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Hubs191 > Lecture 23 > Flashcards

Lecture 23 Flashcards

1
Q

What do sensory neurons carry

A

Afferent signals
- in and up
- info about the environment

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2
Q

What is neuron 1 in the somarosensory cortex

A
  • This neuron starts at the sensory receptor in the body, such as in the skin.
    • Its cell body resides in the dorsal root ganglion, which is located just outside the spinal cord.
    • The peripheral fiber of neuron #1 carries sensory information from the receptor to the central nervous system.
    • The central fiber of neuron #1 ascends towards the brain through the dorsal columns of the spinal cord white matter.
    • Neuron #1 synapses on neuron #2 in the medulla oblongata.
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3
Q

Dendrites: ion Chanel location in sensory neurons

A

Chemically or mechanically gated ion channels ( Na+ and K+ )

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4
Q

What is the dendrities and cell body ion channel location in the intermediate and motor neurons

A

Chemically gated ion channels ( Na+ and K+ )

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5
Q

What is the axon ion channel location

A

Voltage gated ( Na+ and K+ ) channels

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6
Q

What is the Axon thermals, ion channel location

A

Voltage gated Ca2+ channels

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7
Q

What is the sensory neurons, somatic senses

A

Detected by the receptors in the skin, muscle and joints

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8
Q

What is the Visceral senses in the sensory neurons

A

Detected by recptors in the internal organs

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9
Q

What does sensory detection require

A

Stimulus transduction

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10
Q

What does transduction mean

A

Convert or change from one form to another

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11
Q

What is sensory transduction

A

Conversion of sensory stimulus into an action potential

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12
Q

Please tell me an example of stimulus transduction

A

• when you touch something with your finger
• …a mechanoreceptor in the skin of your fingertip gets squished.
• This deforms the membrane, opening mechanically-gated Na+ channels
• …allowing Na+ to enter and depolarise the membrane
…sending action potentials to the brain to make you aware of the touch.

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13
Q

What are the 4 types of information encoded by neural activity

A
  • modality
  • duration
  • intensity
  • location
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14
Q

What is modality

A

A type of stimulus detected by a specific type of receptor

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15
Q

Duration

A

Time period of which action potentials fire in afferrent neurons

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16
Q

Intensity

A

Rate ( frequency ) of action potential firing in afferent neurons

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17
Q

Location

A

Location of receptors withen the body. The somatosensory cortex has a map of locations from which it receives action potentials

18
Q

What are the 4 examples of modality of stimulus

A
  • thermoreceptor
  • chemoreceptor
  • there are 3 types of mechanoreceptors, 1) tactile receptors 2) proprioreceptor 3) baro receptor
  • nociceptor
19
Q

What is thermo receptor and give an example

A

This is for temperature, so a stimulus example is relative temperature ranges

20
Q

What is chemoreceptor

A

Chemical and a stimulus examples is CO2, O2, H concentration in blood

21
Q

What isn’t mechankreceptor

A

There are 3 basic mechano receptors
1) tactile receptor, this is for skin touch, SE: light touch, pressure, texture, vibration, stretch
2) propriceptor, this is propriception, SE: stretch or tension in skin, muscle and/or tendon
3) baro receptor this is pressure , SE: stench of visceral tubes ( eg: blood vessels, airways, intestines)
- Nociceptor! This is for PIAN, SE: excess temperature, chemical or mechanical stimuli

22
Q

In depth of thermoreceptors

A

Thermorecetoes are nerve endings with temperature gated ion channels, they can sense a range of temperature and are sensitive to both increase and decrease of temperatures and are FAST ADAPTING.

23
Q

Transduction of tempeture stimuli

A

Temperature stimuli opens temperature gated Na+ channels,
Allowing Na+ to enter and depolarise the membrane
If the threshold is reached in the thermoreceptor, an action potential will fire and propagate the brain.

24
Q

In-depth of chemo receptors

A

These are specialised receptor cells with chemically gated ion channels
They respond to different chemical concentrations

25
Q

Transduction of chemical stimuli

A

This is the same as the tempeture one:

Chemical stimuli bind and open chemically gated Na+ channels,
Allowing Na+ to enter and depolarise the membrane
If the threshold is reached in the thermoreceptor, an action potential will fire and propagate the brain.

