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PHYL2064 > Sensory systems L1: Introduction > Flashcards

Sensory systems L1: Introduction Flashcards

1
Q

What are the 3 organisations of the nervous system

A
  1. CENTRAL NERVOUS SYSTEM (CNS) includes the brain and spinal cord
  2. PERIPHERAL NERVOUS SYSTEM (PNS): nerve fibers that form the afferent (inputs) and efferent (output) divisions
  3. ENTERIC NERVOUS SYSTEM (ENS) includes the network of nerves of the digestive tract.
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2
Q

What is the central nervous system (CNS)?

A

includes the and spinal cord CNS important for all the integration of the information coming in

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3
Q

What is the peripheral nervous system (PNS)?

A

nerve fibers that form the afferent (inputs eg. Feeling and sensations) and efferent (output eg. Motor (eg. reaction)) divisions

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4
Q

What is the eneteric nervous system (ENS)?

A

includes the network of nerves of the digestive tract.

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5
Q

What are the 2 afferent divisions that carry information to the CNS?

A
  1. Somatic
  2. Visceral
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6
Q

What is the somatic afferent that carries information to the CNS?

A

carries sensory information from skin, skeletal muscles and other sensory inputs (vision, hearing, olfaction, gustation and proprioception)

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7
Q

What is the visceral afferent that carries information to the CNS?

A

carries sensory information from internal viscera such as smooth muscle, glands and organs in body cavities.

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8
Q

What is the afferent division?

A

Brings information from the periphery to the brain

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9
Q

What does the summary of the PNS and CNS look like?

A
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10
Q

What are 3 neuron classes?

A
  1. Afferent neurons (PNS-CNS)
  2. Interneurons (CNS)
  3. Efferent neurons (CNS-PNS)
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11
Q

What are Afferent neurons (PNS-CNS)?

A

sensory neurons that provide information to the CNS about the environment (afferent information)

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12
Q

What are interneurons (CNS)?

A

responsible for integrating afferent information and formulating an efferent response Neuron between neuron

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13
Q

What are efferent neurons (CNS-PNS)?

A

carry instructions from CNS to organs, muscles and glands (efferent information)

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14
Q

What happens when you burn yourself?

A

Eg. burnt yourself –> this loop occurs quickly

  • Sensory input
  • Integrated in the interneuron in CNS Response –> output
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15
Q

Why are there only 3 neurons?

A
  • If there are more neurons it would increase the time it would take for a response to occur when information is given by the environment
    • Eg. when burnt –> hand would move away more slowly = more likely that hand will have more severe burn
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16
Q

What are 5 reasons why we need sensory systems?

A
  1. regulating motor behaviour in accordance with external circumstances
    • Behave and respond to changes
    • Eg. when you see a lion, you need to integrate what is coming in from the visual inputs to then accordingly start running= avoid being eating and die
  2. Coordinating internal activities directed at maintaining homeostasis
    • Different in various environments (eg. in brisbane on a sunny day VS Antarctica in winter = must be able to tell the difference in temperature so that the body can undergo certain changes that will allow survival
  3. Cortical arousal and consciousness
    • Who you are; why you are where you are; situation; how to respond
  4. Perception of the world around us
    • Vision, hearing, tactile feedback (all inputs coming into the body bringing information to detect changes)
  5. Changing emotional states.
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17
Q

Why do we need sensory systems?

A

To know what’s around you = to survive

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18
Q

What are sensory receptors?

A

Sensory receptors are specialized peripheral endings of afferent neurons.

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19
Q

What are 3 characteristics of sensory receptors?

A
  1. Each type or receptor responds to a specific type of stimulus- Eg. different types of receptor–> thermal, nociception, mechano..etc
  2. Receptors translate the energy from the stimulus into electrical signals;
  3. This process is called signal transduction.
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20
Q

What are 4 characteristics of Receptor potentials?

