Autonomic Nervous System I: The Sympathetic Nervous System Flashcards
What is the autonomic system (ANS) broken up into ?
Enteric nervous system
Parasympathetic nervous system
Sympathetic nervous system
Explain human nervous system divisions
Where does thre parasympathetic nervous system inervate ?
Cranial nerve and sacral area
Where does the sympathetic nervous system inervate?
T1-L2
What is the autonomic nervse system controled by ?
Hypothalamus
Futher processing in brainstem eg vomiting brseathign ect
Atutonomic ganglia within the ANS>
The ANS is disynaptic (as opposed to somatic NS monosynaptic)
ANS nerves pass through nerve cell clusters called “ganglia”.
Parasympathetic ganglia are in or near the target organ
Sympathetic ganglia are located in the sympathetic chain (paravertebral ganglia)
What is ganglia ?
A cluster of cells
explain sympathetic chain
Sympathetic ganglia are in the sympathetic chain, which is lateral and ventral to spinal cord.
CNS efferents (preganglionic) from the spine run to the sympathetic chain, form synapses with the postganglionic neurone.
What is the neurotransmitter present in the autonomic nervous system?
Acetylcholine
They activate nicotinic acetylcholine receptors to generate an action potential.
What is the post ganglionic nuerotransmitter in the SNS ?
Noradrenaline
Difference between adrenaline and noradrenaline
arenaline is a neurotransmitter, not a hormone.
It’s not released from neurons it’s released from adrenal glands.
This is general maintanence if you need extra adrenelaine will be produced ?
Adrenergic a1 receptors
Where are they located what do they do ?
Gq protein coupled: PLC → DAG & IP3 → ↑[Ca2+]
Located: Blood vessels, GI sphincters, Eye, salivary gland
Constriction / secretion Vasoconstriction (↑BP) Reduced urine flow Mydriasis Salivary secretion
Adrenergic a2 receptors
Gi protein coupled: ↓AC → ↓cAMP → (↓[Ca2+]i)
Pre synaptic neuron on sns terminals
DECREASES ACTIVITY !!!
Decreased synaptic output
Decreased sympathetic activity
How does Adrenergic a2 receptors work to reduce release of overacitivity in a nueron ?
NEGATIVE FEEDBACK.
Receptors located on presynaptic membrane
Also activated by NT release
Often inhibitory, used as negative feedback systems to prevent overactivity
e.g. α2 adrenoceptors, 5-HT1 receptors
Adrenergic b1 receptors
What they do where they are located ?
Gs protein coupled: ↑AC → ↑cAMP
located: Heart
Kidney (renin release)
Increased heart contractility
Increased heart rate
Increased renin secretion
Adrenergic b2 receptors
Gs protein coupled: ↑AC → ↑cAMP
Located: Lungs, blood vessels, smooth muscle, other
Bronchodilation
Vasodilation
Smooth muscle relaxation
Uterine dilation
Gycogenolysis
Note that NA has very low affinity for beta-2 receptors its noradrenaline which will do this.
Adrenergic b3 receptors
Gs protein coupled: ↑AC → ↑cAMP
Located: Fatty tissues, skeletal muscle, bladder muscle
Lipolysis
Thermogenesis
Bladder relaxation
