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Anatomy 2086 > Lesson 1 General Senses > Flashcards

Lesson 1 General Senses Flashcards

1
Q

what are the two kinds of receptors?

A
  • Receptors with bare nerve endings
    Or
  • True sense organ
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2
Q

what are receptors?

A

Structure specialized to detect a stimulus

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3
Q

what are sense organs?

A

A structure that combines nerve tissue that is surrounded by other tissues; which enhances response to certain types of stimulus.

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4
Q

what is accessory tissue?

A

The extra tissue that surrounds sense organ nerve tissue, that aids in response to stimuli.
- type of tissue includes epithelium, muscular tissue, and connective tissue.

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5
Q

what is transduction?

A

Conversion of energy from one form to a different form.

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6
Q

What is the fundamental purpose of any sensory receptor?

A

Is to convert electrical energy into nerve signals

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7
Q

what are the two stages in the sensory process?

A

1.) Sensation= sensory receptor detection
2.) Perception= conscious experience

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8
Q

what is receptor potential?

A

A small localized electrical change
- if the stimulation is strong enough then the neuron fires AP and nerve signals to the brain.
- part of the sensation stage in the sensory process

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9
Q

what are the kinds of information sensory receptors transmit?

A

1.) Modality
2.) Locations
3.) Intensity
4.) Duration

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10
Q

what is modality?

A

A type of stimulus or the perception it produces.

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11
Q

what is location?

A

where the stimulus is located
- Encoded by which nerve fibers are firing

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12
Q

what is a labeled line?

A

A chain of neurons that sends information to the CNS.
- separates different information from one and other

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13
Q

what is a receptive field?

A

A single sensory neuron area of detection for stimuli.
- Size determines resolutions (ability to distinguish between two close-together stimuli

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14
Q

what is intensity?

A

strength of stimulus
-Ex: whether a sound is loud or soft

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15
Q

How is intensity encoded?

A

1.) Which fibers respond
2.) How many fibers respond
3.) How fast the fibers are firing

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16
Q

what is duration?

A

How long the stimulus last
- encoded by changes in firing frequency over time

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17
Q

what is sensory adaptation?

A

If a stimulus is prolonged, the firing of the neuron slows down over time, and we become less aware of the sensation.
- stop responding

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18
Q

what is phasic receptors?

A
  • adapt quickly
  • bursts of signals when the stimulus starts, then stops in the middle, finally when the stimulus stops signals begin again
    -Ex: smell, hair movement
  • llllllllll———–llllllll
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19
Q

what are tonic receptors?

A
  • adapt slowly
  • AP continue steadily while stimulus is present
    -Ex: body position, muscle tension, and pain
  • lllllllllllllll
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20
Q

what are the classification by stimulus modality

A

1.) Photoreceptors= located in eyes and responds to light

2.) Thermoreceptors= responds to heat and cold

3.) Nociceptor= respond to tissue injury, activation of these receptors produces the feeling of pain

4.) Chemoreceptors= respond to chemicals
- Ex: oders, tastes, body fluid composition

5.) Mechanoreceptors= respond to physical deformation
- vibration, touch, pressure
- organs of hearing and balance use mechanoreceptors

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21
Q

what is analgesia?

A

inability to feel pain

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22
Q

what is hypergesia?

A

increase in sensitivity to pain

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23
Q

what are type-A axons?`

A

large myelinated fibers
- sends signal fast
- prickling/fast pain
- Ex: deep cut, injection
- reaches CNS fast to trigger somatic reflexes before reaching primary somatosensory cortex.

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24
Q

what are type-C axons?

A

small unmyelinated fibers
- slow
- sends burning/aching/slow pain
- activates reticular formation and thalamus
- not specific to exact location of affected area

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25
Q

what are carotid bodies? what do they do?

A

located near the origin of the internal carotid arteries on each side of the neck
- blood going to brain

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26
Q

what are Aortic bodies? what do they do?

A

Located between the major branches of the aortic arch

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27
Q

what is the pain sensation pathway?

A

1.) Reticular formation in brainstem
2.) Thalamus
3.) Primary sensory cortex

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28
Q

what are the three classes of Mechanoreceptors?

A

1.) Tactile receptors
2.) Baroreceptors
3.) Proprioceptors

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29
Q

what are mechanoreceptors?

A

Receptors that respond to stimuli the physically distort the receptor’s plasma membrane; contains mechanically-gated ion channels that open and close in response to stretching, compression, and twisting.

30
Q

what are Tactile receptors?
- Mechanoreceptors

A

Fine touch and pressure receptors
- very sensitive
- narrow receptive field
provides sensory information like:
- exact location
- shape
- size
- texture
- movement at the location

Also include crude touch and crude pressure receptors
- less sensitive
- large receptive field
- gives little information about stimulus

31
Q

What are Baroreceptors?
- Mechanoreceptors

A

Monitors change in pressure
- has free nerve endings that branch with elastic tissues
- Location: walls of distensible organs like blood vessels and digestive organs
- Phasic receptors

32
Q

What are Proprioceptors?
- Mechanoreceptors

A
  • Monitors position of joints
  • Monitor tension in tendons and ligaments
  • Monitor the amount of skeletal muscle contraction
33
Q

what are the three major groups of Proprioceptors?

