Outline 7 - Spinal reflexes Flashcards Preview

Advanced Human Physiology > Outline 7 - Spinal reflexes > Flashcards

Flashcards in Outline 7 - Spinal reflexes Deck (50):
1

The central nervous system consists of

the brain and spinal cord

2

The peripheral nervous system consists of

12 pairs of cranial nerves and 31 pairs of spinal nerves

3

The three types of fiber nerves are:

  • afferent (sensory)
  • efferent (motor)
  • mixed

4

The somatic system refers to 

  • perception and voluntary control
  • i.e. the 5 senses, equilibrium and skeletal muscles
  • It can be divided into somatic sensory, motor and visceral systems

5

The somatic sensory system includes

  • afferent nerves
  • i.e. pressure, temperature, pain, vibration in the skin

it carries information ​toward the CNS

6

The somatic motor system includes

  • efferent nerves
  • it carries information away from the CNS to effectors
  • they control skeletal muscle

7

The visceral system is

  • The autonomic nervous system i.e. internal organs
  • It can be subdivided into the sensory and motor systems
  • There is no perception and involuntary control
  • i.g. glandular epithelial cells, cardiac cells, smooth muscle cells

8

The visceral sensory system includes

  • pressure, chemical and osmolarity receptors
  • Can be divided into two systems:  Parasympathetic and Sympathetic

9

The special senses include

  • Audition
  • Olfaction
  • Gustation
  • Equilibrium
  • Vision

10

Interneurons are

  • aka association neurons
  • they lie between afferent and efferent nerves and shuttle signals through the CNS pathways where integration occurs
  • They make up 99% of neurons in the body

 

11

All reflex arcs have a ______ and a _______.

  1. sensory neuron
  2. motor neuron

12

Stretch reflex, Myotatic Reflex, Knee-Jerk reflex steps

  1. Stimulate muscle spindle (receptor)
  2. Receptor (spindle) sense overstretch of extensor
  3. Sensory neuron (afferent) carries info to SC/alpha motor neuron
  4. Alpha motor neuron stimulates contraction of extensor muscles
    1. NOTE: reflex is monosynaptic and ipsilateral

13

Inverse myotatic reflex, disynaptic reflex steps

  1. Stimulate golgi tendon reflex (GTO receptor)
  2. Sensory neuron (afferent) delivers signal to SC inhibitory interneuron
  3. Inhibitory interneuron inhibits activity of alpha motor neuron to stop muscle contraction
  4. NOTE: reflex is disynaptic and ipsilateral

14

To stimulate muscle contraction, the _______ are stimulated

alpha motor neurons

15

To stop motor contraction, the _________ are inhibited

alpha motor neurons

16

Simple withdrawal reflex steps

  1. Stimulate pain receptor
  2. Sensory/afferent neuron carries info to SC and synapses with (+) excitatory or (-)inhibitory neurons
  3. The (+) neuron stimulates flexor alpha neuron  and flexes muscle
  4. The (-) neuron inhibits extensor alpha neuron to stop contraction of extensor muscle
  5. This reflex is multisynaptic and ipsilateral
  6. Exhibits reciprocal inervation

17

Cross-extensor reflex steps

  1. Pain receptor stimulated when stepping on a tack
  2. Sensory neuron carries input to the SC
    1. (+) neuron stimulates flexor alpha neuron to contract ipsilateral flexor muscle
    2. (-) neuron inhibits extensor alpha neuron to inhibit extension of ipsilatoral extensor muscle
    3. (+) neuron stimulates the extensor alpha neuron to contract the contralateral extensor muscle
    4. (-) neuron inhibits the flexor alpha neuron to inhibit contraction of the flexor muscle
  3. Multisynaptic!

18

Gamma motor neuron control

 

  1. Extrapyramidal pathway originates in cerebellum and regulates gamma motor neurons
  2. GMN starts in ventral horn and increases the sensitivity to muscle stretch
  3. Once stretch is perceived, alpha motor neurons are excited
  4. Alpha motor neurons stimulate contraction to decrease stretch
  5. To prevent contraction of opposing muscle, the cerebellum inhibits GMN

19

During flexion 

alpha motor neurons = 

gamma motor neurons = 

  • alpha motor neurons = are inhibited, extrafusal fibers relax
  • gamma motor neurons = are excited, sensitivity is increased

20

During extension

alpha motor neurons = 

gamma motor neurons = 

  • alpha motor neurons = excited, muscle contracts
  • gamma motor neurons = inhibited, sensitivity decreased

