Hypothalamus and Pituitary Gland

Flashcards covering the definitions and functions of the glands and hormones within the endocrine system, specifically the hypothalamus and pituitary gland, based on lecture notes.

Gland

A cell, a tissue or an organ which secrete useful chemical compounds required for particular function.

Endocrine Glands

Glands which lack ducts and pass their secretion into the blood for transport to site of action.

Exocrine Glands

Glands that have ducts for discharging their secretion, such as sweat, salivary, gastric glands, and the liver.

Hormones

Minute chemical messengers thrown into the blood to act on target organs, which can be steroid, proteins, peptides, or amino acid derivatives.

Endocrine System

A system formed by ductless glands which secretes chemical substances called hormones directly into the blood.

Receptor

A specific protein molecule on the surface or in the cytoplasm of a target cell that picks up a specific hormone.

Hypothalamus

The command center of the endocrine system located in the diencephalon of the brain, anterior and inferior to the thalamus.

Nuclei

Several groups of neuro-secretory cells within the hypothalamus that produce hormones.

Gonadotrophin releasing hormone (GnRH)

A releasing hormone from the hypothalamus that stimulates the pituitary synthesis and release of gonadotrophins ($FSH$ and $LH$).

Somatostatin

An inhibiting hormone from the hypothalamus that inhibits the release of growth hormone ($GH$) from the pituitary.

Infundibulum

A stem or pituitary stalk that suspends the pituitary gland from the hypothalamus.

Adenohypophysis

The anterior portion of the pituitary gland, consisting of the pars distalis and pars intermedia.

Neurohypophysis

The posterior portion of the pituitary gland, also known as the pars nervosa, which stores and releases hormones produced by the hypothalamus.

Growth hormone (GH)

A protein hormone from the anterior pituitary that promotes growth of body tissues.

Prolactin (PRL)

A peptide hormone from the anterior pituitary that promotes milk production from mammary glands.

Thyroid-stimulating hormone (TSH)

A glycoprotein that stimulates thyroid hormone release from the thyroid gland.

Adrenocorticotropic hormone (ACTH)

A peptide hormone that stimulates hormone release by the adrenal cortex.

Follicle-stimulating hormone (FSH)

A glycoprotein that stimulates gamete production in the gonads.

Luteinizing hormone (LH)

A glycoprotein that stimulates androgen production by the gonads.

Antidiuretic hormone (ADH)

Also known as vasopressin, a peptide stored in the posterior pituitary that stimulates water reabsorption by the kidneys.

Oxytocin (OT)

A peptide hormone that stimulates uterine contractions, dilation of the cervix, and the milk ejection reflex.

Melanocyte-stimulating hormone (MSH)

A peptide produced in the intermediate zone of the pituitary that stimulates melanin formation in melanocytes.

Paraventricular nuclei

The specific nuclei in the hypothalamus that produce the hormone oxytocin.

Supraoptic nuclei

The specific nuclei in the hypothalamus that produce Antidiuretic Hormone (ADH).

Osmoreceptors

Specialized cells within the hypothalamus that monitor blood osmolarity by sensing the concentration of sodium ions and other solutes.

Diabetes insipidus

A condition characterized by chronic underproduction of ADH that causes chronic dehydration and electrolyte imbalances.