Peripheral Nervous System Flashcards
Common diseases in which drugs function by mimicking or blocking actions of the nervous system
Diseases of the eye
Cardiovascular diseases
Lung diseases
Skeletal muscle paralysis
Central nervous system
Brain and Spinal Cord
Peripheral Nervous System
Sensory pathways (Afferent)
Motor Pathways (Efferent)
Autonomic Nervous System (Sympathetic and Parasympathetic)
Somatic Nervous System
How many neurons are there between the CNS and a skeletal muscle in the Somatic Nervous System
1 (ends at neuromuscular junction)
How many neurons are there between the CNS and visceral organs in the ANS
2 (there is one autonomic ganglia)
How are autonomic nerves characterized as either sympathetic or parasympathetic
Parasympathetic nerves have cell bodies in the cranial and sacral regions while sympathetic nerves originate in the thoracic and lumbar regions
Function of Sympathetic system
Respond to stress
Function of parasympathetic system
Regulates homeostasis of internal mileu
Which system is continuously active and which is organized for discrete local discharge
Sympathetic; parasympathetic
The vagus nerve ________ the heart rate
slows
Which types of potentials use summation in their response to neurotransmitters
EPSPs and IPSPs
Somatic Motor nerves use which neurotransmitter?
Acetylcholine
Preganglionic fibers for parasympathetic and sympathetic systems use which neurotransmitter?
Acetylcholine (Also with postganglionic parasympathetic fibers)
Post ganglionic Sympathetic nerves usually use which neurotransmitters (what is the exception)?
Norepinephrine
Some sweat glands use Ach as the neurotransmitter (Sympathetic cholinergic fiber)
Stimulation of the adrenal medulla causes release of ________ and ______ into the blood stream
Epinephrine and Norepinephrine
Synthesis of Norepinephrine (What is the rate limiting step)?
Tyrosine → 3,4 dihydroxy-phenylalanine (DOPA) → Dopamine → Norepinephrine
Enzymes:
1) Tyrosine hydroxylase (RATE LIMITING STEP)
2) L-aromatic amino acid decarboxylase
3) Dopamine - β-hydroxylase
What additional step to norepinephrine synthesis can create epinephrine?
Norepinephrine → Epinephrine with phenethanolamine-N-methyltransferase
What transports Dopamine into vesicles (storage granules)
VMAT2 (Vesicular monoamine transporter 2)
Reserpine
Inhibits VMAT2
Treats patient with hypertension (Decreases sympathetic system)
How is norepinephrine taken back up into presynaptic terminal
Norepinephrine transporter (NET) Returned to storage granules
What happens to norepinpehrine in the cleft (transporters and percent transported)
90% taken back up into presynaptic terminal (NET)
8% diffuses
2% brought into postsynaptic terminal (Extraneuronal transporter)
Cocaine in NE pathway
Blocks NET and enhances norepinephrine signal
Which receptor on the presynaptic terminal works as an Gαi receptor and causes negative feedback on the NE release system?
α2-adrenoceptor
What two enzymes are involved in the metabolism of norepinephrine (and epinephrine)
Monamine oxidase (MAO-A and MAO-B) - Deamination Catechol-O-methyltransferase (COMT) - Methylation
What is the transporter that moves Ach into vesicles?
ACh Co-transporter
Two postsynaptic receptors for Ach (Cholinergic receptors)
Nicotinic receptors
Muscarinic receptor
How is Ach removed from the cleft
Acetylocholinesterase
Acetylcholine → Choline → Acetic Acid
What mediates fission and fusion of Ach into cleft (what drug blocks this effect)
SNAPS (Botulinum toxin)
- Produces skeletal muscle paralysis
Where are nicotinic receptors found?
Ganglia
Skeletal muscles
Neuronal CNS
How many different types of muscarinic receptors are there?
5 (all G-protein coupled receptors)
Which system is most associated with muscarinic receptors
Parasympathetic Nervous System (Smooth muscle, cardiac tissue, secretory glands)
3 types of Nicotinic receptors
1) Nm (Neuromuscular junction)
2) Nn (Autonomic ganglia/adrenal medulla) - chromaffin cells secrete catecholamines
3) CNS (Brain and spinal cord)
G proteins associated with each Muscarinic receptor type
M1: Gq (peripheral and central nerves) M2: Gi (Heart, nerves, smooth muscle) M3: Gq (Glands, smooth muscle, endothelium) M4: Gi (CNS) M5: Gq (CNS)
Adrenergic Receptors (GCPRs)
α (α1A, α1B, α1C and α2A, α2B, α2C)
β (β1, β2 and β3)
Adrenergic agonists usually give a __________ response
sympathetic
α-Adrenergic receptors
α1: Gq (Contraction and secretion from glands)
α2: Gi (Decrease NE release, Decrease insulin, contraction)
β-Adrenergic Receptors (all increase cAMP)
β1: Gs (In the heart and kidneys - regulate renin release)
β2: Gs (Relaxation of smooth muscle in the lungs, glucose production in liver)
β3: Gs (Receptor in adipose tissue - mediate lypolysis)
What is the effect of sympathetic stimulation on blood vessels
Constrict arteries (except relax skeletal muscle arteries) and constrict veins
What is the effect of parasympathetic stimulation on blood vessels
No effect
Activation of muscarinic receptors on endothelial cells of blood vessels cause ________
dilation of blood vessels - release NO
What is the effect of sympathetic stimulation on the lungs
Relax bronchiolar smooth muscle
What is the general effect of sympathetic stimulation on the urinary tract
Decreased activity of muscles involved in voiding and increased tone of sphincters
