.
90
What is the pupil?
The center of the iris.
91
What happens to the circular muscles of the iris in bright light?
They contract, increasing the size of the pupil (constriction).
92
What is the function of the retina?
Responsible for converting light into action potentials.
93
What are the two layers of the retina?
*Pigmented layer
*Neural layer
94
What are photoreceptors?
Sensory receptors that detect light and convert it into receptor potentials.
95
What are the two types of photoreceptors?
*Rods
*Cones
96
Where is the macula lutea located?
In the center of the posterior retina.
97
What is the fovea?
A small depression in the center of the macula lutea responsible for central vision.
98
What is the optic disc?
The site where the optic nerve exits the eyeball, also known as the blind spot.
99
What is a cataract?
Loss of transparency of the lens, becoming cloudy due to changes in crystalline proteins.
100
What is the anterior cavity of the eye?
Contains a clear fluid called aqueous humor.
101
What does the posterior cavity contain?
A jelly-like substance called vitreous humor.
102
What is intraocular pressure?
Produced mainly by the aqueous humour and partly by the vitreous humour.
103
What is refraction?
The bending of light rays when they pass into a medium of different density.
104
What is accommodation?
The increase in the curvature of the lens for near vision.
105
What is an emmetropic eye?
The normal eye that can sufficiently refract light rays from an object 6m away.
106
What is myopia?
Nearsightedness, occurs when the eyeball is too long or the lens is too thick.
107
What is hyperopia?
Farsightedness, occurs when the eyeball is short or the lens is too thin.
108
What is astigmatism?
Irregular curvature of the cornea or lens causing blurred vision.
109
What is binocular vision?
Both eyes focus on one set of objects, allowing depth perception.
110
What are the two types of photoreceptors required for normal vision?
*Rods
*Cones
111
What is the outer segment of photoreceptors?
Captures light.
112
What is the role of rods?
Highly sensitive to light, allowing night vision.
113
What is the role of cones?
Allow color vision and sharp vision in bright light.
114
What is rhodopsin?
The photopigment in rods that absorbs light.
115
What are the three types of cones?
*Blue cones
*Green cones
*Red cones
116
What is night blindness?
Inability to see at low light levels due to vitamin A deficiency.
117
What is phototransduction?
The process of converting light energy into a receptor potential.
118
What occurs during isomerization in phototransduction?
Retinal changes shape from cis-retinal to trans-retinal.
119
What happens to trans-retinal during bleaching?
It separates from opsin, causing opsin to turn colorless.
120
What is the visual field?
Everything that can be seen by one eye.
121
What is the optic chiasm?
The point where optic nerves from both eyes meet and cross.
122
What is the function of the lateral geniculate nucleus?
Processes visual information and sends it to the brain’s visual cortex.
123
What is light adaptation?
Adjustment of the visual system to brighter environments.
124
What is dark adaptation?
Increase in sensitivity when entering darkened surroundings.
125
What are the components of the external ear?
*Pinna
*External auditory canal
*Tympanic membrane
126
What do auditory ossicles do?
Amplify and transmit sound vibrations.
127
What is the function of the eustachian tube?
Connects the middle ear to the pharynx and equalizes air pressure.
128
What is the tympanic membrane?
A thin structure between the external auditory canal and middle ear that vibrates to transmit sound.
129
What is cerumen?
Sticky substance (earwax) that helps prevent foreign objects from entering the ear.
130
What is the function of the tensor tympani muscle?
Limits movement of the tympanic membrane to reduce sound intensity
131
What does the stapedius muscle do?
Reduces excessive movement at the oval window
132
What is the role of the Eustachian (auditory) tube?
Connects the middle ear to the pharynx and helps equalize air pressure
133
When does the Eustachian tube open?
During swallowing and yawning
134
What are the three main functions of the ear?
* Transmits and amplifies sound vibrations from the eardrum to the inner ear
* Protects inner ear from loud noises through reflex contractions
* Equalizes air pressure via Eustachian tube
135
What structures are included in the bony labyrinth?
* Cochlea
* Vestibule
* Semicircular canals
136
What is the function of the cochlea?
Responsible for hearing
137
What does the vestibule help detect?
Linear movement and gravity
138
What fluid fills the membranous labyrinth?
Endolymph
139
What is the key property of endolymph?
Has high potassium (K+) levels crucial for generating electrical signals for hearing
140
What is the cochlea's role in hearing?
Converts sound waves into electrical signals
141
What are the three chambers of the cochlea?
* Scala Vestibuli
* Scala Tympani
* Cochlear Duct (scala media)
142
What are the components of the Organ of Corti?
* Inner hair cells
* Outer hair cells
143
What do inner hair cells do?
Convert mechanical sound vibrations into electrical nerve signals
144
What happens when sound waves enter the cochlea?
Vibrations from the stapes at the oval window create waves in the perilymph
145
What is the vestibular system responsible for?
Balance and equilibrium
146
What do the utricle and saccule detect?
* Utricle - horizontal movement
* Saccule - vertical movement
147
What do semicircular canals detect?
Rotational movement
148
What are sound waves composed of?
* Compression
* Rarefaction
149
What is pitch in terms of sound?
Frequency (Hz) which determines how high or low a sound is
150
What is the human hearing range?
20 – 20,000 Hz
151
What is intensity in relation to sound?
Loudness (dB) which measures how strong a sound is
152
What happens to sound waves when they enter the outer ear?
They are captured by the pinna and enter the external auditory canal
153
What occurs when sound waves hit the tympanic membrane?
The tympanic membrane vibrates
154
What do the ossicles do?
Amplify and pass vibrations to the inner ear
155
What does the stapes do?
Pushes on the oval window
156
How does the cochlea respond to pressure waves?
Perilymph moves and creates pressure waves that travel through the cochlea
157
What is the role of hair cells in the cochlea?
Convert vibrations into electrical signals
158
What is presbycusis?
Age-related hearing loss
159
What causes conduction deafness?
* Otosclerosis
* Impacted cerumen
* Eardrum injury
160
What causes sensorineural deafness?
* Damaged hair cells in the cochlea
* Damage to the cochlear nerve
* Brain damage in auditory processing areas
161
What is equilibrium?
Sense of balance, helps you stay upright and know where your body is in space
162
What are the receptor organs for equilibrium?
Vestibular apparatus
163
What are otolithic organs?
* Utricle
* Saccule
164
What do the semicircular ducts detect?
Motion in all directions
165
What is the function of the crista in the semicircular ducts?
Contains hair cells that detect movement
166
What is the function of the cupula in the semicircular ducts?
Moves when you rotate your head
