Ch 10

Question 1

What are the somatic senses?

Answer 1

Touch, temp, pain, itch, proprioception

Question 2

What is a graded potential called in somatic senses?

Answer 2

Receptor potential

Question 3

What is a simple receptor in a sensory neuron?

Answer 3

Free nerve endings

Question 4

What is the pacinian corpuscle?

Answer 4

Complex neural receptor with a connective tissue capsule. Good at feeling vibration/changing sensation

Question 5

How do most of the special senses receptors work?

Answer 5

Special receptor cells are cells that release neurotransmitter onto sensory neurons

Question 6

Was is an adequate stimulus?

Answer 6

Form of energy to which a receptor is most receptive

Question 7

When multiple primary sensory neurons converge to create a large receptive field on the skin, what does this allow for?

Answer 7

Simultaneous subthreshold stimuli can sum at the secondary neuron to initiate an action potential

Question 8

What two pathways can sensory information travel to reach the brain?

Answer 8

Via spinal cord by ascending tracts
Via cranial nerves directly to the brain

Question 9

What kind of senses do not usually reach conscious perception?

Answer 9

Visceral reflexes integrated in brain stem or spinal cord

Question 10

What is a perceptual threshold? What is unique about it?

Answer 10

Level of stimulus necessary to be aware of particular sensation. It is not a fixed value. Ex. You don’t feel your clothes all day

Question 11

What is the pre-central gyrus also known as?

Answer 11

Primary motor cortex

Question 12

What is the post-central gyrus also known as?

Answer 12

Primary somatosensory cortex

Question 13

What special sense does not pass information through the thalamus?

Answer 13

Olfaction

Question 14

Where do equilibrium pathways primarily project?

Answer 14

Cerebellum

Question 15

How does our brain determine the modality of a stimulus?

Answer 15

Indicated by where sensory neurons are activated and where neuronal pathway terminates in the brain

Question 16

How does our brain determine the location of a stimulus?

Answer 16

According to which receptive fields are activated

Question 17

How is lateral inhibition performed?

Answer 17

When multiple secondary neurons are activated, the one with the highest stimulation will trigger intermediate neurons that dampen other secondary neurons will a less-prevalent stimulus. The secondary neuron with the highest stimulation stands out more

Question 18

What about action potentials help the brain to determine stimulus intensity and duration?

Answer 18

Frequency of action potentials is proportional to intensity. Duration of a series of action potentials is proportional to duration

Question 19

What is a tonic receptor?

Answer 19

A receptor that keeps firing as long as the stimulus is there

Question 20

What is a phasic receptor?

Answer 20

A receptor that fires at the beginning of stimulation only. This allows to sense change, like in touch

Question 21

Of phasic and tonic receptors, which respond quickly and slowly?

Answer 21

Tonic receptors are slowly adapting to receptors

Phasic receptors are rapidly adapting

Question 22

What does nociception perceive?

Answer 22

Pain and itch

Question 23

Which somatic senses cross the midline in the medulla?

Answer 23

Fine touch, proprioception, and vibration

Question 24

Which somatic sense cross the midline in the spinal cord?

Answer 24

Coarse touch, nociception, and temperature

Question 25

What stimulus acts on free nerve endings of the somatic senses? Where are these nerves found? What is their adaptation rate?

Answer 25

Temperature, noxious stimuli, hair movement Around the hair roots and under the surface of the skin (epidermis) Variable adaptation

Question 26

What stimulus is best detected by Meissner’s corpuscle? Where are Meissner’s corpuscles? What is the structure of Meissner’s corpuscle? What is the adaptation rate of Meissner’s corpuscle?

Answer 26

Flutter, stroking Superficial layers of skin (dermal papillae) Encapsulated in connective tissue Rapid

Question 27

What stimulus is detected by Pacinian corpuscles? Where are pacinian corpuscles? What is the structure of pacinian corpuscles? What is the adaptation rate of pacinian corpuscles?

Answer 27

Vibration Deep layers of skin (dermis) Encapsulated in connective tissue Rapid

Question 28

What stimulus do Ruffini corpuscles detect? Where are Ruffini corpuscles? What is the structure of Ruffini corpuscles? What is the adaptation rate of Ruffini corpuscles?

Answer 28

Stretch of skin Deep layers of skin (Dermis) Enlarged nerve endings Slow

Question 29

What stimulus is detected by Merkel receptors? Where are Merkel receptors? What is the structure of Merkel receptors? What is the adaptation rate of Merkel receptors?

Answer 29

Steady pressure, texture Superficial layers of skin (epidermis/epidermal basement membrane) Enlarged nerve endings Slow

Question 30

What changes about free nerve endings at 45 degrees Celsius?

Answer 30

Free nerve endings sensing heat stop picking up a stimulus at 45 degrees C. Pain receptors start picking up stimulus at 45 degrees C

Question 31

What is substance P?

Answer 31

Secreted by primary sensory neurons (nociceptors) to mediate inflammatory response

Question 32

What are the characteristics of A beta fibers? What are they associated with?

Answer 32

Large, myelinated Mechanical stimuli

Question 33

What are the characteristics of A delta fibers? What are they associated with?

Answer 33

Small, myelinated Cold, fast pain, mechanical stimuli

Question 34

What are the characteristics of C fibers? What are they associated with?

Answer 34

Small, unmyelinated Slow pain, heat, cold, mechanical stimuli

Question 35

What causes an itch?

Answer 35

Histamines activate C fibers

Question 36

What is the gating theory? Why is gating important?

Answer 36

Tonic, inhibitory interneurons can act on secondary neurons so that C fibers cannot transmit pain signals. C fibers can only transmit if the stimulus is strong enough to overcome the interneuron inhibition on the secondary neurons or if another interneuron inhibits the inhibitory neuron. Somatosensory input can also activate the inhibitory interneuron This allows for nociceptors and other touch-related nerve endings to be on close proximity without every touch causing pain.

Question 37

What kind of somatosensory fiber activates the inhibitory interneuron involved in the gatekeeping theory?

Answer 37

A beta fiber

Question 38

What is ischemia? What is the name for the associated pain?

Answer 38

Lack of adequate blood flow Pain is called angina

Question 39

What is the mechanism of action of Aspirin?

Answer 39

Inhibits COX formation (like in the arachidonic acid cascade) which, in turn, inhibits prostaglandins and thrombocytes (paracrine signals for inflammation)

Question 40

How do opioids work?

Answer 40

Block pain perception by decreasing primary sensory neurons neurotransmitter release and by postsynaptic inhibition of secondary sensory neurons

Question 41

What molecules naturally activate opioid receptors?

Answer 41

Endorphins, enkephalins, dynorphins