2. Senses II: Touch/skin Flashcards
1
Q
- What is the skin?
A
- it is an organ of tactility
2
Q
- What does the skin allow?
A
- it allows us to feel and sense our environment in different ways
3
Q
- What three distinct senses does the skin account for?
A
- responding to pressure
- responding to temperature
- responding to pain
4
Q
- What are the four reasons for dividing the skin into three different senses?
A
- the skin responds differently to a distinct class of stimuli
- the skin has the ability to discriminate among these
stimuli - the skin possesses a distinct set of receptors
- this leads to experiences that differ phenomenologically
when the sense is stimulated
5
Q
- Provide a definition for pressure.
A
- physical pressure on the skin
- this is the stimulus for sensed pressure
6
Q
- Provide a definition for temperature.
A
- the temperature on our skin
- this is the stimulus for temperature
7
Q
- Provide a definition for pain.
A
- this is any stimulus that is intense enough to cause tissue damage
- it may be in the form of:
- pressure
- temperature
- electric shock
- irritant chemicals
8
Q
- What three main layers does the skin consist of?
A
- the epidermis
- the dermis
- the hypodermis
9
Q
- What do the terms “epi” and “dermis” mean in Greek?
A
- “epi” = over / upon
- “dermis” = skin
10
Q
- What does the Epidermis form?
A
- it forms the water proof, protective wrap
- this wrap is found over the body’s surface
- this wrap serves as a barrier to infection
11
Q
- What is the protective Epidermis wrap over the body’s surface made up of?
A
- it is made up of stratified squamos epithelium
- it has an underlying basal lamina
12
Q
- Where is the Dermis located?
A
- it is the skin layer beneath the epidermis
13
Q
- What does the Dermis consist of?
A
- it consists of epithelial tissue
14
Q
- What is the function of the dermis’s epithelial tissue?
A
- it cushions the body from stress and strain
15
Q
- What tightly connects the dermis to the epidermis?
A
- a basement membrane
- this membrane harbours many nerve endings
16
Q
- What does the basement membrane provide?
A
- it provides a sense of touch and heat
17
Q
- Is the Hypodermis a part of the skin?
A
- NO
18
Q
- Where is the Hypodermis located?
A
- it lies below the dermis of the cutis
19
Q
19.What is the purpose of the Hypodermis?
A
- it is to attach the skin to the underlying bone and muscle
- it also supplies the skin with blood vessels and nerves
20
Q
- What is found in the Dermis?
A
- various nerve fibres
- various nerve corpuscles
21
Q
- What do the nerve fibres and the nerve corpuscles of the dermis target?
A
- they target the detection of environmental/external stimuli
on the surface of the skin
22
Q
- What are different peripheral sensory receptors sensitive to?
A
- particular types of stimulus
23
Q
- What happens when the peripheral sensory receptors detect particular sensations?
A
- they are sensitive to these sensations
- they generate new nerve impulses
24
Q
- Where will these new nerve impulses go to if the stimulation is on the lower part of the body?
A
- they will go to the spinal cord
25
Q
- Where will these new nerve impulses go to if the stimulation is on the upper part of the body or the face?
A
- they will go to the brain
- via the cranial nerves
26
Q
- Where will all the information regarding stimulation end up?
A
- the sensory cortex of the brain
27
Q
- Where is the stimulation felt?
A
- in the brain
28
Q
- Where are the nerve impulses generated?
A
- in the dermis
29
Q
- Where will the information of the stimulations felt on the right side of the body end up?
A
- in the left sensory cortex
- in the parietal lobe of the brain
30
Q
- Where will the information of the stimulations felt on the left side of the body end up?
A
- in the right sensory cortex
- in the parietal lobe of the brain
31
Q
- What is located at the very bottom of the epidermis?
A
- the Merkel Cells
- they are very small sensory cells
32
Q
- What connects the Merkel cells to each other?
A
- Merkel cell discs
33
Q
- Are there any other nerve fibres in the epidermis, other than the Merkel cells?
A
- NO
34
Q
- What are the Merkel cells sensitive to?
A
- light touch
35
Q
- What do the Merkel Cells do when they detect light touch?
A
- they detect this type of information in the epidermis
- they carry this information to the brain
36
Q
- What do Merkel cells provide information on?
A
- pressure
- position
- deep static touch features
(shapes / edges)
37
Q
- What detects all mechanical stimuli?
A
- mechanoreceptors
38
Q
- What is an example of mechanoreceptors in the epidermis?
A
- Corpuscular Peripheral Sensory Receptors
39
Q
- What size are Corpuscular Peripheral Sensory Receptors (mechanoreceptors)?
Where are they located?
A
- they are moderately small
- they are located in the dermal papillae
- this is near the surface of the dermis
40
Q
- What is the specific name of these Corpuscular Peripheral Sensory Receptors?
A
- Meissner Corpuscles
41
Q
- What are Meissner Corpuscles responsible for?
A
- they are responsible for transmitting the sensations of:
- fine
- discriminative (accurate distinctions)
- touch and vibrations
42
Q
- What are Pacinian Corpuscles responsible for?
A
- sensitivity to vibration and pressure
43
Q
- What are the Pacinian Corpuscles connected to?
A
- dendrites of sensory neurones
44
Q
- What does the connection between the Pacinian Corpuscles and the dendrites of sensory neurons result in?
A
- mechanical information can now be transferred towards the brain
45
Q
- What exactly do Pacinian Corpuscles detect?
A
- the pressure on the skin
- NOT the touch
46
Q
- Why are the Pacinian Corpuscles near the base of the dermis?
A
- they only fire off to generate new nerve impulses when
there is significant pressure
47
Q
- What allows the skin to be sensitive to temperature?
A
- thermoreceptors
48
Q
- What are the two types of thermoreceptors?
A
- those that detect heat
- those that detect cold
49
Q
- Are thermoreceptors corpuscular.
Why or why not?
A
- they are not
- they are just free nerve endings
- they can be situated close to each other
50
Q
- What allows the skin to be sensitive to pain?
A
- specialised pain receptors
51
Q
- What are these specialised pain receptors called?
A
- nociceptors
52
Q
- What do Nociceptors detect?
A
- they detect noxious stimuli
(NOXIOUS= harmful, poisonous) - they detect the extent of pain
53
Q
- Are Nociceptors corpuscular?
A
- no
- they are just free nerve endings in the dermis
- the presence of these nociceptors in the dermis
is what makes it sensitive to pain - this is why partial thickness injuries are so painful
54
Q
- What are two examples of partial thickness injuries?
A
- cuts
- burns
55
Q
- Do the Nociceptors go into the epidermis?
A
- no
56
Q
- What can be found deeper down in the dermis?
(it can be found even in the hypodermis)
A
- quite large receptors
- they consist of numerous layers
- they are made up of specialised Schwann cells
- they are laminated sensory corpuscles
- they are called Pacinian Corpuscles