endocrine system hormones

insulin

Made by: Pancreatic β (beta) cells (Islets of Langerhans)
Target(s): Most body cells, especially liver, skeletal muscle, and adipose tissue
Action(s): Lowers blood glucose by increasing glucose uptake into cells and promoting glycogen, fat, and protein synthesis
Regulation: High blood glucose stimulates release; low blood glucose inhibits release
Hypersecretion (too much): Hypoglycemia (low blood sugar)
Hyposecretion (too little): Diabetes mellitus → hyperglycemia
Quick Memory Tip: INSULIN puts sugar IN cells.

glucagon

Made by: Pancreatic α (alpha) cells
Target(s): Liver and adipose tissue
Action(s): Raises blood glucose by stimulating glycogen breakdown and glucose production
Regulation: Low blood glucose stimulates release
Hypersecretion (too much): Hyperglycemia
Hyposecretion (too little): Hypoglycemia (rare)
Quick Memory Tip: Glucagon = glucose gone UP.

melatonin

Made by: Pineal gland
Target(s): Brain (especially hypothalamus)
Action(s): Regulates sleep-wake cycle (circadian rhythm)
Regulation: Darkness increases secretion; light decreases secretion
Hypersecretion (too much): Excessive sleepiness
Hyposecretion (too little): Insomnia/sleep disturbances
Quick Memory Tip: Moon = Melatonin = Sleep.

PTH

PARATHYROID HORMONE

Made by: Parathyroid glands
Target(s): Bones, kidneys, intestines
Action(s): Raises blood calcium levels
Regulation: Low blood calcium stimulates release
Hypersecretion (too much): Hypercalcemia, weak bones, kidney stones
Hyposecretion (too little): Hypocalcemia, muscle spasms (tetany)
Quick Memory Tip: PTH Pulls calcium into the blood.

epinephrine

Made by: Adrenal medulla
Target(s): Heart, lungs, liver, skeletal muscle
Action(s): Fight-or-flight response; increases heart rate, blood pressure, blood glucose
Regulation: Sympathetic nervous system during stress
Hypersecretion (too much): High BP, rapid heart rate, anxiety
Hyposecretion (too little): Usually minimal effect
Quick Memory Tip: Epinephrine = Emergency.

NE

NOREPINEPHRINE

Made by: Adrenal medulla
Target(s): Blood vessels, heart
Action(s): Vasoconstriction; increases blood pressure during stress
Regulation: Sympathetic nervous system
Hypersecretion (too much): Hypertension
Hyposecretion (too little): Low blood pressure (rare)
Quick Memory Tip: NE narrows vessels.

T3

TRIIODOTHYRONINE

Made by: Thyroid gland
Target(s): Most body cells
Action(s): Increases metabolism, growth, and heat production
Regulation: TSH stimulates release
Hypersecretion (too much): Hyperthyroidism
Hyposecretion (too little): Hypothyroidism
Quick Memory Tip: T3 = Turbo metabolism.

T4

THYROXINE

Made by: Thyroid gland
Target(s): Most body cells
Action(s): Increases metabolism; converted into T3
Regulation: TSH stimulates release
Hypersecretion (too much): Hyperthyroidism
Hyposecretion (too little): Hypothyroidism
Quick Memory Tip: T4 = Storage form of thyroid hormone.

calcitonin

Made by: Thyroid parafollicular (C) cells
Target(s): Bone
Action(s): Lowers blood calcium by promoting calcium deposition in bone
Regulation: High blood calcium stimulates release
Hypersecretion (too much): Usually no major effects
Hyposecretion (too little): Usually no major effects
Quick Memory Tip: Calcitonin CALMS calcium down.

ADH

ANTIDIURETIC HORMONE

Made by: Hypothalamus (released by posterior pituitary)
Target(s): Kidneys
Action(s): Increases water reabsorption; decreases urine output
Regulation: High blood osmolarity or low blood pressure
Hypersecretion (too much): SIADH → water retention
Hyposecretion (too little): Diabetes insipidus
Quick Memory Tip: ADH Adds water.