21

Loss of the alpha motor neuron or lower motor neuron will result in 

  • flaccid paralysis

22

Loss of the upper motor neuron, will result in 

  • spastic paralysis

23

Damage to the gamma motor neuron will result in 

loss of ability to coordinate muscle activity

24

Sensory info from the legs enters the spine at the level of 

lumbar 

25

Sensory info from the arms enters the spinal column at 

C5 - C6

26

General pathway of sensory information is

  1. receptor, sensory neuron, SC, thalamus, parietal cortex
    1. or
  2. receptor, sensory neuron, SC, cerebellum

27

Dorsal columns

  1. Ascending/Decending
  2. Info carried
  3. Decussation (cross)
  4. Termination
  5. Result of damage

  1. Ascending
  2. 2 pt descrimination, deep pressure, vibration, conscious muscle sense
  3. Medulla
  4. Contralateral somatosensory cortex (parietal)
  5. sensory loss of contralateral side

28

Anterior spinothalamic tract

  1. Ascending/Decending
  2. Info carried
  3. Decussation (cross)
  4. Termination
  5. Result of damage

  1. Ascending
  2. Light touch
  3. Spinal cord
  4. Contralateral somatosensory cortex (parietal)
  5. Partial loss of unconsious muscle sense of the contralateral body parts

29

Lateral spinothalamic tract

  1. Ascending/Decending
  2. Info carried
  3. Decussation (cross)
  4. Termination
  5. Result of damage

  1. Ascending
  2. Pain and temperature
  3. Spinal cord
  4. contralateral somatosensory cortex (parietal)
  5. Pain and temp loss from contralateral body part

30

Posterior spinocerebellar tract

  1. Ascending/Decending
  2. Info carried
  3. Decussation (cross)
  4. Termination
  5. Result of damage

  1. ?
  2. Unconsious muscle and joint sense
  3. NO CROSS
  4. Parial loss of unconsious muscle sense of ipsilateral side of the body

31

Anterior Spinocerebellar tracts

  1. Ascending/Decending
  2. Info carried
  3. Decussation (cross)
  4. Termination
  5. Result of damage

  1. Ascending
  2. Unconscious muscle and joint sense
  3. Spinal cord/ some don't cross
  4. Cerebellum
  5. Partial loss of unsonscious muscle sense of contralateral side

32

Lateral corticospinal tract

  1. Ascending/Descending
  2. Info carried
  3. source
  4. Decussation (cross)
  5. Termination
  6. Result of damage

  1. Descending
  2. voluntary muscle control of appendage
  3. primary motor cortex, parietal lobe
  4. Medulla oblongata
  5. Interneurons or alpha motor neurons of the cord
  6. spastic paralysis of ipsilateral appendage

33

Anterior corticospinal tract

  1. Ascending/Decending
  2. Info carried
  3. Source
  4. Decussation (cross)
  5. Termination
  6. Result of damage

  1. Descending
  2. Movement of axial muscles
  3. primary motor cortex parietal lobe
  4. SC at innervation
  5. spastic paralysis of contralateral axial muscles

34

Extracorticospinal tracts

  1. Ascending/Decending
  2. Info carried
  3. source
  4. Decussation (cross)
  5. Termination
  6. Result of damage

  1. Descending
  2. postural muscle control (balance)
  3. Cerebellum, superior colliculus, red nucleus
  4. ?
  5. gamma motor neurons to adjust sensitivity of muscle spindles
  6. inability to control muscle activites

35

Damage to the afferent fiber of the spnial nerve or ascending pathways results in

loss of sensation (anesthesia)

36

Damage above spinal cord level T2 results in 

  • upper and lower extremeties loss

37

Damage below spinal cord level T2 results in 

  • Lower extremeties loss ONLY

38

Damage to the spinal cord at level (#) would result in what regarding reflexes?

  • no effect of reflexes above damage
  • Loss of reflex at level of damage
  • Hyperreflexia below level of damage

39

Sypathetic fibers have a ______ degree of divergence

high (multiple organ)

40

Parasympathetic fibers have a ____ degree of divergence

low (single organ)

41

Cholinergic receptors receive

acetylcholine

42

Adrenergic receptors receive

norepinephrine and epinephrine

43

Nicotinic NT affect

sympathetic and parasympathetic systems

all postganglionic fibers

44

Muscarinic NT receptors are found on 

parasympathetic postganglionic fibers

causes rest/digest response

45

Cholinergic blockers are

hesamethonium and atropine

46

alpha 1 receptors

adregnergic - vasoconstriction

excited by nicotine (not blocked)

47

alpha 2 

adrenergic - presynaptic inhibition

48

beta 1 receptor

HR and strenth of contraction

49

beta 2

relaxes smoothh msucle of bronchioles

50

autonomic tone

two divisions of ANS usually oppose each other and are always active, although their levels of activity vary