Autonomic Flashcards
The PNS is divided into?
The somatic and autonomic NS
The autonomic NS has which devisions?
Sympathetic, parasympathetic, enteric
Characteristics of the somatic NS
- Voluntary movements
- Main effectors: sceletal muscles
- One synapse between CNS and effector muscle
Characteristics of the autonomic NS
- Involuntary control of bodily functions
- Main effectors: smooth muscles, internal organs
- Two synapses between CNS and effector muscle
Homeodynamics
The integration of homeostatic functions regulated by the autonomic NS with voluntary
movements controlled by the somatic NS
Does the somatic and autonomic NS fight over controll?
No, they support each other to make living possible.
E.g. the autonomic system increases blood flow to muscles when we want to run (using muscles with somatic projections)
Explain the somatic efferent pathway
Information from a lower motor neuron in the spinal cord projects directly to a muscles
Explain the autonomic efferent pathway
Neuron in the spinal cord or brain stem (pre ganglionic) synthesize and secrete ACh project onto a neuron in the periphery (post ganglionic), which sends it’s signals to the smooth muscle either in a synapse or through a varicosity.
varicosities
When the neuron is stimulated, varicosities (some type of terminal) release neurotransmitters along a significant length of the axon and, therefore, over a large surface area of the effector tissue. The neurotransmitter diffuses through the interstitial fluid to wherever its receptors are located in the tissue. This diffuse release of the neurotransmitter affects many tissue cells simultaneously
Difference between neuron and ganglion
Neuron is 1 unit projecting through an axon. A ganglion is a nucleus in the peripheral NS which projects through fibers.
The enteric NS is completely controlled by?
enteric ganglia (control the function of the complete gastrointestinal tract from esophagus to rectum, including gall bladder and pancreas)
Can the ENS control functions of the gastrointestinal tract with it’s separated from the CNS?
Yes
How many neurons in the enteric NS?
500 million (speaks to complexity)
What are the 2 plexi of the enteric NS?
- Myenteric plexus (for smooth muscle movements of the
gastrointestinal tract, peristaltic propulsion of food) - Submucosus plexus (regulates mucosal function)
What’s the largest & most complex division of the ANS
The ENS
Sensory ENS neuron for intestines
GPR65
Sensory ENS neuron for the stomach
GLP1R
Hirschsprung’s disease (HSCR)
characterized by an absence of enteric (intrinsic) neurons from variable lengths of the most distal bowel.
The disease is a developmental disorder, where we have a loss/non-development of enteric neurons –> lead to food not being transported down the tract (gets struck) and we have clog where we need surgery.
Core differences between the sympathetic and parasympathetic NS
1) Sympathetic has a chain and has preganglionic neurons in the spinal cord, the parasymp has preganglionic cells in the brain stem or sacral part of the spinal cord
2) The axons of the preganglionic neurons for the symp are short and axons from the postganglionic cells are long. It’s the opposte from parasym
3) Symp releases Ach from the preganglionic cells and norepinephrine from the preganglionic where parasymp just releases Ach
Symp vs parasymp: function
fight or flight vs rest and digest
Symp vs parasymp: Preganglionic
neurons
Lateral horn thoracic to lumbar spinal cord
vs
Brainstem or lateral grey matter in sacral spinal cord
Symp vs parasymp: Ganglionic
neurons
Sympathetic ganglion on either side of vertebral column
vs.
Terminal or intramural ganglion; close to organs
Symp vs parasymp: axons
Pre-ganglionic: short, Post-ganglionic: long - Extensive innervation
vs
Pre-ganglionic: long, Post-ganglionic: short - Sparse innervation