Question

Hormones secreted by the anterior pituitary gland control the activity of all of the following glands except: a. adrenal medulla c. testes b. thyroid gland d. ovaries

Short answer

adrenal medulla

Step-by-step solution

Understanding the Anterior Pituitary Gland

The anterior pituitary gland secretes several hormones that control various endocrine glands. These hormones include ACTH, TSH, LH, and FSH, among others.

Identify Target Glands of the Anterior Pituitary

ACTH stimulates the adrenal cortex, TSH stimulates the thyroid gland, and LH and FSH stimulate the testes and ovaries. Note that the adrenal cortex and adrenal medulla are different parts of the adrenal gland.

Differentiate Between Adrenal Cortex and Adrenal Medulla

The adrenal medulla is controlled by the nervous system, while the adrenal cortex is controlled by ACTH from the anterior pituitary. Therefore, the adrenal medulla is not regulated by hormones from the anterior pituitary gland.

Compare Options with Control Pathways

From the given options, only the adrenal medulla is an exception and is not controlled by the anterior pituitary gland. The thyroid gland, testes, and ovaries are indeed controlled by the anterior pituitary gland through TSH, LH, and FSH respectively.

Key concepts

Hormone Regulation

The body carefully regulates hormones to maintain balance and proper function. Hormone regulation involves feedback mechanisms, where the body monitors and adjusts hormone levels. For example, the hypothalamus and pituitary gland work together to manage hormone production. When hormone levels reach a certain point, the hypothalamus sends signals to either speed up or slow down the production of certain pituitary hormones. This precise regulation ensures the body responds appropriately to different needs and conditions.

Endocrine System

The endocrine system is a network of glands that produce and release hormones into the bloodstream. These hormones regulate many bodily functions, including growth, metabolism, and reproduction. Major glands in the endocrine system include the hypothalamus, pituitary gland, thyroid gland, adrenal glands, and gonads (testes and ovaries). Each gland has specific functions and releases hormones that target specific organs or tissues. The endocrine system works closely with the nervous system to maintain homeostasis.

Pituitary Gland Hormones

The pituitary gland is often called the 'master gland' because it controls several other glands in the endocrine system. It is divided into the anterior and posterior pituitary. The anterior pituitary releases hormones such as:

• ACTH (adrenocorticotropic hormone) that stimulates the adrenal cortex.
• TSH (thyroid-stimulating hormone) that influences the thyroid gland.
• LH (luteinizing hormone) and FSH (follicle-stimulating hormone) that regulate the testes and ovaries.

These hormones ensure that the target glands release their own hormones to regulate the body’s functions. The posterior pituitary stores and releases hormones like oxytocin and vasopressin that are directly produced by the hypothalamus.

Adrenal Medulla

The adrenal medulla is part of the adrenal glands, located on top of the kidneys. Unlike the adrenal cortex, which is regulated by ACTH from the anterior pituitary, the adrenal medulla is controlled by the nervous system. It produces catecholamines, such as adrenaline and noradrenaline, in response to stress. These hormones prepare the body for a 'fight or flight' response by increasing heart rate, blood pressure, and energy supply. Because the adrenal medulla responds to nervous stimuli instead of endocrine signals, it acts more quickly in emergency situations.