Chapter 16-17 - Nerve Tracts and Autonomic Nervous System Flashcards Preview

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Flashcards in Chapter 16-17 - Nerve Tracts and Autonomic Nervous System Deck (79):
0

Two types of sensory and motor pathways

Ascending - conduct sensory impulses to brain
Descending - conduct motor impulses from the brain

1

Three ways sensory and motor pathways vary in complexity (sensory)

First order neuron - sensory info to CNS
Second order - receives impulse from first, spinal cord or brain stem
Third order - carries signal from thalamus to cerebral cortex

2

The way sensory and motor pathways vary in complexity (somatic motor pathways)

1. Upper motor neuron - in CNS
2. Lower motor neurons - from CNS to effector

3

Sensory and motor pathways vary in complexity (AUTONOMIC MOTOR PATHWAYS)

1. Upper motor neuron - in CNS
2. Preganglionic neuron - from CNS to peripheral ganglion
3. Postganglionic neuron - from ganglion to effector

4

- Sides cross in medulla
- Sensory impulses from skin, muscles, tendons and joints
- Perceived as fine touch, pressure, and body position

Posterior column pathway

5

What pathway is the posterior column pathway apart of?

Ascending pathway

6

What has tracks in the posterior white column?

Posterior column pathway

7

- Sides cross in spinal cord

Spinothalamic pathway

8

Sensation of pain and temperature

Lateral tract in the spinothalamic pathway

9

Spino in first part of the word

Ascending

10

Sensation of crude touch and pressure

Anterior tract in the spinothalamic pathway

11

Two tracts to the Spinocerebellar pathway

1. Anterior tract - slides cross in spinal cord
2. Posterior tract - do not cross over

12

Proprioception for fine coordination

Spinocerebellar pathway

13

What does the thalamus lack?

Synapses

14

Because the thalamus doesn't have synapses, what are the consequences?

- Never makes it to cortex
- Subconscious processing

15

Pathway that control voluntary movement

Corticospinal pathway

16

How is the corticospinal pathway generally direct?

Upper motor neurons synapse onto lower motor neurons

17

Three tracts in the Cortiocospinal pathway

1. Corticobubular tract - motor cranial nerves
2. Lateral corticospinal tract - motor spinal nerves, crosses over in medulla
3. Anterior corticospinal tracts - motor spinal nerves, does not cross over

18

Stimulate and inhibit same lower motor neurons as corticospinal

Medial pathway

19

Three tracts in the medial pathway

Vestibulospinal tracts - position and movement of head
Tectospinal tracts - reflexive head movement
Reticulospinal tracts - gross movements and muscles tone of trunk and proximal limb

20

Pathway that controls muscle tone and precise movement of distal upper limbs

Lateral pathway

21

The tract in the Lateral Pathway

Rubrospinal tract

22

What does the rubrospinal tract do?

- Start in red nucleus, crossover
- Extend to cervical region of spinal cord
- Skeletal muscles of distal upper limb

23

- Functions continuously and independently
- No conscious effort needed

Autonomic Nervous System

24

What activities does the autonomic nervous system control?

Visceral activities (HR, BP, breathing rate, body temperature, and response to stress)

25

The differences between autonomic NS and somatic NS

Autonomic NS - two neurons (results in additional synapses and ganglia)

Somatic NS - one peripheral motor axon (no peripheral synapsing or ganglia)

26

Two neurons in the Autonomic Nervous System

1. Preganglionic
2. Postganglionic

27

Location of preganglionic

- Soma in CNS
- Axon leaves CNS and forms synapse in autonomic ganglia

28

Location/Function of postganglionic

Soma in autonomic ganglia; axon goes to visceral effector

29

Two divisions of the autonomic NS

1. Sympathetic - for stressful situations
2. Parasympathetic - restores body to restful state

30

How do the sympathetic and parasympathetic systems relate?

- May work together
- Each controlling one stage in a sequence of events

31

How can the sympathetic and parasympathetic divisions work antagonistically?

- Cause different behaviors for different situations
- Certain organs are only innervated by one division

32

Where is the sympathetic division?

- Preganglionic fibers originate from thoracic and upper lumbar region
- T1-L2
- Soma in CNS

33

- In sympathetic division
- The process of preganglionic fibers

- Exit CNS
- Joint ventral root
- Travel with motor neurons in spinal nerve
- Leave spinal nerve
- Enter SYMPATHETIC GANGLIA

34

The sympathetic ganglia are made out of what?

Made out of the soma of postganglionic neurons

35

Two types of sympathetic ganglia with meanings

1. Chain ganglia - a sequence of ganglia running parallel to spinal column on either side
2. Collateral ganglia - in other areas of body

36

The amount of ganglia throughout the body

- three cervical
- 12 thoracic
- 2-5 lumbar
- 4-5 sacral
- 1 coccygeal

37

What does fusion of sympathetic chains cause?

Individual variability

38

Sympathetic chains are arranged how?

One on each side

39

The chain ganglion is innervated by what?

Presynaptic fibers from nerves T1 to L2 ONLY

40

What are chain ganglion not innervated by?

- No cervical nerve input
- No input from nerve L3 or inferior

41

Cervical, sacral, and many lummbar ganglia are NOT innervated by what?

Their corresponding spinal nerves

42

Thoracic nerves innervate ?