OT

OXYTOCIN

Made by: Hypothalamus (released by posterior pituitary)
Target(s): Uterus and mammary glands
Action(s): Stimulates labor contractions and milk ejection
Regulation: Positive feedback during labor and breastfeeding
Hypersecretion (too much): Rare
Hyposecretion (too little): Weak labor or poor milk letdown
Quick Memory Tip: Oxytocin = OX hugs babies.

TSH

Thyroid Stimulating Hormone

Made by: Anterior pituitary
Target(s): Thyroid gland
Action(s): Stimulates thyroid growth and T3/T4 secretion
Regulation: TRH stimulates; T3/T4 inhibit (negative feedback)
Hypersecretion (too much): Hyperthyroidism/goiter
Hyposecretion (too little): Hypothyroidism
Quick Memory Tip: TSH Tells the Thyroid.

ACTH

Adrenocorticotropic Hormone

Made by: Anterior pituitary
Target(s): Adrenal cortex
Action(s): Stimulates cortisol secretion
Regulation: CRH stimulates; cortisol inhibits
Hypersecretion (too much): Cushing disease
Hyposecretion (too little): Adrenal insufficiency
Quick Memory Tip: ACTH Activates Cortex.

GH

Growth Hormone

Made by: Anterior pituitary
Target(s): Bones, muscles, liver
Action(s): Stimulates body growth and protein synthesis
Regulation: GHRH stimulates; GHIH inhibits
Hypersecretion (too much): Gigantism/acromegaly
Hyposecretion (too little): Pituitary dwarfism
Quick Memory Tip: GH = Grow Human.

FSH

Follicle Stimulating Hormone

Made by: Anterior pituitary
Target(s): Ovaries and testes
Action(s): Stimulates follicle development and sperm production
Regulation: GnRH stimulates; sex hormones inhibit
Hypersecretion (too much): Precocious puberty (rare)
Hyposecretion (too little): Infertility
Quick Memory Tip: FSH = Follicles & Sperm.

LH

Luteinizing Hormone

Made by: Anterior pituitary
Target(s): Ovaries and testes
Action(s): Triggers ovulation; stimulates testosterone secretion
Regulation: GnRH stimulates
Hypersecretion (too much): Hormonal imbalance
Hyposecretion (too little): Infertility
Quick Memory Tip: LH = Launches ovulation.

PRL

PROLACTIN

Made by: Anterior pituitary
Target(s): Mammary glands
Action(s): Stimulates milk production
Regulation: PIH inhibits; suckling increases release
Hypersecretion (too much): Galactorrhea, infertility
Hyposecretion (too little): Poor milk production
Quick Memory Tip: Prolactin Produces milk.

EPO

ERYTHROPOIETIN

Made by: Kidneys
Target(s): Red bone marrow
Action(s): Stimulates red blood cell production
Regulation: Low blood oxygen stimulates release
Hypersecretion (too much): Polycythemia
Hyposecretion (too little): Anemia (common in kidney disease)
Quick Memory Tip: EPO = Extra RBCs.

estrogen

Made by: Ovaries
Target(s): Female reproductive organs, breasts, bones
Action(s): Female secondary sex characteristics; menstrual cycle regulation
Regulation: FSH/LH
Hypersecretion (too much): Early puberty, irregular bleeding
Hyposecretion (too little): Menopause symptoms, osteoporosis
Quick Memory Tip: Estrogen = Female features.

progesterone

Made by: Ovaries (corpus luteum), placenta
Target(s): Uterus and breasts
Action(s): Maintains uterine lining; supports pregnancy
Regulation: LH
Hypersecretion (too much): Irregular menstrual cycles
Hyposecretion (too little): Difficulty maintaining pregnancy
Quick Memory Tip: Progesterone = Pregnancy hormone.

testosterone

Made by: Testes
Target(s): Male reproductive organs, muscles, bones
Action(s): Male secondary sex characteristics; sperm production; libido
Regulation: LH
Hypersecretion (too much): Early puberty, acne
Hyposecretion (too little): Low libido, infertility
Quick Memory Tip: Testosterone = Testes hormone.

