834266
Description
Flashcards by Hannah Tribe, updated more than 1 year ago
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Created by Hannah Tribe
almost 10 years ago
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| Question | Answer |
| What is Darcy's Law? | Flow = Change in pressure / resistance |
| What is the key point of Poiseuille's Law? | A small change in radius causes a large change in resistance. |
| What is vascular tone? | A balance between sympathetic constriction and dilatation caused by the NO pathway. |
| Name 5 things that cause vasoconstriction. | 1. Neurotransmitters (NA) 2. Adrenaline 3. Endothelin-1 4. Vasopressin (ADH) 5. Angiotensin II |
| Which pathway do each of these use? | Gq/11 |
| What is the result of this? | Levels of Ca++ increase, so more Ca-Calmodulin complexes form which phosphorylate the myosin light chain using MLCK, allowing more cross-bridge formation. |
| What is endothelin-1? | A substance released from endothelial cells onto ETa receptors which causes vasoconstriction |
| How do vasodilators work? | They decrease Ca++ levels in VSMCs by blocking receptors for neurotransmitters and hormones and blocking VDCCs. |
| Other mediators can stimulate vasodilation another way, via NO. What mediators can do this? | ACh, histamine, bradykinin. |
| Where do they act? | On the endothelium |
| How does NO cause vasodilation? | NO enters VSMCs and activates Guanylyl Cyclase enzyme to produce cGMP and PKG. These cause decreased Ca++ levels and therefore dilatation. |
| What are the 2 front-line treatments for hypertension? | 1. AT1 receptor antagonists (e.g. losartan) - prevents AngII binding to receptor. 2. ACE inhibitors (e.g. enalapril) - prevents AngI becoming AngII. |
| What other 2 drugs can be used to treat hypertension? | 1. VDCC blockers (e.g. Nifedipine) 2. Alpha-1 receptor antagonists (e.g. Prazosin) |
| What drug could be used to treat angina? | Nitrates (e.g. glyceryl trinitrate [GTN]) to give NO and cause dilatation |
| What is Viagra and how does it cause vasodilatation? | PDE5 inhibitor, which prevents the breakdown of cGMP so the effects of NO can last longer |
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