The somatic nerves synapse from CNS somatic neurons to skeletal muscles.

The autonomic nerves synapse from CNS preganglionic neurons to postganglionic effector neurons and then to effector organs.  

Pre-ganglionic fibers of the sympathetic nervous system originate in cell bodies in the thoracic and lumbar regions of the spinal cord. 

Then they enter the paravertbral chain of cympathetic ganglia. 

Post ganglionic fibers of the sympathetic nervous system tend to be long and often have multiple innervations. 

Preganglionic nerves of the parasympathetic nervous system originate from cell bodies in the midbrain, medulla oblongata, or sacral region of the spinal cord. 

Then they enter ganglia near to the innervated structure. 

Post ganglionic parasympathic nerve fibers tend to be short because they coming from ganglia in or near target organ. 

They tend to have singular innervations of these nearby target organs. 

Heart : excitation 

GI : inhibition

This is the fight or flight response and is typically associated with the emergency response = getting more blood pumped and decreasing functions like digestion. 

Heart : inhibiton 

GI : excitation 

Beta 1 receptors are present on the heart: SA node, ventricles, AV nodes 

Norephinephrine released from postganglion fibers onto these cells increase heart rate, contractivity and conduction.

Beta-2 receptors are found:

- bronchioles smooth muscle causing dilation of airways

-vasculature of organs/muscle causing vasodilation

Postganglionic fibers release norepinephrine onto these cells and cause dilation. 

Alpha-1 receptors are found in vascular smooth muscle 

When norepinephrine is released onto these receptors it causes peripheral vasoconstriction

Alpha-2 receptors are found on the terminal end of post ganglionic adrenergic fibers releasing epinephrine - producing auto-inhibition of NE. 

Also present on vasculature causing vasocontriction.

Epinephrine 

Norephinephrine 

Isoproteronol

Dopamine 

Dobutamine 

Muscarinic (M1-M5 subtypes) 

Nicotinic (Nm and Nn subtypes) 

What are the subtypes of Muscarinic cholinergic receptors?

Where are they found?

M1 - Receptors in neurons to mediate excititory postsynaptic potential 

M2 - Receptors found in heart to decrease excitibility

M3 - Receptors in smooth muscles, sphincters, and secretory glands

M4 - Receptors found in CNS

M5 - Receptors found in midbrain dopaminergic neurons to increase dopamine release 

What are the subtypes of Nictotinic cholingeric receptors?

Where are they found?

Nm - Receptors are found in muscle of neuromuscular junctions

Nn - Receptors are found in the neurons of the CNS and autonomic ganglia 

Acetylcholine 

Muscarinic and nicotinic receptors take in acetylcholine and regulate a response. 

Norepinephrine & Epinephrine

alpha 1,2 and Beta 1,2 receptors take in these drugs and mediate a response. 

Alpha 1, 2 

Beta 1, 2

Vessels of heart, kidneys - constriction 

Bronchial glands, intestine, kidney (renin), pancreas (acini and islets cells) - - Decreased secretion 

GI - decreased motility and tone 

fat cells - decreased lipolysis 

vascular vasoconstriction, decreased secretion

The heart primarily 

SA node, AV node, ventricles - resulting in INCREASED contractility and conductivity. 

If your co-worker accidentally stabbed you in the finger with a needle containing epinephrine - what drug would you administer to counteracts its effects? 

(ie. How do you keep your finger alive?)

You would use Phentolamine

(an alpha 1 adrenergic antagonist) 

This would prevent the alpha 1 receptors of the periphery from extreme vasocontriction that would occlude the blood supply to the finger 

Or you could let your finger fall off and sue them...

Epinephrine 

Norepinephrine 

Phenylephrine 

Norepinephrine 

Because of this - it is less available in circulation 

Epinephrine 

Norephinephrine

Medetomidine 

Xylazine 

What are the agonists to Beta 1 receptors? 

Epinephrine 

Norepinephrine 

Isoproterenol

Dobutamine 

What are the agonists to Beta 2 receptors? 

Epinephrine 

Ractopamine 

Isoproterenol 

Terbutaline 

What are the antagonists to alpha 1 receptors?

Phenoxybenzamine

Prazosin

Phentolamine 

Phentolamine 

atipamezole 

yohimbine

Atenolol

Propranolol

Dopamine 

At high doses its a beta agonist - stimulating beta 1 receptors on the kidney evoking vasodilation - 

provides the kidneys with better perfusion. 

Although epinephrine is an agonist to all adrenergic receptors, there are more Beta 2 receptors present in the heart and have the predominant effect. 

Thus, it causes increased contractility, increased HR, and increased CO.  

Local anesthetic - peripheral vasocontriction 

Cardiac arrest/ AV block - increased HR, BP, CO

Urinary incontinence

This is because it is an beta 2 agonist which initiates the release of NE. 

 And THAT stimulates the alpha receptors on the urinary sphincter, causing it to contract and have better control at retaining urine.

