Pharmacology

Front 1

What is alpha methyldopa and clonidine used for?

Back 1

Decrease blood pressure by passive vasodilation of resistance arteriole and supression of cardiac output.

alpha 2 agonists

Front 2

Name two determinants of pulse pressure

Back 2

Stroke volume
Arterial compliance

Front 3

What determines DBP?

Back 3

TPR which is determined by resistance arterioles.

R=1/(r^4)

Front 4

Name the determinants of SBP.

Back 4

Stroke volume
Arterial compliance
DBP

Front 5

Describe the relationship between CO and HR.

Back 5

In Adult:
HR is a minor determinant. Primarily determined by SV. This is because as long as VR remains constant, CO remains constant.

In Children:
Increase in HR will increase CO because the left ventricle is a lot smaller. Therefore, the time for the ventricle to fill completely is very short.

Front 6

Describe the relationship between CO and the following:
preload, cardiac contractility and afterload.

Back 6

Increase in preload - Inc CO
Inc contractility - Inc CO
Inc afterload - Dec CO

Front 7

How can you increase CO maximally?

Back 7

Inc preload, Inc contractility and dec afterload.

Front 8

Describe the carotid baroreflex response to a decrease in BP.

Back 8

Decrease Stretch - decrease inhibitory signal to brain - release "brake" on sym - inc sym and dec vagal activity

Overall result:
1. arterial constriction (Inc DBP)
2. Venoconstriction (Inc VR & CO)
3. Cardiac inotropism & HR ( Inc CO)

Front 9

Describe the consequence of suppression of sympathetic outflow.

Back 9

1. Dec stimulation of B-1 receptors - Dec HR, atrial conduction, atrial and ventricular contractility therefore CO falls.

2. Dec stimulation of alpha-1 in resistance arterioles. Passiva vasodilation therefore DBP falls

3. Dec stimulation in capacitance vessels causing passive VD. Dec VR and CO

Front 10

Describe the consequence of increased vagal nerve activity.

Back 10

1. Decrease HR and AV conduction

2. Direct suppression of atrial contractility

3. slight decrease in ventricular contractility.

Front 11

What happens in the alpha-2 stimulation in RVLM?

Back 11

Prevents normal homeostasis regulated by the baroreflexly-mediated increase in sympathetic.

THerefore, fall in BP with clonidine and alpha-methyldopa does not result in cardiac stimulation. Slight bradycardia.

Front 12

What does yohimbine do?

Back 12

Blocks alpha 2 receptors in RVLM.

Increase in efferent sympathetic nerve activity.
Therefore, you get hypertension and tachycardia.

Front 13

Describe the relationship between parasympathetic nerve activity and BP.

Back 13

Decrease in BP = Decrease in parasym. and Increase in sym.

Front 14

ISoproterenol

Back 14

B agonist

Increases HR by direct stimulation of SA node.

Front 15

Describe the 2 mechanisms that drugs can either cause tachycardia or bradycardia.

Back 15

1. Direct stimulation of the SA node

2. Indirectly via arterial baroreflex.

Front 16

Hydralazine

Back 16

Arterial VD

RElaxes smooth muscle to lower BP
Increases HR via arterial baroreflex.

Front 17

Pilocarpine

Back 17

cholinergic agonist

Decrease heart rate by direct action on SA node.

Front 18

Phenylephrine

Back 18

Decrease HR via arterial baroreflex

Front 19

Describe 2 mech to induce bradycardia

Back 19

1. Activation of muscarinic receptor

2. Carotid sinus massage

Front 20

What are the clinical significance of carotid baroreflex?

Back 20

1. Fall in BP - tachycardia
2. From lying/seated to standing - tachycardia
3. increase in BP - bradycardia
4. carotid sinus massage and vestigial reflex - bradycardia