Chapter 16 - Sensory, Motor & Integrative Systems Flashcards
1
Q
What is sensation?
A
The conscious or subconscious awareness of changes in the external or internal environment
2
Q
What is perception?
A
The conscious awareness & interpretation of sensations
- function of cerebral cortex
3
Q
What is sensory modality?
A
Each unique type of sensation
- touch, pain, vision, hearing
4
Q
If a neuron relays impulses for touch, will it also relay for pain?
A
NO!
- a given sensory neuron carries information for only one sensory modality
5
Q
What are general senses?
A
Refer to both somatic senses & visceral senses
6
Q
What are somatic senses?
A
Tactile sensations (touch, pressure, vibration, itch & tickle) Thermal sensations (warm/cold) Pain sensations Proprioceptive sensations
7
Q
What information do visceral senses provide?
A
Provide information about conditions within internal organs
pressure, stretch, chemicals, nausea, hunger, temperature
8
Q
What are the special senses?
A
Smell, taste, hearing, vision, equilibrium/balance
9
Q
How does a sensation arise?
A
- Stimulation of the sensory receptor
- Transduction of the stimulus
- Generation of nerve impulse
- Integration of sensory input
10
Q
What is a sensory receptor?
A
A specialized cell or the dendrites of a sensory neuron
11
Q
What is a stimulus?
A
A change in the environment that can activate certain sensory receptors
12
Q
What is selectivity?
A
How a sensory receptor will react to one stimulus and weakly or not at all to other stimuli
13
Q
What is the receptive field?
A
The body region where stimulation activates the receptor and produces a response
14
Q
What are first-order neurons?
A
Sensory neurons that conduct impulses from the PNS into the CNS
15
Q
What are the classification types of sensory receptors?
A
- Microscopic structure
- Location of the receptors & their origin of stimuli that activate them
- Type of stimulus detected
16
Q
What are the three types of microscopic structures of sensory receptors?
A
- Free nerve endings of first-order sensory neurons
- Encapsulated nerve endings of first-order sensory neurons
- Separate cells that synapse with first-order sensory neurons
17
Q
What are free nerve endings?
A
Bare dendrites
- lack any structural specializations
18
Q
What are some examples of free nerve endings?
A
Receptors for pain, temperature, tickle, itch, and some touch sensations
19
Q
What are encapsulated nerve endings?
A
Dendrites that are enclosed in a connective tissue capsule
20
Q
What are some examples of encapsulated nerve endings?
A
Receptors for pressure, vibration, and some touch sensations
21
Q
What are separate cells? (sensory receptors)
A
Sensory receptors for specialized senses that are specialized
- synapse with sensory neurons
22
Q
What are some example of separate cells? (sensory receptors)
A
Hair cells - for hearing & equilibrium in ear
Gustatory receptor cells - taste buds
Photoreceptors - for vision in the eye
23
Q
Sensory receptors produce what two kinds of graded potentials?
A
- Generator potentials
2. Receptor potentials
24
Q
What is a generator potential?
A
Dendrites of free & encapsulated nerve endings
- when a generator potential is large enough to reach threshold, it triggers one or more nerve impulses in the axon of the first-order sensory neuron
25
What do generator potentials generate?
Action potentials
26
What is a receptor potential?
Separate cells produce receptor potentials
| - trigger release of neurotransmitter though exocytosis of synaptic vesicles
27
What are the three location types of sensory receptors?
1. Exteroceptors
2. Interoceptors
3. Proprioceptors
28
What are exteroceptors sensitive to?
| Where are they located?
Located at or near the external surface of the body
- sensitive to stimuli originating outside the body
- provide information on external environment
29
What are examples of exteroceptors?
Sensations for hearing, vision, smell, taste, touch, pressure, vibration, temperature, and pain
30
What do interoceptors monitor?
| Where are they located?
Located in blood vessels, visceral organs, muscles, and the nervous system
- monitor conditions on the internal environment
- not usually consciously perceived
31
What information do proprioceptors provide?
| Where are they located?
Located in muscles, tendons, joints, and inner ear
| - provide information about body position, muscle length and tension, and position and movement of joints
32
What are the 6 Stimulus Detected types of sensory receptors?
1. Mechanoreceptors
2. Thermoreceptors
3. Nociceptors
4. Photoreceptors
5. Chemoreceptors
6. Osmoreceptors
33
What are mechanoreceptors sensitive to?
Mechanical stimuli
| - deformation, stretching, bending
34
What sensations do mechanoreceptors provide?
