Neuro-ish Flashcards
Respi neuro + Autonomic and Viscero-sensory NS
What is the primary function of visceral reflexes?
Homeostasis
Do afferent signals in a viscero-sensory pathway reach consciousness?
No
Visceral reflex afferent nerve fibers travel together with _________________.
Parasympathetic fibres
Describe the visceral reflex pathway for the homeostasis of blood pressure.
1) Baroreceptors in aortic and carotid sinus → afferent nerve fibers
2) Pass by sensory ganglia (Glossopharyngeal:CN9 & Vagal:CN10)
3) CN10 (parasympathetic) Efferent nerve fiber dorsal vagal nucleus
4) Act on heart receptors
What are 3 causes of acute visceral pain?
1) Obstruction
2) Inflammation
3) Ischemia
What is the mechanism of referred pain?
Viscero-somatic convergence
- sensory neurons innervating different viscera and somatic tissues converge onto same second-order neurons in the spinal cord
What is the difference between somatic motor and sympathetic outflow?
Somatic motor:
- LMN (pyramidal)
- arise from ventral horn
- 1 neuron from spinal cord to skeletal muscle
2) Sympathetic:
- extrapyramidal
- arise from lateral horn
- 2 neurons (pre/post-ganglionic)
What are 3 types of structures supplied by autonomic (viscero-motor) innervation?
1) Glands (sweat)
2) Smooth muscles (vessels, arrector pili)
3) Cardiac muscles
Where do autonomic efferent signals synapse?
From pre to post ganglionic neurons
within autonomic ganglia
What is the difference between pre and post ganglionic nerve fibres in the autonomic nervous system?α
Pre-ganglionic:
- myelinated (white)
- ACh in both sympathetic and parasympathetic response
Post-ganglionic
- unmyelinated (grey)
- NA in sympathetic (except sweat: ACh): adrenergic nerves
- ACh in parasympathetic: cholinergic nerves
What are the different types of receptors for ANS NTs?
AChR: nicotinic, muscarinic
NA: α, ß
Where are the pre-ganglionic neurons of the sympathetic nervous system?
In the Intermedio-Lateral Nucleus (ILN)
- lateral horn of spinal cord from T1-L2 (thoraco-lumbar outflow)
Where are the post-ganglionic neurons of the sympathetic nervous system
1) Mainly in the sympathetic chain/paravertebral ganglia
2) Some in prevertebral ganglia (coeliac, superior mesenteric, inferior mesenteric
3) Adrenal medulla
What are splanchnic nerves?
Preganglionic axons that DO NOT synapse in the sympathetic trunk ganglia
- synapse @ (i) pre-vertebral or (ii) adrenal medulla
How do the pre and post ganglionic neurons of the sympathetic and parasympathetic nervous system differ?
Sympathetic:
- short pre, long post
Parasympathetic
- long pre, short post
