Autonomic System 1 Flashcards
What are the 3 components of the autonomic nervous system?
Sympathetic nervous
Parasympathetic nervous
Enteric nervous system
Explain the patterns of ganglion in the autonomic nervous system
Parasympathetic nervous- preganglionic neuron delivers ACh to ganglion and post ganglion ic neuron delivers ACh to various organ
Sympathetic- preganglionic neuron delivers ACh to ganglion and post ganglion ic neuron delivers ACh to various organ
Sympathetic- preganglionic neuron delivers ACh to ganglion and post ganglionic neuron delivers norepinephrine to various organs
Sympathetic- preganglionic neuron delivers ACh to ganglion and adrenal medulla sends epinephrine to various organs
What are the functions of autonomic nervous system function on smooth muscle ?
Blood vessels—> blood pressure, body temperature
Gastrointestinal tract—> digestion
Bladder—> mictruition
Bronchial tree—> bronchial construction/dilation
Eye(upper eyelid, iris, ciliary body) —> pupillary dilation /constriction
How is the heart affected by the autonomic system?
Heart rate, heart contractility
What are the glands affected by the autonomic nervous system ?
Endocrine glands
Pancreas and adrenal glands—> metabolism
Exocrine glands
- lacrimal glands—> lacrimation (tearing)
- sweat glands —> sweating
- salivary glands —> salivation
What are the functions of the sympathetic nervous system?
“Fight or flight”
Stressful situations
- increase in blood flow in the skeletal muscles
- increase in heart rate
- increase in blood pressure
- increase in blood sugar level
- pupillary dilation (mydriasis)
What are the functions of the parasympathetic nervous system ?
“Rest and digest”
Conservation and restoration of body energy
Decrease in heart rate
Increase in activity of gastrointestinal tract
Papillary construction (myosis)
Describe sympathetic division anatomy
Origin in the thoracolumbar segments (T1-L2)
Short preganglionic neurons
Long postganglionic neurons
Sympathetic ganglia located near the central nervous system
Describe the parasympathetic division anatomy
Origin in the brain stem and sacral segments of the spinal cord (S2-S4)
Long preganglioninc neurons
Short preganglionic neurons
Parasympathetic ganglia located near the target organs
Describe the vagus nerve
Parasympathetic fibers
Innervation of the thoracic and abdominal vscer
Vagomoty: a surgical operation in which one or more branches of the vagus nerve are cut, typically to reduce the rate of gastric secretion (e.g. in treating peptic ulcers)
Contrast the origins of sympathetic and parasympathetic
Sympathetic origin: T1-L2 spinal cord segments (lateral horn)
Parasympathetic origin: brain stem (autonomic motor nuclei of III, VII, IX, and X cranial nerves), and sacral spinal cord segments S2-S4
Contrast the Ganglia location of sympathetic and parasympathetic
Sympathetic-
- Paravertebral sympathetic ganglion chain
- Collateral ganglia (prevertebral)
Parasympathetic-
-ganglion located near or embedded within the target tissue
Contrast cholinergic preganglionic fibers in sympathetic and parasympathetic fibers
Sympathetic- short cholinergic preganglionic fiber
Parasympathetic- long cholinergic preganglionic fiver
Contrast adrenergic fibers in sympathetic and parasympathetic fibers
Long adrenergic postganglionic fibers
Short cholinergenic postganglionic fiber
Contrast the ratio of preganglionic fibers to post ganglionic fibers in sympathetic and parasympathetic fibers
Sympathetic: Ratio of preganglionic fibers to postganglionic fibers is 1:20
Parasympathetic: ratio of preganglionic fibers to postganglionic fibers is 1:3
Briefly contrast the activity of sympathetic and parasympathetic fibers
Sympathetic -activity often involves massive discharge of the entire system
Parasympathetic- activity normally to discrete organs
Contrast the primary neurotransmitter of sympathetic and parasympathetic nervous system
Sympathetic- primary neurotransmitter of the postganglionic neurons is norepinephrine
Parasympathetic- primary neurotransmitter of the postganglionic neurons is acetylcholine
What are the characteristics of the parasympathetic and sympathetic nervous system?
Disynaptic pathway
Preganglionic neuron is myelinated (faster transmission)
Origin of preganglionic neuron is in the central nervous system
Origin of the postganglionic neuron is the autonomic ganglia, in the peripheral NS
Preganglionic neuron releases Acetylcholine as neurotransmitter, which binds to cholinergic nicotinic receptors (nicotinic neuronal subtype Nn)
What are the exceptions to the rule?