Touch, pressure, vibration, proprioception, hearing, equilibrium
- monitor stretching of blood vessels & internal organs
35
What do themoreceptors detect?
Changes in temperature
36
What are nociceptors responsive to?
Respond to painful stimuli resulting from physical or chemical damage
37
What do photoreceptors detect?
Light that strikes the retina of the eye
38
What do chemoreceptors detect?
Chemicals in the mouth (taste), nose (smell) and body fluids
39
What do osmoreceptors detect?
Osmotic pressure of body fluids
40
What is a characteristic of most sensory receptors?
Adaptation
41
What is adaptation?
The generator potential or receptor potential decreases in amplitude during a maintained, constant stimulus
42
What causes the perception of a sensation to fade/dissappear even though the stimulus persists?
Adaptation
43
What are rapidly adapting receptors?
Adapt very quickly
| - specialized for signaling CHANGES in a stimulus
44
Give some examples of rapidly adapting receptors.
Pressure, touch, and smell
45
What are slowly adapting receptors?
Adapt slowly
| - Continue to trigger nerve impulses as long as the stimulus persists
46
Give some example of slowly adapting receptors.
Receptors that monitor stimuli associated with pain, body position, and chemical composition of the blood
47
What is a phasic receptor?
A rapidly adapting receptor
48
What is a tonic receptor?
A slowly adapting receptor
49
What are cutaneous sensations?
Somatic sensations that arise from stimulating the skin surface
50
What are the 4 modalities of somatic sensation?
1. Tactile
2. Thermal
3. Pain
4. Proprioceptive
51
Where do somatic sensations arise?
Arise from stimulation of sensory receptors embedded in the skin or subcutaneous layer, mucous membranes (mouth, vagina, anus), muscles, tendons, joints, inner ear
52
What are the tactile sensations?
Touch, pressure, vibration, itch & tickle
53
What are some examples of tactile receptors in the skin/subcutaneous layer? (6)
```
Meissner corpuscles
Hair root plexuses
Merkel discs
Ruffini corpuscles
Pacinian corpuscles
Free nerve endings
```
54
How does the sensation of touch arise?
Generally from stimulation of tactile receptors in the skin or subcutaneous layer
55
What are the two types of rapidly adapting touch receptors?
1. Meissner corpuscles
| 2. Hair root plexuses
56
What are meissner corpuscles?
| Where are they located?
Touch receptors (rapidly adapting)
- mass of dendrites enclosed by a capsule of connective tissue
- located in the dermal papillae of hairless skin
57
Where are meissner corpuscles abundant?
Fingertips, hands, eyelids, tip of tongue, lips, nipples, soles, clitoris, tip of penis
58
What are hair root plexuses?
Touch receptors (rapidly adapting)
- found in hairy skin
- free nerve endings wrapped around hair follicles
59
What are the two types of slowly adapting touch receptors?
1. Merkel discs
| 2. Ruffini corpuscles
60
What are Merkel discs?
| Where are they located?
Tactile discs (Type I)
- saucer-shaped, flattened free nerve endings
- make contact with merkel cells in stratum basale
61
Where are merkel discs abundant?
Fingertips, hands, lips, external genitalia
62
What are Ruffini corpuscles?
| Where are they located?
Type II
- elongated, encapsulated receptors
- located deep in the dermis & in ligaments & tendons
63
Where are Ruffini corpusces abundant?
| Where are they absent?
Present in hands
| Absent in soles
64
What are Ruffini corpuscles most sensitive to?
Stretching that occurs as digits or limbs are moved
65
What is pressure?
A sustained sensation that is felt over a larger area than touch
- occurs with deformation of deeper tissues
66
What are the receptors that contribute to sensations of pressure?
1. Meissner corpuscles
2. Merkel discs
3. Pacinian corpuscles
67
What are pacinian corpuscles composed of? (lamellated)
Large oval structure composed of multilayered connective tissue capsule that encloses a dendrite
68
Are Pacinian corpuscles rapidly or slowly adapting?
Rapidly
69
Where are Pacinian corpuscles located?
```
Dermis & subcutaneous layer
Submucosal tissues (under mucous & serous membranes)
Joints, tendons & muscles
Periosteum
Mammary glands
External genitalia
Pancreas & urinary bladder
```
70
How do sensations of vibrations arise?
Result from rapidly repetitive sensory signals from tactile receptors
71
What are the receptors for vibration?
1. Meissner corpuscles - lower frequency vibrations
| 2. Pacinian corpuscles - higher frequency vibrations
72
How does the itch sensation arise?
Results from stimulation of free nerve endings by certain chemicals
- often b/c of local inflammatory reponse
73
What is an example of an itch sensation?
