Lecture 4 - General Sensory Mechanisms

Question 1

Expanded Tip Endings Mechanoreceptors

Answer 1

Merkel’s discs and other variants

Question 2

Encapsulated Endings Mechanoreceptors

Answer 2

Meissner’s corpuscles and Kraus’ corpuscles

Question 3

Spray Endings Mechanoreceptors

Answer 3

Ruffini’s corpuscles

Question 4

Encapsulated Endings Mechanoreceptors

Answer 4

Pacinian corpuscles and other variants

Question 5

Hearing Mechanoreceptors

Answer 5

Sound receptors of cochlea

Question 6

Equilibrium Mechanoreceptors

Answer 6

Vestibular receptors

Question 7

Arterial Pressure Mechanoreceptors

Answer 7

Baroreceptors

Question 8

Mechanoreceptors

Answer 8

Include both free and encapsulated endings that receive either skin tactile sensibilities or deep tissue sensibilities

Question 9

Nociceptors

Answer 9

Free nerve endings responding to pain

Question 10

Electromagnetic Receptors

Answer 10

Include rods and cones of the eye for vision

Question 11

Chemoreceptors

Answer 11

Taste, smell, arterial oxygen, osmolarity, blood CO2, blood glucose, amino acids, and fatty acids

Question 12

Thermoreceptors

Answer 12

Cold and warm receptors

Question 13

Differential Sensitivity

Answer 13

Each type of receptor is highly sensitive to one type of stimulus and is almost nonresponsive to other types

Question 14

Modality

Answer 14

Refers to each of the principle types of sensation

Question 15

Labeled Line Principle

Answer 15

Refers to the specificity of nerve fibers for transmitting only one modality of sensation

Question 16

Adaptation

Answer 16

All sensory receptors adapt either partially or completely to any constant stimulus after a period of time; some receptors adapt to a far greater extent than others

Question 17

Receptor Potential

Answer 17

They are local; created by opening “modality” gated channels such as Na+ channels that are opened in response to membrane deformation caused by the touch or pressure; if it is strong enough (through summation), it may generate an action potential at the first node of ranvier on the primary sensory neuron

Question 18

Characteristics of Tonic Receptors

Answer 18

Slow adapting, detect continuous stimulus strength, transmit impulses as long as stimulus is present

Question 19

Types of Tonic Receptors

Answer 19

Muscle spindles, golgi tendon organs, macula and vestibular receptors, baroreceptors, chemoreceptors

Question 20

Characteristics of Phasic Receptors

Answer 20

Rapidly adapting, do NOT transmit a continuous signal, stimulated only when stimulus strength changes, transmit information regarding rate of change

Question 21

Type A Nerve Fiber

Answer 21

Further subdivided into alpha, beta, gamma, and delta; large and medium-sized myelinated fibers of spinal nerves

Question 22

Type C Nerve Fiber

Answer 22

Small, unmyelinated fibers; conduct signals at low velocity; make up more than half of all sensory fibers in most peripheral nerves and all postganglionic autonomic fibers

Question 23

Type A-alpha Fibers (Group Ia)

Answer 23

Fibers from annulospiral endings of muscle spindles

Question 24

Type A-alpha Fibers (Group Ib)

Answer 24

Fibers from Golgi tendon organs

Question 25

Type A-beta,gamma Fibers (Group II)

Answer 25

From cutaneous tactile receptors and flower-spray

Question 26

Type A-delta Fibers (Group III)

Answer 26

Carry temperature, crude touch, and pricking pain

Question 27

Type C Fibers (Group IV)

Answer 27

Carry pain, itch, temperature, and crude touch

Question 28

Spatial Summation

Answer 28

Increasing signal strength is transmitted by using progressively greater number of fibers

Question 29

Receptor Field

Answer 29

Cluster of nerve endings from one pain fiber that covers an area of skin; number of endings is large in center and reduced in periphery; nerve endings from one pain fiber overlap those of other pain fibers

Question 30

Temporal Summation

Answer 30

Increase signal strength by increasing frequency of nerve impulses in each fiber

Question 31

Examples of the Neuronal Pool

Answer 31

Cerebral cortex, basal nuclei, thalamic nuclei, cerebellum, mesencephalon, pons, medulla, and gray matter of spinal cord

Question 32

Stimulatory Field of Neuronal Pool

Answer 32

Neuronal area within the pool stimulated by each incoming nerve fiber; terminals for each input fiber lie on nearest neuron in its field; fewer terminals for each input fiber lie on neurons further away

Question 33

Discharge Zone

Answer 33

Includes all the output fibers stimulated by the incoming fiber

Question 34

Facilitated/Inhibition Zones

Answer 34

Neurons further from the discharge zone that are facilitated but not excited; may be inhibitory or excitatory depending on the input fiber

Question 35

Diverging Neuronal Pathways

Answer 35

May result in amplification of initial signal; may allow transmission of original signal to separate areas

Question 36

Converging Neuronal Pathways

Answer 36

Multiple input fibers converge onto a single output neuron; input fibers may be from a single source or from multiple separate sources

Question 37

Reverberatory Circuits (Oscillatory Circuits)

Answer 37

Caused by positive feedback within neuronal circuit; once stimulated, may discharge repetitively for a long time

Question 38

Somatic Senses

Answer 38

Collect sensory information from all over the body; can be mechanoreceptive, thermoreceptive, and pain

Question 39

Special Senses

Answer 39

Refer to vision, hearing, smell, taste, and equilibrium

Question 40

Exteroreceptive Sensations

Answer 40

From the surface of the body

Question 41

Propriceptive Sensations

Answer 41

Refer to physical state of body; position sensations, muscle and tendon sensations, pressure sensations, equilibrium

Question 42

Deep Sensations

Answer 42

Deep pressure, pain, and vibrations