Optometry Admission Test (OAT) Practice

What function do direct hormones serve in the body?

1. Stimulate other glands

2. Regulate neurotransmitter release

3. Stimulate organs directly

4. Enhance immune response

The correct answer is: Stimulate organs directly

Direct hormones play a crucial role by acting directly on target organs to elicit physiological responses. Unlike tropic hormones, which primarily stimulate the activity of other glands to release hormones, direct hormones bind directly to their respective receptors and promote immediate effects in specific tissues or organs. For instance, hormones like insulin act directly on muscle and fat cells to facilitate glucose uptake, while growth hormone directly influences growth in tissues. This mechanism allows the body to respond promptly to internal and external stimuli, facilitating immediate bodily functions such as metabolism regulation, growth, and other critical processes without the intermediary step of stimulating other glands.