Cervical ganglia

43

Thoracic nerve innervates ?

Thoracic ganglia

44

These things innervate the lumbar and sacral ganglia

Only T12, L1, L2

45

Preganglionic fibers leave the spinal nerve and enter the chain via the ___

white ramus

46

One in the white ramus, chain preganglionic fibers

Take one of three paths

47

Three paths taken in the chain preganglionic fibers

1. Synapse with the ganglia at the point where they enter
2. Travel through the chain to synapse with another ganglion in the chain
3. Pass through and go directly to collateral ganglia or a gland

48

Where do the chain postganglionic fibers exit?

- Exit via gray ramus to spinal nerve to the effector
- Exit via sympathetic nerve to the effector

49

Process of presynaptic fibers going to the collateral ganglia

1. Presynaptic fibers go straight through chain ganglion with synapsing
2. Synapse with postganglionic fibers in collateral ganglia
3. Postganglionic fibers usually go to abdominal viscera

50

Major collateral ganglia

1. Celiac
2. Superior mesenteric
3. Inferior mesenteric

51

What do collateral ganglia do?

Deal for the most part with digestive processes

52

A modified collateral ganglia

Adrenal (suprarenal) medullae

53

What do the preganglionic fibers of Adrenal Medullae do?

- Go through both the chain and collateral ganglia to get to it
- Straight into the medulla of the adrenal gland

54

- Adrenal medullae
- Postganglionic fibers have been modified into glandular cells known as ______

Chromaffin cells

55

The chromaffin cells stimulate the production of the hormones _____ and _____

Epinephrine (E) and Norepinephrine (NE)

56

The hormones E and NE go where?

Go directly to the blood?

57

Sympathetic activation process

1. CNS stimulates preganglionic neurons
- Always release ACh on to a nicotinic receptor
2. Postganglionic neurons
- Release NE on to an adrenergic receptors

58

Stimulates postganglionic neurons or adrenal medulla

Nicotinic receptor

59

Stimulates target issues on postganglionic neurons

Adrenergic receptor

60

Effects of Sympathetic Division

- Increase alertness
- Energy and euphoria
- Excites cardiovascular and respiratory centers
- Increased muscle tone
- Mobilization of energy

61

Summary of sympathetic system

1. Preganglionic fiber is short; postganglionic is long
2. Synapsing occurs in sympathetic chain or collateral ganglia
3. Preganglionic fiber release Ach
4. Postganglionic fiber release NE
5. Prepares body for emergencies
6. Effects widespread and is persistent

62

Where is the parasympathetic system?

Originates from neurons in midbrain, pons, medulla and sacral region of spinal cord

63

Where does the parasympathetic system exit?

- Exit CNS via cranial nerves 3, 7, 9, and 10 and Sacral nerves 2-4

64

Preganglionic fibers in the Parasympathetic NS

- Cranial nerves 3, 4, and 9 go to ganglia near target organs (eyes and facial glands)
- Cranial nerves 10 and S2-4 converge in a large autonomic plexus, exit plexus and then go to target organs (heart, lungs, GI tract, urinary tract, and sexual organs)

65

Postganglionic fibers in parasympathetic system

- Usually very short
- Close to, or even within, target organs
- Effects or parasympathetic system is more focused and localized

66

Functions of the parasympathetic system

1. Constricts pupils
2. Stimulates secretion of digestive glands
3. Secretion of hormones promoting nutrient absorption
4. Increase motility of digestive tract
5. Stimulate defecation
6. Contraction of urinary bladder
7. Constriction of respiratory passages
8. Reduce HR and force of contraction
9. Sexual arousal

67

Parasympathetic activation

1. CNS stimulates preganglionic neurons
- Always release Ach onto a nicotinic receptor (stimulates postganglionic neruons)
2. Postganglionic neurons
- Release Ach onto a muscarinic receptor (stimulates target tissues)

68

Overview of parasympathetic activation

1. All neurons (pre and postganglionic release Ach)
2. Quickly "clean up" after release by Acetylcholinesterase
3. Short lived effects that are localized

69

Summary of Parasympathetic

1. Presynaptic neurons are long and secrete Ach
2. Postsynaptic neruons are short; produce Ach; either excitatory or inhibitory
3. Innervate organs in head and abdominal pelvic region
4. All ganglia in or near targets

70

When most organs receive innervation from both division

Dual innervation

71

Two components to dual innervation

1. Cranial area
2. Thoracic and abdominal regions

72

Explain cranial area in dual innervation

1. Sympathetic reaches via chain ganglia
2. Parasympathetic reaches via cranial ganglia

73

Explain thoracic and abdominal region dual innervation in dual innervation

- Sympathetic and parasympathetic mingle at plexuses

74

Examples of thoracic and abdominal regions of dual innervations

- Cardiac plexus
- Esophageal plexus

75

Simple functional units of the ANS

Visceral Reflexes

76

What do visceral reflexes do?

- Provide an autonomic motor response
- Common for digestive system

77

Two types of visceral reflexes with their meanings

Long reflexes - go to the CNS for processing
Short reflexes - are processed in the autonomic ganglion

78

Control of autonomic activity

- Many control centers in medulla
- Hypothalamus regulates body temperature
- Limbic system and cerebral cortex control ANS when person stressed