Question

Which of the following hormones directly stimulates its target organ? A. ACTH B. TSH C. \(\mathrm{LH}\) D. GH

Short answer

D. GH

Step-by-step solution

Understand the Question

Identify which hormone directly stimulates its target organ, without needing intermediate steps or other hormones.

Analyze Each Hormone

Review the function of each hormone: - ACTH (Adrenocorticotropic Hormone) stimulates the adrenal glands.- TSH (Thyroid Stimulating Hormone) stimulates the thyroid gland.- LH (Luteinizing Hormone) stimulates the gonads (ovaries and testes).- GH (Growth Hormone) stimulates overall body growth, acting directly on tissues.

Determine Direct Stimulation

GH (Growth Hormone) directly acts on tissues throughout the body to promote growth and repair, unlike the other hormones which act through intermediary glands.

Key concepts

hormone function

Hormones are chemical messengers that travel through the bloodstream to tissues or organs. They affect many different processes in the body, like growth, metabolism, and mood.
Hormones are produced by glands in the endocrine system and are released into the bloodstream.
Each hormone has a specific role and functions by binding to receptors on its target organs. Common hormones include:

• Insulin - regulates blood glucose levels.
• Adrenaline - increases heart rate and energy supply.
• Estrogen and Testosterone - involved in reproductive processes.

When a particular hormone reaches its target, it causes specific biological responses that help maintain homeostasis, which is the body's stable internal environment. Understanding hormone function is crucial for diagnosing and treating various endocrine disorders.

direct hormone stimulation

Direct hormone stimulation occurs when a hormone interacts with its target organ without the involvement of intermediary steps or other hormones. This means the hormone binds directly to receptors on the target cells, initiating its effects right away.

• Example: Growth Hormone (GH) is an example of a hormone that directly stimulates its target organs. It acts on bones and muscles to promote growth.

This is in contrast to hormones like ACTH, TSH, and LH, which rely on other endocrine glands to release additional hormones that eventually affect the target organs.
Direct stimulation is essential for rapid response and precise regulation of various physiological functions. For instance, GH plays a key role in children's growth and overall body repair.

growth hormone

Growth hormone (GH), also known as somatotropin, is a peptide hormone that plays a vital role in growth, body composition, cell repair, and metabolism.
Key Functions of Growth Hormone:

• Stimulates growth of bones and muscles
• Increases protein synthesis
• Promotes fat breakdown
• Regulates metabolism

Growth hormone is secreted by the pituitary gland, located at the base of the brain. Its release is regulated by the hypothalamus through growth hormone-releasing hormone (GHRH) and somatostatin.
In children, GH is crucial for normal growth; in adults, it helps maintain muscle mass, bone density, and optimal body function.
Deficiency or excess of GH can lead to disorders such as dwarfism or gigantism, respectively. Therefore, maintaining balanced GH levels is necessary for health and well-being.