Blood Pressure Flashcards
What do the stretch receptors in the atria do?
When blood pressure is increased, the stretch receptors in the atria cause the atria to release atrial natriuretic peptide which decreases the reabsorption of sodium and therefore water, so blood pressure decreases.
What is the response to low blood flow to the kidneys?
The macula densa detects the low blood flow in afferent arterioles of the kidneys and activates an endocrine cascade, by triggering the juxtaglomerular cells to secrete renin (from the stored prorenin). Renin triggers the conversion of angiotensinogen to angiotensin 1, and then the conversion of angiotensin 1 to angiotensin 2 by ACE in the lungs.
Angiotensin 2 causes vasoconstricion (vasoconstriction of afferent arteriolar decreases glomerular filtration rate), reabsorption of Na+ and water, secretion of ADH from the posterior pituitary gland, and secretion of aldosterone from the adrenal cortex.
What respond to low blood pressure by increasing sympathetic activity and therefore vasoconstriction?
Baroreceptors in carotid sinus.
What is blood pressure equal to?
Cardiac output x peripheral resistance
Name 4 pharmacological ways to lower blood pressure.
B1-adrenoceptor antagonists e.g propranolol and atenolol which are negative inotropic and negative chronotropic agents.
Thiazide diuretic e.g bendroflumethiaziade which reduces blood volume by inhibitin Na+/Cl- exchanger on distal convoluted tubule.
ACE inhibitor e.g captopril, which inhibits angiotensin converting enzyme so stops angiotensin 2 being produced.
Calcium channel antagonist e.g verapamil, which is a negative chronotropic and negative inotropic agent.
How does amiodarone work?
It’s an antiarrhythmic agent which prolongs phase 3 (and so the refractory period) of the action potential, so decreases heart rate and vascular resistance.
Name 4 pharmacological ways to lower blood pressure.
B1-adrenoceptor antagonists e.g propranolol and atenolol which are negative inotropic and negative chronotropic agents.
Thiazide diuretic e.g bendroflumethiaziade which reduces blood volume by inhibitin Na+/Cl- exchanger on distal convoluted tubule.
ACE inhibitor e.g captopril, which inhibits angiotensin converting enzyme so stops angiotensin 2 being produced.
Calcium channel antagonist e.g verapamil, which is a negative chronotropic and negative inotropic agent.
How does amiodarone work?
It’s an antiarrhythmic agent which prolongs phase 3 (and so the refractory period) of the action potential, so decreases heart rate and vascular resistance.
Name 3 types of drugs that interfere with the renin-angiotensin-aldosterone system.
ACE inhibitors - stops angiotensin 2 production
Angiotensin 2 receptor antagonists - block AT2 receptors (angiotensin receptor blockers end in -sartan)
Mineralocorticoid receptor antagonists (MRAs) e.g spironolactane
