PNS drugs Flashcards
drugs that directly activate receptors
agonists
drugs that prevent receptor activation
antagonists
drugs can interfere with the termination of transmitter action by two mechanisms
blockage of transmitter uptake
or
inhibition of transmitter degradation
drugs can interfere with the termination of transmitter action by two mechanisms
blockage of transmitter uptake
or
inhibition of transmitter degradation
selectivity is one of the most desirable qualities a drug can have
many neuropharmacologic drugs exhibit high selectivity
to understand any particular PNS drug you need 3 types of information
1- the type or types of receptors through which the drug acts
2-the normal response to activation of those particular receptors
3-what the drug in question does to receptor function (increase or decrease)
What are the three effects that drugs can have on transmitter synthesis?
1- increase transmitter synthesis
2-decrease transmitter synthesis
3- cause the synthesis of transmitter molecules that are more effective than the natural transmitter itself
Functions of the parasympathetic Nervous system
- slow heart rate
- increase gastric secretion
- emptying the bladder
- emptying the bowel
- focusing the ye for near vision
- constricting the pupil
- contracting bronchial smooth muscle
Therapeutic agents that alter the Parasympathetic nervous system are primarily used for their effects on
GI tract
bladder
eye
occasionally used for effects on : heart or lungs
the sympathetic nervous system has three main functions
- regulating the CV system
- regulating body temp
- implementing the acute stress response (fight or flight)
The sympathetic nervous system influences the heart and blood vessels to achieve three homeostatic objectives
- maintenance of blood flow to the brain
- redistribution of blood flow during exercise
- compensation for blood loss, primarily by causing vasoconstriction
The sympathetic nervous system causes
- increased heart rate and BP
- shunting blood away from the skin and viscera and into the skeletal muscles
- dilating the bronchi to improve oxygenation
- dilating the pupils
- mobilize stored energy, providing glucose for the brain and fatty acids for the muscles
Describe feedback regulation
s process that allows a system to adjust itself by responding to incoming information.
What are the main elements of a feedback loop?
1 sensor : monitor the status of the physiological process
2 effector: makes appropriate adjustments in the process
3 neurons connecting the sensor to the effector:
What is the baroreceptor reflex?
feedback loop that helps regulate blood pressure
1) baroreceptors located in the carotid sinus and aortic arch monitor changes in BP and send this info to the brain
2) the brain sends impulses along nerves of ANS including heart and blood vessels to behave in a way to restore BP to normal
What is autonomic tone?
the steady day to day influence exerted by the ANS on a particular organ or organ system
What are the main neurotransmitters of the PNS?
acetylcholine (neurotransmitter employed at each of the junctions of the PNS
norepinephrine (transmitter released by practically all post-ganglionic neurons of sympathetic nervous system
epinephrine (major transmitter released by the adrenal medulla)
What are the two basic receptor categories associated with the PNS?
Cholinergic receptors (mediate responses to ACh)
Adrenergic Receptors (mediate responses to epinephrine and norepinephrine)
What are the three sub-types of cholinergic receptors?
Nicotinic - N
Nicotinic - M
Muscarinic
What are the four sub-types of adrenergic receptors?
alpha 1
alpha 2
beta 1
beta 2
Nicotinic N (neuronal)
name where they are found
name response to activation
found: all autonomic system ganglia and the adrenal medulla
response: STIMULATION of PARASYMPATHETIC and SYMPATHETIC post ganglionic nerves & release of epinephrine from the adrenal medulla
Nicotinic M (muscular)
name where they are found
name response to activation
found: neuromuscular junction
activation: contraction of skeletal muscle
muscarinic
name where they are found
name response to activation
found: all parasympathetic target organs (eye, heart, lung, bladder, GI tract, sweat glands, sex organs, blood vessels)
activation : eye (contraction of ciliary muscle/focus for near vision)
heart: decreased rate
lung: constriction of bronchi, promote secretion
bladder: contraction of detrusor muscle = increased bladder pressure/relaxion of
sphincters = urine leave bladder
GI tract: salivation, increased GI secretions, increased intestinal tone and motility
sweat glands: generalized sweating
sex organs: erection
blood vessels: vasodilation
alpa 1 (adrenergic receptor)
name where they are found
name response to activation
Location: eye, arterioles, skin, viscera, mucous membranes, veins, sex organs (males) , prostatic capsule, bladder
activation: eye (increased pupil size) arterioles (constriction) veins (constriction) sex organs (ejaculation), prostatic capsule (contraction), bladder, contraction of trifgone and sphincter