Short term treatment of heart failure 

This is because it is a beta-1 agonist which are present in high quantity on the heart and will increase cardiac output. 

Because ephedrine is a beta 2 agonist - its stimulates the release of NE, 

It creates a generalized stimulant - this was banned for athletes. 

(and can be made into illegal drugs...) 

Pupil dilation 

This is because it is an alpha 1 agonist causing constriction of the muscles of the eye, including the iris.  

OTC decongestant

as an alpha 1 agonist it constricts the peripheral vasculature and promotes decongestive activity. 

Used in asthma and crisis of airway constriction.  

Albuterol is a beta 2 agonist and will thus cause bronchodilation.  

Must be administered through inhalation because it has a high pKa and will be in ionized form in the blood and absorption is low. (ie. shouldnt be given orally)

Clenbuterol is used to treat Chronic obstructive pulmonary disease (horses and humans) because it is a beta 2 agonist, causing bronchodilation.  Can be administered orally, stays in the system for a long time. 

It is illegal because people MISUSED the drug for its side effect as a repartitioning agent.  

MEANING - The beta 2 receptors on skeletal muscle are activiated and cause and increase in glycolysis - resulting in lean muscle mass.  

Withdrawl time is also very high. 

Since terbutaline is a beta 2 agonist is can be used to treat asthma (in cats & horses) because it is a bronchodilator. 

It has a very short acting (30 minutes) 

Atenolol is used to decrease heartrate because it is a beta 1 receptor antagonist. In situations where there is tachycardia or hypertension (superventricular arrhythmias, hypertrophic cardimyopathy) it is used to decrease heart rate, contractility, and cardiac output.  

Also is being used as an anti-anxiety drug - decreased heart rate during an attack lessens the effect. 

Phenoxybenzamine is a ALPHA 1 Antagonist

Laminitis (horses)

Blocks alpha 1 receptors that would cause vasoconstriction resulting in decreased peripheral resistance.  

Inappropriate Urine Retention (cat and dog)

Blocks alpha 1 receptors on the urinary sphincter that would normally promote constriction, thus reducing the sphincter tone. 

Overcome peripheral vasocontriction from increased epinephrine - ALPHA 1,2 blocker

This can be used if accidental dose of epinephrine given, or if there is an epinephrine secreting pheochromocytoma (tumor).  

ALPHA 1 Antagonist

Used in Preanesthetic agent because it blocks the alpha 1 receptors and allows for and sedative effect while causing vascular smooth muscle to relax. 

On both parasympathetic and sympathetic postganglionic neurons that have ACh secreted onto them, 

(and on the skeletal muscle of the somatic nervous system) 

Drugs that produce ACh-like effects.  

Drugs that produce ACh-like effects at parasympathetic neuro-effector junctions. (This would be at the site of a ACh releasing Postganglionic neuron onto the muscarinic receptor of an effector cell.)

These drugs are generally inhibitory to the heart, and cause SECRETION (of all kinds), increased gut motility

Increased secretion, sweat, saliva, feces, urine, the works...

Agonists to the muscarinic ACh receptor (on the effector cell that is of a postganglionic parasympathetic neuron releasing ACh)

Acetylcholine (highly susceptible to degradation) 

Methacholine

Carbachol (Carbamylcholine) 

Pilocarpine is used to treat GLAUCOMA,  

It decreases the intraocular pressure by constricting the iris and causing miosis.  

KCS (keraconjunctivitis sicca - DRY EYE) - - causes increased secretions of the lacrimal gland by stimulating the muscarinic receptors. 

- slowing of the heart rate (stops heart beat = bad)

- Increased airway resistance (from increased secretions and bronchoconstriction as stimulated by parasympathetic)

- Hypotension ("SLUD" syndrome - from secretory, smooth muscle and sphincter effects)  

AT HIGH CONCENTRATIONS:

Nicotinic effects -> stimulation of sympathetic ganglia -> catecholamine released from adrenal -> muscle fasiculations

Smooth muscle and everywhere else

(eye, bronchial smooth muscle, urinary bladder, GI sphincters)

Acetylcholine

Bethanechol

Acetylcholine 

Nicotine

Succinylcholine

Acetylcholine

Nicotine

Alpha1 receptors are assocaited with which of the following effects:

A) Cardiacceleration

B) Vasodilation 

C) Pupillary Dilation 

D) Bronchodilation 

E) Pupillary Constriction 

Answer: C) Pupillary dilation 

By causing the IRIS to CONSTRICT it causes the pupil to dilate (Mydriasis)

A) would be Beta 1 receptors

B) would be Beta 2 receptors

D) would be Beta 2 receptors 

E) is associated with muscarinic cholinergic receptors (parasympathetic) 

What is the most likely cause of death in organophosphate poisoning?

A) GI Bleeding

B) Hypertension

C) Respiratory Failure 

D) Congestive Heart Failure

E) Cardiac Arrhythmia

Answer: D) Respiratory failure. 