A

1.) Receptors in joint capsules= free nerve endings that detect pressure, tension, movement at joints.

2.) Golgi tendon organs= located between skeletal muscle and its tendon. Monitor external tension generated during skeletal muscle contraction. Stimulated by tension in the tendon.

3.) Muscle spindles= Monitor skeletal muscle length; used to trigger stretch reflex.

34
Q

What are the 6 classes of Tactile receptors?

A

1.) Tactile (Merkel) discs

2.) Hair receptors (root hair plexuses)\

3.) Tactile (Meissner) corpuscles

4.) End bulbs (Krause end bulbs)

5.) Bulbous (Ruffini) corpuscles

6.) Lamellar (Pacinian) corpuscles

35
Q

Which Tactile receptors are unencapsulated nerve endings?

A

1.) Free nerve endings
2.) Tactile (Merkel) discs
3.) Hair receptors (root hair plexuses)

36
Q

Definition of Free nerve endings?

A

They are Tonic receptors with small receptive fields that are bare dendrites.
- detect temperature and pain
- abundant in skin and mucous membranes

37
Q

Definition of Tactile (Merkel) discs?

A

Tonic receptors with small receptive field that are flattened nerve endings; which end at a tactile cell located in basal layer of epidermis.
- sensitive
- detects light touch, texture, edges, and shapes

38
Q

Definition of Hair receptors (root hair plexuses)?

A

Phasic receptors that are dendrites coiled around hair follicle and respond to movement of the hair
- very sensitive

39
Q

What are Encapsulated nerve endings?

A

Nerve fibers wrapped in Glial cells (support cells) or connective tissue; the wrapping enhances sensitivity or selectivity of response.
1.) Tactile (Meissner) corpuscles
2.) End bulbs (Krause end bulbs)
3.) Bulbous (Ruffini) corpuscles
4.) Lamellar (pacinian)corpuscles

40
Q

Definition of Tactile (Meissner) corpuscles?

A

2 or 3 nerve fibers within a fluid-filled capsule of flattened schwann cells. (PNS)
- Phasic receptors
- detect fine/light touch and texture
- Location: edges of dermal papillae, hairless areas of skin (fingertips, palms, eyelids, nipples, and genitals)

41
Q

Definition of End Bulbs (Krause end bulbs)

A

Sensory nerve fibers that are surrounded by connective tissue.
- Location: Mucous membranes
- similar to Tactile corpuscles

42
Q

Definition of Bulbous (Ruffini) corpuscles?

A

Flattened, elongated capsules containing a few myelinated axons in an incomplete fibrous capsule.
- Tonic receptors
- Location: reticular layer of dermis (bottom layer under papillary layer)
- Detects heavy touch, pressure, stretching of skin, deformation of fingertips, and joint movement.

43
Q

Definition of Lamellar (pacinian) corpuscles?

A

Large, ovoid receptors with a single dendrite surrounded by layers of flattened schwann cells and fibroblasts (support cells).
- Phasic receptors
- detects deep pressure and vibration
- sensitive to pulsing or high-frequency vibrations
- Location: periosteum of bone, joint capsules, some viscera, and deep in dermis (especially on hands, feet, breasts, and genitals)

44
Q

Classification of receptors by origin of stimuli.
- what are the three origins of stimuli?

A

1.) Exteroceptors= sense stimuli external to the body.
- receptors for vision, hearing, taste, smell, and cutaneous sensations like touch, heat, cold, pain

2.) Interoceptors= detect internal stimuli
- stomach and intestines

3.) Proprioceptors= sense body position and movements, purely somatic sensation
- location: muscle, tendons, and joint capsules

45
Q

Classification of receptors by distribution
- what are the two form of receptor distribution?

A

1.) General (somatosensory, somesthetic) senses= widely distributed in skin, muscles, tendons, joints, viscera.
- some are simple, and some are just bare dendrites
- touch, pressure, stretch, temp, pain, blood pressure/composition.

2.) Special senses= limited to head, innervated by cranial nerves, and involve complex sense organs
- uses the brain structures specialized for vision, hearing, equilibrium, taste and smell

46
Q

what are Nerves?

A

bundle of axons located in the PNS

47
Q

what are Nuclei?

A

cluster of cell bodies located in the CNS

48
Q

what are Tracts?

A

bundle of axons located in the CNS

49
Q

what is the definition of a sensory pathway?

A

The delivering of somatic or visceral sensory information to their final destination inside the CNS using tracts, nuclei, and nerves.

50
Q

what is the Somatic Nervous System (SNS)?

