General Sensory Mechanisms Flashcards Preview

A. White- Human Physiology > General Sensory Mechanisms > Flashcards

Flashcards in General Sensory Mechanisms Deck (34):
1

What type of receptor is a mechanoreceptor?

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

2

What are the mechanoreceptors with expanded tip endings?

Merkel's discs

3

What are the mechanoreceptors with encapsulated endings?

Meissner's corpuscles

Kraus' corpuscles

4

What are mechanoreceptors with spray endings?

Ruffini's corpuscles

5

What are three basic types of mechanoreceptors?

Hearing (cochlea)

Equilibrium (vestibular)

Arterial pressure (baroreceptors)

6

What is the function of thermoreceptors?

They have cold and warm receptors

7

What are nociceptors?

Free nerve endings responding to pain

8

What are the function of electromagnetic receptors?

They include rods and cones of the eye for vision.

9

What are the functions of chemoreceptors?

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

10

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.

11

What is modality?

It refers to each of the principal types of sensation

12

Describe the labeled line principle

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

13

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

They adapt to the stimulus.

14

What are four mechanisms of stimulation for receptors?

Mechanical deformation

Application of a chemical

Temperature change

Electromagnetic radiation

15

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.

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?

Tonic receptor

17

What are types of tonic receptors?

Muscle spindles

Golgi tendon organs

Macula and vestibular receptors

Baroreceptors

Chemoreceptors

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?

Phasic receptor

19

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.

20

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.

21

What are group Ia (type A alpha) fibers?

Fibers from annulospiral endings of muscle spindles.

22

What are group Ib (type A alpha) fibers?

Fibers from Golgi tendon organs

23

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

From cutaneous tactile receptors and flower-spray.

24

What are group III (type A delta) fibers?

They carry temperature, crude touch, and prickling pain

25

What are group IV (type C) fibers?

Carry pain, itch, temperature and crude touch.

26

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.

27

What are some examples of neuronal pools?

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

28

What is the stimulatory field of a neuronal pool?

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

29

What is the discharge zone of a neuronal pool?

Includes all the output fibers stimulated by the incoming fiber.

30

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.

31

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.

32

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.

33

What are reverbatory circuits?

Circuits caused by positive feedback within the neuronal circuit.

The circuit, once stimulated, may discharge repetitively for a long time.

34

What are the five basic types of sensory receptors?

Mechanoreceptors

Thermoreceptors

Noceiceptors

Electromagnetic receptors

Chemoreceptors