ROT 2: Rat Blood Pressure Simulation

Question 1

Isoproterenol is a ___ agonist

Answer 1

beta agonist. Has higher affinity for Beta 1 than NE

Has higher affinity for Beta 2 than E and NE

Isoproeternol is just a more powerful agonist in general.

Question 2

Propranolol is a beta ___

Answer 2

antagonist.

Question 3

atropine is a ____ antagonist

Answer 3

muscarinic. blocks Ach receptors at the synapse between post gang neuron and the actual gland/tissue it innervates.

(the nicotinic receptor is in the nervous system pathway between the pre and post ganglion)

Question 4

When looking at the dosing graphs, how do you calculate the time elapse?

Answer 4

Elapsed time is from just before drug administration to the time of maximum response (peak)

Question 5

Mean arterial BP calculation. Why is it not just an average between Ps and Pd?

Answer 5

Pd+ (1/3)(Ps-Pd)

Not an average because the cardiac cycle spends more time in diastolic phase

Question 6

Generally, heart rate and blood pressure does the same thing at the same time at the max response except

Answer 6

for isoproterenol. There is a drop in BP and a direct effect on the heart.

Question 7

Explain the difference between the effects of NE and isoproterenol on arterial BP. By what mechanisms do these effects occur? explain the effect of isoproterenol on pulse pressure

Answer 7

Both Ne and iso are beta agonists, but Iso has a stronger affinity for Beta 1 than Ne.

iso is a stronger agonist and causes a larger heart rate response than NE.

NE triggers an increase in heart rate and increase in BP. (doesn’t have as much affinity or beta 2 receptors, therefore, it doesn’t trigger much relaxation which would contribute to a drop in BP)

BUT: iso also triggers a DECREASE in BP, which doesn’t really make sense..?

THIS IS BECAUSE the huge increase in heart rate caused by iso prevents full ventricular filling and decreases cardiac output. Less output = less arterial pressure.

ALSO, iso acts on BETA 2 receptors which causes a RELAXATION, resulting in a DECREASE IN PRESSURE.T he low BP due to IP wil cause the baroreceptors to respond, causing the HR to INCREASE even more.

Question 8

T/F: isoproterenol also acts on alpha receptors. What does this do?

Answer 8

It does not act on alpha receptors. This means that iso works primarily on beta and thus only on cardiac and skeletal muscle area.

no alpha receptor activation means it DOES NOT EXERT effects on arteriolar smooth muscle or pre and post parasympathetic nerve endings.

Question 9

If you add iso, what happens to the arterioles?

Answer 9

iso will not affect arterioles because it does not act on alpha 1 receptors,which is the type of adrenergic receptor on the arterioles.

Question 10

explain the results for propranolol followed by isoproterenol, compared to treatment with isoproterenol alone

Answer 10

alone; iso is a beta agonist. Beta 1 agonist = increase in heart rate by allowing increase Na+ and Ca2+ flux, causing faster contractions and bettter cross bridging

Beta 2 agonist = causes relaxation and a decrease in BP. The drop in BP by iso alone will cause baroreceptors to send signals and the medulla will increase the HR even more.

Propranolol is a BETA BLOCKER. Prevents the binding of iso. If you added propranolol before adding iso, you should see less of an increase in HR and less of a decrease in BP.

Question 11

Where is histamine produced in the body?

Answer 11

histamine is produced by basophils and by MAST CELLS found in nearby connective tissues. Histamine increases the permeability of the capillaries to white blood cells and some proteins,

Question 12

Where is vasopressin produced in the body?

Answer 12

hormone made by the hypothalamus in the brain and stored in the posterior pituitary gland. It tells your kidneys how much water to conserve. ADH constantly regulates and balances the amount of water in your blood.

Question 13

Where is angiotensin produced in the body? How is it activated?

Answer 13

Angiotensin I is produced by the action of RENIN (an enzyme produced by the kidneys) on a protein called ANGIOTENSINOGEN, which is formed by the liver.

Angiotensin I is transformed into angiotensin II (activated) in the blood by the action of angiotensin-converting enzyme (ACE).

Question 14

How does vasopressin affec BP? on heart rate?

Answer 14

Vasopressin aka ADH prevents dehydration by facilitating water retention.

will increase BP if given a massive dose because water will be retained. Sticks more aquaporins in collecting duct of kidneys.

Because Bp increases, heart rate will decrease

Question 15

What is a pharmacoligcal dose?

Answer 15

a large amount of dose that you would never see in real life naturally in the body.

Question 16

If baroreceptors detect an increase in HR or BP, it stimulates the _____ to decrease HR

Answer 16

stimulates the parasympathetic NS by means of sending afferent signals to the medulla, which activates the cardioinhibitor center.

Question 17

Explain the effect of histamine on mean blood pressure. What is the role of histamine in the microcirculation?

Answer 17

histamine promotes capillary dilation and causes a DECREASE IN BLOOD PRESSURE. This drop in blood pressure may induce a slight increase in HR.

In terms of microcirculation, capillaries become more permeable to fluids and white blood cells can be leaked out to induce immune responses.

Question 18

Mechanism of angiotensin activation? How does it affect the blood pressure? what other things does it do?

Answer 18

Mechanism:

Angiotensin is made by ANGIOTENSINOGEN in the LIVER. When BP is LOW, RENIN gets released by juxtaglomerular cells in the KIDNEYs. Angiotensin is produced in the liver, and ACE in the lungs ACTIVATES angtiotensin I to angiotensin II.

Angiotensin II CONSTRCITS ARTERIOLES and increases BP by increasing resistance.

Angiotensin II also triggers the release of ADH to increase BP by causing water retention (by adding more aquaporins in the collecting duct).

Angiotensin II also causes the RELEASE OF ALDOSTERONE, which increases Na+ uptake and thus water due to osmosis.

All three together increase BP.

Question 19

How does aldosterone affect blood pressure?

Answer 19

aldosterone (which can be released when stimulated by angiotensin II), causes Na+ uptake in the kidneys during filtration. Water follows Na+ through osmosis, causing an increase in BP.

Question 20

Angiotensin is a

Answer 20

peptide

Question 21

Acetylcholine application simulates the role of the parasympathetic nervous system in control of heart rate. Explain its mechanism of action. Why is there a confliction between Ach on heart and starlings law?

Answer 21

Ach mainly affects the atrial myocardium (and ventricle a bit). Causes HYPERPOLARIZATION of the hart nodes, which slows down the myogenic activity (spontaneous depolarization), causing APs in the contractile myocytes to be less frequent and thus causing cotnractions to slow down.

there is a contradiction because Ach actually causes BP to DECREASE, but starlings law states that if the heart rate slows down, there is more ventricular filling and thus more blood being pumped out and thus larger BP.

Question 22

Atropine blocks ___ sites

Answer 22

muscarinic sites

Question 23

Why did we inject the rat with saline before the exposing it to drugs?

Answer 23

to control for effects of an increase in blood volume. may cause a minimal blood pressure increase.