Hypothalamic and Pituitary Hormones Lecture Flashcards

Flashcards based on lecture notes covering hypothalamic and pituitary hormone physiology, chemical structures, structure-activity relationships, and clinical applications.

Pituitary Gland

A gland that weighs about $0.6\,g$ and rests at the base of the brain in the bony \text{sella turcica} near the optic chiasm and the cavernous sinuses.

Portal Venous System

A blood vessel system that connects the hypothalamus and pituitary; it drains the hypothalamus and perfuses the anterior pituitary gland.

Thyrotropin-Releasing Hormone (TRH)

A tripeptide with the sequence $\text{pGlu–His–Pro–NH}_2$ synthesized in the hypothalamus that stimulates the anterior pituitary to release thyroid-stimulating hormone (TSH).

pyroglutamyl (pGlu) at N-terminus

A structural feature of TRH that protects the peptide from aminopeptidase degradation and is essential for receptor binding.

C-terminal amidation ($-NH_2$)

A structural feature essential for biological activity in TRH and CRH that protects against carboxypeptidase degradation.

Dopamine

A neurotransmitter consisting of a catechol structure and an amine group that controls movement, cognitive function, and memory, and inhibits the release of prolactin.

Catechol structure

A structural feature of dopamine featuring phenol and hydroxyl groups at positions $3$ and $4$, essential for receptor binding and activity at $\text{D1-like}$ receptors.

Growth Hormone-Releasing Hormone (GHRH)

A $44$-amino acid peptide secreted by the hypothalamus that stimulates the release of growth hormone (GH) from the anterior pituitary.

Somatostatin

A hormone produced in the hypothalamus that exists in two forms ($14$ or $28$ amino acids) and inhibits the release of somatotropin (GH), thyrotropin, glucagon, and insulin.

Somatostatin-14

The shorter, active form of somatostatin consisting of $14$ amino acids ($\text{NH}_2\text{–Phe–Trp–Ser–Thr–Pro–Phe–Ser–His–Trp–Asn–Cys–Phe–Tyr–OH}$).

Gonadotropin Releasing Hormone (GnRH)

A decapeptide hypophysiotropic hormone composed of $10$ amino acids that stimulates the release of LH and FSH from the anterior pituitary gland.

Corticotropin-Releasing Hormone (CRH)

A $41$-amino acid peptide secreted by the hypothalamus that triggers the release of adrenocorticotropic hormone (ACTH) from the pituitary gland.

Thyroxine (T4)

A hormone of the thyroid gland derived from tyrosine that is deiodinated at the periphery to $T_3$; it stimulates metabolic activity.

Triiodothyronine (T3)

The most active thyroid hormone which regulates growth development, controls metabolism and body temperature, and inhibits the secretion of thyrotropin.

Growth Hormone (GH)

Also known as somatotropin, it is a single-chain, $191$-amino acid peptide that promotes protein synthesis and lean body weight mass.

IGF-1 (Somatomedin-C)

The mediator through which the growth-promoting effects of growth hormone are expressed.

Thyroid-stimulating hormone (TSH)

A hormone secreted by the anterior pituitary that controls the release of thyroid hormones and the growth of the thyroid gland.

Adrenocorticotropic hormone (ACTH)

An anterior pituitary hormone that stimulates the growth of the adrenal gland and the synthesis of corticosteroids; its secretion increases in response to stress and hypoglycemia.

Follicle Stimulating Hormone (FSH)

A gonadotropin that stimulates the growth of Graafian follicles in the ovary and promotes spermatogenesis in males.

Luteinizing Hormone (LH)

A glycoprotein that stimulates the secretion of sex hormones by the ovaries and testes and is involved in the maturation of spermatozoa and ova.

Prolactin (PRL)

An anterior pituitary hormone that stimulates the development and growth of mammary glands and is essential for the initiation and maintenance of milk production.

Melanocyte-stimulating hormone (MSH)

A polypeptide hormone secreted by the pars intermedia of the pituitary gland that controls pigmentation intensity.

Oxytocin

A neuropeptide used as a medication to cause uterine contractions to start labor and stop bleeding following delivery.

Vasopressin (Antidiuretic Hormone)

A hormone that plays a key role in maintaining osmolality and the volume of water in the extracellular fluid.

Somatropin

A prototype drug consisting of recombinant human growth hormone ($\text{rhGH}$) used to treat deficiency states leading to short stature.

Mecasermin

A recombinant $\text{IGF-1}$ receptor agonist used for severe $\text{IGF-1}$ deficiency that is unresponsive to growth hormone.

Pegvisomant

A growth hormone receptor antagonist used to treat acromegaly by blocking receptor dimerization and inhibiting $\text{IGF-1}$ production.

Tesamorelin

A synthetic peptide analog of Growth Hormone-Releasing Hormone used for the treatment of $\text{HIV}$-associated lipodystrophy.

Turner Syndrome

A genetic condition ($45,X$) where growth hormone treatment may increase final height by $10-15\,cm$ ($4-6$ inches).

Slipped capital femoral epiphysis (SCFE)

A condition referring to a shift at the upper part of the thighbone (femur) that results in a weakened hip joint, noted as a potential concern in endocrinology.

Somatotropes

Acidophilic cells in the anterior pituitary gland that secrete growth hormone (somatotropin).