cholinergic and adrenergic pharmacology Flashcards
what are Cholinergic and adrenergic pharmacology responsible for
- control of blood pressure
- control of heart rate
- anaesthetic agents
- regulation of airway tone
- pressures in the eye
- control of gI function
how do Cholinergic and adrenergic pharmacology control blood pressure
raise it in shock, lower it in hypertension
how do Cholinergic and adrenergic pharmacology control heart rate
speed up lethal bradycardias, slow down dangerous tachycardias
how do Cholinergic and adrenergic pharmacology control anaesthetic agents
muscle relaxants
how do Cholinergic and adrenergic pharmacology regulate airway tone
treat life threatening bronchospasm
how do Cholinergic and adrenergic pharmacology work with eye pressure
prevent glaucoma causing blindness
how do cholinergic and adrenergic pharmacology control Gi function
diarrhoea and constipation
how many neurones innervate muscle in the somatic nervous system
one neurone comes from the CNS to innervate muscle
how many neurones innervate muscle in the autonomic nervous system
there are two nerves in series: pre and post-ganglionic fibres
describe parasympathetic ganglia
are near their targets with short post-ganglionic nerves,
describe sympathetic ganglia
are near the spinal cord with longer post-ganglionic fibres
describe the parasympathetic nervous system
Cranial nerves like the oculomotor nerve, facial nerve and vagus nerve carry signals to the body
A further sacral outflow innervates the pelvis
Short post-synaptic nerve fibres reach the targets and release acetylcholine (ACh), which acts on muscarinic receptors of various subtypes
describe the sympathetic nervous system
Regulates the fight-and-flight response
Nerve fibres originating in the spinal cord terminate in ganglia near the cord, then send out long nerve fibres to blood vessels, muscles etc.
They release noradrenaline which activates adrenergic receptors, of which there are two main types (alpha/ beta) with subtypes
what are mediators of the nervous system
acetylcholine and
noradenrelaine
what do Parasympathetic and sympathetic fibres coming out of the CNS release
both release ACh
acts on nicotinic receptors
what do post-ganglionic parasympathetic fibres release
more acetylcholine
acting on muscarinic receptors
what do post-ganglionic sympathetic fibres release
noradrenaline
acting on alpha and beta adrenoceptors
describe muscarinic receptors
M1-5; GPCRs
G proteins can activate various types of second messenger signals with different consequences for the cells
The G-Protein-Coupled Receptor structure is widely used in the body for signalling
where are M1 receptors
mainly in the brain
where are M2 receptors
mainly in the heart. (their activation slows the heart, so we can block these)
where are M3 receptors
glandular and smooth muscle. (cause bronchoconstriction, sweating, salivary gland secretion
where are M4/5 receptors
mainly in the CNS
what causes Anti-cholinergic side effects
Many drugs have some anticholinergic activity and side-effects through these pathways
what are anti-cholinergic side effects in the brain
anticholinergics worsen memory and may cause confusion
what are anti-cholinergic side effects peripherally
- get constipation
- drying of the mouth
- blurring of the vision
- worsening of glaucoma
what are alpha agonists
substances that activate the sympathetic nervous system by stimulation of alpha receptors
what does alpha 1activation cause
vasoconstriction, particularly in the skin and splanchnic beds: less so in brain, lung, heart
what does adrenaline do
will raise blood pressure and cardiac work in other settings
what occurs in nasal decongestion
topical alpha activation
impact of alpha 1 on blood pressure
raises it
impact of alpha 2 on blood pressure
lowers it
what does an alpha blocker do
opposite effect to the agonists
Block alpha 1 to lower blood pressure: doxazosin
Tamsulosin blocks a specific subtype (alpha 1A) in the prostate, to help treat prostatic hypertrophy
impact of beta 1 activation
activation will increase heart rate and chronotropic effects, and may increase risk of arrhythmias
impact of beta 2 activation
activation is life saving in asthma, and can delay onset of premature labour
impact of beta 3 agonists
can reduce over-active bladder symptoms
what do beta blockers do
Lower blood pressure (reduction in cardiac output reduction in central sympathetic outflow activity), reduce cardiac work, treat arrhythmias
can drugs have mixed alpha and beta blockers
yes
Some drugs have mixed alpha/ beta blocking roles with varying theoretical benefits
uses of beta blockers
Angina
MI prevention
High blood pressure
Heart failure
side effects of beta blokcers
Tiredness
Bronchoconstriction
Bradycardia
Cardiac depression
