Introduction to the autonomic nervous system Flashcards
Difference between synapses in autonomic and somatic nervous system?
In somatic there is no synapse with another neruone before the innervation of the target. (one neurone relay)
In autonomic there is (two neurone relay)
In which nervous system will you find parasympathetic and sympathetic innervation?
Autonomic
In the Ans, what kind of visceral sensory information will afferent neurons acquire?
Internal environment
Bp
Temperature
Electrolyte balance
In the Ans where does Visceral sensory information is relayed to?
Hypothalamus = homeostasis
Nuclei of the medulla
Local preganglionic neuron
What are the two main output systems for visceral ANS?
- Autonomic system in the lateral hypothalamus projecting to lateral medulla
- Endocrine signals via pituitary
Where can visceral afferent neurons initiate autonomic reflxes?
Local ganglion, spinal and superspinal level
Where can you find cell bodies for autonomic afferent neurons?
Hint- same for somatic
Dorsal root ganglion
Ganglia of cranial nerves
What dictates the responce of a visceral effector cells
neurotransmitter and receptors present on the visceral effector cells
Can be either stimulation/excitation or suppression/inhibition
Where do Pre-ganglionic neurone in ANS come from? Are they mylinated or unmylinated?
CNS (brain + spinal cord)
They are mylinated
Where do Post-ganglionic neurone in ANS come from? Are they mylinated or unmylinated?
Start from Ganglion (periphery) project to effector
Unmylinated
Are neurones in the somatic NS myelinated or unmyelinated?
myelinated
Which cranials nerves have parasympathetic innervation?
3- occularmotor
7- facial
9-glossopharangeal
10-Vagus
Which cranial nerve has the most parasympathtic innervation?
Vagus (95%)
Which plexus does the vagus nerve innovate? Which organs are associated with each?
-Cardiac and pulmonary plexi
-Celiac plexus
Liver and gallbladder
Stomach
-Hypogastric plexus
Spleen
Kidneys
Small intestine
Colon (proximal)
What is you enteric NS?
Celiac and hypogastric plexi = enteric nervous system
3rd division of ANS
Ganglion are interconnected from the main plexi by unmyelinated axons
It contains:
Primary afferents
Secretormotor neurons (+/-)
interneurons
Function of myenteric plexus and submucosal plexus in the Enteric nervous system
Myenteric plexus: -Controls motility -Circular and longitudinal muscle Submucosal plexus: -Controls secretion and muscle in muscularis mucosae layer
What do neurons from the sacral region (pelvic splanchnic) innervate? What is the clinical relevance?
S2-S4- Distal colon Rectum Pelvic viscera External genitalia
Clinical relevance:
Surgery for colorectal cancer puts pelvic splanchnic at risk of damage-
Bladder, bowel and sexual dysfunction
What are the spinal cord nerve roots for the sympathetic trunk?
T1-L2
Where do Preganglionic fibres from the SNS synpase?
1. Paravertebral ganglia T1-4 Sympathetic chain 2. Prevertebral ganglia preganglionc fibers from T5-L2 pass through sympathetic chain to prevertebral ganglia
- Adrenal gland
How many sympathetic chains are there? Where are they located?
2 on either side of the spinal cord
How many pairs of ganglion are in each sympathetic trunk?
25 pairs joined by nerve trunk
What is divergence in the SNS?
pre-ganglionic fibres branch out to postganglionic fibres at different levels of the chain
What is Convergence in the SNS?
a postganglionic neuron can receive information from many pre-ganglioinic fibres
How do preganglionic axons of SNS leave the spinal cord?
Leave via ventral root between T1 and L2 and travel via the white rami
