Chapter 11: Endocrine System

Endocrine System

A system that works with the nervous system to maintain homeostasis by secreting hormones into body fluids to affect target cells.

Hormones

Chemical messengers (steroid or non-steroid) secreted by cells, tissues, and organs of the endocrine system that act on target cells in the bloodstream.

Glands

Organs that secrete products; endocrine glands secrete hormones into body fluids, while exocrine glands secrete products into ducts.

Negative Feedback Systems

Mechanisms that control hormonal releases by inhibiting gland secretion when the substance it regulates reaches a certain level, helping maintain homeostasis.

Steroid Hormones

Hormones synthesized from cholesterol, lipid-soluble, and able to pass through cell membranes to bind to receptors in the target cell's nucleus.

Nonsteroid Hormones

Hormones that bind to receptors on target cell membranes, triggering signal transduction and a cascade of biological activities inside the cell.

Pituitary Gland

An endocrine gland attached to the brain's base, consisting of anterior and posterior parts that secrete various hormones under the control of the hypothalamus.

Thyroid Gland

An endocrine gland located below the larynx, producing hormones like thyroxine and triiodothyronine that regulate energy metabolism and growth.

Parathyroid Glands

Small glands located on the posterior of the thyroid that secrete parathyroid hormone to regulate blood calcium and phosphate levels.

Adrenal Gland

Glands located atop each kidney, consisting of the adrenal medulla and cortex that secrete hormones like epinephrine, norepinephrine, aldosterone, and cortisol.

Pancreas

An endocrine gland posterior to the stomach that secretes hormones like insulin and glucagon to regulate blood sugar levels and metabolism.

Growth Hormone

Promotes growth of body tissues

Prolactin

Milk production

Thyroid Secreting Hormone

stimulates thyroid hormone release

Thyrotropin-Releasing Hormone

released by the hypothalamus, regulates the release of TSH

Adrenocorticotropic Hormone

controls the secretion of hormones from the adrenal cortex

Follicle-Stimulating Hormone

Stimulates gamete production

Luteinizing Hormone

Stimulates androgen production

Oxytocin (OT)

Stimulates uterine contractions in labor and childbirth and stimulates contractions of breast tissue to aid in lactation

Thyroxine and Triiodothyronine

regulate energy metabolism

Calcitonin

Reduces Blood Calcium levels

Parathyroid Hormone

increases blood calcium ion concentration and decreases phosphate ion concentration.

Epinephrine and Norepinephrine

increase heart rate, the force of cardiac muscle contraction, breathing rate, and blood glucose level, increase blood pressure

Aldosterone

regulates the concentration of mineral electrolytes

Cortisol

inhibits protein synthesis and increases blood concentration of amino acids.

Glucagon

stimulates the liver to break down glycogen and convert noncarbohydrates into glucose, increases blood sugar concentration

Insulin

liver forms glycogen from glucose and inhibits conversion. promotes facilitated diffusion of glucose across the cell membranes that have insulin receptors.

Melatonin

regulates circadian rhythms

Pineal Gland

between hemispheres

Thymus

posterior to sternum

Thymosin

production of differentiation of certain white blood cells.

Placenta produces…

Estrogens, progesterone, and gonadotropin

Atrial Natriuretic peptide

urinary sodium excretion

Erythropoietin

red blood cell growth