A
  1. A stimulus activates depolarizing receptors, that promote- Changes happening at the nerve endings —> activation = depolarisation net entry of Na+ entry
  2. If the activation of these receptors is strong enough enough (Na+ entry) action potentials are generated; (GENERATION)
  3. These action potentials are then move along the afferent fibres to the CNS; (PROPAGATION)
  4. The strength of the stimulus determines the frequency of the action potentials. (STRENGTH)
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21
Q

What is generation for receptor potentials?

A

If the activation of these receptors is strong enough enough (Na+ entry) action potentials are generated;

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22
Q

What is propagation for receptor potentials?

A

These action potentials are then move along the afferent fibres to the CNS If stimulus is strong enough to generate an AP will propagate down the axon to pass information

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23
Q

What is strength for receptor potentials?

A

The strength of the stimulus determines the frequency of the action potentials.

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24
Q

What is Specialized afferent ending?

A
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25
Q

What is specialised afferent ending responsible for?

A

Responsible for pain

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26
Q

What are separate receptor cells?

A

Receptor for heat or cold

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27
Q

What is _____?

A
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28
Q

Receptors may adapt ____ or ____ to sustain stimulation

A

slowly; rapidly

29
Q

What are 2 types of adaptation for receptors?

A
  1. Tonic
  2. Phasic
30
Q

What are tonic receptors?

A

(very slow adaptation or no adaptation at all). Important to maintain information about a stimulus that is valuable. Example muscle receptors.

31
Q

With tonic receptors, once they are activated, they stay activated (doesn’t adapt at al and will constantly send signals ). What is the advantage?

A

Eg. don’t want pain receptors to adapt = as pain alerts the body that they are in danger in acute (won’t receive information even though its painful= damage to tissue)

32
Q

What are phasic receptors?

A

(adapt rapidly). They are important when we need to have information about change in stimulus intensity rather than the constant relay of information. Example: tactile (touch) receptors. Adapt = Stop generation of AP

33
Q

For phasic receptors, why do we want adaptation?

A
  • Brain wants to cancel out the feelings and sensations that will remain constant (eg. feeling of clothes on body, wearing glasses)
  • Will activate when things change (eg. put on watch or clothes, remove watch) • But when constantly on (eg. watch) –> wont be activated
34
Q

What does receptive field refer to?

A

Receptor –> has a certain size refers to the area surrounding a receptor field of detection.

35
Q

What is acuity?

A

How much the field is activated? varies inversely with the size of receptive fields: smaller receptive fields show higher acuity.

  • It is also influenced by lateral inhibition.
36
Q

Smaller receptive fields show _____(higher/lower) acuity

A

higher

37
Q

Eg. high acuity and low receptive field = skin (hands or face, lips) Why?

A

Need to get as much information as possible

38
Q

What happens when there are 2 points felt?

A
39
Q

What happens when there are 1 point felt?

A
40
Q

What does activity in afferent neurons look like?

A
41
Q

What does lateral inhibition look like?

A
42
Q

What are inhibitory interneurons?

A

Shut down near by cells = good specificity/specific point that has small receptive field and high acuity

  • Tune down the perfect spot (areas that are extremely sensitive –> lips, hands, face)
  • Brain can only sense APs
43
Q

What are the 2 pathyways that the afferent information goes?

A
  1. Reflex arc (monosynaptic, e.g. patellar reflex)- Goes from one cell to the next cell –> not much integration (Hot stove example)
  2. Brain via ascending pathways (sequence of synaptically connected neurons, labelled lines, associated with sophisticated processing).
    • Send information from the periphery to the brain
44
Q

Each sensory modality has its own specific ______, sequence of neurons and is projected to a specific region in the _____.

A

receptor; cortex

45
Q

Everything is pretty much pre-wired (eg. receptors in L fingertip will only be activated these receptors activated. Why?

