Which of the following is a disorder of the adrenal cortex?

Cushing's syndrome is indeed a disorder of the adrenal cortex and is characterized by excessive levels of cortisol in the body. This can result from various factors, including the overproduction of cortisol by the adrenal glands, often due to a tumor in the pituitary gland (known as Cushing's disease), or it can occur due to adrenal tumors or excessive administration of corticosteroid medications.

The adrenal cortex is responsible for producing hormones such as cortisol, aldosterone, and androgens, and disorders affecting this area can lead to significant hormonal imbalances and a variety of systemic effects. In the case of Cushing's syndrome, patients may present with symptoms such as obesity, hypertension, glucose intolerance, and changes in skin texture, among others.

In contrast, the other options listed do not originate from the adrenal cortex. Chronic bronchitis and asthma are respiratory disorders associated with airway inflammation and obstruction, while pneumonia is an infection of the lungs, typically caused by bacteria, viruses, or fungi, affecting the alveoli and respiratory function rather than adrenal function. This highlights the distinction between respiratory conditions and endocrine disorders like Cushing's syndrome.