Adrenal medulla: directly innervated by preganglionic sympathetic fibers
Sweat glands:
Innervated by cholinergic sympathetic postganglionic neurons
Receptors on the sweat glands are cholinergic muscarinic: M3
Renal Vasculature smooth muscle:
Innervated by dopaminergic sympathetic postganglionic neurons
Receptors on the renal vasculature are dopaminergic: D1
What is the function of chromaffin cells in the adrenal gland?
Preganglionic sympathetic axons synapse on chromaffin cells: Ach binds to Nn receptors
Chromaffin cells releases catecholamines into the CIRCULATION: 80% epinephrine(E), 20% Norepinephrine (NE)
Explain cholinergic transmission in the presynaptic nerve
- Acetyl CoA is synthesized in the mitochondria
- Choline transported into the neuronal terminal by a sodium-dependent carrier (CHT1)
- ACh is synthesized in the cytoplasm from Acetyl-CoA and choline, a reaction catalyzed by choline acetyltransferase (ChAT)
- ACh transported into vesicles by a the vesicular ACh transporter (VAChT)
- ACh released occurs when an action potential reaches the terminal and triggers calcium influx through voltage-gated calcium channels
Explain cholinergic transmission in the synapse
Released ACh:
- ACh binds to cholinergic receptors: nicotinic or muscarinic in the postsynaptic membrane
- ACh binds to presynaptic M2 ACh receptors, which inhibit Ach release
- Acetylcholinesterase (AChE) splits ACh into choline and acetate
Explain adrenergic transmission in the presynaptic nerve
Presynaptic nerve
- Tyrosine is transported into the adrenergic neuron by system L
- tyrosine is then converted to L-DOPA by the enzyme tyrosine hydroxylase
- DOPA is converted to dopamine by DOPA decarboxylase
- Vesicular monoamine transporter (VMAT) translocate dopamine into synaptic vesicles
- Intravesicular dopamine-B-hydroxylase converts dopamine to NE
Explain andrenergic transmission in the synaptic cleft
Norepinephrine (NE):
- released NE binds adrenergic receptors: alpha or beta on the postsynaptic membrane
- Released NE binds to presynaptic a2 autoreceptors which inhibits NE release
- Termination of the action of NE results from diffusion away from the receptor site and reuptake into the nerve terminal, mediated by the Na+-dependent NE transporter(NET)
What are the types of cholinergic receptors?
Nicotinic (ion channel linked) (muscle type-Nm and neuronal type Nn)
Muscarinic receptors (G-protein linked)(M1, M2,M3)
What are the types of nicotinic receptors at the skeletal muscle (NMJ)?
Nicotinic muscle subtype Nm- function: skeletal muscle contraction
Use ligand gated
Sodium/potassium channels
Explain the subtype, function of nicotinic receptors of the brain
Nicotinic neuronal subtype (Nn)- function: neuronal development learning and memory
Signal mechanism: ligand gated
Sodium/potassium channels
Explain the subtype, function of nicotinic receptors of the adrenal medulla
Nicotinic neuronal subtype Nn
Chromaffin cells releases Catecholamines to bloodstream
Ligand-gated
Sodium/potassium channels
Explain the subtype, function of nicotinic receptors of the autonomic ganglion
Nicotinic neuronal subtype Nn
Postganglionic neuron activation
Ligand-gated
Sodium/potassium channels
Give the function of M1 muscuranic receptors in the brain
Brain (neurons) function: higher cognitive functions
Signal mechanism Gq-protein- linked: Increased IP3 increased DAG Increased Ca2+
Explain the function of autonomic ganglia (neuron)
Uses M1 muscuranic receptors like the brain
Autonomic ganglia (neurons)
Function/effect: stimulates enteric nervous system
Signal mechanism
Gq-protein-linked:
Increased IP3
Increased DAG
Increased Ca2+
Explain the role of M2 in presynaptice nerve terminal
M2 receptor neurons
Function: inhibition of ACh release
Signal mechanism: Gi -protein linked:
Decreased cAMP
Explain the function of M2 muscuranic receptors on the heart
Heart (mainly in the atria)
Decreased heart rate
Decreased contractility of atria
Signal: Gi-protein-linked results in decreased cAMP
Explain the function of M3 muscuranic receptors on exocrine glands
Increased exocrine secretions (lacrimal, sweat, salivary, gastric acid)
Signal mechanism
Gq-protein-linked:
Increased IP3
Increased DAG
Increased Ca2+
Explain the function of M3 muscuranic receptors on pancreatic B cells
Increased insulin release
Gq-protein-linked:
Increased IP3
Increased DAG
Increased Ca2+
Explain the function of M3 muscuranic receptors on gastrointestinal smooth muscles
Increased gut peristalsis
Gq-protein-linked:
Increased IP3
Increased DAG
Increased Ca2+
Explain the function of M3 muscuranic receptors on detrusor muscle
Increased bladder contraction
Gq-protein-linked:
Increased IP3
Increased DAG
Increased Ca2+
What role does M3 muscuranic receptors play in the functioning of the eye?
