Lecture 18: Sensory and Motor Pathways Flashcards
1
Q
What Do Sensory Receptors In PNS Monitor?
A
Specific conditions inside and outside the body
2
Q
General Somatic Senses (6)
A
Temperature, Pain, Touch, Pressure, Vibration, Proprioception
3
Q
Special Senses (5)
A
Olfaction, Vision, Gustation, Equilibrium, Hearing
4
Q
What Does The Afferent Division Of The Nervous System Include?
A
Nerves, nuclei, and tracts that deliver somatic and visceral sensory info to the CNS
5
Q
Where Does Somatic Sensory Get Sent To?
A
Cerebral cortex and cerebellum
6
Q
Where Do Visceral Sensory Get Sent To?
A
Brainstem and diencephalon
7
Q
Postcentral Gyrus
A
Posterior to central sulcus,
Somatic sensory
8
Q
Where Is Special Sensory Information Processed?
A
Specialed sensory cortices in cerebral cortex and areas in brainstem
9
Q
Stronger the ________, the higher the __________
A
Stimulus,
Frequency
10
Q
Sensation
A
Information arriving in the brain
11
Q
Perception
A
Conscious awareness of sensation
12
Q
Touch Receptors Are Sensitive To _______ Pressure
A
Light
13
Q
Taste Receptors Are Sensitive To _______ Stimuli
A
Chemical
14
Q
Receptor Specificity
A
Respond to specific stimulus and carry it to the brain
15
Q
What Type Of Receptors Respond To Many Stimuli?
A
Free Nerve Endings
16
Q
Receptive Field
A
The region of the body that a single receptor cell monitors
17
Q
The Larger The Receptive Field…..
A
The harder it is to localize a stimulus
18
Q
Tonic Receptors
A
Always fire when stimuli are present (pain receptors)
19
Q
Phasic Receptors
A
Only fire when a change occurs in stimuli (touch and temperature receptors)
20
Q
Peripheral Adaptation Occurs In…
A
Phasic receptors
21
Q
Adaptation
A
A reduction in sensitivity in the presence of a constant stimulus
22
Q
Central Adaptation
A
Occurs in the CNS at the subconscious level,
Inhibition of sensory pathways,
Getting used to certain stimulus
23
Q
Nociceptors
A
Pain receptor,
Free nerve endings (large receptive fields)
24
Q
Where Are Nociceptors Common? (3)
A
Skin,
Joint capsules,
Periosteum
25
What Are Nociceptors Sensitive To?
Extreme temperature,
Tissue damage,
Dissolved chemicals from injured cells
26
What Are Nociceptor Sensations Carried By?
Type A fibers,
| Type C fibers
27
Type A Fibers
Carry 'fast' pain signals (deep cut or injection pain),
| Often trigger spinal reflexes (flexor reflex)
28
Type C Fibers
Carry 'slow' pain signals (burning or aching pain),
| Difficult to localize
29
Thermoreceptors
Temperature,
Free nerve endings,
Phasic receptors (peripheral adaptation occurs in constant temps)
30
Where Are Thermoreceptors Common? (3)
Skin,
Skeletal muscles,
Hypothalamus
31
What Are Thermoreceptors Sensitive To?
Changes in temperature
32
Chemoreceptors
Chemical,
| Free nerve endings
33
What Do Chemoreceptors Monitor?
pH, CO2, O2 levels
34
Where Are Chemoreceptors Common? (2)
Carotid arteries,
| Aorta
35
Mechanoreceptors
Contain mechanically-gated ion channels that open or close in response to stretching, compression or twisting
36
3 Classes Of Mechanoreceptors
Tactile Receptors (touch),
Baroreceptors (pressure),
Proprioceptors (join/muscle position)
37
What Are Tactile Receptors Sensitive To? (3)
Touch,
Pressure (not BP),
Vibration
38
6 Types of Tactile Receptors
```
Free Nerve Endings,
Root Hair Plexus,
Tactile Discs (Merkel Discs),
Tactile Corpuscles,
Lamellated Corpuscles,
Ruffini Corpuscles
```
39
Free Nerve Endings
Tactile Receptor,
Touch and pressure in skin,
Pressure distorts skin and nerve ending, causing the action potential
40
Root Hair Plexus
Tactile Receptor,
Movement of hair in hair follicles,
Bent/distorted hair sends an action potential after the channels are opened
41
Tactile Discs (Merkel Discs)
Tactile Receptor,
Find touch and pressure,
Small receptive fields in epidermis (Merkel cells in stratum germinativum)
42
Tactile Corpuscles
Tactile Receptor,
Fine touch, pressure, vibration,
Dermis of skin in fingertips and lips
43
Lamellated Corpuscles
```
Tactile Receptor,
Large receptor organs,
Deep pressure,
In dermis of skin in fingers and joint capsules,
All layers have to be distorted to feel
```
44
Ruffini Corpuscles
Tactile Receptor,
Pressure and distortion,
Deep within dermis of the skin,
Twisting and deep pressure
45
Baroreceptors
Type of mechanoreceptor,
Monitor pressure changes in an organ,
Free nerve endings
46
Location of Baroreceptors (4)
Some arteries,
Lungs,
Digestive Tracts,
Urinary Tracts
47
Proprioceptors
```
Type of mechanoreceptor,
Cerebellum and postcentral gyrus,
Monitor position of joints and tension in tendons and ligaments,
Muscle spindles,
Golgi tendon organs,
Free nerve endings
```
48
What Neurons Transmit Somatic Sensory Information To The Cerebral Cortex?
