Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physiology II Exam 1 > General Sensory Mechanisms > Flashcards

General Sensory Mechanisms Flashcards

1
Q

What are the two “types” of mechanoreceptors?

A

-free and encapsulated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the free/expanded tip ending mechanoreceptors? Skin tactile sensibilities

A

-Merkel’s discs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the encapsulated ending mechanoreceptors? Skin tactile sensibilities

A
  • Meissner’s corpuscles

- Kraus’ corpuscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the deep tissue sensibility mechanoreceptors? What are examples of each?

A

-free and expanded tip
-spray endings
+Ruffini’s corpuscles
-encapsulated endings
+Pacinian corpuscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the 4 receptor characteristics?

A
  • differential sensitivity: sensitive to one type if stimulus and is almost non responsive to other types
  • modality: refers to each of the principle types of sensation
  • labeled line principle: specificity of nerve fibers for transmitting only one modality of sensation
  • adaptation of receptors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the 4 mechanisms of stimulation for receptors?

A

Mechanical deformation

Application of a chemical

Temperature change

Electromagnetic radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are tonic receptors and what are some examples?

A
  • slow adapting
  • detect continuous stimulus strength
  • transmit impulses as long as stimulus is present

Examples:

  • muscle spindles
  • macula and vestibular receptors
  • Golgi tendon organs
  • baroreceptors
  • chemoreceptors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are phasic receptors?

A
  • fast adapting
  • do not transmit a continuous signal
  • stimulated only thing when stimulus strength changes
  • transmit info regarding rate of change
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the different nerve fiber types?

A
  • type A
  • type C
  • group Ia
  • group Ib
  • group II
  • group III
  • group IV
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are type A nerve fibers?

A
  • further subdivided into alpha, beta, and delta

- large and medium-sized myelinated fibers of spinal nerves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are type C nerve fibers?

A
  • small, unmyelinated fibers
  • conduct signals at low velocity
  • make up more than half of all sensory fibers in most peripheral nerves and all postganglionic autonomic fibers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are group Ia fibers?

A

-fibers from annuli spiral endings of muscle spindles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are group Ib fibers?

A

-fibers from Golgi tendon organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are group I fibers?

A

-from cutaneous tactile receptors and flower spray

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are group III fibers?

A

-carry temp, crude touch, and pricking pain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are group IV fibers?

A

Carry pain, temp, and crude touch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is spatial summation?

A
  • increasing signal strength is transmitted by using progressively greater number of fibers
  • entire cluster of nerve ending from pain fiber covers an area so skin referred to as the receptor field for that fiber
  • number of endings is large in center of field but is reduced in periphery
  • nerve endings from one pain fiber overlap those of other pain fibers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is temporal summation?

A

-increase signal strength by increasing frequency of nerve impulses in each fiber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the stimulators field of a neuronal pool?

A
  • neuronal area within the pool stimulated by each incoming never fiber
  • terminals for. Each input fiber lie on the nearest neuron its field
  • fewer terminals for each input lie on neurons further away
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the discharge zone of the neuronal pool?

A

-includes all output fibers stimulated by the incoming fiber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the facilitated/inhibition zone of the neuronal pool?

A
  • neurons further from the discharge zone that are facilitated but not excited
  • may be inhibitory or excitatory depending on the input fiber
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the difference between diverging and converging neuronal pathways?

A

Diverging

  • may result in amplification of initial signal
  • may allow transmission of original signal to separate areas

Converging

  • multiple input fibers converge onto a single output neuron
  • input fibers may be from a single source or from multiple separate sources
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are reverberatory circuits?

A
  • aka oscillatory circuits
  • caused by positive feedback within neuronal circuit
  • circuit once stimulated may discharge repetitively for a long time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the two types of senses?

A

-somatic senses
+collect sensory info from all over the body
+include mechanoreceptors, thermoreceptors, and nocireceptors

-special senses
+vision, hearing, smell, taste, and equilibrium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are the three types of sensation?

A
  • exteroreceptive sensation: from surface of body
  • proprioceptive sensation: physical state of body (position, muscle and tendon sensations, pressure sensations, ad equilibrium
  • deep sensations: deep pressure, pain, and vibrations
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are the 5 basic sensory receptors?

A
  • mechanoreceptors
  • thermoreceptors
  • nocireceptors
  • electromagnetic receptors
  • chemoreceptors
27
Q

What are exteroreceptive sensations?

A

-sensation from the surface of the body

28
Q

What are proprioceptive sensations?

A 
-refer to physical state of the body
   \+position sensations
   \+muscle and tendon
   \+pressure
   \+equilibrium
29
Q

What are deep sensations?

A

-deep pressure, pain, and vibrations

30
Q

In terms of ascending pathways, what are the three neuron pathways?

