General Sensory Mechanisms

Question 1

What type of receptor is a mechanoreceptor?

Answer 1

A receptor that includes free and encapsulated endings receiving skin tactile sensibilities.

Question 2

What are the mechanoreceptors with expanded tip endings?

Answer 2

Merkel’s discs

Question 3

What are the mechanoreceptors with encapsulated endings?

Answer 3

Meissner’s corpuscles

Kraus’ corpuscles

Question 4

What are mechanoreceptors with spray endings?

Answer 4

Ruffini’s corpuscles

Question 5

What are three basic types of mechanoreceptors?

Answer 5

Hearing (cochlea)

Equilibrium (vestibular)

Arterial pressure (baroreceptors)

Question 6

What is the function of thermoreceptors?

Answer 6

They have cold and warm receptors

Question 7

What are nociceptors?

Answer 7

Free nerve endings responding to pain

Question 8

What are the function of electromagnetic receptors?

Answer 8

They include rods and cones of the eye for vision.

Question 9

What are the functions of chemoreceptors?

Answer 9

Taste 
Smell
Arterial oxygen
Osmolarity
Blood carbon dioxide
Blood glucose, amino acids and fatty acids.

Question 10

What is meant by differential sensitivities?

Answer 10

It means that each type of receptor is highly sensitive to one type of stimulus and is almost nonresponsive to other types.

Question 11

What is modality?

Answer 11

It refers to each of the principal types of sensation

Question 12

Describe the labeled line principle

Answer 12

It refers to the specificity of nerve fibers for transmitting only one modality of sensation.

Question 13

What do sensory receptors do when presented with a constant stimulus after a period of time?

Answer 13

They adapt to the stimulus.

Question 14

What are four mechanisms of stimulation for receptors?

Answer 14

Mechanical deformation

Application of a chemical

Temperature change

Electromagnetic radiation

Question 15

When applying a mechanical stimulus to a Pacinian corpuscle, what is the relationship between stimulus and receptor potential?

Answer 15

As stimulus strength increases, receptor potential increases and then levels off.

Question 16

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?

Answer 16

Tonic receptor

Question 17

What are types of tonic receptors?

Answer 17

Muscle spindles

Golgi tendon organs

Macula and vestibular receptors

Baroreceptors

Chemoreceptors

Question 18

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?

Answer 18

Phasic receptor

Question 19

What are characteristics of type A nerve fibers?

Answer 19

They are large and medium sized myelinated fibers of spinal nerves.

They are divided into alpha, beta, gamma and delta nerve fibers.

Question 20

What type of fibers are type c fibers?

Answer 20

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.

Question 21

What are group Ia (type A alpha) fibers?

Answer 21

Fibers from annulospiral endings of muscle spindles.

Question 22

What are group Ib (type A alpha) fibers?

Answer 22

Fibers from Golgi tendon organs

Question 23

What are group II (type A beta, gamma) fibers?

Answer 23

From cutaneous tactile receptors and flower-spray.

Question 24

What are group III (type A delta) fibers?

Answer 24

They carry temperature, crude touch, and prickling pain

Question 25

What are group IV (type C) fibers?

Answer 25

Carry pain, itch, temperature and crude touch.

Question 26

What is a difference between spatial and temporal summation?

Answer 26

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.

Question 27

What are some examples of neuronal pools?

Answer 27

``` Cerebral cortex Basal nuclei Thalamic nuclei Cerebellum Mesencephalon Pons Medulla Gray matter of spinal cord ```

Question 28

What is the stimulatory field of a neuronal pool?

Answer 28

The neuronal area within the pool stimulated by each incoming nerve fiber.

Question 29

What is the discharge zone of a neuronal pool?

Answer 29

Includes all the output fibers stimulated by the incoming fiber.

Question 30

What are the facilitated/inhibition zones?

Answer 30

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.

Question 31

What is the signficance of of diverging neuronal pathways?

Answer 31

They result in amplification of initial signal and allow transmission of the original signal to separate areas.

Question 32

What are convering neuronal pathways?

Answer 32

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.

Question 33

What are reverbatory circuits?

Answer 33

Circuits caused by positive feedback within the neuronal circuit. The circuit, once stimulated, may discharge repetitively for a long time.

Question 34

What are the five basic types of sensory receptors?

Answer 34

Mechanoreceptors Thermoreceptors Noceiceptors Electromagnetic receptors Chemoreceptors