A PH sensitive cell is an example of,e of an chemoreceptor

26
Q

In depth about Mechaoreceptos

A

They are nerve endings with mechanical,t gated ion channels
They respond to physical forces that distort the plasma membrane ( deformation

27
Q

Transduction of mechanical stimuli

A

Mechanical stimuli deform the membrane causing mechanically gated Na+ channels to open
This allows Na+ to move in and depolarise the membrane
And is the threshold is reached in the menchnoreceptor, an action potential will fire and propagate to the brain

28
Q

Mechanoreeceptors: tactile receptor

A
  • responds to light touch, pressure, vibration and stretch of skin
  • Some are tonic ( slow adapting )
  • some are phasic ( fast adapting )
29
Q

Me hnoreceptors: proprioceptors

A
  • respond to stretch, tension in receptors
  • inform about limb position
  • are tonic ( slow adapting )
30
Q

Mechanicoreceptors: baro receptors

A
  • detect pressure in/strech of tubes ( eg:blood sugar )
31
Q

In depth of Nociceptors

A
  • this is a Nerve ending that responds to noxious stimuli ( harmful, painful ) and is tippically caused by tissue damage
  • They have either temperature gated, chemically gated or mechicallt gated ions channels responding to extreme stimuli
  • are tonic ( slow adapting )
32
Q

Transduction of noxious stimuli

A

Noxious stimuli causes ion channels to open allowing Na+ to enter and depolarise the membrane
If the threshold is reached in the nociceptor, an action potential will fire and propagate to the brain

33
Q

Duriation of stimulus, tonic receptors

A

Tonic receptors are continually active, providing a continuous signal to the central nervous system (CNS) that reflects the background level of stimulation.
- These receptors maintain a relatively constant firing rate over time, even in the presence of a sustained stimulus.
- The action potential (AP) frequency may change when the intensity of the stimulus changes, but the receptors continue to respond as long as the stimulus is present.
- Tonic receptors are associated with slowly adapting responses, meaning they continue to respond for a prolonged duration to sustained stimuli.
- Examples include muscle spindles involved in proprioception (sensing body position and movement) and nociceptors responsible for detecting pain.

34
Q

Duration of stimuli, phasic receptors

A
  • Phasic receptors, on the other hand, respond rapidly to changes in the stimulus but adapt quickly to sustained stimuli.
  • They are characterized by a burst of activity when the stimulus is first applied but then rapidly decrease their firing rate, becoming less responsive over time if the stimulus remains constant.
  • Phasic receptors are associated with fast-adapting responses, meaning they quickly adapt to sustained stimuli and may stop firing even if the stimulus is still present.
  • Examples include receptors for touch, vibration, and pressure, which are crucial for detecting changes in the environment but may become less responsive to constant stimuli.
35
Q

Intensity of stimulus, action potential frequency

A

NO AP = NO SENSATION
SOME AP = SOME SENSATION
MORE AP = MORE INTENSE SWNSATION

36
Q

Intensity of stimulus, Ap frequency plus number of neurons activated

A
  • below threshold there is no response in afferent neuron
  • increasing stimulus increases action potential frequency
  • stronger stimuli can also activate more receptors and action potentials in more sensory axons
37
Q

Location of stimulus, receptive Feilds

A

• The area of skin with receptive endings for a single sensory neuron
• 1 receptive field to 1 sensory neuron
Size and density of receptive fields affect discriminatory touch (sensitivity) and ability to localize a stimulus.

38
Q

Location of stimulus - size and density of receptive Feilds - sensitivity and localisation

A

Large and more widely spaced receptive fields provide:
• less sensitivity and
• less accurate localization
• e.g. in arms, legs, torso

Small and densely packed receptive fields provide:
• More sensitivity (better two- point discrimination)
• more accurate localization
e.g. hand, fingers and lips

39
Q

Location of stimulus - sometorsensory cortex map

A

Somatic sensory neurons send signals from different parts of the body and Up axons within the dorsal column pathway to the somatosensory cortex of the brain Creating a somatotopic map

40
Q

Location of stimulus , receptive Feilds and the somatopic map. TRUNK TORSO AND LIMBS

A

• Areas of skin with larger receptive fields so this has less representation in the brain because there are fewer neurons involved

Remember: 1 sensory neuron per receptive field

41
Q

Location of stimulus : lips and hands, receptive Feilds and somatopic map

A

• Areas of skin with smaller receptive fields
• have more representation in the brain because there are more neurons involved

Remember: 1 sensory neuron per receptive field

Hubs191 (26 decks)

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