autonomic nervous system Flashcards
somatic nervous system
part of the nervous system that innervates skeletal (voluntary) muscle
- motor system
autonomic nervous system
part of nervous system that innervates smooth muscle, cardiac muscle, and secretory glands (sweat, digestive)
what kind of movement is the autonomic nervous system responsible for?
involuntary
what does the autonomic nervous system do?
stabilize the internal environment (homeostasis)
another name for ANS
visceral motor system
what transmitter is at neuromuscular junction?
Acetylcholine
synapse with skeletal muscle
- motor neuron attaches to muscle via motor end plate
- formation of neuromuscular junction
- regular neuron signaling
synapse with smooth muscle
- autonomic nerve over smooth muscle
- synaptic cleft is larger
- does not actually attach with anything
- neurotransmitter is released into synaptic cleft “en passant” (in passing)
- less pressure, more diffusion
preganglionic neurons are
- myelinated
- B fiber (not alpha motor neurons)
- cholinergic (use acetylcholine as transmitter)
postganglionic neurons
- unmyelinated
- C fiber (unmyelinated - Schwann cells don’t wrap around)
- cholinergic or noradrenergic (neurotransmitters = acetylcholine, noradrenaline, or norepinephrine)
divisions of the autonomic nervous system
- sympathetic
- parasympathetic
characteristics of the sympathetic nervous system
- thoraco-lumbar (T1-L2) nerves
- utilizes energy in an emotion, high energy situation (inc. heart rate)
- noradrenergic
- short pre-ganglions (near spinal cord)
- long post-ganglionic
- capable of diffuse discharge (mass discharge - fight or flight)
- full activation at once
characteristics of the parasympathetic nervous system
- cranio-sacral
- energy conservation (digestive, glands, relaxation)
- cholinergic
- long pre-ganglions
- short post-ganglions
- discrete discharge (not connected, individual)
why are sweat glands an exception to sympathetic and parasympathetic pathways?
they utilized cholinergic (instead of noradrenergic) sympathetics
in general how does the enteric nervous system work?
- sensory fibers
- motor neurons stimulate muscles, glands, network of ganglia
- influence by sympathetic and parasympathetic NS
enteric nervous system is located where?
in walls of GI tract
enteric nervous system innervates what?
smooth muscle and glands of GI tract
what is the enteric nervous system?
a division of the autonomic nervous system that has its own reflex circuits (NS for the guts)
- there are as many neurons in the gut as there are in the spinal cord
function of the enteric nervous system
- regulate motility and secretion in the GI tract
- receive inputs from the sympathetic and parasympathetic divisions
patterns of discharge
- tonic discharge
- mass discharge
what does the ANS maintain?
blood pressure and body temperature
adrenal medulla is part of
sympathetic NS
effects of adrenal medullary hormones
- increase blood glucose
- mobilization of fat
- increased alertness
types of interactions between sympathetic and parasympathetic NS
- antagonistic interactions
- cooperative interactions
- single innervation
antagonistic interaction involves…
- heart rate
- bronchiolar smooth muscle
- gastro-intestinal tract
- pupil dilation
- one NS will act, the other will react to balance
cooperative interactions involve…
- salivary glands
- genitalia
- both systems work together
single innervation involves…
- blood vessels
- kidney
- sweat glands
- adrenal medulla
- receive signal of only one NS innervation
autonomic nervous system pathway
- signal is sent to the intermediate horn
- presynaptic signal travels through the ventral horn/ventral root
- synapses at DRG with 2nd neuron
- postsynaptic neuron travels to viscera (like stomach, etc.)
- cell bodies are in the intermediate horn
somatic nervous system pathway
- signal is sent to ventral horn
- cell bodies are located in ventral horn (alpha motor neurons)
- signal is sent from ventral horn to the muscle fibers
characteristics of SNS (compared to ANS)
- cell bodies are located in anterior horn (ventral horn)
- alpha motor neurons
- neurotransmitter utilized is acetylcholine
- voluntary signals and movements
- excitatory signaling of skeletal muscle (DOES NOT INHIBIT)
characteristics of ANS (compared to SNS)
- cells bodies are located in the intermediate horn
- have pre and post-ganglionic neurons
- controls involuntary movement
- can be excitatory or inhibitory (I.e. increase heart rate or decrease heart rate)
paravertebral ganglia
a chain of ganglia that runs parallel with the vertebral column
ganglionic order (pathway)
- pre-ganglionic neurons go from lateral horn into the ventral root
- exits the root and enters the chain via white ramus (myelinated B fibers)
- goes into ganglion
- synapses with post-ganglionic neuron
- post-ganglionic neuron sends axon out gray ramus (unmyelinated C fibers)
- post-ganglionic neuron joins the spinal nerve and goes to target
sympathetic NS pre-ganglion neurotransmitter = _______
acetylcholine
sympathetic NS post-ganglion neurotransmitter = _______
norepinephrine
parasympathetic NS pre-ganglion and post-ganglion neurotransmitter = _______
acetylcholine
examples of what sympathetic NS impacts
- pupils
- salivary glands
- heart
- bronchi of lungs
- liver
- stomach
- small intestines
- adrenal glands
- kidney
- large intestine
- rectum
- bladder
- genitals
- skin
- sweat glands
examples of what parasympathetic NS impacts
- eye
- salivary glands
- bronchi of lungs
- heart
- stomach
- small intestine
- large intestine
- bladder
- genitals
tonic discharge
discharge all the time (constant)
mass discharge
full activation of everything (AKA sympatho-adrenal reaction)
example of mass discharge
- fight or flight
- seeing or getting bit by a shark
pathway of adrenal medulla
- sympatho-adrenal reaction (short pre-ganglion)
- ACh neurotransmitter synapse at adrenal medulla
- post-ganglion = secretory cells of norepinephrine and epinephrine to blood vessels
