Endocrine System

Hormones and Glands

Endocrine System

Communication system that sends long-lasting and more generalized hormones to target cells via the bloodstream in response to stimuli

Nervous System

Communication system that sends specific and lightning-fast action potentials to target cells in response to stimuli

Exocrine Glands

Glands with ducts that secrete products outside of the cell, and tends to have extracellular effects

Endocrine Glands

Glands with no ducts that are secreted directly into the bloodstream and have intracellular effects

Adenohypophysis

Anterior pituitary gland. Is a true endocrine gland, linked to hypothalamus via the hypophysial portal system, and secretes FSH, LH, TSH, ACTH, PRL, and GH.

Follicle-stimulating hormone (FSH)

Hormone secreted by the Adenohypophysis that stimulates the secretion of ovarian sex hormones, sperm production, and the development of the ovarian follicles

Luteinizing hormone (LH)

Hormone secreted by the Adenohypophysis that stimulates ovulation and progesterone production in females and the production of testosterone in males

Thyroid-stimulating hormone (TSH)

Hormone secreted by the Adenohypophysis that simulates the secretion of thyroid hormones

Adrenocorticotropic hormone (ACTH)

Hormone secreted by the Adenohypophysis that stimulates the adrenal cortex to secrete glucocorticoids

Prolactin (PRL)

Hormone secreted by the Adenohypophysis that stimulates milk production in the mammary glands

Growth Hormone (GH)

Hormone secreted by the Adenohypophysis that stimulates mitosis and cellular differentiation

Neurohypophysis

Posterior pituitary gland. Not a true gland, as it contains nerve tissue. Nerves in the hypothalamus pass down to the pituitary gland via the hypothalamo–hypophysial tract, and the nerves secreted from the gland are actually made in the hypothalamus

Antidiuretic hormone (ADH)

Vasopressin; hormone created by the hypothalamus and secreted by the neurohypophysis that retains water, decreases urination, and constricts the blood vessels (vasoconstriction)

Oxytocin

Hormone created by the hypothalamus and secreted by the neurohypophysis that is responsible for sexual pleasure, emotional bonding, the movement of milk in the mammary glands, and labor

Hypothalamus

Neuroendocrine structure that forms the floor and walls of the third ventricle of the brain; creates eight hormones, two of which are released by the posterior pituitary gland

Gonadotropin-releasing hormone (GnRH)

Hormone created and released by the hypothalamus that stimulates the release of LH and FSH

Thyrotropin-releasing hormone (TRH)

Hormone created and released by the hypothalamus that stimulates the release of TSH

Corticotropin-releasing hormone (CRH)

Hormone created and released by the hypothalamus that stimulates the release of ACTH

Prolactin-inhibiting hormone (PIH)

Hormone created and released by the hypothalamus that inhibits the secretion of the hormone prolactin

Growth hormone-releasing hormone (GHRH)

Hormone created and released by the hypothalamus that stimulates the release of growth hormone

Somatostatin

Hormone created and released by the hypothalamus that inhibits the release of growth hormone and thyroid-stimulating hormone

Pineal gland

Shrunken gland located in the brain that is responsible for secreting melatonin

Melatonin

Hormone released by the pineal gland that has a role in sleep and the circadian rhythm

Thymus

Gland superior to the heart that also plays a role in the lymphatic and immune systems; serves as the site of maturation for T cells and secretes thymopoietin, thymosin, and thymulin to help develop the lymphatic system

Thymopoietin, thymosin, and thymulin

Hormones secreted by the thymus that develops the lymphatic system

Thyroid

Butterfly-shaped gland just below the larynx that secretes thyroxine and triiodothyronine in response to TSH release

Thyroxine (T4) and triiodothyronine (T3)

A pair of hormones secreted by the thyroid gland that increases the metabolic rate of the body, which subsequently increases O2 demand, appetite, alertness, reflex speed, and growth hormone secretion

Parafollicular Cells

Cells located in the thyroid that secretes calcitonin

Calcitonin

Hormone secreted by the parafollicular cells in the thyroid that stimulates bone formation and osteoblasts in children

Parathyroid glands

Glands located on the thyroid that secretes parathyroid hormone

Parathyroid hormone (PTH)

Hormone secreted by the parathyroid glands that promotes the synthesis of calcitriol and the subsequent retention of calcium ions

Adrenal Glands

Two glands that sit on the top of the kidneys that releases hormones that regulate metabolism and prepare the body for “fight or flight”

Adrenal Medulla

The inner 10-20% of the adrenal gland; has neuroendocrine properties and is able to release both dopamine and catecholamines into the bloodstream

Catecholamines

Epinephrine and Norepinephrine; hormones that increase alertness and prepare the body for physical activity

Adrenal Cortex

Outer portion of the adrenal gland that secretes mineralocorticoids, sex steroids, and glucocorticoids

Mineralocorticoids

Steroid hormones like aldosterone secreted by the adrenal cortex that regulates electrolyte balance

Aldosterone

A mineralocorticoid that stimulates sodium retention and potassium excretion. It is part of a system with renin and angiotensin (RAA).

Glucocorticoids

Hormones secreted by the adrenal cortex that regulate the metabolism of fuels like glucose

Cortisol and Corticosterone

Pair of hormones secreted by the adrenal cortex that helps break down fats and proteins, the release of fatty acids and glucose into the blood, and gluconeogenesis

Androgens

Sex steroid secreted by the adrenal cortex that sets libito and plays a large role in male development

Estradiol

Sex steroid secreted in small amounts by the adrenal cortex that sustains adult bone mass after menopause

Pancreas

Gland that sits above the beginning of the small intestine that contains alpha and beta cells responsible for managing the levels of glucose in the blood

Glucagon

Hormone secreted by alpha cells in the pancreas; raises blood glucose, stimulates gluconeogenesis and glycogenolysis, releases free fatty acids from fat tissue, and promotes amino acid absorption for gluconeogenesis

Insulin

Hormone secreted by beta cells in the pancreas; lowers blood glucose, gets cells to absorb and store glucose, and promotes synthesis of glycogen, fat, and protein. The brain, liver, kidneys, and red blood cells do not need this hormone to function

Gonads

The ovaries in females and testes in males. Are both exocrine and endocrine in nature

Estradiol, progesterone, and inhibin

Hormones secreted by the ovaries

Testosterone, weaker androgens, estrogen, and inhibin

Testicular hormones

Skin

Able to convert a cholesterol-like steroid into cholecalciferol using the UV light from the sun

Liver

Digestive organ involved in the production of at least five hormones; calcidiol, angiotensinogen, erythropoietin, IGF-I, and hepcidin

Kidneys

Produces three hormones'; calcitriol (active form of vitamin D), renin, and erythropoietin

Heart

Able to secrete two natriuretic peptides to decrease blood pressure

Stomach/small intestine

Digestive organs that can secrete at least 10 hormones that can coordinate digestive motility and glandular secretion; cholecystokinin, gastrin, ghrelin, and peptide YY

Adipose tissue

Tissue that is able to secrete leptin, which slows appetite

Osseous tissue

Tissue that secretes osteocalcin, which increases number of beta cells, insulin output, and insulin sensitivity

Placenta

Secretes estrogen and progesterone to regulate pregnancy and the development of the fetus and mammary glands

Peptides and catecholamines

Water-soluble hormones that cannot pass through the target cells; must bind to surface receptors to activate intracellular processes through second messangers

Steroids and thyroid hormones

Lipid-soluble hormones that can pass through the target cell’s cell membrane; binds to internal receptors and influence the expression of genes of the target cell