Chapter 15 SNS Flashcards Preview

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Flashcards in Chapter 15 SNS Deck (38):
1

Visceral sensory information is primarily distributed to what brain regions?

reflex centers of the brain stem and diencephalon

2

Transduction

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

3

Receptive field

The area monitored by a single receptor cell.

4

Generator potential

A depolarizing receptor potential in a neural receptor

5

Labeled line

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

6

Sensory coding

the translation of complex sensory information into meaningful patterns.

7

Tonic receptors

Are always active

8

Phasic receptors

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

9

Adaptation

A reduction in the pressure of a constant stimuli
Includes slow and fast adapting receptors

10

Fast- adapting receptors

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

11

Slow-adapting receptors

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

12

General sensory receptors are classified by

the type of stimuli that excites them

13

Exteroceptors

Provide information about the external environment

14

Proprioceptors

Report the position and movement of skeletal muscles

15

Interoceptors

Monitor visceral organs and their functions

16

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

Nociceptors
Thermoreceptors
Mechanoreceptors
Chemoreceptors

17

Nociceptors

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)

18

Endorphins and enkephalins are neuromodulators that

inhibit activity along pain sensations

19

Thernoreceptors

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

20

Mechanoreceptors

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

21

Tactile receptors

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

22

Baroreceptors

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

23

Proprioceptors

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

24

Chemoreceptors

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

25

3 order neurons in ascending order

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)

26

3 major somatic sensory pathways

1. Spinothalamic
2. Posterior column pathway
3. Spinocerebellar

27

Spinithalamic pathway

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

28

Posterior column pathway

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

29

Spinocerebellar pathway

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

30

Our ability to recognize stimulus depends on

projection of information from the thalamus to the primary sensory cortex

31

Two motor neurons that are always involved in somatic motor pathways

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

32

Descending tracts of the spinal cord

Corticospinal pathway
Lateral pathways
Medial pathways

33

Corticospinal pathway (3 pairs of descending tracts)

Corticobulbar tracts
Lateral corticospinal
Medial corticospinal

34

Corticobulbar tracts

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

35

Medial pathway

Helps control gross motor motor movements of the trunk and proximal limbs. They include 3 tracts:
1. vestibulospinal
2. tectospinal
3. reticulospinal

36

Lateral pathway

Contols distal limb muscles and more precise movements
Cross over and descend the spinal cord through the rubrospinal tracts

37

Basal neucleiq

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

38

Cerebellum

Monitor proprioception, visual information, and balance.,