ANS 2 Flashcards
what are the 3 types of interactions between the SNS and PNS?
- antagonistic - opposing directions
- complementary - similiar
- co-operative
what do the pre-ganglionic fibres of both PNS and SNS release?
Ach
what do the post ganglionic PNS fibres release?
Acetylcholine
what do the post ganglionic SNS fibres release?
- noradrenaline
what post ganglionic SNS fibres are cholinergic?
- sweat glands
- pilorector muscles
what are the 4 main receptor types?
- g protein coupled receptor
- tyrosine kinase receptors
- ionitrophic receptors
- steroid hormone receptors
what are ionotropic receptors?
gated ion channels linked to a receptor that opens with ligand binding
eg nicotinic cholineric Ach receptors
what are G protein coupled receptors?
- 7 transmembrane domain receptors linked to a membrane bound protein complex
what are the main types of G protein coupled receptors?
- Gs - stimulatory
- Gq- stimulatory
- Gi- inhibitory
Describe** nicotinic cholinergic receptors**
- ionotropic receptors linked to cation (Na+) channel
- influx of cations links to depolarisation
- found in muscles (N1), nerves (N2)
- common in both SNS and PNS
Describe muscarinic cholinergic receptors
subtypes, which are stim and inhib
- 5 subtypes- M1-M5
- odd numbered - stimulatory and linked to Gq
- even numbered are inhibitory and linked to Gi
what type of receptor does noradrenaline act on?
- adrenoceptors- G protein coupled receptors
what receptor does the sympathetic cholinergic fibres act on?
muscarinic receptors
what are the **2 main types of adrenergic receptors **& which catecholmine do they bind to?
- alpha - noradrenaline >adrenaline
- beta- adrenaline> noradrenaline
what are the 2 subtypes of alpha adrenoceptors?
- alpha1
- alpha 2
what are the 2 subtypes of beta adrenoceptors?
- beta 1
- beta 2
- beta 3
what g alpha subunit is alpha 1 adrenoceptor linked to and what effect does it have?
- Gq- stimulatory
- stimulates PLC and increase [Ca2+]
- found on vascular smooth muscle
- can cause vasoconstriction
what alpha subunit is alpha 2 adrenoceptors linked to and what effect does it have?
- Gi- inhibitory
- decreases cAMP
- found in vascular beds, Gi smooth muscle and platelets
what alpha subunit is beta1 adrenoceptor linked to & what effect does it have?
- Gs- stimulatory
- acts to increase cAMP
- found in heart
what type of alpha subunit is beta 2 adrenoceptors linked to & what effect does it have?
- Gs- stimulatory
- increases cAMP
- found in smooth muscles that dilate - eg vessels
what g alpha subunit is beta 3 adrenoceptor linked to & what effect does it have?
- linked to Gs - stimulatory
- increases cAMP
- found in adipose tissue where it promotes lipolysis
what enzyme breaks down Ach and what is it broken down into?
- acetylcholinestarase
- choline and acetic acid
what happens to NA after a synapse?
- uptake 1 transports NA** into prejunctional cell**
- uptake 2 transports NA into post junctional cell
- in the cell - it is broken down by mono-amino oxidase MOA or catechol-O-methyl transferase (COMT)
what are the main targets/functions of drugs relating to the ANS?
- some relate to ANS function
- some interfere with NT release
- some interfere or mimic NT action - ie antagonists or agonists
- some interfere with NT recycling- ie preventing breakown of NT potentiating its effect
what type of chemicals can inhibit acetylcholinesterase?
pesticides - they inhibit and therefore they increase the amount of Ach in cleft
what are parasympathomimetic drugs?
drugs that activate the PNS, by mimicking the effects of Ach
what are** parasympatholytic** drugs?
drugs that oppose the effects of the PNS
what are examples of muscarinic agonists (ie parasympathomimetic drugs)?
- atropine
- ipratropium - used in asthma as a bronchodilator
what are examples of adrenergic receptor agonists? (ie sympathomimetic drugs)
- phenylephrine - alpha 1 adrenoceptor agonist
- clonidine - a2 adrenoceptor agonist
- salbutamol - B2 adrenoceptor agonist
