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Article by Dr Manasa S, B.A.M.S

AIAPGET Points

–        The pituitary gland is also known as the hypophysis.

–        INFUNDIBULUM connects Pituitary to Hypothalamus.

–        The anterior pituitary (adenohypophysis) is derived from oral ectoderm (Rathke’s pouch).

–        The posterior pituitary (neurohypophysis) is derived from neural ectoderm.

–        Pars Distalis is the main hormone-secreting region of the Anterior pituitary.

–        Pituitary adenomas are the most common disorders affecting the pituitary gland.

–        Posterior Pituitary also called as NEUROHYPOPHYSIS is composed of UNMYELINATED NEURAL TISSUE.

–        Dopamine is the only inhibitory hormone of the anterior pituitary.

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Pituitary Gland

What Is the Pituitary Gland?

The pituitary gland is a small, pea-sized endocrine gland located at the base of the brain, just below the hypothalamus, to which it is connected by a stalk called the infundibulum.
Despite its small size, it plays a central role in regulating the endocrine system and is often referred to as the “master gland.”

The pituitary gland produces, stores, and releases several hormones that regulate the function of many other endocrine glands, including the thyroid, adrenal glands, and gonads, as well as influencing growth, metabolism, reproduction, and water balance.

Location and Anatomy

Located at the base of the brain, behind the bridge of the nose
Lies directly below the hypothalamus
Housed in a depression of the sphenoid bone called the sella turcica
Positioned just below the optic chiasma
Adjacent to the cavernous sinus and near the circle of Willis
Connected to the hypothalamus by the pituitary stalk (infundibulum)
Covered by dura mater and separated by the sellar diaphragm, which allows passage of the stalk.

Size:

Weight: < 1 gram
Size: approximately pea or kidney bean sized
Vertical diameter: ~ 8 mm
Horizontal diameter: ~ 12 mm
Anterior pituitary forms ~80% of gland weight

Pituitary, Hypothalamus & The Vata Ecosystem

The location of Pituitary Gland is where Prana Vata is located. Prana Vata controls many functions that the pituitary gland controls, directly or through / in association with hypothalamus. Hormones functionally resemble Vata. Sadhaka Pitta and Tarpaka Kapha are also located in the close vicinity of Prana Vata i.e. in the head. Though Prana Vata is the main dosha subtype which controls many functions just like Pituitary and Hypothalamus does, Sadhaka Pitta and Tarpaka Kapha too have their role. We know that Pitta and Kapha and their subtypes cannot function independently and are dependent on Vata. The integrity and axis between these dosha subtypes located in the head should be balanced and undeterred for many bodily functions to take place. Through the concept of Avaranas, we also learn that different Vata subtypes are connected to the other subtypes and vice versa and are also mutually influencing. This closed circuit of all vata subtypes, the functions they jointly operate and the pathological conditions and diseases that they produce when one has a dominating or masking influence over the other explains the Vata theory in relation to the hormonal / endocrine chemistry.

Example – From the hormone perspective – TSH stimulates thyroid to produce its hormones. Thyroid gland is in the seat of Prana Vata and Thyroid in the seat of Udana Vata and also Prana Vata. So, the pathway of how TSH works can be put in line with the Prana-Udana functional axis.

Similarly ACTH, FSH & LH & ADH works in the pathway similar to the Prana-Apana functional axis. Reproduction and sexual functions, labour and childbirth controlled by Pituitary, are also controlled by the Prana-Apana axis. The metabolic control by pituitary is taken care of by the Prana-Samana-Vyana functional axis.

Structural Division of Pituitary Gland

The pituitary gland has two major lobes, each with distinct structure and function:

1. Anterior Pituitary (Adenohypophysis)

Structural Features

–        Larger lobe

–        Composed of glandular epithelial cells

–        Connected to hypothalamus via portal blood circulation

–        Responsible for synthesis and secretion of most pituitary hormones

Subdivisions

–        Pars distalis – main hormone-secreting region

–        Pars tuberalis – surrounds the infundibular stalk

–        Pars intermedia – thin layer between anterior and posterior lobes

Key Functional Role

Produces trophic hormones that regulate:
– Thyroid
– Adrenal cortex
– Gonads
– Growth and metabolism

Hormones Secreted:

–         Growth Hormone (GH)

–         Thyroid-Stimulating Hormone (TSH)

–         Adrenocorticotropic Hormone (ACTH)

–         Follicle-Stimulating Hormone (FSH)

–         Luteinizing Hormone (LH)

–         Prolactin

2. Posterior Pituitary (Neurohypophysis)

Structural Features

–        Smaller lobe

–        Composed of unmyelinated neural tissue

–        Direct extension of the hypothalamus

–        Connected via nerve fibers through the infundibulum

Functional Role

–        Does not synthesize hormones

–        Stores and releases hormones produced in the hypothalamus

Hormones Released (Synthesized in Hypothalamus):

–        Antidiuretic Hormone (ADH / Vasopressin)

–        Oxytocin

Key Concept: Posterior pituitary stores and releases hormones; it does not synthesize them.

Function of the Pituitary Gland

The pituitary gland regulates multiple vital body functions by releasing hormones that act on target organs and other endocrine glands.

Major Functions:

–         Growth and development

–         Metabolism

–         Reproduction and sexual function

–         Stress response

–         Lactation

–         Water and electrolyte balance

–         Labor and childbirth

Functional Concept

The pituitary gland acts like a thermostat:

–         Continuously monitors body needs

–         Adjusts hormone output to maintain balance

–         Works under the guidance of the hypothalamus

Hypothalamus–Pituitary Relationship

Together, the hypothalamus and pituitary form the hypothalamo-pituitary axis, the central regulatory unit of the endocrine system.