Anitgens in mosquito bites
74
What mediates the tickle sensation?
Free nerve endings
75
What is the phantom limb sensation?
Individuals who still perceive sensations (itching, pressure, tingling or pain) in an amputated limb
76
How is the phantom limb sensation activated?
Severed endings of sensory axons are still present in the remaining stump
- if they are activated, the cerebral cortex interprets the sensation as coming from the sensory receptors in the non-existing limb
77
What is the other explanation for phantom limb sensation?
The cerebral cortex undergoes extensive functional reorganization that allows it to respond to stimuli from another body part
- gives rise to false sensory perceptions
78
What are themoreceptors?
Free nerve endings, sense hot & cold
- adapt rapidly at the onset of a stimulus
- receptive fields about 1 mm in diameter on the skin surface
79
What are the two kinds of themoreceptors?
1. Cold receptors
| 2. Warm receptors
80
Where are cold receptors located?
In the stratum basale of the epidermis
- connected to myelinated A fibres
- few connected to unmyelinated C fibres
81
What temperatures activate cold receptors?
10 - 40 degrees Celsius
82
Where are warm receptors located?
In the dermis
| - connected to unmyelinated C fibres
83
What temperatures activate warm receptors?
32 - 48 degrees Celsius
84
What happens at temperatures below 10 and above 48 degrees celsius?
Pain receptors are stimulated
85
What is the function of pain receptors?
Protective function
| - signals the presence of noxious, tissue-damaging conditions
86
What are nociceptors?
Pain receptors
| - free nerve endings
87
Where are nociceptors located?
In every tissue, except brain tissue
88
What can activate nociceptors?
Intense thermal, mechanical or chemical stimuli
89
Why can pain persist even after a pain-producing stimulus is removed?
B/c pain-mediating chemicals linger
| B/c nociceptors exhibit very little adaptation
90
What are the two kinds of pain?
1. Fast
| 2. Slow
91
Describe fast pain.
| how fast it occurs, type of fibre
Occurs very rapidly, within 0.1 seconds after a stimulus is applied
- nerve impulses propagate along myelinated A fibres
92
How can fast pain be described?
Acute, sharp, pricking pain
| - needle prick, knife cut
93
Describe slow pain.
| how fast it occurs, type of fibre
Begins a second or more after the stimulus is applied
- gradually increases in intestity over seconds/minutes
- along unmyelinated C fibres
94
How can slow pain be described?
Chronic, burning, aching, throbbing
| - skin deep or within organs
95
What is superficial somatic pain?
Pain that arises from stimulation of receptors in the skin
96
What is deep somatic pain?
Pain that arises from stimulation in skeletal muscles, joints, tendons, & fascia
97
What is visceral pain?
Pain that arises from stimulation of nociceptors in visceral organs
98
What does diffuse mean?
Involves large areas
99
True or false?
| Fast pain is more diffuse.
False!
| Fast pain is very precisely localized to the stimulated area
100
What is referred pain?
Pain is felt in or just deep to the skin that overlies the stimulated organ
- visceral pain
101
What do proprioceptive sensations allow us to do?
Know where our head and limbs are located and how they are moving without looking at them
102
What is kinesthesia?
The perception of body movements
103
What are proprioceptors?
Receptors for proprioceptive sensations
104
Do proprioceptors adapt rapidly or slowly?
Slowly!
- Slowly and only slightly
- brain continually receives nerve impulses related to the position of different body parts and makes adjustments to ensure coordination
105
What are muscle spindles?
| What do they monitor?
Proprioceptors in skeletal muscles
| - monitor changes in the length of skeletal muscles & participate in stretch reflexes
106
What is muscle tone?
Small degree of constraction that is present while the muscle is at rest
107
What are intrafusal muscle fibres?
Skeletal muscle fibers that serve as specialized sensory organs (proprioceptors) that detect the amount and rate of change in length of a muscle.
108
What does each muscle spindle consist of?
Several slowly adapting sensory nerve endings that wrap around 3 - 10 specialized muscle fibers
109
Where are muscle spindles abundant?
In muscles that produce finely controlled movements
110
What are gamma motor neurons?
Motor neurons that terminate near both ends of the intrafusal fibers and adjust the tension in a muscle spindle to variations in the length of the muscle
- receive input from CNS
111
What are extrafusal muscle fibers?
Ordinary skeletal muscle fibers that surround muscle spindles
112
What are alpha motor neurons?
Innervate extrafusal muscle fibers of skeletal muscle and are directly responsible for initiating their contraction.