A
  • Since brain can only detect AP
  • How can AP tell the brain the receptor activated is the L finger tip unless they had some pre-set neurons present in cortex of brain = will know where the sensory input is coming from
  • If not pre-set/wired neurons in brain –> will get activation of some somewhere but would be unable to tell where the input is coming from
46
Q

What does the cortex look like?

A
47
Q

What is the sensory homunculus?

A
48
Q

What are 2 types of stimuli do receptors respond to?

A
  1. Solute senses: molecules dissolved in water. Lock and key receptors.
  2. Solvent senses: water and turgor sensors. How receptors get activated?
49
Q

What are solute senses?

A

molecules dissolved in water. Lock and key receptors.

Binding to activated

50
Q

What are solvent senses?

A

water and turgor sensors. Changing in membrane –> activated

51
Q

What are 6 types of receptors?

A
  1. Photoreceptors
  2. Chemoreceptors
  3. Mechanoreceptors
  4. Osmoreceptors
  5. Nociceptors
  6. Thermoreceptors
52
Q

What are photoreceptors?

A

Responsive to photons (with visible wavelengths of light). Humans can see from 400 to 700 nm of light. Eg. in eyes

53
Q

What are chemoreceptors?

A

Responsive to specific chemicals. Receptors included are:

  • For smell and taste
  • For O2 and CO2 (blood) Brainstem
  • Chemical content of digestive tract
54
Q

What are mechanoreceptors?

A

Sensitive to mechanical energy. Eg. skin

55
Q

What are osmoreceptors?

A

Detect changes in solute concentrations in body fluids and resultant changes un osmotic activity

56
Q

What are nociceptors?

A

Pain receptors that are sensitive to tissue damage or distortion of tissue.

57
Q

What are thermoreceptors?

A

Sensitive to heat and cold.

Better at detecting heat (eg. when in winter –> cold is cold) but eventually cold can cause pain (spin-over activation of nociceptors–> more pain coming in –> don’t know whats going on )

58
Q

Sensory systems convey ____ types of information

A

four

  1. Modality: what type of sensation is it?
  2. Location: where is it?
  3. Intensity: how strong is the stimulus?
  4. Timing: when/how often does it happen?
59
Q

Modality: what type of sensation is it? What are 3 characteristics?

A
  1. Type or receptor activated
  2. Pathway
  3. Specific area in the cerebral cortex. Eg. pain in my right leg that has been activated
60
Q

Location: where is it? What are 3 characteristics?

A
  1. Location of the activated receptive fields
  2. Pathway
  3. Specific area in the somatosensory cortex (homunculus).

Where it is? –> just look at area

61
Q

Intensity: how strong is the stimulus? What are 2 characteristics?

A
  1. Frequency of action potentials
  2. Number of receptors activated.
62
Q

Timing: when/how often does it happen? What are 2 characteristics?

A
  1. Beginning and end of AP burst/trains
  2. Number of AP trains.
63
Q

The only stimuli that can be detected are those for which _____ are present

A

receptors

64
Q

What is perception?

A

the conscious interpretation of the external world;

  • what the brain perceives from its input is an abstraction and not reality
  • Illusions demonstrate the difference between sensation and perception.
65
Q

What is sensation vs perception?

A

S: detection of the stimulus coming in (pain being activated in the body to brain)

P: how we perceive the stimulus (eg. perception of the pain)

Pain can be different for different people even in same scenario s

66
Q

What is the Amnes room?

A

Room with different height

Assumption of parallel walls is so strong –> unable to recognise the different height

67
Q

What is the 2 conceptually distinct sources of information that visual perception is a complex combination of?

A
  1. Bottom up: data driven, image-based information whose origins can be traced directly back to the specific sensory system.
  2. Top down: information or expectations supplied by each individual person is used to interpret and modify the basic percept
68
Q

What is bottom up?

A

data driven, image-based information whose origins can be traced directly back to the specific sensory system.

69
Q

What is top down?

A

information or expectations supplied by each individual person is used to interpret and modify the basic percept

PHYL2064 (29 decks)

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