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Flashcards in Autonomics/Chapman's Points Deck (42)
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1

Afferents into the spinal cord gray matter synapse at what layers?

Upper layers

2

Interneurons and motorneuron cell bodies are at what spinal cord gray matter layers?

Lower layers

3

A majority of the interneurons receive input from?

BOTH visceral and somatic afferents

4

Do visceral and somatic afferents overlap?

Yes

5

Interactions with somatic _____ localize pain

Efferents

6

Cortical inhibition

Descending influences on reflexes
- Excitation amplifies output
- Inhibition reduces output

7

Facilitated segment concept

Constant afferent bombardment by injured somatic or visceral fibers leads to segmental excitation which produces excessive efferent response

8

For facilitated segment concept, the low threshold spinal reflexes represent a _____ pathway state caused by continuous bombardment of inputs

Hyper-excited pathway

9

What did the facilitated segment concept researchers use to show somatic reflex changes?

EMG

10

Sensitization

Process of increasing a response of a neural pathway with repetitive stimulation

11

Habituation

Process of decreasing a response of a neural pathway with continuous stimulation

12

The nociceptive theory of facilitation says that _____ and ____ exist together to maintain homeostasis

Sensitization and Habituation

13

Current theory as to cause for facilitation involves?

Alteration of nociceptive input

14

Describe the order of events for the nociceptive theory of facilitation

Once a stimulus is strong enough it travels to cord and branches
- releases peptides
- chemical soup (inflammatory cascade) spreads in tissues and cord
- Lowers threshold for nociceptors and interneurons
= Results in a larger than normal motor and autonomic output in those spinal level associated areas

15

Facilitation

Maintenance of a pool of neurons in a state of subthreshold excitation
- LESS afferent stimulation is needed to trigger discharge of impulses

16

What may cause facilitation?

Aberrant patterns of afferent input
Sustained increase in afferent input

17

Once facilitation is established, how is it maintained?

Normal CNS activity - self sustaining

18

Allostasis

Response to stress in attempt to regain homeostasis

19

What is the longterm neural effect of segmental facilitation?

Allostasis overload

20

Describe the steps to allostasis overload

Stimulus
Chemical soup of inflammatory mediators
Primary afferent sensitization
Hyperalgesia and prolonged response
Central sensitization of spinal cord neurons
Brainstem decreases descending inhibition
= allostasis overload

21

Allostasis overload can cause?

HTN, Depression, anxiety, memory loss, etc.

22

What are the 4 reflex types?

1. Somatosomatic
2. Somatovisceral
3. Viscerosomatic
4. Viscerovisceral

23

Somatosomatic reflex

Somatic stimuli produces reflex response in somatic structures
- ex. withdrawal response

24

Somatovisceral reflex

Somatic stimuli produces reflex response in visceral structures

25

Ex. of somatovisceral reflex

Somatocardiac
Somatogastric
Somatoadrenal
-- somatic stimuli (pain) causes visceral response

26

Somatocardiac reflex (somatovisceral)

Nociceptive pain somatic stimuli causes an increased HR and BP

27

Somatoadrenal reflex (somatovisceral)

Nociceptive pain somatic stimuli causes the release of catecholamines (adrenalin)

28

Viscerosomatic reflex

Visceral stimuli produces reflex response in somatic structures
ex. Cardiac visceral pain experienced as somatic pain

29

Viscerovisceral reflex

Visceral stimuli produce reflex response in visceral structures

30

Ex. of a viscerovisceral reflex

Gastrocolic = Distention of gut --> contraction of gut muscle
- when you eat you poop