- receive input from CNS
113
Where are tendon organs located?
At the junction of a tendon & a muscle
114
What is the function of tendon organs?
Protect tendons & their associated muscles from damage due to excessive tension
- slow adaptation
115
What are joint kinesthetic receptors?
Free nerve endings & Ruffini corpuscles
- respond to pressure
Pacinian corpuscles
- respond to acceleration and deceleration of joints during movement
Tendon organs
- adjust reflex inhibition of adjacent muscles when excessive strain is placed on the joint
116
Where are joint kinesthetic receptors located?
Within and around the articular cartilage of synovial joints
117
What do somatic sensory pathways relay?
Information from the somatic sensory receptors to the primary somatosensory area in the cerebral cortex & cerebellum
118
What are the set of three neurons?
1. First-order
2. Second-order
3. Third-order
119
What do first-order neurons do?
Conduct impulses from somatic receptors into the brain stem or spinal cord
- cranial nerves: face, mouth, teeth, eyes
- spinal nerves: neck, trunk, limbs, posterior aspect of head
120
What is the function of second-order neurons?
Conduct impulses from the brain stem & spinal cord to the thalamus
121
Which order of neurons decussate?
Second-order
| - cross over to the opposite side in the brain stem or spinal cord before ascending to thalamus
122
What is the function of third-order neurons?
Conduct impulses from the thalamus to the primary somatosensory area of the cortex on the same side
123
What are the three ways that somatic sensory impulses ascend to the cerebral cortex?
1. Posterior column - medial lemniscus pathway
2. Anterolateral (spinothalamic)
3. Trigeminothalamic
124
Which nerve impulses ascend along the posterior column - medial lemniscus pathway?
Nerve impulses for touch, pressure, vibration, and conscious proprioception
- all three orders of neurons
125
Which nerve impulses ascend along the anterlater (spinothalamic) pathway?
Nerve impulses for pain, temperature, itch & tickle from the limbs, trunk, neck & posterior head ascend to cerebral cortex
- all three orders of neurons
126
Which nerve impulses ascend along the trigeminothalamic pathways?
Nerve impulses for somatic sensations (tactile, thermal, pain) from the face, nasal cavity, oral cavity and teeth
127
Where is the primary somatosensory area located?
Occupies the postcentral gyri of the parietal lobes of the cerebral cortex
128
What does each region of the primary somatosensory area receive?
Sensory input from a different part of the body
| - left side of body = right cerebral hemisphere
129
Which parts of the body provide input to large regions of the primary somatosensory area?
Lips, face, tongue and hand
130
What is sensory homunculus?
Distorted sensory map of the body
- large regions for lips
- small regions for trunk
131
What are the two routes that proprioceptive impulses take to reach the cerebellum?
1. Posterior spinocerebellar tract
| 2. Anterior spinocerebellar tract
132
What sensory impulses are conveyed along the posterior and anterior spinocerebellar tracts?
Critical for posture, balance, and coordination of skilled movements
133
What are lower motor neurons? (LMN)
- cell bodies in the brain stem & spinal cord
- axons extend through CRANIAL nerves to innervate skeletal muscles of the face & head
- axons extend through SPINAL nerves to innervate skeletal muscles of limbs & trunk
134
Which type of motor neuron provides output from the CNS to skeletal muscle fibers?
Lower motor neurons
135
What are upper motor neurons? (UMN)
- Essential for the execution of voluntary movements of the body (UMN from cerebral cortex)
- Regulate muscle tone, control postural muscles, & help maintain balance (UMN from brain stem)
136
What are the 4 neural circuits that participate in control of movement by providing input to lower motor neurons?
Somatic motor pathways
1. Local circuit neurons
2. Upper motor neurons
3. Basal nuclei neurons
4. Cerebellar neurons
137
What are the two kinds of somatic motor pathways?
1. Direct motor pathways
| 2. Indirect motor pathways
138
What do direct motor pathways provide input to?
To lower motor neurons via axons that extend directly from the cerebral cortex
139
What do indirect motor pathways provide input to?
To lower motor neurons from motor centers in the basal nuclei, cerebellum & cerebral cortex
140
Where is the primary motor area located and what is it's function?
- Located in the precentral gyrus of the frontal lobe
| - Major control region for the execution of voluntary movements
141
What do direct motor pathways consist of?
Corticospinal pathway & corticobulbar pathway
142
What are the pathway functions of the lateral corticospinal pathway?
Conveys nerve impulses from motor cortex to skeletal muscles on opposite side of body
- precise, voluntary movements of distal parts of limbs
143
What are the pathway functions of the anterior corticospinal pathway?
