Cardiovascular Block Flashcards
What are the actions of bradykinins?
Vascular
- Dilate arterioles and venules
- Increase vascular permeability
Neural
- Stimulate nerve endings = pain
Other
- Contract uterus, airways and gut
- Epithelial secretion in airways & gut
What are the targets, neurotransmitter, receptor and response of parasympathetic innervation of the heart?
Target: SA and AV node NT: ACh Receptor: Muscarinic Response: Bradycardia
What is an allosteric site?
A site of binding on a receptor other than where the endogenous ligand binds.
What is the different between a descriptive and analytical research question?
A descriptive eg how common is CHD
Analytical - does smoking increase the risk of CHD?
What are the steps of ACh production?
Choline is transported through the choline transporter into the cell cytosol. There it reacts with AcetylCoA (from mitochondria), catalysed by choline-acetyltransferase and becomes acetylcholine. It is packaged into synaptic vesicles through a ACh carrier.
What are the phases of SA pacemaker APs
4: Spontaneous depol to the threshold due to funny Na current and T type Ca++ channels (both into of the cell)
0: Depol - Ca into the cell via L type Ca++ channels - relatively slow
3: Repol due to K+ efflux
What is the early and end diastolic pressure in the LV?
Early: 5mmHg End: 15mmHg
Nitric Oxide is a potent…
Vasodilator
What are Nm type receptors?
Receptors that cause contraction of the skeletal muscle.
What are exosomes?
small membrane bound particle cells release. small, mini vesicles - can regulate organ tissue and function. contain mRNA and iRNA - therefore can be taken up and change transcriptional processes in that cell.
What is the name of the small area with a smooth surface adjacent to the pulmonary valve in the right ventricle?
Conus arteriosus
What is the mechanism of parasympathetic innervation slowing the heart?
ACh > muscarinic receptors > increase in G-protein > decrease in cAMP > increase opening of K+ channels > repolarisation is prolonged > longer to reach threshold > HR decreased
What affect does ACh have on endothelial cells?
It stimulates the release of a relaxing factor (NO).
What are the ridges in the right ventricle called?
Trabeculae carnae
What are the 4 classes of antidysrhythmias?
- Na channel blocker - slows Na depolarisation in ventricular APs
- Beta-adrenoceptor antagonist - blocks sympathetic innervation of SA and AV nodes
- K+ channel inhibitors - Slows phase 3 repolarisation of ventricular AP
- Ca2+ channel blockers - on SA and AV nodes, slows depolarisation til the threshold
What is the orthosteric site?
Where the endogenous ligand binds on a given receptor.
The downstream neurotransmitter in the sympathetic nervous system is noradrenaline is all cases except two, what are they?
Sympathetic innervation of sweat glands and adrenals where ACh is the post ganglionic neurotransmitter.
What receptor does smoking cessation drug nicotine act on?
The nicotinic receptors of the somatic and autonomic NS - it is a agonist.
What is the smooth aspect of the right atrium called?
Sinus venarum
What are the 7 points are which you can target neurotransmission at the synapse?
- Synthesis of the neurotransmitter 2. Storage of the neurotransmitter 3. Leakage of neurotransmitter out of vesicles 4. Release of neurotransmitter into the synapse 5. Degradation of the neurotransmitter in the synaptic cleft 6. Uptake of the neurotransmitter back into the pre-synaptic axon 7. Action of the neurotransmitter on its receptor
What are some effects of agonists of muscarinic receptors of the autonomic NS
Salivation, lacrimation (tears), urination, defecation
Sweating
Slowing of the heart
Bronchoconstriction Eg. Pilocarpine - glaucoma
What is the mean circulatory filling pressure?
The pressure of the blood in circulation if the heart was to stop.
What is the physiological role of NO?
Flow-dependent vasodilation - released in response to shear force
Inhibit platelet adhesion and aggregation
Neurotransmission
What is the name of the point at which the rough area of the right atrium abruptly stops?
Crista terminalis
What does “positively cooperative” refer to?
The bind of one O2 to Hb facilitates the binding of a further three O2’s. While the dissociation of one O2 makes dissociation of the remaining O2 easier.
What is the mechanism of sympathetic innervation increasing HR?
NA and adrenaline > beta1-adrenoceptors > G protein increases > cAMP increases > opening of Ca2+ channels > time for depolarisation to the threshold (phase 4) is shortened at SA and AV nodes > HR increased
What are the steps of receptor mediate NO synthesis in endothelial cells?
ACh or bradykinin, or mechanical stress are detected by receptors > increase in intracellular Ca2+ > NO synthase is activated > arginine is converted into NO and released into adjacent smooth muscle cells.
How does NO cause relaxation of vascular smooth muscle cells?
Enters the cells > activates guanylate cyclase > GTP is converted to cGMP > relaxation