First, second, third order neurons
49
First Order Neuron Of Sensory Pathway
Sensory neuron that carries information into CNS (spinal cord),
Cell body in dorsal root ganglion
50
Second Order Neuron Of Sensory Pathway
Sensory neuron that carries information to the thalamus,
| Axon crosses over before reaching thalamus (usually in medulla oblongata)
51
Decussation
Crossing over
52
Third Order Neuron Of Sensory Pathway
Carries information from thalamus to cortex
53
Somatic Sensory Pathways To Cerebrum (2)
Posterior Column Pathway,
| Spinothalamic Pathway
54
Posterior Column Pathway
Ascending tracts in posterior white columns,
| Carries localized fine touch, pressure, vibration, and proprioception
55
Spinothalamic Pathways
Spinal cord to thalamus,
| Ascending tracts in lateral and anterior white columns
56
Somatic Sensory Pathway to Cerebellum
Spinocerebellar Pathway
57
Spinocerebellar Pathway
Ascending tracts in lateral white columns,
| Only 2 neurons involved
58
What Does The First Order Neuron Of Posterior Column Pathway Do?
Carries signal from periphery to medulla oblongata
59
What Does The Second Order Neuron Of Posterior Column Pathway Do?
Decussates and carries signal to thalamus
60
What Does The Third Order Neuron Of Posterior Column Pathway Do?
Carries signal to primary sensory cortex
61
Spinothalamic Pathway
Carries poorly localized 'crude' touch, pressure, pain, and temperature
62
What Does The First Order Neuron Of Spinothalamic Pathway Do?
Carries signal from periphery to spinal cord
63
What Does The Second Order Neuron Of Spinothalamic Pathway Do?
Decussates in spinal cord and carries signal to thalamus
64
What Does The Third Order Neuron Of Spinothalamic Pathway Do?
Carries signal to primary sensory cortex
65
Spinocerebellar Pathway
Carries only proprioception
66
What Does The First Order Neuron Of Spinocerebellar Pathway Do?
Caries signal from periphery into spinal cord
67
What Does The Second Order Neuron Of Spinocerebellar Pathway Do?
Carries signal to cerebellum (may or may not decussate)
68
Somatic Motor Pathways
Control skeletal muscles,
| Involve at least 2 motor neurons
69
Upper Motor Neuron
Cell body lives in CNS processing center,
| Synapses on lower motor neuron
70
Low Motor Neuron
Cell body lies in a nucleus in the brainstem (cranial nerves) or spinal cord (spinal nerves),
Innervates a motor unit in skeletal muscle in PNS
71
3 Somatic Motor Pathways
Corticospinal Pathway,
Medial Pathway,
Lateral Pathway
72
How Is The Activity In The Pathways Adjusted?
By basal nuclei and cerebellum to follow coordinated movements
73
Corticospinal Pathway
Cortex to spinal cord
74
Upper Motor Neurons Of Corticospinal Pathway
Come from primary motor cortex (percentral gryus),
| Most decussate in medulla oblongata
75
Where Do Upper Motor Neurons Of Corticospinal Pathway Synapse At?
Cranial nerves in motor nuclei in brainstem,
| Spinal nerves in anterior gray horns of spinal cord
76
Where Do Lower Motor Neurons Of Corticospinal Pathway Come From?
Cranial nerve nuclei or anterior gray horns of spinal cord,
| Innervate motor unit in skeletal muscle
77
Medial And Lateral Pathways
Carry motor commands issued from areas of the cerebrum, diencephalon, and brainstem
78
Medial Pathway
Controls gross movements of trunk and proximal limbs
79
What Information Do Medial Motor Pathways Carry? (4)
Motor information related to posture, balance, visual, and auditory reflexes
80
Where Do Upper Motor Neurons Of Medial Pathways Come From?
Nuclei of CN 8 and other brainstem nuclei
81
Where Do Lower Motor Neurons Of Medial Pathways Come From?
Anterior gray horns of spinal cord
82
Lateral Pathway
Controls fine movements of distal upper extremities
83
Where Do Upper Motor Neurons Of Lower Pathways Come From?
Nuclei in midbrain
84
Where Do Lower Motor Neurons Of Lower Pathways Come From?
Anterior gray horn of cervical spinal cord
85
Basal Nuclei And Cerebellum
Exert control of somatic motor pathways by facilitating or inhibiting upper motor neurons,
Do this in response to incoming sensory information (proprioception and visual info)
86
Visceral Pathways
Visceral sensory system carries sensory information from internal organs to regions of brainstem but does not reach the cerebral cortex