Conveys nerve impulses from motor cortex to skeletal muscles on opposite side of body
- movements of trunk, and proximal parts of limbs
144
What are the pathway functions of the corticobulbar pathway?
Conveys nerve impulses from motor cortex to skeletal muscles of head & neck
- coordinate precise, voluntary movements
145
What are the 4 indirect pathways?
| What are their pathway functions?
1. Rubrospinal - precise, voluntary movements of distal parts of upper limbs
2. Tectospinal - move head, eyes & trunk in response to visual & auditory stimuli
3. Vestibulospinal - maintains posture & balance, in response to head movements
4. Medial & lateral reticulospinal - maintains posture & regulates muscle tone
146
What are the functions of the basal ganglia?
1. Major role in the initiation & termination of movements
2. Suppress unwanted movements by their inhibitory effects
3. Influence muscle tone
4. Help initiate & terminate some cognitive processes (attention, memory, & planning)
5. Regulate emotional behaviours
147
The cerebellum function involves which 4 activities?
1. monitoring intentions for movement
2. monitoring actual movement
3. comparing command signals with sensory information
4. sending out corrective feedback
148
What are the integrative functions of the cerebrum?
- sleep & wakefulness
- learning & memory
- emotional responses
149
What is the circadian rhythm and how is it established?
24 hour cycle (sleep & wakefulness)
| - established by the suprachiasmatic nucleus of the hypothalamus
150
What is the reticular activating system (RAS) responsible for?
Responsible for regulating wakefulness and sleep-wake transitions
151
What is arousal and what does it involve?
Awakening from sleep
| - involves increased activity in the RAS
152
In order for arousal to occur, what must be stimulated?
The RAS
| - once the RAS is activated, the cerebral cortex is activated and then arousal occurs
153
What is consciousness?
State of wakefulness
154
Which sense does not result in the stimulation of the RAS?
Olfactory receptors
| - strong odors may fail to cause arousal
155
What is sleep?
A state of altered consciousness or partial unconsciousness from which an individual can be aroused
156
What does sleep deprivation impair?
Attention, learning, & performance
157
What are the 4 stages of NREM?
| non-rapid eye movement
1. Transition stage between wakfulness & sleep
2. Light sleep - person is more difficult to awaken
3. Moderate deep sleep - body temperature & blood pressure decreases
4. Deep sleep -brain metabolism decreases, reflexes are intact
158
During a typical 7 or 8 hour sleep period, how many episodes of REM sleep are there?
3-5
159
What is REM sleep?
Rapid eye movement
| - eyes move rapidly back and forth under closed eyelids
160
When dos REM sleep occur?
A person will ascend through stages 3 and 2 before entering REM sleep
161
How much REM sleep does an adult have in a typical night?
90-120 minutes
162
Do dreams occur in NREM or REM sleep?
REM sleep
163
When does sleep walking occur?
NREM - stage 4 (deep sleep)
164
What is learning?
The ability to acquire new information or skills through instruction or experience
165
What is memory?
The process by which information acquired through learning is stored & received
166
What is plasticity?
Ability to change our behaviors in response to stimuli from the external & internal environments
167
What is immediate memory?
The ability to recall ongoing experiences for a few seconds
| - allows us to know where we are & what we are doing
168
What is short term memory?
Temporary ability to recall a few pieces of information for seconds to minutes
169
What is long term memory?
A more permanent type of memory
| - can last days to years
170
What is memory consolidation?
Reinforcement that results from the frequent retrieval of a piece of information
171
What is long-term potentiation (LTP)?
Believed to underlie some aspects of memory
- transmission at some synapses within the hippocampus is enhanced for hours or weeks after a brief period of high-frequency stimulation
172
What is parkinson disease?
Progressive disorder of CNS
- involuntary skeletal muscle contractions oftern interfere with voluntary movements
- slowness of movements
- decreased range of motion
173
What is cerebral palsy?
Motor disorder that results in the loss of muscle control and coordination
- caused by damage of the motor areas of the brain during fetal life, birth or infancy
174
What is insomnia?
Difficulty in falling asleep or staying asleep
| - causes: stress, caffeine, disruption of circadian rhythms, depression
175
What is narcolepsy?
REM sleep cannot be inhibited during waking periods
| - involuntary periods of sleep that last about 15 minutes occur throughout the day
176
What is sleep apnea?
A disorder in which a person repeatedly stops breathing for 10 or more seconds while sleeping
- occurs b/c a loss of muscle tone in pharyngeal muscles allows the airways to collapse