A

Motor neurons and pathways that provides voluntary control of skeletal muscles.
- somatic motor commands start in the motor center in the brain and follows the somatic motor pathway of:

  • Motor Nuclei= in the CNS
  • Tracts= in the CNS
  • Neurons= in the PNS
51
Q

what is the Autonomic Nervous system (ANS)?

A

sends involuntary commands to viscera. Two divisions
1.) sympathetic
2.) parasympathetic

52
Q

Definition of Sensory Projection?

A

transmission of information from receptors to specific location in cerebral cortex. These signals travel along projection pathways.

53
Q

What are the three ways somatosensory signal travel?

A

1.) First-order neuron
2.) Second-order neuron
3.) Third-order neuron

54
Q

What are First-order neurons?

A
  • Signals travel from brain through cranial nerves and into either the pons or medulla (signal start in brain)
  • Signals from below the head, enter into the posterior horn (spinal cord) via dorsal root
  • Body signal –> dorsal root–> posterior horn
  • touch, pressure, and proprioception fibers= large, myelinated, fast
  • temp fibers are small and unmyelinated, slower
55
Q

What are Second-order neurons?

A

Decussate (cross) to opposite side (contralateral) in spinal cord, medulla, or pons
- ends in the thalamus, except for proprioception, which ends in cerebellum

56
Q

What are Third-order neurons?

A

Thalamus to primary somatosensory cortex of cerebrum.

57
Q

What are the three major somatic sensory pathways?

A

1.) Spinothalamic pathway

2.) Posterior column pathway

3.) Spinocerebellar pathway

58
Q

What is the Spinothalamic pathway?

A

Provides conscious sensation of poorly localized (crude) touch, pressure, pain, and temp.

59
Q

What is the Posterior Column pathway?

A

Carries highly localized fine touch, pressure, vibration, and proprioception.

60
Q

What is the Spinocerebellar pathway?

A

Carries proprioceptive information from skeletal muscles, tendons, and joints.
- information terminates at the cerebellum for processing.

61
Q

What diseases cause loss of pain perception?

A
  • Leprosy
  • Diabetes mellitus
  • Nerve damage (peripheral neuropathy) results in neglect of injuries
62
Q

what are two types of Pain?

A

1.) Nociceptive pain= stems from tissue injury; occurs when nociceptors are activated

2.) Neuropathic pain= stems from injuries to nerves, spinal cord, meninges, brain

63
Q

what are the three origins of Nociceptive pain?

A

1.) Visceral pain= comes from internal organs
- diffuse, dull, hard to locate
- sensations of squeezing, cramping, nausea
- caused by stretch, chemical irritation, ischemia

2.) Deep somatic pain= comes from bones, joints, and muscles
- Ex: arthritis, sprains, bone. fractures

3.) Superficial somatic pain= usually comes from the skin
- Ex: pain from cuts, burns, insect stings

64
Q

What are the two types of nerve fibers involved in pain responses?

A

1.) Fast pain= immediate, sharp, localized pain
- type A, myelinated, large
- also called discriminative pain because we can tell exactly where its coming from

2.) Slow pain= burning, dull, aching pain
- type C, unmyelinated, small
- longer-lasting and more diffuse pain

65
Q

What is Referred pain?

A

Pain in viscera often perceived as originating from superficial sites (such as skin)
- caused from convergence of neural pathways in CNS
- Brain can not distinguish source
- Ex: heart pain felt in shoulder or arm because both send pain input to spinal cord segments T1 to T5

66
Q

what is analgesic?

A

pain-relieving mechanisms in the CNS

67
Q

What is endogenous opioids?

A

Analgesic peptides secreted by CNS, pituitary, digestive tract, and others.
- act as neuromodulators that block pain and give pleasure
- Ex: Enkephalins, endorphins, and dynorphins

68
Q

what is spinal gating?

A

How opioids block pain
- stops pain signals at posterior horn of spinal cord
- interneurons stimulated to release enkephalins
- inhibit second-order pain neurons

69
Q

what are the somatic motor pathway disorders we went over?

A

1.) Amyotrophic Lateral Sclerosis (ALS)

2.) Cerebral palsy (CP)

70
Q

what is Amyotrophic Lateral Sclerosis (ALS)

A

A progressive degenerative disorder affecting motor neurons in the spinal cord, brain stem, and cerebral hemisphere.
- Death of these motor neurons causes atrophy in associated skeletal muscles
- Genetic 5-10% other unknown
-TREATMENT= oral medications such as Riluzole (does not reverse damage) mitigate symptoms

71
Q

what is Cerebral palsy (CP)?

A

Number of disorders affecting voluntary motor control, motor skills, posture/balance, memory, speech, learning
- dysfunction is not progressive it is consistent throughout life
- appear during infancy or childhood
- Possible causes: unusually stressful birth, maternal exposure to drugs, genetic defect affecting the motor pathways
- Treatment: medication, muscle relaxants and pain relievers, therapies

Anatomy 2086 (4 decks)

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