Lab 17: Endocrine System

Adrenal glands

Glands located above each kidney that are subdivided into an outer cortex and an inner medulla. The cortex produces many steroids and the medulla secretes the fight or flight hormones.

Pituitary gland

Also called the hypophysis, it is located inferior to the hypothalamus and is connected to the hypothalamus by a narrow stalk of tissue called the infundibulum.

Melatonin

Hormone responsible for regulating the circadian rhythm, the body's 24-hour clock.

Thymosins

Hormones that play a role in the maturation of T lymphocytes.

Adrenal capsule

Most superficial layer of the adrenal gland. Not labeled in image, pinkest in color.

Adrenal cortex

Outer region of each adrenal gland.

Zona reticularis

Part of the adrenal cortex that secretes androgens. Labeled letter c in image.

Zona fasciculata

Part of the adrenal cortex that secretes glucocorticoids. Labeled letter b in image.

Zona glomerulosa

Part of the adrenal cortex that secretes mineralocorticoids. Labeled letter a in image.

Pineal gland

Part of the diencephalon, located on the posterior wall of the thalamus; secretes melatonin

Thyroid gland

A butterfly-shaped organ located in the anterior neck, partially wrapping around the trachea just below the larynx. Produces and releases calcitonin, thyroxine (T4) and triiodothyronine (T3).

Hyposecretion

A gland that secretes too little hormone.

Hypersecretion

A gland that secretes too much hormone.

Anterior lobe of pituitary

A lobe of the pituitary gland, also called the adenohypophysis, composed of glandular tissue regulated by the hypothalamus. Produces and releases seven hormones; growth hormone(GT), adrenocorticotrophic hormone (ACTH), thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH),luteinizing hormone (LH), prolactin (PRL) and melanocyte-stimulating hormone (MSH). Labeled #1 in photo.

Posterior lobe of pituitary

A lobe of the pituitary gland, also called the neurohypophysis, composed of neurons that originate in the hypothalamus. Releases two hormones, antidiuretic hormone (ADH) and oxytocin (OXT). Labeled #2 in photo.

Infundibulum

A narrow stalk of tissue hat connects the pituitary gland to the hypothalamus.

Hypophyseal portal system

A set of blood vessels that carry regulatory hormone produced in the hypothalamus to the anterior lobe of the pituitary.

Parafollicular cells

Cells located next to follicular cells, that secrete calcitonin.

Chief cells of parathyroid

Cells of parathyroid gland that produce parathyroid hormone.

Follicular cells

Cells that line the thyroid follicles that produce thyroxine and triiodothyronine

Hormone

Chemical messengers that travel through the bloodstream and can alter the activity of cells in the body.

Pancreatic islet

Contains endocrine cells of pancreas. On slides, it appears as a lighter area surrounded by darker acinar cells.

Alpha cells

Endocrine cells of the pancreas that secretes glucagon.

Beta cells

Endocrine cells of the pancreas that secretes insulin.

Pinealocytes

Endocrine cells of the pineal gland that secrete melatonin.

Pancreatic acini

Exocrine cells of pancreas. Composes the tissue surrounding the pancreatic islets that secrete digestive enzymes and buffers.

Adrenal medulla

Inner region of each adrenal gland.

Pancreas

Located along the greater curvature of the stomach, with a wide head connected to the duodenum (small intestine) by the pancreatic duct. It is both an exocrine gland that releases enzymes and buffers into the small intestine, and an endocrine, releasing insulin and glucagon into the blood.

Thymus gland

Located in the superior mediastinum of the thoracic cavity posterior to the sternum. It secretes thymosins.

Parathyroid gland

Located on the posterior surface of the thyroid gland, composed of chief cells (secrete parathyroid hormone PTH) and oxyphil cells.

Thyroid follicles

Microscopic structures of the thyroid gland composed of simple cuboidal epithelium and containing protein material called colloid. Cells of follicles produce thyroxine and triiodotyronine.

Glucagon

Secreted by alpha cells of the pancreas, a hormone that targets the liver and raises blood glucose levels by stimulating the liver to break down glycogen and release glucose into the bloodstream.

Insulin

Secreted by beta cells of the pancreas, a hormone that targets essentially every cell o the body. Function to lower blood glucose levels by stimulating the uptake of glucose form the bloodstream by the cells of the body.

Parathyroid hormone (PTH)

Secreted by chief cells and targets bone and kidneys. Raises blood calcium levels by causing calcium to be removed from bone and reabsorbed by the kidney.

Thyroxine (T4)

Secreted by follicle cells and targets essentially every cell of the body to regulate oxygen utilization and rate of metabolism of the cells.

Triiodothyronine (T3)

Secreted by follicle cells and targets essentially every cell of the body to regulate oxygen utilization and rate of metabolism of the cells.

Calcitonin (CT)

Secreted by parafollicular cells and targets the bone and kidneys. Reduces blood calcium levels by causing calcium to be deposited into bone and excreted by the kidneys.

Glucocorticoids

Secreted by the adrenal cortex and target the kidneys. Affects rate of glucose metabolism.

Mineralocorticoids

Secreted by the adrenal cortex and target the kidneys. Increase renal absorption of sodium.

Androgens

Secreted by the adrenal cortex. Has little effect in adults; precursor of male and female sex hormones.

Epinephrine (EP)

Secreted by the adrenal medulla and targets most cells; increases cardiac activity, blood pressure, and blood glucose levels.

Norepinephrine (NEP)

Secreted by the adrenal medulla and targets most cells; increases cardiac activity, blood pressure, and blood glucose levels.

Adrenal medulla tissue

Secretes epinephrine and norepinephrine. Labeled letter d in image.

Endocrine gland

Secretes hormones directly into the bloodstream.

Growth hormone (GH)

Targets bones, muscles, and other tissues; stimulates cell growth and division. Produced and released by anterior pituitary.

Prolactin (PRL)

Targets mammary glands; stimulates milk production. Produced and released by anterior pituitary.

Melanocyte-stimulating hormone (MSH)

Targets melanocytes; stimulates melanin production. Produced and released by anterior pituitary.

Antidiuretic hormone (ADH)

Targets renal tubules; stimulates water reabsorption. Released by posterior pituitary.

Adrenocorticotrophic hormone (ACTH)

Targets the adrenal cortex; stimulates release of adrenal cortex hormones. Produced and released by anterior pituitary.

Follicle-stimulating hormone (FSH)

Targets the gonads; stimulates development of ova and sperm. Produced and released by anterior pituitary.

Luteinizing hormone (LH)

Targets the gonads; stimulates secretion of sex hormones. Produced and released by anterior pituitary.

Thyroid-stimulating hormone (TSH)

Targets the thyroid gland; stimulates release of thyroid hormones. Produced and released by anterior pituitary.

Oxytocin (OXT)

Targets the uterus and mammary glands; stimulates uterine contractions during labor and delivery and release of milk. Released by posterior pituitary.