20110106 Lecture 5 notes.txt
From Iusmphysiology
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*The ANS includes the parasympathetic and sympathetic nervous systems and the enteric nervous system | *The ANS includes the parasympathetic and sympathetic nervous systems and the enteric nervous system | ||
**Enteric covered in GI lectures. | **Enteric covered in GI lectures. | ||
| + | *The autonomic system is responsible for controlling the unconscious activities of the body like secretion, heart rate, ''et cetera''. | ||
===The autonomic nervous system overview=== | ===The autonomic nervous system overview=== | ||
Revision as of 01:31, 18 January 2011
- started here on 01/06/2011 at 8:20AM.
Learning Objectives
- Understand the division of the Autonomic Nervous System (ANS) into Sympathetic and Parasympathetic subsystems
- Understand the anatomic & physiologic differences between these two divisions
- Understand the functions controlled by the Autonomic Nervous System
The autonomic nervous system is responsible for maintaining the constant internal environment in our body
- The ANS includes the parasympathetic and sympathetic nervous systems and the enteric nervous system
- Enteric covered in GI lectures.
- The autonomic system is responsible for controlling the unconscious activities of the body like secretion, heart rate, et cetera.
The autonomic nervous system overview
- Parasympathetic and sympathetic produce opposite effects.
- The excpetions are the sweat glands, blood vessls; only get sympathetic innervation.
- The ANS focuses on regulating smooth muscle, heart rate, and glands.
- BP, heart rate, pupil size, one more
The sympathetic and parasympathetics are two-neuron systems
Sympathetic division of the autonomic nervous system
- AKA thoracolumbar division
- The sympathetics are in the lateral horns of the spinal cord, between t1 and l3.
- Presynaptic axons go to the sympathetic ganglion
- The superior cervical ganglion innervates the head.
- The middle cervical ganglion innervates the lung and heart.
- The adrenal medulla and the sweat glands and errector pilli and blood vessels only receive sympathetic innervation.
Sympathetic neuron routes
- Preganglionic sympathetic neurons reside in the lateral horns of the spinal cord (Tl -L3)
- There are two types of sympathetic fibers:
- B type which are myelinated
- C type which are unmyelinated
- The sympathetic nerves pass through the white ramus
- White because it is mostly myelinated fibers.
- Some will synapse in the ganglion, others will travel along the (caudally or coronally) along the chain.
- Others will move out of the chain, even.
- Those that synapse in the ganglion, then leave via grey rami to join the spinal nerves again to travel to the effector cells.
- Those (presynaptics) that move through the ganglia without synapsing move on to paravertebral ganglion (around the aorta, very short distance away) to synapse
- Paravertebral ganglia are around the aorta (celiac, mesenteric, etc.)
- Most nerves synapse on many (around 200) ganglia, not just one.
- Sympathetic post-synaptics generally follow blood vessels
Adrenal Medulla
- Fight or flight response
- Starts in the lateral horn of T10 through L1
- Moves along splanchnic nerves
- Unmyelinated = C type fibers
- Reaches adrenal medulla
- Activates chromatin cells via neuronal region
- Considered to be part of the sympathetic nervous system
Catecholamine exocytosis
- Splanchnic nerves synapses on chromaffin cells
- Splanchnic nerves release vesicles with acetylcholine
- Chromaffin cells have ach receptors
- When chromafinn cells bind the acetylcholine receptors, Na channels are opened such that Na rushes into the chromaffin cell.
- Upon Na efflux, the voltage changes causing depolarization
- Then voltage-gated Ca+ channels open because of initial depolarization
- Dense core vesicles have catecholamines
**Usually catecholamines in clear vesicles, but these ...?
- Epinepherine and norepinepherine released into the blood by vesicle release
Does epithelial cell of the blood vessel have to take it up and release it?
Parasympathetic nervous division
- The parasympathetic division is also known as the craniosacral division.
