General Sensory Mechanisms Flashcards
What type of receptor is a mechanoreceptor?
A receptor that includes free and encapsulated endings receiving skin tactile sensibilities.
What are the mechanoreceptors with expanded tip endings?
Merkel’s discs
What are the mechanoreceptors with encapsulated endings?
Meissner’s corpuscles
Kraus’ corpuscles
What are mechanoreceptors with spray endings?
Ruffini’s corpuscles
What are three basic types of mechanoreceptors?
Hearing (cochlea)
Equilibrium (vestibular)
Arterial pressure (baroreceptors)
What is the function of thermoreceptors?
They have cold and warm receptors
What are nociceptors?
Free nerve endings responding to pain
What are the function of electromagnetic receptors?
They include rods and cones of the eye for vision.
What are the functions of chemoreceptors?
Taste Smell Arterial oxygen Osmolarity Blood carbon dioxide Blood glucose, amino acids and fatty acids.
What is meant by differential sensitivities?
It means that each type of receptor is highly sensitive to one type of stimulus and is almost nonresponsive to other types.
What is modality?
It refers to each of the principal types of sensation
Describe the labeled line principle
It refers to the specificity of nerve fibers for transmitting only one modality of sensation.
What do sensory receptors do when presented with a constant stimulus after a period of time?
They adapt to the stimulus.
What are four mechanisms of stimulation for receptors?
Mechanical deformation
Application of a chemical
Temperature change
Electromagnetic radiation
When applying a mechanical stimulus to a Pacinian corpuscle, what is the relationship between stimulus and receptor potential?
As stimulus strength increases, receptor potential increases and then levels off.
You are studying receptors and are examining one that is slow adapting, has continuous stimulus strength and transmits impulses as long as stimulus is present. What type of receptor are you observing?
Tonic receptor
What are types of tonic receptors?
Muscle spindles
Golgi tendon organs
Macula and vestibular receptors
Baroreceptors
Chemoreceptors
You are studying receptors, and are examining one that rapidly adapts, does not transmit a continuous signal, and is stimulated only when stimulus strength changes. What type of receptor are you examining?
Phasic receptor
What are characteristics of type A nerve fibers?
They are large and medium sized myelinated fibers of spinal nerves.
They are divided into alpha, beta, gamma and delta nerve fibers.
What type of fibers are type c fibers?
Small and unmyelinated.
They conduct signals at low velocity.
They make up more than half of all sensory fibers in most peripheral nerves and all postganglionic autonomic fibers.
What are group Ia (type A alpha) fibers?
Fibers from annulospiral endings of muscle spindles.
What are group Ib (type A alpha) fibers?
Fibers from Golgi tendon organs
What are group II (type A beta, gamma) fibers?
From cutaneous tactile receptors and flower-spray.
What are group III (type A delta) fibers?
They carry temperature, crude touch, and prickling pain
What are group IV (type C) fibers?
Carry pain, itch, temperature and crude touch.
What is a difference between spatial and temporal summation?
In spatial summation, increasing signal strength is transmitted by using progressively greater number of fibers.
In temporal summation, increasing signal strength is transmitted by increasing the frequency of nerve impulses in each fiber.
What are some examples of neuronal pools?
Cerebral cortex Basal nuclei Thalamic nuclei Cerebellum Mesencephalon Pons Medulla Gray matter of spinal cord
What is the stimulatory field of a neuronal pool?
The neuronal area within the pool stimulated by each incoming nerve fiber.
What is the discharge zone of a neuronal pool?
Includes all the output fibers stimulated by the incoming fiber.
What are the facilitated/inhibition zones?
They are zones with neurons further from the discharge zone that are facilitated, but not excited.
May be inhibitory or excitatory depending on the input fiber.
What is the signficance of of diverging neuronal pathways?
They result in amplification of initial signal and allow transmission of the original signal to separate areas.
What are convering neuronal pathways?
Pathways in which multiple input fibers converge onto a single output neuron.
Input fibers may be from a single source or from multiple separate sources.
What are reverbatory circuits?
Circuits caused by positive feedback within the neuronal circuit.
The circuit, once stimulated, may discharge repetitively for a long time.
What are the five basic types of sensory receptors?
Mechanoreceptors
Thermoreceptors
Noceiceptors
Electromagnetic receptors
Chemoreceptors