A

-primary sensory neurons
+from external receptors
+travel through dorsal roots of spinal cord
+synapse with secondary neurons

-secondary neurons
+make up tracts in spinal cord and brainstem
+usually terminate in thalamus
+synapse with tertiary neurons

-tertiary neurons
+from thalamus to primary sensory cortex
+travel through internal capsule

31
Q

What are the systems utilized for conscious and unconscious perception?

A

Conscious:

  • spinothalamic system
  • medial Lemniscal system

Unconscious:

  • spinocerebellar
  • spino-olivary
  • spinotectal
  • spinoreticular
32
Q

What are the two subdivisions of the spinothalamic system?

A
  • lateral spinothalamic tract

- anterior spinothalamic tract

33
Q

What does the lateral spinothalamic tract do? How does it travel?

A

-carries pain and temperature

  • primary fibers ascend or descend 1-2 spinal cord segments before synapsing with secondary fibers
  • secondary axons decussate through anterior gray and white commissures
  • secondary axons make up the lateral spinothalamic tract traveling in the lateral column of the spinal cord
  • secondary fibers are joined in brainstem by fibers of the trigeminothalamic tract (pain and temp from face and teeth)
  • secondary fiber collaterals project to reticular formation (stimulate wakefulness and consciousness)
  • secondary fibers project to ventral posterolateral nucleus of thalamus
  • secondary fibers synapse with tertiary fibers in VPL nucleus
  • tertiary fibers synapse in post central gurus (somatic sensory area 3,1,2)
  • tertiary fibers form part of internal capsule
34
Q

What does the anterior spinothalamic tract do? How does it travel?

A

-carries light touch, pressure, tickle, itch

  • primary neurons may ascend 8-10 spinal cord segments before synapsing with secondary neurons
  • secondary fibers decussate in anterior gray or white commissures
  • secondary fibers ascend to synapse with tertiary fibers in VPL nucleus of thalamus
  • tertiary fibers ascend through internal capsule to primary sensory cortex
35
Q

What is the medial Lemniscal system? How does in travel in the spinal cord?

A
  • aka posterior column system
  • carries sensations for two point sensation (fine touch), pressure, and vibration
  • primary fibers ascend entire length of spinal cord and synapse with secondary neurons in medulla (fasciculus gracilis and fasciculus cuneatus)
  • fiber of the gracilis synapse in nucleus gracilis (convey sensations from below mid thoracic level)
  • fibers of cuneatus synapse with nucleus cuneatus (convey sensations from above midthoracic level and proprioceptive sensation from arms to cerebellum)
  • secondary fibers decussate
  • secondary fibers ascend in VPL of thalamus
  • tertiary fibers ascend through internal; capsule to primary sensory cortex
36
Q

What makes up the primary somatosensory area and the somatosensory association area?

A
  • Brodmann’s areas 1,2,3

- Brodmann’s area 5 and 7

37
Q

What is the sensory homunculus?

A

-areas of the brain that receive the sensory information for various body parts

38
Q

What would a widespread excision of somatosensory area I cause?

A
  • loss of ability to localize the different sensations in the different parts of the body, crude localization possible
  • loss of ability to judge critical degrees of pressure against the body
  • loss of ability to judge weights of objects
  • loss of ability to judge shapes or forms (astreognosis)
  • loss of ability to judge textures of material
  • pain and temp sense is still preserved but poorly localized
39
Q

Where does somatosensory area II receive signals from?

A
  • brain stem, transmitted upward from both sides of the body
  • secondarily from somatosensory area I
  • other areas of the body, including visual and auditory
40
Q

Projections from somatosensory area ___ are required for function of somatosensory area ____. The opposite is not true.

A

I, II

41
Q

What are the layers of the somatosensory cortex? What do each of these layers do?

A

-Layers I and II (superficial):
+receive input signals from lower brain centers

-Layers II and III:
+send information through corpus callosum to opposite hemisphere

-Layers V and VI (deep):
+large neurons in V project to distant areas such as basal nuclei, brain stem, and spinal cord
+axons from layer VI project to the thalamus

-Layer IV:
+received incoming sensory input

42
Q

How are potentials created?

A

Opening “modality” gated channels (eg. Na channels) that are opened in response to membrane deformation caused by touch or pressure

43
Q

What type of potential do receptors create?

A

-local decremental poterntial

44
Q

Most pathways are made up of three neurons. What are these three neurons utilized in sensory pathways?

A

-primary neurons: originate from peripheral receptors such as Merkel receptors
+enter spinal cord/brain via dorsal roots of spinal/cranial nerves
+cell bodies are located in the dorsal root ganglia
+synapse in spinal cord with secondary neurons

-secondary neurons: originate in spinal cord gray matter
+travel through spinal cord in one of the myelinated columns
+decussate
+synapse in thalamus with tertiary neurons

-tertiary neurons: travel through internal capsule (myelinated pathway between thalamus and some basal nuclei)
+synapse in somatosensory cortex

45
Q

What does two point touch refer to?

