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Anatomy > Chapter 16-17: Nerve Tracts and the Autonomic Nervous System > Flashcards

Chapter 16-17: Nerve Tracts and the Autonomic Nervous System Flashcards

1
Q

What are the two types of pathways?

A

ascending –>conduct sensory impulses to brain

descending –>conduct motor impulses from brain

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2
Q

Sensory and Motor pathways vary in complexity. what are the different orders for sensory? describe them

A

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

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3
Q

what are the two somatic pathways?

A

upper motor neuron = in CNS

lower motor neurons = from CNS to effector

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4
Q

what are the three autonomic motor pathways?

A

upper motor neuron = in CNS
Preganglionic neuron = from CNS to peripheral ganglion
Postganglionic neuron = from ganglion to effector

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5
Q

What are the three Ascending Pathways?

A

Posterior Column Pathway
Spinothalamic Pathway
Spinocerebellar Pathway

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6
Q

describe Posterior Column Pathway

A

sides cross in medulla

  • sensory impulses from skin, muscles, tendons & joints
  • perceived as fine touch, pressure & body position
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7
Q

describe Spinothalamic pathway

A 
sides cross in spinal cord 
lateral tract
-sensation of pain and temperature 
anterior tract
-sensation of crude touch and pressure
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8
Q

describe Spinocerebellar Pathway

A

-anterior tract (sides cross in spinal cord)
-posterior tract (do not cross over)
-proprioception for fine coordination
-no synapse in thalamus
(Never makes it to cortex)
(subconscious processing)

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9
Q

What are the three descending pathways?

A

Corticospinal Pathway
Medial Pathway
Lateral Pathway

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10
Q

describe Corticospinal pathway

A
  • controls voluntary movements
  • generally direct
  • upper motor neurons synapse onto lower motor neurons
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11
Q

What are the three tracts in the Corticospinal pathway? describe them

A
  1. ) corticobulbar 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
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12
Q

What does the Medial pathway do?

A

stimulate & inhibit same lower motor neurons as corticospinal

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13
Q

What are the three tracts in the Medial pathway?

A

1.) vestibulospinal tracts
-position & movement of head
2.) tectospinal tracts
-reflexive head movements
3.) reticulospinal tracts
gross movements & muscle tone of trunk and proximal limb

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14
Q

What does the Lateral pathway do?

A
  • muscle tone & precise movements of distal upper limb

- stimulate & inhibit same lower motor neurons as corticospinal

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15
Q

What is the tract called that is located in the Lateral pathway? describe it

A

rubrospinal tracts

  • start in red nucleus–> cross-over
  • extend to cervical region of spinal cord
  • skeletal muscles of distal upper limb
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16
Q

Slide 16 for tree diagram of Descending Pathways

A

:)

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17
Q

describe the Autonomic nervous system (3)

A
  1. ) Functions continuously & independently
  2. ) No conscious effort needed
  3. ) Controls visceral activities
    - HR, BP, breathing rate, body temperature, response to stress
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18
Q

Compare the Autonomic and Somatic NS

A

Autonomic NS:
The pathway usually consists of two neurons
-Results in an additional synapse
-May result in additional ganglia

Somatic NS:
usually has only one peripheral motor axon
-No peripheral synapsing or ganglia

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19
Q

For the Autonomic Nerve fibers, what are the two neurons? describe them

A

Preganglionic:

  • Soma in CNS
  • axon leaves CNS & forms synapse in autonomic ganglia

Postganglionic:
-Soma in autonomic ganglia; axon goes to visceral effector

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20
Q

What are the two divisions of the Autonomic NS. briefly state when they are used

A

Sympathetic: for stressful situations
Parasympathetic: restores body to restful state

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21
Q

Do the parasympathetic and sympathetic division work together or against each other? explain

A

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

Often work antagonistically

  • Cause different behaviors for different situations
  • Certain organs are only innervated by one division
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22
Q

describe the sympathetic division

A
  • Preganglionic fibers originate from thoracic & upper lumbar region
  • T1-L2
  • Soma in CNS
23
Q

describe the preganglionic fibers in the sympathetic division

A 
exit CNS
join ventral root
travel with motor neurons in spinal nerve
leave spinal nerve
Enter sympathetic ganglia
24
Q

What are the sympathetic ganglia made up of?

A

soma of postganglionic neurons

25
Q

What are the two sympathetic ganglia? describe them

A
  1. ) Chain Ganglia
    - A sequence of ganglia running parallel to spinal column on either side.
  2. ) Collateral ganglia:
    - in other areas of body
26
Q

How many and where are the sympathetic ganglia located on the vertebrae?

A 
3 cervical
12 thoracic
2-5 lumbar 
4-5 sacral 
1 coccygeal

*Fusion causes individual variability

27
Q

The chain ganglion is innervated by presynaptic fibers from nerves ___-___ ONLY

A

T1-L2
***NO cervical nerve input
NO input from nerve L3 or inferior
(slide 25)

28
Q

Cervical, sacral, and many lumbar ganglia (are/are not) innervated by their corresponding spinal nerves. Explain if needed

A

are NOT.

