Barajon - ANS

Question 1

what is the purpose of the autonomic nervous system?

- acts upon…

Answer 1

the ANS control the internal enviroment, maintaining homeostasis, acting on:

• Heart (cardiac muscle): rate and force of contraction
• smooth muscle: organs, blood vessels, piloerector
• Gland secretion

Question 2

what is the difference between somatic and visceral efferents?

Answer 2

1. visceral is autonomous and involuntary
2. visceral pathways contian at least 2 neurons between CNS and target
3. visceral pathways may be inhibitory

Question 3

how is the VNS divided?

Answer 3

VNS&raquo_space;>

1. Visceral afferent
2. Visceral efferent

Question 4

What does visceral afferents supply?

Answer 4

visceral afferent is sensory and recieves information from the core only

Question 5

how is the visceral efferent of the visceral nervous system divided? (what is the other name for visceral efferent system)

Answer 5

visceral efferent (motor)&raquo_space;> ANS
1. sympathetic (to core and periphery)
2. parasympathetic (to core only)
3 (metasympathetic)

Question 6

what is the difference between pre and post-ganglionic neurons?

Answer 6

pre-ganglions neurons are those projecting from the CNS and their axons are finely myelinated on exit of the CNS.

post-ganglionic neurons are those projecting from peripheral ganglia heading towards their target and their axons are unmyelinated.

Question 7

what are the divisions of the ANS based on?

Answer 7

1. localisation of ganglia
2. neurotransmitters of the visceromotor ganglia
3. function - response on their activation

Question 8

what is the difference between the ANS divisions:

- localisation of ganglia?

Answer 8

• sympathetic ganglia are found in the paravertebral chain and pre-vertebral plexus (close to CNS)
• parasympathetic and metasympathtic ganglia are found close or in its wall of the target being innervated.

Question 9

what is the difference in divisions of VNS?

- neurotransmitters

Answer 9

1. visceral afferents, pre and post use ACh
2. parasympathetic visceral efferents (craniosacral):
   - preganglionic - ACh
   - postganglionic - ACh
3. sympathetic visceral efferents (thoracolumbar):
   - preganglionic - ACh
   - postganglionic - NE
   + exception with sympathetic: innervation of adrenal medulla chromaffin cells, use ACh to stimulate release of NE and E (epinephrine)

Question 10

what are the locations of CNS neurons to the ANS divisions?

Answer 10

• parasympathetic: craniosacral
  
  • cranial: CN III, VII, IX, X
  • sacral: S2-S4
• sympathetic: thoracolumbar
  
  • thoracolumbar: T1-L2

Question 11

most organs have both ANS divisions, usually work as antagonists. what are the organs with only one ANS division innervation?

Answer 11

parasympathetic only: lacrimal glands

sympathetic only: adrenal medulla,
arterioles of Skeletal muscle
skin, viscera and kidneys

Question 12

what are the pathways of sympathetic outflow?

Answer 12

from T1-L2 preganglionic neurons&raquo_space; ganglia&raquo_space; target

+ ganglia

 - some preganglionic neurons synapse on closest ganglion (thoracic/upper lumbar)
 - some preganglionic ascend or descend in the paravertebral chain and synapse in the cervical or lumbosacral ganglia
 - some preganglionic neurons cross the paravertebral chain to synapse on the pre-aortic ganglia : splanchnic nerves