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PHAR20300 > BETA RECEPTORS > Flashcards

BETA RECEPTORS Flashcards

1
Q

How do B1 receptors work?

A

Couple to Gas (stimulatory)
Activates adenylyl cyclase and
increases cAMP conc
activation of PKA.

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2
Q

Where are B1 receptors found?

A 
SA node
AV node
Cardiac myocytes
Kidneys 
Vasomotor centre
Adipocytes
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3
Q

What effect does activation of B1 receptors in SA node have?

A

Increase in heart rate

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4
Q

What effect does activation of B1 receptors in cardiac myocytes have?

A

Increase in force of contraction

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5
Q

What effect does activation of B1 receptors in AV node have?

A

Decrease in refractory period between APs so increase in heart rate as a result

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6
Q

What is the overall effect of activation of B1 receptors?

A

Increase in HR and therefore an increase in SV and increase in CO which has a profound effect on BP

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7
Q

Where in particular in the kidneys are B1 receptors expressed?

A

Juxtaglomerula apparatus

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8
Q

B1 receptors in juxtaglomerula apparatus control the release of ______

A

renin

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9
Q

Renin controls the conversion of?

A

Angiotensin I to angiotensin II

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10
Q

Angiotensin II is a powerful vasodilator. True or false?

A

False - vasoconstrictor and therefore increases peripheral resistance and increases BP

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11
Q

Angiotensin regulates secretion of which two things?

A

Aldosterone and ADH

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12
Q

What is the role of aldosterone?

A

Na+ reabsorption into kidneys and K+ secretion therefore creating osmotic gradient for water to be reabsorbed into blood

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13
Q

What is the role of ADH?

A

Prevents loss of water from urine

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14
Q

What is the net effect of activation of B1 receptors in kidneys?

A

Increase in blood volume and so an increase in BP

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15
Q

B1 receptors and B2 receptors function in the same way. True or false?

A

True

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16
Q

How do B2 receptors work?

A

Couple to Gas
Stimulates adenylyl cyclase
increase concentration of cAMP
Activation of PKA

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17
Q

Where are B2 receptors expressed?

A

Bronchial smooth muscle

Endothelial cells of specific blood vessels within skeletal muscle

18
Q

B2 receptors control bronchodilation. True or false?

A

True

19
Q

Which receptor controls production of NO and how does it do this?

A

B2 - present in endothelial cells of specific blood vessels within skeletal muscle and control the production of NO - vasodilator

20
Q

Why doesn’t activation of B2 receptors on blood vessels within skeletal muscle have much of an effect on BP?

A

Because although production of NO leads to vasodilation, there are a1 receptors present on vascular smooth muscle cells - vasoconstriction

21
Q

On activation of B2 receptors on blood vessels within skeletal muscle, blood flow is diverted away from skeletal muscle. True or false?

A

False - diverted towards skeletal muscle

22
Q

What is a side effect of drugs that act on B2 receptors?

A

Muscle tremor

23
Q

Activation of which receptor can lead to glycogenolysis in the liver and skeletal muscle?

A

B2 receptors

24
Q

B2 antagonists are used as bronchodilators. True or false?

A

False - B2 agonists

25
Q

Name two short acting B2-selective agonists that are used as bronchodilators

A

Salbutamol

Terbutaline

26
Q

Name two long active B2-selective agonists that are used as bronchodilators

A

Salmeterol

Eformoterol

27
Q

Why is tachycardia a side effect of B2 agonist bronchodilators?

A

Due to activation of cardiac B receptors which cause increase in HR

28
Q

Hypokalaemia is a side effect of B2 agonist bronchodilators. Why?

A

loss of potassium due to activation of Na+/K+ pump in skeletal muscle

29
Q

How are side effects of B2 agonist bronchodilators minimised?

A

By inhalation of drugs rather than oral administration

30
Q

Propranolol is a non-competitive antagonist. True or false?

A

False - competitive

31
Q

Is atenolol a selective or non-selective antagonist?

A

Selective B1

32
Q

Why does propranolol have a better CNS penetration than atenolol?

A

Because it is more lipid soluble, whereas atenolol is relatively water soluble

33
Q

What is the equation for BP?

A

BP = CO x PR

34
Q

Why does tachycardia decrease coronary perfusion?

A

Because there is less time to perfuse the heart

35
Q

How are B1 antagonists used in treatment of angina?

A

By blocking B1 receptors, there is a decrease in HR and so diastole is prolonged, which increases coronary blood flow and oxygen delivery

36
Q

B-antagonists can be used in treatment of pheochromocytoma. True or false?

A

True - used for cardio-protection alongside phentolamine and phenoxybenzamine

37
Q

Fastest AP is in AVN. True or false?

A

False - SAN

38
Q

How can B-antagonists be used to correct dysrhythmias?

A

reduce HR and prevent ectopic foci from occurring within muscle cells - restoring sinus rhythm

39
Q

Vivid dreams are a side effect of propranolol but not atenolol. True or false?

A

True

40
Q

Why does increased sensitivity to catecholamines lead to dysrhythmias?

A

Because pacemaker potential is activated, caused by inward movement of ca2+. This causes non-pacemaker cells to create AP separate from SAN leading to ectopic foci

41
Q

B-blockers are used to control symptoms in thyrotoxicosis. True or false?

A

True

42
Q

B-blockers can be used in treatment of chronic simple glaucoma by reducing aq humor. True or false?

A

True

PHAR20300 (25 decks)

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