Thoracic nerves innervate cervical ganglia
Thoracic nerves innervate thoracic ganglia
ONLY T12, L1 and L2 innervate the lumbar and sacral ganglia

29
Q

______________ leave the spinal nerve and enter the _____ via the ________. Once there, one of three paths are taken. What are these three paths?

A

Preganglionic fibers; chain; white ramus

  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
30
Q

Postganglionic fibers exit via the….. (2 things)

A

Exit via gray ramus to spinal nerve to the effector

Exit via sympathetic nerve to the effector

31
Q

describe collateral ganglia

A
  • Presynaptic fibers go straight through chain ganglion without synapsing
  • Synapse with postganglionic fibers in collateral ganglia
  • Postganglionic fibers usually go to abdominal viscera
32
Q

What are the three major collateral ganglia?

A

Celiac
Superior mesenteric
Inferior mesenteric

33
Q

what do the collateral ganglia do?

A

Deal for the most part with digestive processes

34
Q

what is a Adrenal (suprarenal) medullae

A

a modified collateral ganglia that stimulates the production of the hormones norepinephrine and epinephrine (go directly into the blood)

35
Q

for the Adrenal (suprarenal) medullae, describe the preganglionic and postganglionic fibers

A

Preganglionic fibers

  • go through both the chain and collateral ganglia to get to it
  • straight into the medulla of the adrenal gland

Postganglionic fibers have been modified into glandular cells known as chromaffin cells

(slide 34-35 for pictures)

36
Q

describe sympathetic activation

A

1.) CNS stimulates preganglionic neurons:
-always release ACh
-on to a nicotinic receptor
(stimulates postganglionic neurons or adrenal medulla)
2.) postganglionic neurons:
-release NE on to an adrenergic receptor
(stimulates target tissues)

37
Q

What are the 5 effects of the sympathetic nervous system?

A 
Increase alertness
Energy & euphoria
Excites cardiovascular & respiratory centers
Increased muscle tone
Mobilization of energy
38
Q

summarize the sympathetic (6 things)

A
  1. ) Preganglionic fiber is short; postganglionic is long
  2. ) Synapsing occurs in sympathetic chain or collateral ganglia
  3. ) Preganglionic fiber releases Ach
  4. ) Postganglionic fiber releases NE
  5. ) Prepares body for emergencies
  6. ) Effects widespread & persistent
39
Q

Where does the parasympathetic system originate and exit?

A
  • Originates from neurons in midbrain, pons, medulla & sacral region of spinal cord
  • exit CNS via cranial nerves 3, 7, 9 & 10 and sacral nerves 2-4
40
Q

For the parasympathetic preganglionic fibers, Cranial nerves III, VII, and IX go to _________________

A

ganglia near target organs

eyes and facial glands

41
Q

For the parasympathetic preganglionic fibers, Cranial nerve X and S2-4……. (3)

A
  • converge in a large autonomic plexus
  • Exit plexus and then to target organs
  • Heart, lungs, GI tract, urinary tract, sexual organs
42
Q

describe the postganglionic fibers in the parasympathetic

A

Usually very short
Close to, or even within, target organs
Effects of parasympathetic system are more focused and localized.

43
Q

What are the effects of the parasympathetic nervous system? (9)

A 
Constrict pupils
Stimulate secretion of digestive glands
Secretion of hormones promoting nutrient absorption
Increase motility of digestive tract
Stimulate defecation
Contraction of urinary bladder
Constriction of respiratory passages
Reduce HR & force of contraction
Sexual arousal
44
Q

describe parasympatheric activation

A

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

45
Q

3 important facts about parasympathetic activation

A
  • All neurons (pre- and postganglionic) release Ach
  • Quickly ‘cleaned up’ after release by Acetylcholinesterase.
  • Short lived effects that are localized
46
Q

Summarize the parasympathetic (4)

A
  • Presynaptic neurons are long & secrete Ach
  • Postsynaptic neurons are short, produce Ach; either excitatory or inhibitory
  • Innervate organs in head & abdominal pelvic region
  • All ganglia in or near targets
47
Q

what does dual innervation mean?

A

Most organs receive innervation from both divisions

48
Q

in the cranial area, where do both divisions receive innervation? and via what ganglia?

A

Sympathetic reaches via chain ganglia

Parasympathetic reaches via cranial ganglia

49
Q

in the Thoracic & abdominal region, where do both divisions receive innervation?

A

Sympathetic & parasympathetic mingle at plexuses
Examples:
Cardiac plexus
Esophageal plexus

50
Q

describe visceral reflexes (3)

A

Simple functional units of the ANS
Provide an autonomic motor response
Common for digestive system

51
Q

What are the two types of visceral reflexes?

A

Long reflexes: go to the CNS for processing

Short reflexes: are processed in the autonomic ganglion

52
Q

There are many autonomic control centers in the_____

A

medulla

53
Q

the hypothalamus regulates______

A

body temperature

54
Q

______________control ANS when ______________

A

Limbic system and cerebral cortex; person is stressed

Anatomy (23 decks)

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