1. Central Nervous System (CNS)
W5D1H2 ANS Review: 10 key slides
Nervous System
Central Nervous System (CNS)
Brain & Spinal Cord
Peripheral Nervous
System
Autonomic Nervous System
(ANS)
Somatic Nervous System
Not subject to voluntary control
Effectors:
Smooth muscle
Cardiac muscle
Glands
Mostly under voluntary control
Effectors:
Skeletal muscle

2. Sympathetic
Parasympathetic
“fight or flight”
“rest and digest”

3. Neurotransmitters released at the first and second synapse
Sympathetic: NE
Acetylcholine Norepinephrine
NAChR
CNS
pre
post
ANS effectors
ACH
Parasympathetic:
ACH
Acetylcholine Acetylcholine
ACH
CNS
nAChR
mAChR

4. Adrenergic receptors (sympathetic NS)
ACh
nAChR
CNS
Adrenergic receptor NE
Examples of receptor localization:
a1 smooth muscle
a2 sympathetic nerve terminals
b1 heart, juxtaglomular cells
b2 smooth muscle
b3 fat cells, bladder
ALL ADRENERGIC RECEPTORS ARE G PROTEIN COUPLED RECEPTORS!

5. smooth muscle relaxation Smooth Muscle Contraction
Adrenergic Receptors
Alpha Receptors
Beta Receptors
Stimulate lipolysis b3
Adipose a2 b1 b2
Smooth
Heart a1 Gq
PLC
IP3 & DAG
Ca2+
Activation
of PKC
Smooth
Inhibit myosin
phosphatase
smooth muscle relaxation
enhanced HR,
contractility etc. Gs Gi
inhibit
adenylyl
cyclase
cAMP
Stimulate adenyl
cyclase
cAMP
Activation of PKA
Remember there are multiple types of a1 type receptors etc. You will learn more about these later.
Inhibits NE release
In smooth muscle
PKA inhibits MLCK via phosphorylation
In cardiac Increased SERCA
Smooth Muscle Contraction

6. Muscarinic Receptors (Parasympathetic NS)
G-protein coupled receptors M2 M3
found in heart
(slows HR)
found in smooth muscle, glands,
endothelial cells
can mediate constriction (bronchioles)
or relaxation (vasculature)

7. Smooth muscle relaxation Smooth muscle contraction
Muscarinic receptors and signal transduction Gq M3
Endothelial cells
PLC
IP3 & DAG
Ca2+
NO production
Smooth muscle relaxation Gi M2
Heart muscle
inhibit
adenylyl
cyclase
cAMP
No activation of PKA
Cardiac muscle relaxation
K+ channel
opens
Smooth muscle M3 Gq
PLC
IP3 & DAG
Smooth muscle contraction
Ca2+
Activation
of PKC
Inhibit myosin
phosphatase

8. Synthesis of Norepinephrine
Tyrosine
Tyrosine
hydroxylase
This is the rate limiting step!
DOPA
DOPA
Decarboxylase
Dopamine
Dopamine
 oxidase
In the vesicle
Norepinephrine

9. Nitric oxide in non-adrenergic non-cholinergic nerves (NANC)
1 AP in nerve opens voltage-gated Ca2+ channels and increases [Ca2+]
2 In the nerve terminal Ca activates calmodulin
Ca-Calm NO
4 NO is produced
3 Ca-calmodulin activates NO synthase
NOS* NO
5 NO diffuses from nerve
ending into the smooth
muscle cell
Smooth muscle relaxation

10. Responding to the stimulus
Increased
Blood Pressure
Stretches wall of
Carotid Artery
(Carotid Sinus)
Excites Mechano-sensitive
Baroreceptor
Activates
Inhibits
Parasympathetic
Sympathetic
Decrease Blood
Pressure
Heart rate