CONTROL AND DRUGS Flashcards
What are the main transmitters of the ANS?
- Ach
- Noradrenaline (norepinephrine)
Where is Ach released in SNS?
- At preganglionic synapse
Where is Ach released in PNS?
At preganglionic synapse aswell!!
Where is Ach released in somatic efferent?
- At NMJ
Is Ach released at the adrenal medulla?
YES!
What is the neurotransmitter for the ganglia regardelss of whether it is in SNS or PNS?
- Acetylcholine!!
Are sweat glands from the PNS or SNS and what is the neurotransmitter released at the end?
- Sympathetic nervous system by sympathetic cholinergic nerves
- Neurotransmitter is Ach (release this instead of noradrenaline)
What is a co transmitter and what is it involved in?
- Stored with the main transmitter (like Ach), released at the same time and have their own receptors that they interact with.
- Involved in moderating
What are examples of cotransmitters?
- ATP
- NO (cotype role in parsympathetics)
- NPY (SNS)
- Vasoactive Intestinal Peptide (VIP) in PNS
Do nerves release Ach or Noradrenaline as the main neurotransmitter?
NO! Some don’t release EITHER!
What are nerves called that don’t release Ach nor NA called and what is an example?
- Non Adrenergic Non Cholinergic
- e.g. Nitric oxide (NO) main CO- neurotransmitter released from PNS nerves for erection
Where are Ach and NA synthesised?
In the nerve terminal
Uptake of precursor is an a…..
active transport system
- Enzymes then convert precursor into Active neurotransmitter
What would happen if a neurotransmitter stayed in a terminal for too long?
- Enzymes would break it down (degradation products)
How do we solve the issue of neurotransmitters being broken down if in terminal for too long?
- Store it with co-transmitters in vesicles
Where is Ach broken down?
- In the neuro effector junction
Where is NA broken down?
- Reuptake in the nerve terminals
Which transmitter is NOT stored within vesicles?
- Nitric Oxide (NO)
Which transmitters ARE stored within vesicles?
- Ach
- NA (noradrenaline)
- ATP
What effect does the PNS have on our body?
- Constricts pupils
- Constricts bronchioles
- Lowers heart rate
- NO EFFECT ON BLOOD VESSELS
- INCREASES MOTILITY
Does the PNS have an effect on blood vessels?
- NO!!
What effect does the SNS have on the body?
- Dilate pupils
- Bronchdilation
- Increased heart rate
- CONSTRICT blood vessels to increase blood pressure( (small amount of dilation from muscles)
- decrease in motility
- increase in sweating (Ach)
What is bronchodilation caused by?
- Release of adrenaline from adrenal medulla
What are the RECEPTORS of the ANS for Acetylcholine?
- Nicotinic
- Muscarinic
What are the RECEPTORS of the ANS for NA?
- Alpha
- Beta
Can receptors be in a tissue even if they don’t have nerve supply?
- YES!
e. g1. Ach receptors present in blood vessels (even though there are no nerves to the receptors)
e. g.2. NA–> Receptrors in bronchial smooth muscle even though no nerves supplying them
Where are the nicotinic receptors located?
- At the ganglia and muscle
What is miosis in the context of ANS?
- Pupil constriction
Can autonomic receptors also exist in other parts of the body not associated with the ANS?
- YES!! There is Ach in the CNS (brain)
- so have to take into account how drugs will affect receptors in BOTH CNS and ANS (because it will hit receptors in both)
What does a muscarinic receptor mediate?
- Response of Ach (PARASYMPATHETIC affects of Ach)
Where are muscarinic receptors located?
- On the tissue (so PNS)
What actions are caused by muscarinic receptors (end organ) in the PNS?
- Miosis
- Increased Gi motility
- Bronchoconstriciton
What are the actions caused by nicotinic receptors ?
- Stimulation of the post ganlgionic parasympathetci nerve fibres
- Stimulation of the post ganglionic sympathetic nerve fibres
Do muscarinic receptors mediate the actions of sympathetic cholinergic nerves as an acception?
- YES! For example in sweating. They do an this is an acception because muscarinics are usually for the parasympathetics
Why are adrenoreceptors classified into alpha and beta?
- Based on the rank order of potency (how well they caused a response) of NorAdrenaline, Adrenaline and isoprenaline
- NA was best out of agonists (good at vasocnostriction)
- BUT isoproline was best at bronchodilation, increasing HR etc.
What are alpha receptors classified as? (best to worst effect-chain of 3)
- NA–> Adren–> Iso
NA is the best