Pharm and Nervous system Flashcards
________ innervates internal organs, blood vessels, glands - essentially all organs that contain at least some smooth muscle; purpose is to maintain homeostasis and respond to stress; referred to as the involuntary nervous system because it is beyond conscious control
Autonomic nervous system -
___________ innervates skeletal muscle; under the conscious control of higher centers in the brain; referred to as the voluntary nervous system
Somatic motor nervous system –
Autonomic nerve has intermediate synpase at:
autonomic ganglion
What is nerve fnx of autonomic nerve
can be excitatory or inhibitor
What are the target organ for somatic nerve
skeletal muscles
intermediate synapse for somatic nerve
none
Nerve myelination is _______ on somatic nerves
present
Nerve myelination is ________ on post gangs of ANS
absent
Consequences of Nerve Sectioning in somatic nerve:
Paralysis and atrophy of muscle
Consequences of Nerve Sectioning in Autonomic nerve
Retain some level of spontaneous activity (Release from central control)
Ratio of Segment Lengths
Short Pre-ganglionic, Long Post-ganglionic is:
Long Pre-ganglionic, Short Post-ganglionic:
SNS
PNS
Degree of divergence in PNS
low, 1:3 for a pre;post ratio
Degree of divergence in SNS
HIGH for Pre:post, very divergent effects
Nerve fnx for SNS
excitatory or inhibitor
nerve funx for PNS
excitatory or inhibitory
What regulates activity of structures not under voluntary control that function below the level of consciousness (respiration, circulation, digestion, temperature, metabolism, sweating, endocrine gland secretion)
Autonomic nerves
Sympathetic
a. normally_________ active
b. the degree of activity varies from moment to moment and from organ to organ thus allowing :
continuously
adjustment to a changing environment
- ___________ heart rate and blood pressure
- shift in blood flow from skin & splanchnic regions to skeletal muscles
- ________ blood glucose and free fatty acids
increased
increase
What happens to bronchioles and pupils during SNS stimulation
dilate
Actions of SNS reinforced by_________ released from the adrenal medulla
epinephrine
concerned with conservation and maintenance of organ function during periods of minimal activity
PNS
PNS causes pupillary______
constriction
emptying of bladder and rectum during PNS or SNS
PNS
How do nerve impulses elicit responses of tissues
through liberation of specific chemical neurotransmitters
Vagusstöff discovered:
Acetylcholine
Acceleranstöff discovered:
Epinephrine
frogs, norepinephrine in mammals
Steps involved in neurotransmission
- Axonal conduction
2. Junctional transmission
passage of an impulse along an axon
Axonal conduction
passage of an impulse across a synaptic or neuroeffector junction
Junctional transmission
Transmitters in Peripheral Nerves:
Which ones are the most important
acetylcholine and norepinephrine (Levophed®)/epinephrine
Rate limiting step in making Norepinephrine
- rate-limiting step = tyrosine hydroxylase
What is a specific blocker of tyrosine hydroxylase
- α-methyltyrosine
Dopamine synthesized in nerve terminals is transported into storage vesicles via
the vesicular monoamine transporter 2 (VMAT2)
Where is dopamine converted to norepinephrine?
in vesicles
What drug can block conversion of dopamine to norepinephrine in the vesicle?
reserpine
upon________, granules fuse with the nerve terminal membrane and release norepinephrine into the synaptic cleft.
depolarization
norepinephrine is removed from the synaptic cleft by:reuptake into the nerve terminals by the
norepinephrine transporter called NET
This is blocked by cocaine and some tricyclic antidepressants
NET
This method removes 87% of Nepi from cleft
Norepinephrine transporter
% of Nepi that removed from cleft by
diffusion
uptake by extraneuronal transporters (ENT [also referred to as OCT 3 and formerly called uptake 2], OCT 1, and OCT 2) account for what % of diffusion of Nepi from cleft
5%
The primary mechanism by which the actions of norepinephrine are terminated is by reuptake into nerve terminals is by
NET
This enZ oxidatively deaminates catecholamines -
MAO
MAO is found where:
found on the outer surface of mitochondria; located in adrenergic nerve terminals, but also widely distributed with the highest amounts found in
liver and kidney
two isozymes of MAO
MAO-A & MAO-B
This enZ transfers a methyl group to the 3-hydroxy position of the phenyl ring
COMT
cytosolic enzyme that is widely distributed with high levels in liver and
kidney (not found in adrenergic neurons)
COMT
Intraneuronal norepinephrine not taken into storage granules is metabolized by :
MAO
metabolites of MAO diffuse from nerve terminals and are subsequently metabolized to
VMA (3-methoxy-4-hydroxymandelic acid) - VMA is the primary metabolite secreted into urine
concentration of_______ in urine reflects the level of sympathetic drive and is used to diagnose presence of catecholamine-secreting tumors (pheochromocytoma)
VMA
presence of catecholamine-secreting tumors (pheochromocytoma) can be detected by
VMA
Extraneuronal metabolism by what two enZ are important mechanism for the clearance of circulating and exogenously administered catecholamines
(by COMT and MAO)
choline is taken up into nerve terminals via
a Na+-dependent carrier
the rate-limiting step in acetylcholine synthesis
choline taken up into nerve terminals via Na+ dependent carrier
Na+ carrier that takes choline up into the nerve terminals
hemicholinium
EnZ responsible for synthesis of acetylcholine from acetyl-CoA and choline in nerve terminals
choline acetyl transferase
acetylcholine is transported into vesicle by another transporter
(VAChT, vesicle-associated ACh transporter)
acetylcholine is released into the synaptic cleft by
exocytosis; inhibited by botulinum toxin
botulinum toxin does what to Ach exocytosis:
inhibits it
Acetylcholine is very rapidly hydrolyzed and inactivated by:
enzyme acetylcholinesterase (AChE)
Acetylcholine and norepinephrine/epinephrine use same/different receptors to mediate end- organ responses
different
End organ response is as much a function of the receptor mediating the response as it is
of the neurotransmitter that elicits the response
Receptors for Acetylcholine
(cholinergic receptors)
two types of cholingergic receptors
nicotinic and muscarinic
Nicotinic receptors act on
ganglion, skeletal muscle, neuronal CNS
Nicotinic receptors are
ligand-gated ion channels
subunit that acetylcholine binds to
alpha
Muscarinic Receptors
– G protein-coupled receptors
