They raise blood glucose for different purposes, on different timescales, and as part of different packages of effects.

Catecholamines are rapidly secreted in response to stress of any kind and during emergency situations, and their glucose effect is one item in a coordinated emergency response that also increases alertness, pupilary dilation, piloerection, sweating, heart beat, strength of heart contraction and rate of respiration, and breaks down lipids and proteins. The glucose is being mobilised for immediate violent exertion.

Glucagon is a peptide hormone whose role is stated quite differently: it plays an important role in maintaining the normal blood glucose levels. It acts mainly on hepatocytes, stimulating glycogenolysis and gluconeogenesis and reducing cellular glucose uptake and utilisation. This is routine housekeeping between meals, not an emergency, and it is paired with insulin so that glucose homeostasis is maintained jointly by the two.

The general point: the same biochemical step can serve either a crisis or a routine, and the body keeps separate hormones for the two contexts so that a mildly falling blood sugar does not trigger a full fight-or-flight response.

Raised blood sugar. Glucocorticoids stimulate gluconeogenesis — the making of new glucose — and are the corticoids specifically described as involved in carbohydrate metabolism. Sustained high levels therefore keep pushing glucose into the blood.

Muscle wasting. Glucocorticoids stimulate proteolysis (breakdown of protein) and inhibit cellular uptake and utilisation of amino acids. Both actions run against the maintenance of muscle protein: existing protein is broken down and the amino acids needed to rebuild it are not taken up.

Frequent infections. Glucocorticoids, particularly cortisol, produce anti-inflammatory reactions and suppress the immune response. The very property that makes cortisol useful against inflammation leaves the patient less able to resist pathogens.

The lesson: a hormone's side effects are not accidents but its own normal actions, occurring at the wrong dose or for too long. Note also that cortisol is involved in maintaining the cardio-vascular system and kidney functions and stimulates RBC production, so prolonged excess disturbs those too.

Aldosterone acts mainly at the renal tubules and stimulates the reabsorption of Na⁺ and water and the excretion of K⁺ and phosphate ions.

The chain to blood pressure. Reabsorbing sodium raises the solute content of the blood, and water follows it osmotically. More water retained means a larger body fluid volume. Since blood pressure depends on the volume of fluid within the vessels, a larger volume raises the pressure; conversely, less aldosterone means more sodium and water lost in urine, a smaller volume, and lower pressure.

Hence the four things NCERT lists together: aldosterone helps in the maintenance of electrolytes, body fluid volume, osmotic pressure and blood pressure. They are not four separate jobs but four consequences of one action — controlling how much salt and water the kidney gives back to the blood.

A wider view: compare this with vasopressin (ADH) from the posterior pituitary, which stimulates resorption of water and electrolytes by the distal tubules, and with atrial natriuretic factor from the heart, which lowers blood pressure. The kidney is the common final target through which several hormones regulate the internal fluid environment.

The pancreas is a composite gland acting as both exocrine and endocrine gland. The bulk of the tissue is exocrine, producing digestive secretions; the endocrine pancreas consists of the Islets of Langerhans, about 1 to 2 million of them, representing only 1 to 2 per cent of the pancreatic tissue.

Why the small part is critical. The β-cells of the islets secrete insulin, which plays a major role in the regulation of glucose homeostasis, acting on hepatocytes and adipocytes to enhance cellular glucose uptake and utilisation and to stimulate glycogenesis. Nothing else in the body can do this. Without insulin, blood glucose is not lowered, and prolonged hyperglycemia leads to diabetes mellitus, associated with loss of glucose through urine and formation of harmful compounds known as ketone bodies.

Why the large part is less immediately critical. Loss of exocrine function impairs digestion, which is serious but slower to kill and partly manageable, and some digestion can proceed with other secretions.

The general principle: physiological importance is not proportional to tissue mass. Hormones act as intercellular messengers produced in trace amounts, so a very small mass of tissue can hold a function on which the whole body depends. Happily, this also means the deficiency can be replaced from outside — diabetic patients are successfully treated with insulin therapy.

What they do. The small amounts of androgenic steroids secreted by the adrenal cortex play a role in the growth of axial hair, pubic hair and facial hair during puberty.

Why this matters in both sexes. The principal source of androgens in males is the testis — the Leydig cells produce androgens, mainly testosterone. But the adrenal cortex is present in both sexes, so it provides a route by which androgen-dependent features can appear in females as well, who have no testis. This is why the growth of axial and pubic hair at puberty is a feature of both sexes.

What it illustrates. Three things, each a theme of this chapter:

(i) A single gland can secrete chemically and functionally unrelated hormones. The adrenal cortex makes glucocorticoids for carbohydrate metabolism, mineralocorticoids for water and electrolytes, and androgenic steroids for hair growth at puberty — and this same pattern appears in the thyroid (iodothyronines plus thyrocalcitonin) and the pancreas (α- and β-cells with opposite effects).

(ii) The same hormone can come from more than one source. Androgens are produced by both the testis and the adrenal cortex.

(iii) Trace amounts suffice. "Small amounts" are enough to produce a visible developmental change, which is exactly what the definition of a hormone predicts — non-nutrient chemicals acting as intercellular messengers and produced in trace amounts.