A

-the ability to distinguish two separate points as close as 2mm apart

46
Q

What pathway does two point discrimination travel?

A

-dorsal column-medial lemniscal pathway

47
Q

What is lateral inhibition?

A

-important in blocking the lateral spread of excitatory signals of two point discrimination
-increases the degree of contrast in the cerebral cortex
-occurs at each synaptic level:
+dorsal column nuclei
+ventrobasal nuclei of thalamus
+somatosensory cortex

48
Q

Trace the dorsal column-medial lemniscal pathway.

A
  • primary neurons (peripheral sensory neurons) travel through a spinal nerve and through the dorsal root ganglia
  • primary neurons continue into the spinal cord and travel up the spinal cord through the dorsal columns
  • secondary up through the medulla and synapse with tertiary in the ventrobasal complex of the thalamus
  • the tertiary goes to the postcentral gyrus (homunculus)
49
Q

How do axons from the lower limbs and upper limbs in the dorsal column-medial lemniscal pathway differ?

A

-lower limbs travel in the medial portions of the two dorsal columns -> gracilis
+synapse in lower medulla in gracilis

-upper limbs travel in the lateral portions of the dorsal columns -> cuneatus
+synapse in the lower medulla in cuneatus

50
Q

What are the characteristics of fast pain? (ON EXAM)

A
  • felt within 0.1sec after stimulus is applied
  • not felt in most deep tissues
  • elicited by mechanical and thermal stimuli
  • typically carried by A(gamma) pain fibers
  • pain fiber terminate in lamina I of the dorsal horns of the spinal cord
51
Q

What are characteristics of slow pain? (ON EXAM)

A
  • begins about 1sec after stimulus is applied and increases with time
  • aching, slow burning, throbbing, nausea, and chronic
  • elicited by mechanical, thermal, and chemical stimuli
  • carried by C fibers which terminate in layers II and III (substantia gelatinous a) of the dorsal horns of the spinal cord
52
Q

Describe how pain travels and differentiate between slow and fast pain pathways.

A
  • pain travels through ANTEROLATERAL pathways
  • primary pain fibers synapse in the dorsal horns of the spinal cord (layers 1,2,3) with the secondary fibers
  • secondary fibers decussate and make up anterolateral pathways

FAST:

  • make up neospinothalamic tracts and synapse terminate in the ventrobasal nuclei of thalamus -> ascend to somatosensory cortex
  • use Glu as neurotransmitter

SLOW:

  • make up paleospinothalamic pathway
  • secondary fibers terminate throughout the brainstem, some pass all the way to the thalamus
  • release both Glu and substance P (slower than Glu)
53
Q

What is Brown-Sequard syndrome?

A
  • occurs when there is a hemisection of the spinal cord
  • motor functions are blocked on the side of the transection in all segments below the level of the transection
  • sensation of pain, heat, and cold are lost on opposite sides of the body in dermatomes 2-6 segments below the transection
  • kin esthetic and position sensations, vibration sensation, discrete localization, and two point discrimination are lost on the side of the transection in all dermatomes below the transection
54
Q

What does the analgesia system consist of?

A
  • periaquaductal gray and periventricular regions of brainstem and third ventricle
  • Raphe magnus nucleus and reticular nuclei in medulla
  • pain inhibitory complex in dorsal horns of spinal cord
55
Q

Describe the analgesia system.

A
  • enkephalins has an ability to suppress pain by synapsing directly onto a pain receptor turning it off
  • body’s natural painkiller system
  • doesn’t always work, typically in extreme situations
56
Q

What are the three receptors that discriminate thermal gradations?

A
  • cold
  • warmth
  • pain
57
Q

Describe the warm nerve endings.

A
  • free nerve ending

- mainly transmitted over C type fibers

58
Q

Describe cold receptors.

A
  • 3-10x more numerous than warm nerve receptors

- small type A(gamma) myelinated endings

59
Q

How are cold and warm receptors thought to be stimulated?

A
  • changes in their metabolic rate

- transmitted in pathways parallel to pain signals

60
Q

What is referred pain?

A
  • occurs when visceral fibers are stimulated and stimulate some of the pain fibers that conduct pain signals from the skin
  • severe pain results when there is diffuse stimulation of pain nerve endings throughout the viscera
  • can result from ischemia
  • transmitted via C pain fibers
61
Q

What essentially causes referred pain?

A

-crossed visceral and skin nerve fibers

62
Q

What is a prominent example of referred pain?

A

-headache

63
Q

How can you get headaches when the brain is insensitive to pain?

A

-membranes and meninges surrounding the brain

Physiology II Exam 1 (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions