2.2.1. ANS Flashcards
What does the ANS do?
The ANS controls the body’s internal environment and the functions of organ systems in an involuntary fashion
What are the functional divisions of the ANS
Parasympathetic
Sympathetic
Enteric
Where do we find splanchnic nerves?
Sacral spinal cord
Where do we find visceral ganglia?
In the organ they innervate
What nerves do we find in the brainstem?
Cranial nerves
What does the myenteric plexus control?
Peristalsis (coordination of the rhythmic contract-shorten-contract-shorten movement of the muscularis externa
Peristalsis?
rhythmic contract-shorten-contract-shorten movement of the muscularis externa (moves your bowels to squeeze stuff out of you :) )
What does the submucosalplexus control?
Muscularis mucosae and villi (shortening of villi and a squishing out of nutrients in the crypts and between villi)
Main neurotransmitters for the sympathetic nervous system?
Catecholamines
Idea of the sympathetic nervous system.
Fight or flight response and homeostasis
Parasympathetic Nervous System idea
The parasympathetic ANS regulates internal organs or glands and controls the ‘rest and digest’ and ‘feed and breed’ activates of the body when at rest.
Main neurotransmitter of the parasympathetic nervous system
acetylcholines
Neurotransmitters of the enteric ANS
Acetylcholine, serotonin and dopamine
What is another name for glia?
Schwann cells
Two functions of the PNS?
- Transmit signals from the CNS to peripheral tissues
2. Receive and transmit information from the environment to the CNS
Efferent neurons
transmits signals from CNS to peripheral tissues
Afferent neurons
Receive and transmit information from the environment to the CNS
Peripheral nerve infrastructure
-Axons and their supporting Schwann cells in peripheral nerve are held together by connective tissue and travel in bundles called fascicles
Epineurium
connective bundle sheath that holds a collection of neurons together
Perineurium
Surrounds a fascicle of nerve fibers. Must be rejoined in microsurgery for limb reattachment
Endoneurium
Invests single nerve fiber layers; is a layer of delicate connective tissue around the myelin sheath of each myelinated nerve fiber
Where are schwann cells in the CNS?
There aren’t any
What do schwann cells do?
schwann cells produce the myelin and enwrap all large diameter axons (>1.0um).
What embryonic layer do Schwann cells come from?
Neural crest
What are the presynaptic neurpns of the brainstem?
Cranial nerves
What are the presynaptic neurons of the organs?
Visceral ganglia
What are the presynaptic neurons of the sacral spinal cord?
Splanchnic nerves
Presynaptic neurons in the cervical and upper lumbar spinal cord?
Paravertebral ganglion
What does the Enteric ANS control?
The submucosal plexus and the myenteric plexus
What is a ganglia?
a cluster of sensory (e.g. dorsal root ganglia) or autonomic (sympathetic or parasympathetic) neuronal cells bodies
Sensory receptors:
- Free nerve endings
- Pacinian Corpuscles
- Krausener’s Corpuscles
- Meissner’s Corpuscles
Free nerve endings
pain
Pacinian corpuscles
Mechanoreceptor for pressure
Krause?
Vibration for high frequency at the clitoris and penis
Meissner’s corpuscles
Mechanoreceptor light touch (fingers and lips)
Trace an example reflex arc from a meissner’s corpuscle.
meissner senses signal, then the signal travels down the sensory ganglion into the dorsal horn of the spinal cord via the dorsal root. Then, signal is sent via synaptic contact to the motor neuron which shares the same nerve as the sensory neuron
