Midterm 1 - Unit 3 Lecture 1 Flashcards
what is the function of the somatosensory system
To detect the position and motion of our body parts
what is Proprioception
sense of position of the limbs in space and relative to body; sense of oneself
what is Kinaesthesia
sense of movement
what is Exteroception
Sense through interaction with the external environment
what are the general compoenents of the somatosensory system
Receptor encodes stimulation
Action potential along peripheral axon to dorsal root ganglion and into spinal cord
Sensory Processing:
Spinal Reflexes
Ascends to brainstem, cerebellum and cerebral areas
what are the 4 peripheral receptors
cutaneous receptors
joint receptors
muscle spindles
golgi tendon organs
what do cutaneous receptors detect
touch, pressure, vibration, temperature, and (pain)
what do joint receptors detect
joint angles and range motion
what do muscle spindles detect
muscle length and change in muscle length
what do golgi tendon organs detect
muscle tension or force
what are the two types of intrafusal fibres:
Nuclear bag and nuclear chain
what sensory neurons wrap the intrafusal muscle fibres
Type Ia and Type II sensory fibers
how are muscle spindles able to Signal muscle length and change in muscle length
by the Type Ia and Type II sensory fibers
what happens to the firing rate when there is muscle shortening(contraction)
decrease in firing rate
what happens to the firing rate when there is muscle lengthening
increase in firing rate
what does Type Ia afferent signal
the length of the muscle (static) AS WELL as changes in the length during movement (dynamic)
what does Type II afferents signal
signal the length of the muscle (static) and less so the change in length (dynamic)
what do the Type Ia sensory fibres innervate
Innervate nuclear bag and chain intrafusal muscle
what do the Type II sensory fibres innervate
innervate mainly nuclear chain intrafusal muscle fibres
why does the Type II sensory fibres not detect the change in length(dynamic)
because it doesn’t innervate the nuclear bag
what type of sensory fibre innervates the golgi tendon organ(GTO)
Innervated by Ib afferent fiber
GTO sensitive to __________
tension (active or passive)
For example, when tension generated by the muscle increases, Ib afferents are activated
what are the 4 main types of Cutaneous Receptors?
Merkle disks/cells
Ruffini endings
Pacinian
Meissner corpuscles
which are the slow adapting receptors
Merkle disks/cells and Ruffini endings
(Respond while the stimulus is present)
which are the fast adapting receptors
Pacinian and Meissner corpuscles
(Respond during change )
where are joint receptors located
Located within the joint capsule
what do joint receptors detect
Sensitive to extreme ranges of movement
what is the Flexion withdrawal reflex
limb withdrawn from a painful stimulus
what is the Stretch reflex
the contraction of a muscle in response to its passive stretching
stretch reflex regulates the length of the muscle automatically by increasing its contractility
designed as a protective mechanism, to prevent strain and tear injuries to the muscles and tendons.
what is the Crossed extension reflex
allows the body to compensate on one side for a stimulus on the other.
For example, when one foot steps on a nail, the crossed extensor reflex shifts the body’s weight onto the other foot, protecting and withdrawing the foot on the nail.
what type of reflex is the Crossed extension reflex
contralateral reflex
what are reflexes
Involuntary
Stereotyped: roughly the same response to the same simple stimulus
Fast-responding
how does sensory information get to the brain?
Dorsal Column-Medial Lemniscus Pathway
Anterolateral Pathway
what is the function of the Dorsal Column-Medial Lemniscus Pathway
Recognizing objects by touch
Controlling and coordinating movement
what is the function of the Anterolateral Pathway
Localizing noxious sensations
Distinguishing between warm and cold
