Chapter 15 SNS

Question 1

Visceral sensory information is primarily distributed to what brain regions?

Answer 1

reflex centers of the brain stem and diencephalon

Question 2

Transduction

Answer 2

sensory receptors detect arriving stimulus, translate it into an action potential which conducts it to the CNS.

Question 3

Receptive field

Answer 3

The area monitored by a single receptor cell.

Question 4

Generator potential

Answer 4

A depolarizing receptor potential in a neural receptor

Question 5

Labeled line

Answer 5

The link between a peripheral receptor and cortical neuron which consists of axons carrying information about modality (touch, pressure, light and sound)

Question 6

Sensory coding

Answer 6

the translation of complex sensory information into meaningful patterns.

Question 7

Tonic receptors

Answer 7

Are always active

Question 8

Phasic receptors

Answer 8

Usually not active, provide information about intensity and rate of change in stimuli

Question 9

Adaptation

Answer 9

A reduction in the pressure of a constant stimuli

Includes slow and fast adapting receptors

Question 10

Fast- adapting receptors

Answer 10

Peripheral adaptation that occurs when the level of receptor activity changes. They respond strongly at first then gradually decrees-phasic (thermoreceptors)

Question 11

Slow-adapting receptors

Answer 11

Tonic fibers, show little peripheral adaptation they include pain receptors (nociceptors)

Question 12

General sensory receptors are classified by

Answer 12

the type of stimuli that excites them

Question 13

Exteroceptors

Answer 13

Provide information about the external environment

Question 14

Proprioceptors

Answer 14

Report the position and movement of skeletal muscles

Question 15

Interoceptors

Answer 15

Monitor visceral organs and their functions

Question 16

Detailed classification of 4 types of receptors by stimulus that excites them

Answer 16

Nociceptors
Thermoreceptors
Mechanoreceptors
Chemoreceptors

Question 17

Nociceptors

Answer 17

Pain receptors that are especially common in the superficial skin, in joints, in periostea, and round artery walls
Maybe sensitive to:
1. extremes in temperature
2. mechanical damage
3. dissolved chemicals
Type A fibers carry fast pain (pricking)
Type C fibers carry slow pain (burning and aching)

Question 18

Endorphins and enkephalins are neuromodulators that

Answer 18

inhibit activity along pain sensations

Question 19

Thernoreceptors

Answer 19

free nerve endings located in the skin and skeletal muscles, in the liver and hypothalamus. Consist of hot and cold but cold are 3-4 times more numerous

Question 20

Mechanoreceptors

Answer 20

Contain mechanically gated ion channels that close in response to stretching, compression, twisting or other distortions of their membrane. 
3 classes are:
1. Tactile
2. Baroreceptors
3. Proprioceptors

Question 21

Tactile receptors

Answer 21

Provide sensations of touch, pressure and vibration

1. free nerve endings: in epidermal cells and the cornea
2. root hair plexus: adapt rapidly
3. tactile discs/merkle: fine touch
4. tactile corpuscle/meissner’s: recieve fine touch pressure and vibration
5. lamellated corpuscle/pacinian: deep pressure
6. ruffini corpuscle: located in deep dermis and show little adaptation

Question 22

Baroreceptors

Answer 22

Monitor changes in pressure in an organ and walls of major blood vessels. (carotid sinuses and aortic sinuses) Also in the lungs.
Respond immediately to changes in pressure

Question 23

Proprioceptors

Answer 23

Monitor the position of joints, tendons and skeletal muscles
3 types are:
1. Muscle spindles: monitor stretch
2. Golgi tendon organs: joint between skeletal muscles and tendons
3. Receptors in joint capsule
Do not adapt and constantly send information to the CNS

Question 24

Chemoreceptors

Answer 24

Detect small changes in specific chemicals or compounds . Generally only respond to water or lipid soluble compounds.
Monitor pH and CO2 levels in the blood

Question 25

3 order neurons in ascending order

Answer 25

first order: delivers sensation to the CNS (meaning spinal cord)
second order: interneuron that maybe located in the spinal cord or brain
third order (if sensation is to reach awareness the 2nd order synapses with a 3rd order)

Question 26

3 major somatic sensory pathways

Answer 26

1. Spinothalamic
2. Posterior column pathway
3. Spinocerebellar

Question 27

Spinithalamic pathway

Answer 27

Provides conscious sensation of poorly localized (crude) touch, pain and pressure.
1st: synapses in posterior grey horn with 2nd
2nd: Interneurons cross the spinal cord before ascending to the thalamus
3rd synapses with the primary motor cortex

Question 28

Posterior column pathway

Answer 28

Carries fine touch sensations of touch pressure vibration and propioception. Contains the faciculus gracilis and fasciculus cuneatus.

1st: enters through dorsal root ganglion and ascends to synapse in the medulla with the 2nd
2nd: which then crosses the medulla and ascends to the thalamus to synapse with the 3rd
3rd: enters the primary sensory cortex

Question 29

Spinocerebellar pathway

Answer 29

1sr: synapse in the posterior grey horns, the anterior tract crosses over and the posterior tract does not.
2nd: ascend to the cerebellum.
Does not reach our awareness
“double cross” so they synapse on the same side as the original stimulous

Question 30

Our ability to recognize stimulus depends on

Answer 30

projection of information from the thalamus to the primary sensory cortex

Question 31

Two motor neurons that are always involved in somatic motor pathways

Answer 31

Upper motor neurons: cell body lies in the CNS processing center
Lower motor neurons: cell body lies in a nucleus of the brain stem of spinal cord

Question 32

Descending tracts of the spinal cord

Answer 32

Corticospinal pathway
Lateral pathways
Medial pathways

Question 33

Corticospinal pathway (3 pairs of descending tracts)

Answer 33

Corticobulbar tracts
Lateral corticospinal
Medial corticospinal

Question 34

Corticobulbar tracts

Answer 34

Synapse on the lower motor neuclei of cranial nerves III, IV, V, VI, VII, IX, XII. Provide conscious control over these regions and innervate the motor centers of the medial and lateral pathways

Question 35

Medial pathway

Answer 35

Helps control gross motor motor movements of the trunk and proximal limbs. They include 3 tracts:

1. vestibulospinal
2. tectospinal
3. reticulospinal

Question 36

Lateral pathway

Answer 36

Contols distal limb muscles and more precise movements

Cross over and descend the spinal cord through the rubrospinal tracts

Question 37

Basal neucleiq

Answer 37

Provide back ground patterns of movement involved in voluntary movement patterns by:

Question 38

Cerebellum

Answer 38

Monitor proprioception, visual information, and balance.,