Sofia was nervous about her upcoming exam, and to quiet her anxiety she placed a

Question

Sofia was nervous about her upcoming exam, and to quiet her anxiety she placed a finger on her radial artery and concentrated as she attempted to lower her pulse rate. It felt good to close her eyes! Her pupils had been dilated for an eye exam that morning. She sniffed and took a cold pill from her purse. It contained pseudoephedrine, with a warning that people with hypertension should be careful. Well, her blood pressure was under control with a combination of drugs that included atenolol. When the exam arrived, she took a puff from her asthma inhaler and began.

Some of the new terms and concepts you will encounter include: Alpha and beta-adrenergic receptor types and their effects Atropine, atenolol, pseudoephedrine, albuterol, and sympathomimetics

Sofia used atenolol among other drugs for her hypertension, took a cold medicine that contained pseudoephedrine, and used a puffer for asthma.

Which receptors do these drugs stimulate or block, and what are their effects?

What might have provoked Sofia's asthma, and how would the inhaler help?

Sofia had her pupils dilated for an eye exam that morning.

What drug was used to dilate her pupils, and how did that drug work?

Sofia monitored her pulse rate in an attempt to calm her anxiety.

How does the autonomic system control the pulse rate? What technique is she employing, and can it work?

Explanation / Answer

Q1.Pseudoephedrine is a sympatomimetic drug that acts on adrenergic system mainly alpha and beta 2 adrenergic receptors. It produces nasal decongestion by causing vasoconstriction of blood vessels by acting on the alpha adrenergic receptors present in the walls of blood vessels and by causing relaxation of the bronchi by acting on the beta 2 adrenergic receptors present on smooth muscles of bronchioles.

Atenolol is beta blocker i.e. it blocks the beta adrenergic receptors specifically beta 1 adrenergic receptor. These receptors are located mainly in the heart and kidney. Atenolol is mainly used to decrease the blood pressure in hypertensive patients. It acts by inhibiting the binding of sympathetic neurotransmitters adrenaline or epinephrine on beta 1 receptor which causes decreased cardiac output, decrease heart rate and automacity. In higher dose it can even block beta 2 receptors present in bronchi smooth muscles.

Asthma inhaler mainly contains beta adrenergic receptors agonist which mainly act on beta 2 receptors present in the bronchi smooth muscles. They bind to these receptors and cause relaxation of smooth muscles. There are different types short acting and long acting. Short acting beta 2 receptor agonist are very commonly used as rescue medication in asthma patients.

Q2. Atenolol which was taken by Sofia earlier caused blocking of beta 2 receptors of bronchi smooth muscles or bronchospasm which made her take asthma rescue medication which stimultes the beta 2 receptors and causes relaxation of bonchi smooth muscles giving her immediate relief.

Q3. An anticholinergic drug tropicamide is generally used to dilate the pupils for eye exams to give a better image of the back of the eye. It causes relaxtion of eye muscles preventing them from contraction even to sensitivity of light. Its effects start within 40 minutes of drug administration and lasts for a day. It is administered via eye drops.

Q4 Pulse rate or heart rate is controlled by two branches of autonomic system sympathetic and parasympathetic. The sympathetic system releases hormones catecholamines (epinephrine and norepinephrine) which increase pulse rate. The parasympathetic system releases acetylcholine which decreases the pulse rate. The autonomic system controls the pulse rate using these two branches as response to stimuli. The pulse rate can increase or decrease in condition of anxiety,fear excitement etc.

Sofia was using meditation by focusing on the pulse rate and closing her eyes relaxing her body and breathing slowly which is an effective method to reduce anxiety.

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