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Define: somatic nervous system
- - skeletal muscle control during voluntary movement
- - conducts sensory info (ie pain, touch)
- - voluntary control
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Describe: autonomic nervous system
- controls for:
- - cardiac muscles
- - smooth muscles
- - glandular secretions
- two systems that oppose eachother with some voluntary control
- - Sympathetic NS
- - Parasympathetic NS
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Describe the conditions of the Sympathetic Nervous System
- - CATABOLIC (epends energy)
- - "S" for speeds up
- - under STRESS --> "fight or flight"
- - inc. HR
- - vasoconstriction
- - brochoDILATION
- - dec. secretions
- - inc. excretions (urine)
- - inc. tissue oxygenation
- - inc. CO
- - NT: Norepinephrine/Epi
- - can be voluntary
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Describe the conditions of: Parasympathetic Nervous System
- - ANABOLIC (conservers E)
- - "P" poke along or slow down
- - RESTING state
- - dec. HR
- - NT: Ach
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What is the function of ANS?
- - control cardiac muscle
- - control smooth muscle
- - glandular secretions
-
ANS pathway organization
- Presynaptic Neuron:
- from brain -> autonomic ganglia (where they transmit NS signal to postsynaptic neuron by releasing Ach to synapic cleft
- Postsynpatic Neuron: impulses -> end organs (heart, gut, etc)
- how?
- Norepi in sypathetic NS
- Ach
in parasympathetic NS
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what are the 2 NT that transmit impulses of the SNS?
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On release from the presynpatipic neuron, NE diffuses across the synaptic cleft and binds to ________ _______ receptors (which are ___, ___, ___, ___)
- postsynpatic adrenergic receptors
- α1, α2, β1, β2
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Where is the sympathetic R α1?
GAVEMI α1
- gut
- arterioles
- veins
- EYEmyocardium
- intestines
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What are the effects of α1 when stimulated?
- it is a SYMPATHETIC Receptor: Fight or Flight
- GAVEMI
- ↓motility
- vasoconstriction
- constriction of radial muscle of the eyes↓glanular secretions
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Where is the α2 sympathetic receptor located?
- CNS pre and postsympathetic terminals
- β islet cells of pancreas (makes proinsulin -> insulin once in bld stream)
- larger vessels
- skin
- mucosa
- - kidneys
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What are the effects when the α2 sympathetic receptors are simiulated?
- Decreases NE release
- Dec. β islet cell secretion
dec sympathetic outflow from brain
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where are the β1 sympathetic receptors located?
- "1 heart"
- myocardial tissue
- conduction system
-
What are the effects of β1 when stimulated?
- ↑ HR
- ↑contractility
- ↑ conduction velocity
- ↑ automaticity
- ↑ stroke volume (able to contract quicker)
- + chronotropicity: increased rate of heart contracting
- + Inotropicity: increased contractibility
- myocardium needs a lot of oxygen
-
where is the β2 sympathetic receptors located?
- "2 lungs"
- trachea
- bronchioles and bronchi
- uterus (contractions)
- arterioles (except brain and skin)
- viens
- vascular smooth muscles
- liver
-
what are the effects when β2 is stimulated?
- tracheal/bronchial relaxation
- uterine relxation
- circulatory dilation
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During times of stress, the adrenal gland releases _____ into the blood. Like NE, circulating ______ is an agonist/antagonist at adrenergic (sympathetic) receptors.
- epinephrine
- epinephrine
- agonist
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What is the mechanism by which impulses (messages) are transmitted in the parasympathetic division?
Ach transmitts all parasympathetic to end organs (ie heart, lungs) by binding to muscarinic Rs
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What other 3 mechanisms does Ach contribute to in the Parasympathetic division?
And where does it occur for sympa and para ganglion?
1. transmits both sympa and parasympathetic impulses from preganglionic neurons in brain and spinal cord -> nicotinic receptors on postgamglionic neurons of ANS
2. Can cause muscle contraction when Ach is released from neurons. Ach binds to nicotinic receptors on muscle cells which causes a Ca ++ influx
3. Acts as a NT in the brian, mostly on muscarinic Rs
- Sympathetic ganglia located in the spinal cord
- Parasympathetic ganglia located near the end organs
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All ganglion transmission is ____________. Therefore, drugs which block ganglionic transmission inhibit either sympathetic or parasympathetic signals, depending on which system is predominany at the moment.
CHOLINERGIC
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What are the 2 main NT for the parasympathetic division?
Ach and dopamine
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Catecholamines - NT synthesis of ANS
Tyrosine -> dopamine -> NE
Tyrosine -> dopa -> dopamine (in presynaptic neurons) and diffuses into synaptic vesicles and hydroxlates into -> NE
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Catecholamines - NT synthesis of ANS
When a nerve is stimulated ____ enters the presynaptic neuron and causes vesicles to fuse with the plasma mb and release ____ into the synpatic cleft
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NE can bind with ___, ____, and ___ adrenergic receptors.
α1, β1, and β2
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Direct sympathomimetic drugs (to NE) such as ______ can bind to α1, β1, and β2 as well, with/without interacting with the presynpatic neuron.
α2 adrenergic R are located on ____-synaptic neurons, so when stimulated by NE, it will stimulate/inhibit subsequent NE release from the terminal
- Epinephrine
- pre-synaptic
- inhibit
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Catecholamines - NT synthesis of ANS
COM-T Catechol-o-methyl transferase _____ catecholamines such as NE, but more commonly NE is ______ into the presynaptic neuron to be re-stored or degraded by _______.
- degrades
- transported back
- MAO - mitochondrial monoamine oxidase
-
Indirect ____________ are drugs that work by entering the presynaptic terminal and displacing NE.
indirect sympathomimetic
-
Metoproplol/Lopressor®
- top 10 drugs
- B1 specific (cardio)
- beta blockage effects: should NOT be w/drawn abruptly to avoid acute tachycardia, HT, and/or ischemia
- avoided in those with bronchospastic dz
- adequate alpha blocker
required prior to use of any beta blocker for patients with unTx pheochromocytoma
- USE (outpatient):
- Tx of angina pectoris, HT, acute MI
Extended release: to reduce mortality/hospitalization in pts with heart failure receiving ACE inhibitors, diuretics or digoxin
ocular side effects: blurred vision, visual distrubances
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