Topic 3: Sensory Receptors Flashcards
A ________ ________(organ) is a structure that recognizes a stimulus.
Sensory receptor
A ________ is a detectable change in the internal or external environment.
Stimulus
Under the appropriate circumstances, a receptor can transducer (convert) the stimulus into a _____ signal. These signals are then carried into the CNS to be analyzed.
Nerve
T/F: A sensory receptor may be a specialized portion of the neuronal membrane, a separate cell associated with a neuron ending, or a group of such cells. Sometimes the receptor and the neuron itself are together referred to as a receptor.
True
Each sensory receptor responds most readily to one particular form of energy. This is called its ________ ________.
Adequate stimulus
__________ : the magnitude or intensity that must be exceeded for a certain reaction or condition to occur.
Threshold
T/F: Receptors can only respond to their adequate stimulus.
False: Receptors also respond to forms of energy other than the adequate stimulus, but the threshold for these nonspecific responses is much higher.
__________ is the process by which stimuli are converted to action potentials (APs) by sensory receptors.
Transduction
__________ is the process by which nerve signals enter and ascend the CNS in various tracts.
Transmission
_________ is the process by which electrochemical activity from other ascending inputs for example, touch, or signals descending from the brain (via emotions) can increase or decrease sensory transmission. In this manner the intensity of sensory input to the cerebral cortex can be controlled.
Modulation
__________ is the process which results in subjective feelings. It is a poorly understood combination of transduction, transmission, and modulation. It can be altered by many phenomena including sleep and emotions such as fear, rage, and depression.
Perception
T/F: All unipolar neurons are attached to some sort of
sensory receptor.
True
All unipolar cell bodies form a cluster called a ______ ____ ________ at every level of the spinal cord.
Dorsal root ganglion
Unipolar neurons enter the ______ ____ at each level and on both sides of the spinal cord.
Dorsal horn
Unipolar neurons in cranial nerves that have a sensory component, for example CN V, also have _______.
Ganglia
__________ _________ is the smallest amount of change needed in a stimulus before a change is noticed.
Difference threshold
_______’s ___ states that the change needed to notice a difference between two stimuli is proportional to the original intensity of the stimulus.
Weber’s Law
Every receptor has a defined area in the periphery, over which it can receive input. This is called the _______ _________, and each one is the responsibility of a single axon.
Receptive Field
_______ __________ is the ability to accurately locate the site of stimulation and to detect that neighbouring stimuli are actually separate.
Spatial discrimination
_______ _________ depends in part on the density of receptors and the size of the receptive fields in a particular skin region.
Tactile sensitivity
More sensitive areas have _______ fields and a _______ concentration of receptors.
More sensitive areas have smaller fields and a higher concentration of receptors.
The ____-______ threshold is the minimal distance in which two separate stimuli can be distinguished as separate.
Two-point
In different parts of the skin, the concentration of the various sensory receptors changes and this accounts for varying abilities in _______ _________ in different regions.
spatial discrimination
On the back, the density of tactile receptors is greatly _______, and spatial discrimination is relatively ____.
On the back, the density of tactile receptors is greatly reduced, and spatial discrimination is relatively poor.
A ___________ is an area of the skin that is a combination of the adjacent receptive fields of the sensory receptors of a single nerve. They are named according to the peripheral nerve which supplies them.
Dermatome
T/F: Dermatome maps are incredibly accurate and there is very little overlap.
False!! There is considerable overlap. This means that the loss of a single nerve root rarely produces significant loss of skin sensitivity.
_________ _____s are found in small patches in the distal extremities.These are distinct and non- overlapping areas of skin.
Autonomous zones
_____ __________ have a confusing arrangement stemming from limb rotation during development at about 5 weeks as an adaptation to the erect position.
Limb dermatomes
Dermatomes are useful in localizing the site of damage in the spinal cord and brainstem particularly in __________ (caused by compression, inflammation and/or injury to a spinal nerve).
Radiculopathy
A _______ ____ with nerve compression is by far the most common cause of a radiculopathy.
Herniated disc