- Parasympathetic nerves come from S2-S4 and the brain.
- Oculomoter = CN3
- Invervates the eye
- Sympathetic ganglia are very close to the spinal cord
- B type fibers are very short (presynaptic)
Are presynaptic fibers of sympathetic system always of type B?
- Parasympathetic presynaptic fibers are very long and post-synaptic fibers are short.
- There are only 4 parasympathetic ganglia
- Pterogopalatine
- Submandibular
- Otic
- Ciliary
- These provide much of the innervation to glands of the head
The brainstem nuclei associated with cranial nerves III, VII, IX, and X host parasympathetic preganglionic neurons
- CN3 comes from the Edinger-Westphal nucleus and travels to the ciliar ganglion
- CN7 comes from the superior salivatory nucleus and travels to the pterygopalatine and submandibular ganglia
- CN9 comes from the inferior salivatory nucleus and travels to the otic ganglia
- CN10 comes from the nucleus ambiguus and the dorsal motor nucleus of the vagus; it supplies the terminal ganglia in the viscera of the thorax and abdomen
Autonomic nervous system chemistry
- Parasympathetic presynaptic are long and release ach.
- In parasympathetic ganglia, the nicotinic receptor is expressed.
- Parasympathetic effector cells generally express muscarinic g-protein receptor.
- Sympathetics are in the lateral horn and have short pre-synatpic fibers
- Sympathetic effector cells generally express adrenergic receptors.
- There are alpha and beta adrenergic receptors.
- Epinepherine can bind at adrenergic receptors, mostly beta versions
- Heart, etc.
- At the ganglia in sympathetic arcs, ach is usually released to be bound by ganglionic cells on nicotinic receptors.
Autonomic postganglionic axons do not form true synapses
- Vesicles are released to provide NT for smooth muscle stimulation.
- Two types of smooth muscle:
- Multiunit
- Ex: smooth muscle of the eye
- Singleunit
- Blood vessels
- Connected wtih gap jxns
- NT from post-ganglionic nerve affects one cell and AP is passed from smooth muscle to smooth muscle by gap jxns
- Multiunit
Autonomic Functions
- Pupil:
- Para constricts, sympathetic dilates
- Sweat glands
- Para no action, symp secretion
- Blood vessels
- Para no action, symp constrict or dilate (alpha-1-R, beta-R
- Muscle
- Para no action, symp constrict
- Heart rate
- Para decreases, symp increases
- Bronchioles
- Para constricts, symp dilates
- GI
- See slide
Ganglionic sympathetic neurons express nicotinic acetylcholine receptor-channels
- was laughing too hard about "practicing" to catch anything.
This and the remaining slides were unclear.
Metabotropic receptors on the target cells
- Metabotropic receptors are usually g-protein receptors.
- They differ by what the g-protein activates.
- This is how we have different reactions for different tissues.
*He started to go over each of these three figures and highlighted pretty much all the text at the bottom *Then he got worried about time and moved on w/o talking about the last of the three.
alpha-1 and m1-muscarinic receptors
- Alpha-1 and m1-muscarinic receptors modulate cation channel activity in smooth muscle cells.
**They do this by modulating Gq11?
References
- Baron W.F., Boulpaep E.L. Medical physiology, Elsevier Saunders, Second Updated Edition, 2009
- Koeppen B.M., Stanton B.A. Berne and Levy Physiology, 6th Updated edition, Elseiver-Mosby, 2010
- Guyton A.C., Hall J.E. Textbook of medical physiology, ElsevierSaunders, 11th Ed., 2006
- Purves D., Augustine G.J., Fitzpatrick D., Hall W.C., LaMantia A-S., McNamara J.O., Williams S.M. Neuroscience, Sinauer Associates, Inc., 3rd Ed., 2004
- Netter F.H. Atlas of human anatomy. Elsevier Health Sciences, 2006
- stopped here on 01/06/2011 at 9AM
