Chapter 16

Question 2

As sensory impulses reach CNS, they become part of?

Answer 2

large pool of sensory input

→each piece of incoming info is combined with other arriving & previously stored info in integration process

Question 3

Integration occurs at?

Answer 3

many places along pathways in spinal cord, brain stem, cerebellum, basal nuclei & cerebral cortex

Question 4

Sensations

Answer 4

conscious perception or subconscious awareness of changes occuring in external or internal environment

Question 5

Sensory Modality

Answer 5

each unique type of sensation

Question 6

A given sensory neuron carries info for how many modalities?

Answer 6

jus`t one

Question 7

2 classes of sensory modalities

Answer 7

1) general senses
2) special senses

Question 8

General senses

Answer 8

somatic senses

visceral senses

Question 9

somatic senses

Answer 9

include:

tactile → touch, pressure, vibration, itch, tickle

thermal → warm/cold

pain

proprioception→ awareness of limb & joint position in space

• conscious awareness

Question 10

visceral senses

Answer 10

provide info about conditions within internal organs

only become conscious when pain receptors stimulated

Question 11

Process of sensation begins in?

Answer 11

sensory receptor

• can be either specialized cell or dendrites of sensory neuron

Question 12

Selectivity of sensory receptors

Answer 12

characteristic of sensory receptors

particular kind of stimulus (change in env) activates certain sensory receptors, while others only respond weakly or not at all

Question 13

Process of Sensation (4 steps)

Answer 13

1) Stimulation of Sensory Receptor
2) Transduction of Stimulus
3) Generation of Nerve Impulses
4) Integration of Sensory Input

Question 14

1) Stimulation of Sensory Receptor

Answer 14

an appropriate **stimulus **must occur within receptor’s **receptive field **(region where stimulation activates receptor & produces response)

Question 15

2) Transduction of the stimulus

Answer 15

sensory receptor converts energy in stimulus to **graded potential **

(GPs vary in amplitude (size) depending on strength of stimulus & are not propagated)

exhibits **selectivity **(can only transduce 1 kind of stimulus)

Question 16

3) Generation of Nerve Impulses

Answer 16

when sum of GPs in (first-order) sensory neuron reaches **threshold, **triggers 1+ **nerve impulses **which propagate towards **CNS **

Question 17

4) Integration of Sensory Input

Answer 17

particular region of CNS integrates # or variety or sensory nerve impulses

results in **conscious sensation/perceptions **in cerebral cortex

Question 18

**Sensory Receptors **can be grouped into several classes based on **structural **& **functional characteristics **(3)

Answer 18

1) microscopic structure
2) location of receptors & origin of stimuli that activate them
3) type of stimulus **detected **

Question 19

Receptors named according to:

1) microscopic structure

Answer 19

1) Free nerve endings of first-order sensory neurons
2) encapsulated nerve endings of first-order sensory neurons
3) seperate nerve cells that synapse with first-order neurons

Question 20

1) Free nerve endings of first-order sensory neurons

Answer 20

bare dendrites without structural specifications

• include: **pain, temperature, tickle, itch **

Question 21

2) encapsulated nerve endings of first-order sensory neurons

Answer 21

dendrites enclosed in CT capsule

**pressure & vibration **

Question 22

3) seperate nerve cells that synapse with first-order neurons

Answer 22

include **specialized receptor cells **for special senses

**taste buds, hair cells **for hearing, photoreceptors

Question 23

Receptors named according to:
2) location & origin of stimuli that activates them

Answer 23

1) Exteroceptors
2) Interoceptors
3) Proprioceptors

Question 24

1) Exteroceptors

Answer 24

located at or near external surface of body and respond to external stimuli

Question 25

2) Interoceptors

Answer 25

visceroceptors - located in **blood vessels, organs, muscles ** produce impulses which usually are not consciously percieved

Question 26

3) Proprioceptors

Answer 26

located in **muscle, tendon, joints & inner ear ** - provide info about **body position, muscle length & tension, ****movement **of**joints **

Question 27

Receptors named according to **type of stimulus detected **

Answer 27

1) Mechanoceptors 2) thermoreceptors 3) nociceptors 4) photoceptors 5) chemoreceptors 6) osmoreceptors

Question 28

1) Mechanoceptors

Answer 28

sensitive to deformation

Question 29

2) thermoreceptors

Answer 29

detect changes in temp

Question 30

3) nociceptors

Answer 30

respond to painful stimuli

Question 31

4) photoceptors

Answer 31

activated by photons of light

Question 32

5) chemoreceptors

Answer 32

detect chemicals in **mouth **(**taste**), **nose **(**smell**) & body fluids

Question 33

6) osmoreceptors

Answer 33

detect osmotic pressure of body fluids

Question 34

Adaptation

Answer 34

characteristic feature of most sensory receptors in which **generator or receptor **potential **decreases **in amplitude during sustained or constant stimulus

Question 35

Why does the perception of a sensation fade or disappear even though stimulus persists?

