Sensory and Motor Information Flashcards
What is the function of the somatosensory system?
tells us what the body is doing and what is going on in the environment
What are the two types of skin?
hairy and glabrous
What is the function of hairy skin?
a low sensitivity type of skin
What is the function of glabrous skin?
a hairless skin which has many sensory receptors
What do nociceptors do?
perceive pain and temperature via free nerve endings
How to nociceptors work?
damage to the dendrite or surrounding cells causes the release of prostaglandin which stimulates the dendrite and produces an action potential
How do pain killers work?
block the synthesis of prostaglandin
What do haptic receptors do?
perceive fine touch or pressure and is able to distinguish touch, pull, vibration, flutter and indentation
How do haptic receptors work?
the mechanical stimulation of a hair produces an action potential
What do Merkel’s receptors do?
transmit information about steady skin indentation
What do Meissner’s corpuscles do?
perceive light touch
What do Ruffini’s corpuscles do?
perceive steady skin indentation
What do Pacinian corpuscles do?
perceive vibration and deeper pressure
What is proprioception?
the perception of the location and movement of the body
How is proprioception perceived?
movements stretch the receptors to mechanically stimulate dendrites and produces an action potential
What detects a muscle stretch?
muscle spindles
What detects a tendon stretch?
golgi tendon organs
What detects joint movement?
joint receptors
How do rapidly adapting receptors work?
receptors briefly respond to the beginning and end of a stimulus on a body
What are the benefits of rapidly adapting receptors?
gives a good response to repeated stimuli
How do slowly adapting receptors work?
receptors respond as long as a sensory stimulus is on the body
What are the benefits of slowly adapting receptors?
good for detecting painful stimulus which is beneficial for evolutionary reasons
Describe the axons of nociceptive neurons
Small with little or no myelination (slow)
Describe the axons of proprioceptive and haptic neurons
large, well myelinated axons (fast)
Describe deafferentiation
loss of incoming sensory input usually due to damage to sensory nerve fibres
What are some effects of deafferentiation?
motor control is not lost but some actions would require visual feedback, daily tasks could not be performed and afferent feedback is required for fine movements
What does the dorsal spinothalamic tract do?
carries haptic and proprioceptive information
How is information carried along the dorsal spinothalamic tract?
axons from the dorsal-root ganglion neuron enter the spinal cord and ascend ipsilaterally to synapse in the dorsal column nuclei
What does the ventral spinothalamic tract do?
carries nociceptive information
How is information carried along the ventral spinothalamic tract?
axons from the contralateral spinal cord ascend to the brain
What is a monosynaptic reflex?
a reflex requiring one synapse between sensory input and movement e.g. knee jerk
What does the vestibular system do?
responds to body position and movement of the head in relation to gravity
What does the vestibular system consist of?
three semicircular canals and otolith organs (utricle and saccule)
How is head movement detected?
endolymph fluid located in the semicircular canals pushes against hair cells bending the cilia creating action potentials
How does the direction in which the cilia are bent affect the potential?
the direction will create depolarisation or hyperpolarisation
How is acceleration detected?
the utricle and saccule contain hair cells embedded in a gelatinous substances which are pushed on my otoconia altering the rate of action potentials
What is otoconia?
small crystals of calcium carbonate in the utricle and saccule
What is the function of the primary somatosensory cortex?
receives projections from the thalamus and begins the process of constructing perceptions from somatosensory information
What is the function of the secondary somatosensory cortex?
located behind the primary somatosensory cortex, it continues the construction of perceptions projecting to the frontal cortex
What did Wilder Penfield research?
the effects of stimulation on the cortical surface of the brain using electrodes
What did Jon Kaas research?
developed Enfield’s work and used smaller electrodes to more precisely locate the functional layout of the cortex
