Pituitary Gland Structure and Function

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Questions and Answers

What is the primary function of the anterior pituitary gland?

It serves as the site for blood filtration.

It regulates various endocrine glands through hormone secretion. (correct)

It stores hormones produced by the hypothalamus.

It directly produces all hormones in the body.

Which type of cells in the anterior pituitary are considered precursors and do not have granules?

Corticotropes

Chromophil cells

Somatotropes

Chromophobe cells (correct)

What hormones are secreted by the somatotropes in the anterior pituitary?

Follicle-stimulating hormone (FSH)

Growth hormone (GH) (correct)

Thyroid-stimulating hormone (TSH)

Adrenocorticotropic hormone (ACTH)

Which of the following is NOT classified as a glycoprotein hormone released from the anterior pituitary?

Prolactin Signup and view all the answers

Which of the following correctly identifies the constituents of glycoprotein hormones?

Two peptide chains, with identical alpha chains and varying beta chains Signup and view all the answers

Which type of anterior pituitary cells secrete adrenocorticotropic hormone (ACTH)?

Corticotropes Signup and view all the answers

What is the role of basophilic cells in the anterior pituitary?

They are responsible for secreting stimulating hormones such as TSH, FSH, and LH. Signup and view all the answers

What is the relationship between the precursor compound BIG ACTH and its derivatives?

BIG ACTH undergoes enzymatic cleavage to form ACTH and smaller peptides. Signup and view all the answers

What is the primary function of the first 24 amino acids of ACTH?

Regulating skin pigmentation Signup and view all the answers

Which hormone is believed to be synonymous with prolactin-inhibitory hormone (PIH)?

Dopamine Signup and view all the answers

Which of the following hormones stimulates the release of thyroid-stimulating hormone?

Thyrotropic-releasing hormone (TRH) Signup and view all the answers

Which component of beta lipotrophs is noted for its analgesic properties?

Beta-endorphin Signup and view all the answers

Which hormone from the hypothalamus inhibits the release of growth hormone?

Growth hormone-inhibitory hormone (GHIH) Signup and view all the answers

What characterizes the first five hormones released by the anterior pituitary?

They stimulate other endocrine glands. Signup and view all the answers

Where are neurohormones produced before being transported to the anterior pituitary?

The median eminence and tuber cinereum Signup and view all the answers

Which hormone does gonadotropin-releasing hormone (GnRH) stimulate the release of?

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) Signup and view all the answers

What is the primary embryological origin of the anterior pituitary gland?

Ectodermal in origin from the pharyngeal epithelium. Signup and view all the answers

Which structure lies between the anterior and posterior pituitary glands?

Pars intermedia Signup and view all the answers

What is the weight range of a normal pituitary gland?

0.5 to 1 g Signup and view all the answers

How are hormones transported from the hypothalamus to the anterior pituitary?

Hypophyseal portal system Signup and view all the answers

Which of the following correctly describes the relationship between the hypothalamus and pituitary gland?

The relationship is called hypothalamo-hypophyseal. Signup and view all the answers

Which structural characteristic distinguishes the posterior pituitary from the anterior pituitary?

It arises from neuroectoderm. Signup and view all the answers

What is the diameter of the pituitary gland?

1 cm Signup and view all the answers

Which term describes the small gland located in the depression of the sphenoid bone?

Pituitary gland Signup and view all the answers

Study Notes

Objectives

Describe the pituitary gland's structure and its relation to function
Define anterior pituitary cell types and their regulation
Define growth hormone's role in growth and metabolism, including IGF-I's role
List growth hormone secretion regulators and their mechanisms
Understand abnormal pituitary function and treatment options

Pituitary Gland

The pituitary gland, also known as the hypophysis, is a small endocrine gland (1 cm diameter, 0.5-1 g weight) located in the sella turcica of the sphenoid bone at the skull base.
It's connected to the hypothalamus by the pituitary stalk (hypophyseal stalk).
Divided into two divisions:
- Anterior pituitary (adenohypophysis)
- Posterior pituitary (neurohypophysis)
These divisions, though close, are embryologically and functionally distinct.
The pars intermedia is a small, relatively avascular structure between the divisions.

Pituitary Anatomy

Both anterior and posterior pituitary divisions develop from different embryonic sources
- Anterior pituitary develops from pharyngeal epithelium (Rathke's pouch)
- Posterior pituitary develops from the hypothalamus (downward diverticulum)
The two divisions grow toward each other and fuse.
The relationship between the hypothalamus and pituitary gland is called the hypothalamo-hypophyseal relationship.

Anterior Pituitary (Adenohypophysis)

Divided into three parts (Pars distalis, Pars tuberalis, Pars intermedia)
Consists of two cell types:
- Chromophobe cells: These cells make up approximately 50% of the anterior pituitary and are not secretory in nature; thought to be precursor cells for chromophil cells.
- Chromophil cells: These cells are darkly stained and contain granules. They are further classified:
  - Acidophilic cells (alpha cells): about 35%
  - Basophilic cells (beta cells): about 15%
Different chromophil cell types secrete specific hormones with various functions, including:
- Somatotropes: secrete growth hormone (GH)
- Corticotropes: secrete adrenocorticotropic hormone (ACTH)
- Thyrotropes: secrete thyroid-stimulating hormone (TSH)
- Gonadotropes: secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
- Lactotropes: secrete prolactin

Histology

Anterior pituitary has two types of cells based on staining properties: Chromophobe cells and Chromophil cells.
Chromophobe cells don't stain easily, are not secretory in nature and make up 50% of anterior pituitary.
Chromophil cells stain darkly and are secretory in nature.
- Acidophilic(alpha cells) are approximately 35%
- Basophilic(beta cells) are approximately 15%
Chromophil cells are further divided based on the hormone they secrete.

Regulation of Secretion

Hypothalamic hormones (releasing and inhibiting hormones) control anterior pituitary hormone release.
These hormones are transported to the anterior pituitary through the hypothalamo-hypophyseal portal vessels.

Hormones

Some hormones are "tropic" meaning they stimulate other endocrine glands.
Other hormones, like prolactin, target other tissues and influence their function.
Specific hormones secreted by the Anterior Pituitary:
- Growth hormone (GH) or somatotropic hormone (STH)
- Thyroid-stimulating hormone (TSH) or thyrotropic hormone
- Adrenocorticotropic hormone (ACTH)
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Prolactin (PRL)

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Description

Explore the intricate structure and functions of the pituitary gland in this quiz. Understand the roles of anterior and posterior divisions, their cell types, and the regulation of growth hormone secretion and its effects on metabolism. Test your knowledge on abnormal pituitary functions and treatment options.