Answer 35

because of **adaption ** *bc of accommodation response at receptor level, frequence of nerve impulses traveling to cerebral cortex decreases & perception of sensation fades despite persisting stimulus *

Question 36

Receptors vary in how quickly they adapt (2)

Answer 36

Rapidly adapting receptors - **specialized for signaling changes in stimulus **(pressure, touch, smell) Slowly adapting receptors - **adapt slowly & continue to trigger nerve impulses as long as stimulus persists **(pain, body position & chemical composition of blood)

Question 37

Thermoreceptors (2)

Answer 37

**cold & warm **receptors - both adapt quickly at onset of stimulus

Question 38

What temperature range will stimulate pain receptors instead of thermal receptors?

Answer 38

**below 10 degrees celsius ** **above 48 degrees celsius **

Question 39

Nociceptors

Answer 39

chemoreceptive free nerve endings activated by tissue damage from intense thermal, mechanical or chemical stimuli - found in **every tissue of body EXCEPT brain **

Question 40

(2) types of pain

Answer 40

1) fast 2) slow

Question 41

Fast pain

Answer 41

- Perception (**acute**, **well localized**) occurs **rapidly** bc nerve impulses propagate along **medium-diameter, myelinated A fibers**

Question 42

Slow Pain

Answer 42

begins after stimulus applied & **gradually increases in intensity** over period of several seconds/minutes - impulses conduct along **small-diameter unmyelinated C fibers ** - may be excruciating, often burning, aching, throbbing

Question 43

**Superficial **somatic pain

Answer 43

**pain** that arises from **stimulation** of **receptors** in **skin **

Question 44

**Deep** somatic pain

Answer 44

caused by stimulation of receptors in **skeletal muscles, joints, tendons & fascia **

Question 45

**Visceral **pain

Answer 45

from stimulation of **nociceptors **in visceral organs - felt in or just deep to skin overlying stimulated organ or in surface area far from stimulated organ (**referred pain**)

Question 46

**Proprioceptive sensations **allow us to know?

Answer 46

where are limbs are even with closed eyes

Question 47

**proprioceptors **inform us of?

Answer 47

degree of **muscle contraction, tension in tendons & joint positions **

Question 48

Tendon Organs

Answer 48

located at **junction of tendon & muscle ** - monitor tension

Question 49

Muscle Spindles

Answer 49

**proprioceptors **in skeletal muscle that monitor changes in length & participate in stretch reflexes

Question 50

How does brain set overall level of **muscle tone** (small degree of **contraction** that is present while **muscle is at rest)**

Answer 50

By **adjusting how vigorously muscle spindle responds** to stretching of skeletal muscle

Question 51

Muscle Spindles **consist of?**

Answer 51

several **slowly adapting **sensory nerve endings wrapped around **3-10 **specialized muscle fibers (**intrafusal muscle fibers**)

Question 52

Location of Muscle Spindles

Answer 52

plentiful in **muscles that control fine movements** more sparse in those that **control course/forceful movements **

Question 53

**2 ****kinds **of graded potentials produced by sensory receptors

Answer 53

1) **generator **potentials 2) **receptor **potentials

Question 54

1) **generator **potentials - produced by?

Answer 54

produced by dendrites of **free nerve endings, encapsulated nerve endings **& receptive part of **olfactory receptors ** - if large enough to reach **threshold, **triggers 1+ nerve impulses in first-order neuron axon which propogate along axon into CNS

Question 55

2) **receptor** potentials

Answer 55

produced by sensory receptors that are **seperate cells** - triggers release of **neurotransmitters** through **exocytosis **of synaptic vesicle - **diffuse** across synaptic cleft & produce **postsynaptic potential** in first-order neuron - may trigger 1+ nerve impulses which propogate along axon into CNS