Field Internship Student Data Acquisition Project. (FISDAP) Airway Practice Exam

What effect do Beta-1 receptors have on the body?

1. Decreased heart rate

2. Increased heart rate

3. Bronchodilation

4. Increased blood flow to the lungs

The correct answer is: Increased heart rate

Beta-1 receptors are predominantly found in the heart and are a type of adrenergic receptor that responds to catecholamines, such as epinephrine and norepinephrine. When these receptors are activated, they lead to an increase in heart rate, known as positive chronotropic effects. This occurs due to an increase in the conduction velocity through the sinoatrial (SA) node, the natural pacemaker of the heart, thereby stimulating an increased heart rate. In addition to raising the heart rate, activation of Beta-1 receptors also enhances myocardial contractility, which means the force of the heart's contractions increases, and improves conduction through the atrioventricular (AV) node. This overall response is crucial during situations of stress or exercise, where the body requires more oxygenated blood to be circulated rapidly. The other options do not accurately represent the effects of Beta-1 receptors. For instance, decreased heart rate represents the opposite action of what Beta-1 activation would cause. Bronchodilation is primarily associated with Beta-2 receptor activation, which affects the smooth muscle in the airways rather than heart function. Similarly, increased blood flow to the lungs relates more to vascular dynamics influenced by different receptors, rather than a direct result of Beta-