7.1 Autonomic Nervous System

Question 1

What do the motor neurons in the ANS do

Answer 1

• Innervate smooth muscle, cardiac muscle & glands
• Make adjustments to ensure optimal support for body activities
• Operate via subconscious control

Question 2

divisions of the autonomic nervous system

Answer 2

sympathetic and parasympathetic

Question 3

comparison of neurons and actions in somatic and autonomic nerous system

Answer 3

• Somatic
  
  • cell bodies in central NS
  • single neuron from CNS to effector organs
  • release ACh
  • always stimulatroy
• Autonomic
  
  • cell bodies in central NS
  • two neuron chain from CNS -> effector organ
    
    • preganglionic myelinated axons releases Ach to non myelinated postganglionic
  • release ACh OR NE to effector
  • stimulatory or inhibitory

Question 4

the ANS has ____ innervation

Answer 4

Dual innervation

(inputs from sympathetic and non sympathetic NS)

• almost all visceral organs served by both divisions but cause opposite effects

Question 5

compare origin of fibers, length and location of ganglia in PSNS vs SNS

Answer 5

• Parasympathetic
  
  • origin of fibers: craniosacral (brain & S2-4)
  • Length: long pregnaglionic, short postganglionic
  • location of ganglia: visceral effector organs
• Sympathetic
  
  • origin of fibers: thoracolumbar (T1-L2)
  • legnth: short preganglionic, long postganglionic
  • location of ganglia: close to spinal chord (synpase close to it)

Question 6

What is the role of the parasympathetic division?

Answer 6

• maintenance activities & conserves body energy
  ex: a person who relaxes, reading, after a meal:
• > Blood pressure, heart rate & respiratory rates are low
• > Gastrointestinal tract activity is high
• > Pupils are constricted & lenses are accommodated for close vision

” D division: digestion, defication and urine porduction”

Question 7

what roots are involed in PSNS division outflow

Answer 7

Oculomotor (CN III)

Facial (CN VII)

Glossopharyngeal (CN IX)

Vagus (CN X)

Question 8

what is the ganlia, lits location and effector organs for

oculomotor (CN III)

Answer 8

Ganglia: cilliary ganglion

ganglia location: posterior orbit

Effector organ: eye (ciliary muscle & sphincter pupillae)

*makes pupil smaller

Question 9

what is the ganlia, lits location and effector organs for

facial (CN VII)

Answer 9

Ganglia: Pterygopalatine and submandicular ganglion

Location of ganglion: pterygopalatine fossa & infratemporal fossa

effector organ: Nasal, palatine & lacrimal glands, & Submandibular & sublingual salivary glands

Question 10

what is the ganlia, lits location and effector organs for

glossopharyngeal (CN IX)

Answer 10

ganglia: otic ganglion
location: infratemporal fossa

effector organ: parotid salivary glands

Question 11

what is the ganlia, lits location and effector organs for

Vagus nerve (CN X)

Answer 11

ganglia: intramural ganglion
location: in walls of target organs

effector organs: most visceral organs

Question 12

what is the ganlia, its location and effector organs for

sacral parasympathetic division outflow

Answer 12

*S_2-S₄

• ganglia: intramural ganglion
  location: within walls of target organs

effector organs: Distal large intestine, urinary bladder, ureters & reproductive organs

Question 13

what is the role of the sympathetic divison

Answer 13

• Mobilizes body during activity: fight or fight
• promtoes adjustments during exercise or when threatened
• > Blood flow is shunted to skeletal muscles & heart
• > Bronchioles dilate
• > Liver releases glucose
• > pupils dilate (wide eyes)

” e division: exercise, excitment, emergency, embarassment”

Question 14

where are the preganglionic neruons in the sympathetic divisons?

Answer 14

• in spinal chord segments T₁-L₂
• sympathetic neruons produce spinal chord lateral horns (extra gray horns in spinal chord)

Question 15

where do preganglionic fibers of the sympathetic division pass through in spinach chord

Answer 15

• pass trhough white rami communicates to enter the sympathetic trunk (paravertebral ganglia)

Question 16

where are the sympathetic trunk ganglia?

Answer 16

• hve 23 sympathic trunk ganglia in sympathetic trunk
• located in all areas of spinal chord (cervical, thoracic, lumbar, sacral and occygeal)

Question 17

what are the 3 things that a preganglionic fiber may do upon entering a sympathetic trunk ganglion

Answer 17

1. synapse at same level
2. synapse at a higher or lower level
3. synpase in a distant collateral ganglion anterior to vertebral column

Question 18

describe what happens when a preganglionic fiber enters the sympathetic trunk ganlion and synpases at the same level

Answer 18

1. starts at lateral horn
2. exists spinal chord form ventral root
3. enters sympathetic trunk ganglion via white ramus communicans
4. exists sympathetic trunk via gray ramus to effector

Question 19

describe what happens when a preganglionic fiber enters the sympathetic trunk ganlion and synpases at a higher or lower level

Answer 19

1. starts at lateral horn
2. exists spinal chord at ventral root
3. trhough white ramus communicans -> sympathetic trunk ganlgion up or down a few levels

*if didnt do this would only get innveration T1-L2

4. exists via gray ramus communicans to effector

Question 20

describe what happens when a preganglionic fiber enters the sympathetic trunk ganlion and synapses in a distant collateral ganglion anterior to vertebral column

Answer 20

1. starts at lateral horn in cell body
2. exists spinal chord via central root
3. goes through white ramus, travels through sympateic trunk
4. goes to a collateral pre vertebral ganglion (colleciton of nerve cell bodies)
5. to target

Question 21

describe the pathway of the SNS to the head

Answer 21

• fibers emerge from T1- T4 (upper part) and synpase in superior cervial ganglion
• these fibers
• > innervate skin and blood vessels of head
• > stimulate dilator muscles of iris
• > inhibit nasal and salivary galnds

Question 22

describe the SNS pathways to the thorax

Answer 22

• preganglionic fibers emerge from T1-T6 & synapse in cervical trunk ganglia

- postganglionic fibers emerge from ganglia and enter nerves C4-C8 to innervate

• > heart (via cardiac plexus) and lungs (via pulmonary plexus)
• > thyroid gland
• > skin (majority)

Question 23

Describe the SNS pathway to the abdomen

Answer 23

• preganglionic fibers from T5-L2 travel throuhg splanchnic nerves to synapse in prevertebral (collateral) gnaglia

*contribute to plexuses

• > celiac ganglion: liver, gall bladder, stomach, spell, pancreas *proximal duodenum
• > superior mesenteric ganglia: pancreas, distal duodenum, jejunum ,ileum, ascending colon + transverse colon
• > inferior nesenteric ganglia: descending colon, sigmoid colon + upper rectum

Question 24

describe the SNS pathway to the pelvis

Answer 24

• pathways synapse in sympathetic trunk ganglia
• sacral splanchnic nerves: inneravte genitalia and blasser

Question 25

describe the SNS pathway to the adrenal medualla

Answer 25

*pathway is only 1 neuron

• preganglionic fibers pass directly to adrenal meduall without synpases in celiac ganglion
• upon stimualtion, adrenal emdulla secretes: norepinephrine and ***epiephrine into blood directly

*upon sympathetic activation get quick efefcts bc adrenal medially pumps direclty into blood