What Does the Pituitary Gland Do? Key Roles in the Human Body
The pituitary gland is a brain-based endocrine gland. It creates hormone-like substances which are chemical messengers that help organs communicate.
The endocrine system includes the pituitary gland. By releasing hormones into your bloodstream, the pituitary gland aids in the control of your body's processes. These hormones go through your bloodstream to their intended destination.
They usually cause the release of the second hormone in this situation. The target can be specialised endocrine glands or other types of body tissue, such as cell groups.
Because it regulates several other hormone-releasing glands, the pituitary gland is sometimes referred to as the master gland. The pituitary gland regulates several glands, including the thyroid, ovaries, testicles (testes), and adrenal glands.
Pituitary Gland - Function and Disorders
Function
The thyroid gland, adrenal gland, ovaries, and testicles are all controlled by the master gland. While it controls these glands, it receives orders from its neighbour, the hypothalamus.
The pituitary gland produces hormones that tell the glands how much hormone they should produce.
The pituitary gland also manufactures hormones for the body's organs like:
Oxytocin stimulates contractions in the uterus and mammary glands, which in turn aid in childbirth and milk production.
Vasopressin is an antidiuretic hormone that helps the kidneys function properly.
A beta-melanocyte-stimulating hormone is a hormone that causes the skin to darken.
Endorphins are neurotransmitters that help the brain and immune system reduce pain and control the immune system.
Hormones that promote muscle and bone growth.
Enkephalins are pain-blocking brain chemicals.
Most hormones are released every one to three hours, following the body's circadian rhythm. Hormone production peaks throughout the day and declines at night.
Disorders
Pituitary disorders are caused by the pituitary gland being either excessively active or inactive. An isolated portion of the pituitary gland, known as a pituitary adenoma, frequently causes complications (if it is large it may be called pituitary macroadenoma).
These tumours are normally benign and non-cancerous. Adenomas of the pituitary gland can create issues by:
Excess of one or more hormones is released.
Not producing hormones but pressing on normal pituitary tissue, causing the normal function to be disrupted; and/or
Putting pressure on surrounding structures, such as the eye's nerve, results in blurred vision or the loss of a portion of eyesight.
The pituitary gland produces too much of one or more of its hormones in the following conditions:
Acromegaly
Cushing's syndrome
Prolactinoma
The pituitary gland produces insufficient hormones in the following conditions:
When adult growth hormones are deficient.
Diabetes insipidus which is a kind of diabetes that affects the kidneys.
Hypopituitarism.
Tumours of the pituitary gland.
Hypothalamic tumours or injuries that have a knock-on impact on the pituitary gland.
FAQs on Pituitary Gland: Structure, Functions & Disorders
1. What is the pituitary gland and why is it often called the 'Master Gland' of the endocrine system?
The pituitary gland is a small, pea-sized endocrine gland located at the base of the brain. It is known as the 'Master Gland' because it produces and secretes several crucial hormones that control the functions of other endocrine glands, such as the thyroid, adrenal glands, and gonads, thereby regulating growth, metabolism, and reproduction throughout the body.
2. Where exactly is the pituitary gland located in the human body?
The pituitary gland is situated in a small, bony cavity at the base of the skull called the sella turcica. It is found just below the brain, inferior to the hypothalamus, to which it is connected by a stalk-like structure. Its strategic location allows for direct communication and control by the brain.
3. What are the main parts of the pituitary gland and how do they differ in function?
The pituitary gland is divided into two main lobes with distinct functions:
Anterior Pituitary (Adenohypophysis): This lobe synthesises and secretes its own hormones, including Growth Hormone (GH), Thyroid-Stimulating Hormone (TSH), and others that regulate various bodily functions.
Posterior Pituitary (Neurohypophysis): This lobe does not produce its own hormones. Instead, it stores and releases hormones like Oxytocin and Antidiuretic Hormone (ADH) which are produced by the hypothalamus.
4. Which important hormones are secreted by the anterior pituitary, and what are their primary roles?
The anterior pituitary secretes several key hormones. The most important ones include:
Growth Hormone (GH): Regulates growth and metabolism.
Thyroid-Stimulating Hormone (TSH): Stimulates the thyroid gland to produce thyroid hormones.
Adrenocorticotropic Hormone (ACTH): Stimulates the adrenal glands to release cortisol.
Follicle-Stimulating Hormone (FSH) and Luteinising Hormone (LH): Collectively known as gonadotropins, they regulate reproductive functions in both males and females.
Prolactin (PRL): Stimulates milk production in females.
5. How does the hypothalamus control the functions of the pituitary gland?
The hypothalamus acts as the command centre for the pituitary gland. It controls the anterior pituitary by secreting releasing hormones (like GnRH) and inhibiting hormones (like somatostatin) into a portal blood system. For the posterior pituitary, control is more direct; it is an extension of the hypothalamus, and nerve signals from the hypothalamus trigger the release of stored hormones like ADH and oxytocin.
6. What are some examples of disorders caused by the improper functioning of the pituitary gland?
Improper functioning of the pituitary gland, leading to either over-secretion (hypersecretion) or under-secretion (hyposecretion) of hormones, can cause several disorders. For example:
Dwarfism: Caused by a deficiency of Growth Hormone in childhood.
Gigantism: Caused by an excess of Growth Hormone in childhood.
Acromegaly: Caused by an excess of Growth Hormone in adulthood, leading to the enlargement of bones in the face, hands, and feet.
Diabetes Insipidus: Caused by a deficiency of Antidiuretic Hormone (ADH), leading to excessive thirst and urination.
7. Can you explain the relationship between the pituitary gland and the thyroid gland using an example?
The pituitary-thyroid relationship is a classic example of hormonal control. The hypothalamus releases TRH, which signals the anterior pituitary to secrete Thyroid-Stimulating Hormone (TSH). TSH then travels through the bloodstream to the thyroid gland, stimulating it to produce and release its own hormones (T3 and T4). This hierarchical control demonstrates the pituitary's role as a 'master' regulator.
8. How does the effect of excess Growth Hormone (GH) differ if it occurs in childhood versus adulthood?
The timing of GH over-secretion critically determines its effects. If it occurs in childhood before the growth plates in long bones have fused, it results in Gigantism, causing a proportional increase in overall height. However, if it occurs in adulthood after the growth plates have closed, it results in Acromegaly, which does not increase height but causes disfigurement through the thickening of bones in the hands, feet, and face.
9. What is a negative feedback loop, and how does it apply to hormones regulated by the pituitary gland?
A negative feedback loop is a self-regulating biological system where the output of a process inhibits its own production, maintaining balance or homeostasis. For instance, the pituitary releases ACTH, which stimulates the adrenal glands to produce cortisol. When cortisol levels in the blood become high, cortisol itself signals the pituitary and hypothalamus to stop releasing ACTH and CRH, respectively. This prevents excessive cortisol production and maintains stable hormone levels.