Communication Pathways

–         Anterior pituitary: controlled by hypothalamic releasing and inhibitory hormones via portal circulation

–         Posterior pituitary: controlled by direct nerve impulses from hypothalamic neurons

Hypothalamic Hormones Acting on Pituitary

–         Corticotropin-releasing hormone (CRH)

–         Thyrotropin-releasing hormone (TRH)

–         Gonadotropin-releasing hormone (GnRH)

–         Growth hormone-releasing hormone (GHRH)

–         Somatostatin (inhibits GH & TSH)

–         Dopamine (inhibits prolactin)

Exam pearl:
Dopamine is the only inhibitory hormone of the anterior pituitary.

Effect of Pituitary Hormones on Other Organs

Pituitary hormones regulate:

–         Thyroid gland (via TSH)

–         Adrenal glands (via ACTH)

–         Gonads (via FSH & LH)

–         Bones & muscles (via GH)

–         Breast tissue (via prolactin)

–         Kidneys (via ADH)

Damage to either the hypothalamus or pituitary often affects both systems due to their close anatomical and functional relationship.

Exam-Friendly One-Line Summary

The pituitary gland is a pea-sized endocrine gland located in the sella turcica that regulates growth, metabolism, reproduction and stress by secreting hormones under hypothalamic control.

Symptoms of Pituitary Disorders

Due to Mass Effect:

–         Headache

–         Loss of peripheral vision

–         Raised intracranial pressure

Due to Hormonal Imbalance:

–         Growth abnormalities

–         Infertility

–         Irregular menstruation

–         Sexual dysfunction

–         Weight changes

–         Mood disturbances

Disorders of the Pituitary Gland

1. Pituitary Adenomas

Benign tumors (10–15% of intracranial tumors)

May be:

–        Functioning (hormone-secreting)

–        Non-functioning

Common features:

–        Headache

–        Visual field defects (bitemporal hemianopia)

Most common type: Prolactinoma

2. Hypopituitarism

Deficiency of one or more pituitary hormones

Causes:

–        Surgery

–        Radiation

–        Tumors

–        Trauma

Examples:

–         GH deficiency

–         Central diabetes insipidus (ADH deficiency)

–         Central hypothyroidism

–         Central adrenal insufficiency

–         Hypogonadism

3. Hyperpituitarism

–        Excess hormone secretion

–        Usually due to functioning adenomas

Examples:

–         Acromegaly (↑ GH in adults)

–         Gigantism (↑ GH in children)

–         Cushing’s disease (↑ ACTH)

–         Hyperprolactinemia

4. Empty Sella Syndrome

–         Flattened or shrunken pituitary gland

–         Diagnosed radiologically

–         Often asymptomatic

–         May be associated with headaches or hormone imbalance

Clinical Importance (Exam Perspective)

–         Pituitary disorders commonly present with visual defects, growth abnormalities, infertility, and metabolic disturbances

–         Hormonal evaluation and imaging (MRI) are key diagnostic tools

–         Many conditions are treatable with surgery, medication, or hormone replacement

Diagnosis of Pituitary Disorders

Blood tests for pituitary hormones

MRI (pituitary-focused)

Dynamic tests:

–        GH suppression test

–        GH stimulation test

–        Dexamethasone suppression test

–        Insulin tolerance test

Maintaining Pituitary Health

–         Prevent head injuries

–         Use helmets and seat belts

–         Manage stress

–         Address eating disorders early

A Quick Revision on Pituitary Gland

The pituitary gland (hypophysis) is a pea-sized endocrine gland located at the base of the brain in the sella turcica of the sphenoid bone.

It is structurally and functionally connected to the hypothalamus, forming the hypothalamo-pituitary axis, the central regulatory system of endocrinology.

The pituitary is traditionally called the “master gland” because its hormones regulate the activity of most other endocrine glands.

The gland has two distinct lobes:

–        Anterior pituitary (adenohypophysis) – glandular, hormone-producing

–        Posterior pituitary (neurohypophysis) – neural, hormone-releasing

Anterior pituitary synthesizes and secretes hormones, whereas the posterior pituitary stores and releases hypothalamic hormones.

Pituitary hormones influence growth, metabolism, reproduction, stress response, lactation, and water balance.

Hormone secretion from the pituitary is primarily regulated by releasing and inhibiting hormones from the hypothalamus via feedback mechanisms.

The pituitary receives blood supply through a specialized vascular system called the hypothalamo-hypophyseal portal circulation (important exam concept).

Disorders of the pituitary can cause hormone excess or deficiency, leading to conditions such as gigantism, acromegaly, hypopituitarism, and Cushing’s disease.

Due to its close anatomical relationship with the optic chiasm, pituitary tumors often present with visual field defects, especially bitemporal hemianopia.

https://link.springer.com/subjects/pituitary-gland

https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2023.1233714/full

Division of Endocrinology, Diabetes, Metabolism, and Nutrition-Research – Pituitary, Gonad and Adrenal Research

Pituitary gland articles within Nature Reviews Endocrinology

The Morphology of the Pituitary Gland: A Meta-Analysis with Implications for Diagnostic Imaging

Recent Progress in Stem Cell Research of the Pituitary Gland and Pituitary Adenoma

https://www.sciencedirect.com/science/article/abs/pii/S0165032716323229

https://pubmed.ncbi.nlm.nih.gov/28412090/