Autonomic CVS Control Flashcards
Describe the sympathetic effect and identify the associated receptor of;
- Eye pupil
- Airways
3 Heart - Sweat glands
- Dilation- A1
- Relax- B2
- Increased rate and force of contraction- B1
- Localised secretion- A1, Generalised secretion- M3
Describe the parasympathetic effect and identify the associated receptor of;
- Eye pupil
- Airways
3 Heart - Sweat glands
- Contracts- M3
- Contract- M3
- Lower heart rate- M2
- No effect
What happens to heart rate if you denervate the heart, why?
Which nerve carries sympathetic impulses to heart from Ganglion
Beats faster, as it generates its own beat and is normally inhibited by Vagus nerve of PNS
Cardiac accelerator nerve
Regarding Parasympathetic input to heart;
- Where do postganglionic cells synapse
- What trainsmitter do they release
- What receptors are acted on
- Name 1 effect on heart
- On epicardial surface OR at SA/ AV node
- Release ACh
- M2 receptor
- Decreased Chronotropy
Regarding Sympathetic input to heart;
- What does it innervate
- What transmitter is released
- What receptor is acted on? What other receptors are also present
- Name 2 effects on heart
- SA, AV node and Myocardium
- Noradrenaline
- B1 mainly, B2 and B3 also present
- Positive Chronotropy and Inotropy
How does Parasympathetic activity affect the Pacemaker Potential
- Via M2 receptors, which are Gi coupled, so decreased amount of cAMP made
- Less HCN channels activated, so slower pacemaker potential
How does Sympathetic activity affect the Pacemaker Potential
- Via B1 receptors, which are Gs coupled, so more cAMP made
2. More HCN channels activated, so faster pacemaker potential
How does Noradrenaline increase Contraction Force
- NA acts on B1 receptors in Myocardium, more cAMP, more PKA activity
- Phosphorylation of Ca channels= More Ca influx during Plateau of AP-> Increased Ca uptake in SR
- Positive Inotropy
How are most vessels innervated, sympathetically or parasympathetically?
Give one example of an exception
Sympathetically, except specialised tissue such as erectile tissue
What are the main receptors on vascular smooth muscle cells?
What other receptors are present? name 3 tissues where they’re found
Main are A1. B2 are also present
B2 can be found in blood vessels in Liver/ Myocardium/ Skeletal muscle
Compare the amounts of Noradrenaline released when the vessels Dilate/ Constrict from their normal state? What is this state called
Normal= Vasomotor Tone
Tone-> Dilate= Les Noradrenaline released
Tone-> Constrict= More Noradrenaline released
Circulating adrenaline has a higher affinity for which vascular receptor, compared to which one?
Compare the binding of Adrenaline to Vascular receptors at Physiological and Higher concentrations, and state the effect of on the vessels.
Higher affinity for B2, rather than A1
Physiological conc.-> Adrenaline prefers to bind to B2-> Dilation
Higher conc.-> Adrenaline also binds to A1->Constriction
Explain the cellular mechanism of how B2 activation causes Vasodilation
More cAMP made-> more PKA activity-> Opens K+ channels and inhibits MLCK-> Smooth muscle relaxes
Explain the cellular mechanism of how A1 activation causes Vasoconstriction
More IP3 made-> Increase in Intracellular Ca-> Smooth muscle contraction
- What does active tissue produce
- What is the effect of these substances
- How do they compare to B2 activation for perfusion of skeletal and coronary muscle
- Metabolites (H+, K+, Increased pCO2)
- Vasodilator effect
- More important for perfusion of skeletal and coronary muscle than B2-receptor activation
