Flashcards in Week 3 - finished Deck (64)
The perception of our relationship to our environment
What are the 4 sensory modalities?
How is the perception of touch elicited?
By the mechanical stimulation of the body surface
What is proprioception? How is the perception of it elicited?
It is information about joint angles, position and the orientation of our body in space.
It is elicited by the mechanical displacement of joints, overlying skin and muscle.
How is the perception of pain elicited?
By noxious or tissue damaging stimuli
How is the perception of temperature elicited?
By warm or cold stimuli acting on receptors specific to either hot or cold
What are the 4 types of mechanoreceptors in glabrous skin?
Which of the mechanoreceptors are type 1 receptors and where are they found?
These are Merkles receptors and Meisners corpuscles and they are found at the function of the dermis and the epidermis.
Which of the mechanoreceptors are type 2 receptors and where are they found?
There are Pacinian and Ruffini's corpuscles and they are found deep in the dermis.
Define a receptive field
The area of skin sensitised by each type of receptor
With type 1 and type 2 receptors, which of these groups have a role in determining fine touch and fine discrimination
Describe the division of mechanoreceptors into their response to constant stimuli
Meisners corpuscles and Pacinian corpuscles can be put into the category of rapidly adapting receptors, as they are the first to respond upon contact but are quickly silenced and may possibly fire again upon removal of stimulus.
Merkles receptors and Ruffini's corpuscles are known as slow adapting receptors and they will continue to fire as long as stimulus is maintained.
What is the role of fast adapting receptors in sensation?
They gather information on temporal changes in stimulus.
They play a large role in the perception of texture
What is the role or slow adapting receptors in sensation?
Often provides isomorphic representation of the surface chatarcteristics of the stimuli.
Below what temperature do cold thermoreceptors increase their rate of firing?
Below 32 degrees
Above what temperature do hot thermoreceptors increase their rate of firing?
Above 32 degrees
At approx what temperature do hot thermoreceptors shut down and are replaced by signals from nociceptors?
At approx 45 degrees
At approx what temperature do cold thermoreceptors shut down and are replaced by signals from nociceptors?
Below 10 degrees.
What 3 primary locations is position sense information gathered?
- joint capsules (mechanoreceptors within the joint)
- muscles acting over the joints (mechanoreceptors withing muscle)
- the skin overlying both (cutaneous receptors)
What do the mechanoreceptors within the joint capsule do in relation to position sense?
They record extreme joint angles, and are rarely used to sense smaller joint movements.
What do the cutaneous receptors do in relation to position sense?
They respond to compression and distension of the skin overlying moving joints
What do the mechanoreceptors within the muscle do in relation to position sense?
Muscle spindle are our primary input into perception of joint location and are sensitive to even the most minute changes in muscle length.
What factors is conduction velocity dependant on?
Degree of myelination
Is the propagation speed of a nerve impulse related to stimulus strength?
How much faster can a large myelinated AB axon conduct signals than a smaller unmyelinated C fibre?
Up to 200 times
What are the largest fibre types? Describe them
(5-20 microns & 130 m/sec)
myelinated somatic sensory & motor to skeletal muscle
What are the middle sized fibre type? Describe them
(2-3 microns & 15 m/sec)
myelinated visceral sensory & autonomic preganglionic
What are the smallest size of fibre type? Describe them
(.5-1.5 microns & 2 m/sec)
unmyelinated sensory & autonomic motor
What is nociception?
Information transmitted about actual of potential tissue damage