Chapter 16 The Endocrine System

Hormones

Chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues

Exocrine glands

Secrete chemical substances into ducts that carry these products to other organs or outside the body.

Endocrine glands

Secrete chemical substances directly into the bloodstream, which delivers them throughout the body.

Target cells

Cells that have receptor proteins for a specific hormone, which will bind with that hormone like a key and lock.

Peptide hormone

A hormone made of amino acids that bind to a receptor in the plasma membrane, and causes a chain reaction inside the cell.

Steroid hormones

A lipid-based hormone that can directly enter the cell by crossing the hydrophobic barrier of the plasma membrane, directly binds to DNA and affects gene activity/protein synthesis.

Hypothalamus

A neural structure lying below the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward.

Posterior pituitary gland

Stores hormones produced by the hypothalamus (ADH and oxytocin)

Antidiuretic hormone (ADH)

Regulates water-salt balance by reabsorbing water into the bloodstream.

Oxytocin

Causes uterine contractions during childbirth and allows milk to be released during nursing.

Diabetes insipidus

Inability to produce ADH, causing high production of urine resulting in severe dehydration and loss of ions.

Anterior pituitary gland

Produces many hormones which regulate other endocrine glands & directly affect target cells

Thyroid-stimulating hormone (TSH)

Stimulates the thyroid to produce thyroid hormones.

Adrenocorticotropic hormone (ACTH)

Stimulates the adrenal cortex to produce cortisol.

Gonadotropic hormones (FSH & LH)

Stimulate gonads (ovaries and testes) to produce sex cells and sex hormones.

Prolactin (PRL)

Stimulates mammary glands to develop and produce milk only after childbirth.

Growth hormone (GH)

Promotes skeletal and muscular growth.

Pituitary dwarfism

Too little GH is produced during childhood; results in small stature.

Gigantism

Too much GH is produced during childhood; results in poor health

Acromegaly

Overproduction of GH as an adult; results in larger than normal feet, hands, and face.

Thyroid gland

Gland located below the larynx in the neck; regulates metabolism.

Calcitonin

A hormone produced by the thyroid gland which helps lower blood calcium levels by stimulating the deposition of calcium into bones.

Simple goiter

Thyroid enlarges due to lack of iodine in the diet.

Hypothyroidism

Low blood levels of thyroid hormone.

Congenital hypothyroidism

Thyroid does not develop properly and is characterized in a short, stocky person who may have mental disabilities.

Myxedema

Hypothyroidism in adults characterized by lethargy, weight gain, loss of hair, cold intolerance, and thick, puffy skin.

Hyperthyroidism

Excess thyroid hormones in the blood.

Exophthalmic goiter

An overactive thyroid gland characterized by enlargement, protrusion of the eyes, hyperactivity, irritability, and insomnia.

Parathyroid hormone (PTH)

A hormone released by the parathyroid glands, it causes blood calcium levels to increase by promoting cells to break down bone as well as reabsorption of calcium by the kidneys.

Adrenal medulla (inner region)

Controlled by the nervous system.

Adrenal cortex (outer region)

Portions are controlled by ACTH from the anterior pituitary.

Epinephrine and norepinephrine

Hormones released by the adrenal medulla that allows a short-term response to stress (fight or flight response).

Glucocorticoids

Hormones secreted by the adrenal cortex, such as cortisol, that suppress the body's inflammatory response, regulate metabolism, and allow for a response to long-term stress.

Mineralocorticoids

Hormones produced by the adrenal cortex that regulate salt and water balance.

Addison's disease

Hyposecretion of glucocorticoids by the adrenal cortex, characterized by bronzing of the skin.

Cushing syndrome

Hypersecretion of glucocorticoids by the adrenal cortex, characterized by weight gain in the trunk of the body but not the arms and legs.

Pancreas

Organ behind the stomach that is both an exocrine and endocrine gland.

Islets of Langerhans

Endocrine cells of the pancreas that produce insulin and glucagon.

Insulin

Hormone secreted by the pancreas when blood glucose is high; stimulates the uptake of glucose by cells (muscle and liver) which then store it as glycogen.

Glucagon

Hormone secreted by the pancreas when blood glucose is low; stimulates the breakdown of glycogen in the liver to glucose.

Diabetes mellitus

The inability of the body to control blood glucose levels, in which cells do not produce or respond to insulin.

Androgens

Male sex hormones that stimulate sex organ and characteristic development.

Progesterone and estrogen

Female sex hormones that stimulate sex organ and characteristic development.

Thymus

An endocrine gland beneath the sternum involved in immune function.

Pineal gland

Endocrine gland involved in regulating the circadian rhythm.

Circadian rhythm

Sleep/wake cycle