Week 11 - Pharmacology Flashcards
What are agonists?
What are antagonists?
Activate receptors
Block receptors
What are the types of drug actions?
- Interact with ion channels
- Activate / inhibit enzymes (statins, penicillin)
- Inhibition of transporters / pumps
- Interact with DNA (anticancer)
What are the sries of events for the action of salbutamol?
Binds to receptors
Receptor is activated
Receptor couples to G-protein
Association of alpha subunit
GDP-GTP
Activation of adenylyl cyclase
AMP-cAMP
Relaxation
What happens during modality?
- Receptors respond to specific energy / modality
- Specific sensation from type of receptor activated
- Concentrate on simple somatosensory system
What is the role of the pacinian corpuscle?
Vibration and rapid movements
What are the properties of transduction?
Stimulation - touch / vibration –> sensory AP
Occurs at naked nerve terminal
Involves changes in ion channel activity
Non-propagated potential
What happens during encoding?
What is an adaptation of encoding?
Sensitivity = ability to encode and detect stimuli of wide range of strengths –> increase sensitivity = use neurons with different AP thresholds and population encoding (use large no. of neurons for small stimuli detection, + chance of detection)
Temporal change in output in response to a stimulus –> + sensitivity and + cellular efficiency
What is involved in pain?
What are the 2 types of pain?
Nerve response to noxious stimuli –> above normal range, can cause damage, withdrawal behaviour
Specialised nerve fibres –> myelinated = fast, sharp pricking acute pain (Aδ), mechanical mainly, unmyelinated = slow, dull ache (C fibres), polymodal (mechanical + thermal for example)
TRPV1s = burning, heat
Meissner’s Corpuscles = tingling, numbness
What are the properties of the autonomic nervous system?
Smooth + cardiac muscle –> sympathetic (positive heart inotropy and chronotropy, gut vasoconstriction, skeletal muscle vasodilation, + sensory awareness, sweat secretion) or parasympathetic
What happens during sympathetic flight or flight response?
Heart inotropy and chronotropy
Vasoconstriction in gut
Vasodilation in skeletal muscle
Sensory awareness – eg vision
Sweat secretion
What are the prevertebral ganglia?
Celiac ganglion
Superior cervical ganglion
Superior mesenteric ganglia
What is the sympathetic outflow from spinal cord III (cervical region)?
Follow blood vessel and enter skull
What is the sympathetic outflow from spinal cord IV?
Midline plecuses
What is included in the parasympathetic nervouse system?
Cranio-sacral outflow
Long-pre and short-post ganglionic fibres
Cranial nerves III (occulomotor), VII (facial), IX (glossopharyngeal), X (vagus)
Where do the parasympathetic cranial and sacral nerves lead to?
What tissues only have parasympathetic innervation?
Ciliary muscle
Constrictor pupillae
(eyes)
Which nerves are radial and circular eye ,muscles supplied by?
Radial = sympathetic
Circular = parasympathetic
What are the effects of parasympathomimetic drugs?
Agonists of parasympathetic systems (Miosis (pupil constriction), decrease in near point, decrease in intraocular pressure)
What are the effects of parasympatholytic drugs?
Blockers of parasympathetic systems (mydriasis (dilation of pupil), cycloplegia, increased intraocular pressure)
What are the effects of sympathomimetic drugs?
Agonists of sympathetic systems (mydriasis, increased IOP)
What are the effects of sympatholytic drugs?
Blockers of sympathetic systems (miosis)
What are the 4 adrenoceptor subtypes and their functions / properties?
What type of agonist is adrenaline and how does it work?
Directly acting sympathomimetics adrenoceptor agonist:
Used for cardiac arrest, sepsis and septic shock
Delivered intravenously
Stimulation of b1 starts / increases heart rate
Used for anaphylactic shock
What type of agonist is salbutamol and how does it work?
Directly acting sympathomimetics adrenoceptor agonist:
Beta-2 adrenoceptor agonist
Bronchodilation
Bronchial asthma
What type of drug are NA reuptake inhibtors and how do they work?
Indirectly acting sympathomimetic drugs:
TCAs for depression treatment –> enhances NA function and 5-HT, block reuptake by varicosity
Other effects enhanced
What type of drug are cocaine and amphetamine and how do they work?
Indirectly acting sympathomimetic drugs:
CNS stimulant and NA reuptake inhibitor
+ sympathetic excitation
Amphetamine = causes exocytotic NA from neuronal uptake
What are propranolol and prazosin and how do they work?
Adrenoceptor antagonists:
Prazosin = selectively blocks alpha receptor
Propranolol = selectively blocks beta receptor (B2 agonist so stop salbutamol effects) - is used for:
Ischaemic heart disease
Reduce cardiac load during heartbeat
Beta blockers
Is administered orally
How are muscarinic receptors characterised?
Activated by muscarine
Act via metabotropic events
Neural, cardiac and glandular are family members
Utilise different 2nd messengers
Act on different target proteins
When are muscarinic receptor agonists used theraputically?
What are some side effects?
Oxybutynin:
Used for incontinence
–Non-selective parasympatholytic or anti-muscarinic
–Prevents unwanted bladder contractions
–Side-effects same as atropine which include: blurred vision,
tachycardia, dry mouth
What are ophthalmic uses of muscarinic agonists?
How do they work?
Pilocarpine:
Glaucoma
- Constriction of circular muscle
- Opens up drainage channel
- + aqueous humour drainage
- intraocular pressure.
When is the muscarinic antagonist tropicamide used ophthalmically?
For ocular examination:
Mydriasis
- Relaxation of circular muscle of iris
- Relaxation of ciliary muscle
What are the actions of anticholinesterases?
Examples of drugs used?
- Reversible
- Competitive inhibitors
Physostigmine (used for glaucome, bladder stimulation and treatment for atropine poisoning)
Neostigmine (treatment for myasthenia graves)