Eye: pupillary sphincter muscle, ciliary muscle
Function: pupillary constriction and accommodation
Gq-protein-linked:
Increased IP3
Increased DAG
Increased Ca2+
What is the function of M3 muscarinic receptors in the bronchial smooth muscle?
Bronchial constriction
Gq-protein-linked:
Increased IP3
Increased DAG
Increased Ca2+
What is the function of M3 muscarinic receptors in endothelial cells?
Endothelium NO-mediated vasodilation
Gq-protein-linked:
Increased IP3
Increased DAG
Increased Ca2+
What are the adrenergic receptors ?
a-receptors : G-protein linked( had type a1 and a2)
B-receptors: G-protein linked( B1, B2, B3)
What is the function of a1 receptors in the vascular smooth muscle ?
Located in vascular smooth muscle
Causes vascular smooth muscle contraction
Signal:
Gq-protein linked
What is the function of a1 receptors in the eye
Eye: dilator papillae muscle
Function: pupillary dilation
Signal:
Gq-protein linked
What is the function of a1 receptors in intestinal and bladder sphincter smooth muscle?
Intestinal and bladder contraction
Signal:
Gq-protein linked
What is the function of A2 receptors in presynaotic nerve terminals?
Decreased norepinephrine release
Signal:
Gi-protein linked
What is function of a2 receptors in pancreatic B cells?
Pancreatic B cells
Decreased insulin receptors
Gi-protein-linked
What is the function of B1 receptors for the heart ?
Increased heart rate
Increased contractility
Signal mechanism:
Gs protein linked
Increased cAMP
What are the functions of B1 receptors on the kidney (Juxtaglomerular cells)?
Increased renin release
Signal mechanism:
Gs protein linked
Increased cAMP
What is the function of B1 receptor for adipocytes?
Increased lypolysis
Signal mechanism:
Gs protein linked
Increased cAMP
What is the function of B2 receptors in bronchial smooth muscle?
Causes bronchial dilation
Signal mechanism:
Gs protein linked
Increased cAMP
What is the function of blood vessels of skeletal muscle ?
Vasodilation
Signal mechanism:
Gs protein linked
Increased cAMP
What is the function of B2 receptors in uterine smooth muscle (myometrium) ?
Decreased uterine tone
Signal mechanism:
Gs-protein linked
Increased cAMP
What is the function B3 receptors on brown adipose tissue ?
Thermogenesis
Increased lypolysis
Signal mechanism:
Gs-protein linked
Increased cAMP
What is the function of the autonomic nervous system on skin?
Sweat glands- secretion
Piloerector muscle -contraction.
No parasympathetic response
What is the impact of the autonomic nervous system on Blood vessels ?
Skin - sympathetic-constriction
Skeletal muscle- sympathetic-dilation
Viscera- sympathetic- construction
Parasymoathetic- none
What is the function of the autonomic nervous system in the SA node ?
Parasympathetic- decreased heart rate.
Sympathetic- increased heart rate
What is the impact of the the autonomic nervous system on the AV node?
Parasympathetic- Decrease conduction velocity
Sympathetic- increase conduction velocity
What is the function of the autonomic nervous system of the Atria?
Parasympathetic- decrease contractility
Sympathetic- increase contractility
What is the function of the autonomic nervous system on the ventricle?
Parasympathetic- little effect
Sympathetic- increase contractility
What is the function of the autonomic nervous system on the lungs ?
Bronchioles parasympathetic- constriction
Sympathetic- dilation
Glands- parasympathetic-secretion
Sympathetic- decreased secretion
What is the function of the autonomic nervous system in the gastrointestinal tract?
Wall muscles= parasympathetic- contraction sympathetic- relaxation
Sphincters= parasympathetic-relaxation sympathetic- contraction
Glands= parasympathetic-stimulation sympathetic- inhibition