Organophosphate cholinesterase inhibitors prevent the hydrolysis of ACh, so ACh accumulates at synapses, evokes bronchoconstriction and secretion (parasympathetic).  Also causes paralysis of respiratory muscles (diaphragm) = Respiratory failure

Which of the following adrenergic agonists at clinical dose produces dilation of vessels in muscle, constriction of cutaneous vessels, and positive inotropic effects on the heart (increased contraction)?

A) Phenylopropanolamine

B) Isoproterenol

C) Isoxsuprine 

D) Epinephrine

E) Dobutamine 

Answer: D) Epinephrine - 

Agonist of alpha 1 receptors causing peripheral vasoconstriction, agonist of Beta 1 causing increased heart contractility and Beta 2 agonist causing muscle vasodilation. 

ACTIVATES ALPHA 1, BETA 1, BETA 2!!

A) phenylopropanolamine - alpha 1 agonist only 

B) Isoproterenol - Beta 1,2 agonist but NOT Alpha 1

C) Isoxsuprine - Beta 2 agonist only 

E) Dobutamine - Beta 1 agonist only 

Which of the following bronchodilators is considered the safest for use in an animal with cardiac disease?

A) Isoproterenol

B) Terbutaline 

C) Ephedrine

D) Epinephrine 

Answer: B) Terbutaline 

This is because terbutaline is selective agonist for Beta 2 receptors to cause bronchodilation only. 

A) Isoproterenol & D) Epinephrine stimulate Beta 2 but also have strong effect on Beta1s which would put more stress on the heart. 

C) Ephedrine - works primarily on beta 2 receptors that stimulate release of NE so this would activate all adrenergic receptors (alpha1,2, beta1,2)

Nicotinic receptors are found in all of the following locations, except:

A) Parasympathetic ganglia 

B) Sympathetic ganglia 

C) Skeletal muscle

D) Bronchial smooth muscle 

E) Adrenal medulla

Answer: D) Bronchial smooth muscle

The bronchial smooth muscle has muscarinic or adrenergic receptors as effector cells.  

All other have ACh released onto their nicotinic receptors

Which of the following autonomic drugs would be most likely to increase myometrial contractility?

A) Atropine

B) Dobutamine

C) Ractopamine 

D) Xylazine 

Answer D) Xylazine which is an alpha agonist and alpha 1 receptors evoke smooth muscle contractions of the uterus

(add this to the list of abortion methods...)

A) atropine - is a muscarinic receptor antagonist

B) Dobutamine - beta 1 agonist

C) Ractopamine - Beta 2 agonist

Which of the following is the sign of bethanechol stimulation of muscarinic receptors?

A) Skeletal muscle twitching 

B) Urination 

C) Constipation 

D) Dry Mucous mumebranes 

Answer: B) Urination - muscarinic receptors increase the contractions of the bladder and relax urinary sphincter - (more secretion!!)

A) skeletal muscle twitching (fasiculations) would be seen with a cholinesterase inhibitor (ACh not broken down and continuously stimulating)

C) Constipation - muscarinic receptors increase GI motility

D) Dry mucous membwanes - muscarinic receptors increase secretions

Which of the following muscarinic receptors subtypes mediates the bethanechol-induced decrease in heart rate and contractility?

A) M1

B) M2

C) M3 

Answer: B) M2

M2 receptors are found on the heart 

M1 - is found mostly in the GI tract 

M3 - is everywhere else (but mostly smooth muscle) 

Which of the following adrenergic receptors sutypes mediates the phenylpropanolamine-induced contraction of the trigone and sphincter muscle of the urinary bladder, a treatment for urinary incontenance?

A) Alpha 1 

B) Alpha 2 

C) Beta 1 

D) Beta 2 

Answer: A) Alpha 1 

Alpha 1 receptors are present on the urinary sphincter and bladder and respond by contracting the sphincters. 

Which of the following would be most likely to increase airway resistance in a dog with pulmonary obstruction?

A) Albuterol 

B) Atenolol

C) Isoproterenol

D) Phenoxybenzamine 

E) Propranolol

Answer: E) Propranolol - which is an ANTAGONIST to Beta receptors.  This would block the beta 2s responsible for creating bronchodilation. 

A) Albuterol is a a beta2 AGONIST and would evoke bronchodilation 

B) Atenolol is only a beta 1 antagonist - no effect

C) Isoproterenol is a beta agonist - would help 

D) Phenoxybenzamine is an alpha 1 antagonist - no effect

Which of the following Beta2 adrenergic agonists can be used legally as a repartitioning agent in cattle and swine and doesnt require a preslaughter withdrawl? 

(repartioning - leaner muscles from glycolysis)

A) Albuterol 

B) Clenbuterol 

C) Ractopamine 

D) Terbutaline 

Answer: C) Ractopamine - causes increased glycolysis

A) Albuterol - used for bronchodilation, too short acting to cause muscle glycolysis 

B) Clenbuterol - DOES cause repartitioning but has a LONG withdrawl and is illegal 

D) Terbutaline - is used for its bronchodilation properties and is also too short to cause repartitioning