TRH

Thyrotropin Releasing Hormone

Made by: Hypothalamus
Target(s): Anterior pituitary
Action(s): Stimulates TSH release
Regulation: Low thyroid hormones stimulate release
Hypersecretion (too much): Increased TSH
Hyposecretion (too little): Decreased TSH
Quick Memory Tip: TRH → TSH.

CRH

Corticotropin Releasing Hormone

Made by: Hypothalamus
Target(s): Anterior pituitary
Action(s): Stimulates ACTH release
Regulation: Stress; cortisol negative feedback
Hypersecretion (too much): Increased cortisol production
Hyposecretion (too little): Low ACTH/cortisol
Quick Memory Tip: CRH → ACTH → Cortisol.

GnRH

Gonadotropin Releasing Hormone

Made by: Hypothalamus
Target(s): Anterior pituitary
Action(s): Stimulates FSH and LH release
Regulation: Sex hormone feedback
Hypersecretion (too much): Precocious puberty
Hyposecretion (too little): Delayed puberty/infertility
Quick Memory Tip: GnRH = Gonad hormones.

GHRH

Growth Hormone Releasing Hormone

Made by: Hypothalamus
Target(s): Anterior pituitary
Action(s): Stimulates GH release
Regulation: Sleep, exercise, low glucose
Hypersecretion (too much): Excess GH
Hyposecretion (too little): Reduced GH
Quick Memory Tip: GHRH = GH Release.

GHIH

Growth Hormone Inhibiting Hormone/Somatostatin

Made by: Hypothalamus
Target(s): Anterior pituitary
Action(s): Inhibits GH and TSH release
Regulation: High GH levels stimulate release
Hypersecretion (too much): Low GH
Hyposecretion (too little): High GH
Quick Memory Tip: GHIH = GH Inhibitor.

PIH

Prolactin Inhibiting Hormone/Dopamine

Made by: Hypothalamus
Target(s): Anterior pituitary
Action(s): Inhibits prolactin release
Regulation: Constant secretion unless breastfeeding
Hypersecretion (too much): Low prolactin
Hyposecretion (too little): High prolactin (galactorrhea)
Quick Memory Tip: Dopamine Drops prolactin.

thymosin

Made by: Thymus
Target(s): T lymphocytes
Action(s): Promotes T-cell maturation
Regulation: Childhood development
Hypersecretion (too much): Rare
Hyposecretion (too little): Reduced immune function
Quick Memory Tip: Thymosin Trains T cells.

cortisol

Made by: Adrenal cortex (zona fasciculata)
Target(s): Most body tissues
Action(s): Raises blood glucose; stress response; anti-inflammatory effects
Regulation: ACTH
Hypersecretion (too much): Cushing syndrome
Hyposecretion (too little): Addison disease
Quick Memory Tip: Cortisol = Chronic stress hormone.

cortisone

Made by: Adrenal cortex (formed from cortisol)
Target(s): Most body tissues
Action(s): Anti-inflammatory glucocorticoid (less active than cortisol)
Regulation: ACTH (indirectly)
Hypersecretion (too much): Similar to cortisol excess
Hyposecretion (too little): Similar to cortisol deficiency
Quick Memory Tip: Cortisone = Cortisol's calmer cousin.

androgens

Made by: Adrenal cortex (zona reticularis)
Target(s): Many body tissues
Action(s): Contribute to puberty, libido, and body hair growth
Regulation: ACTH
Hypersecretion (too much): Virilization in females
Hyposecretion (too little): Usually minimal effects
Quick Memory Tip: Adrenal androgens = extra sex hormones.

aldosterone

Made by: Adrenal cortex (zona glomerulosa)
Target(s): Kidneys
Action(s): Increases sodium and water reabsorption; increases potassium excretion
Regulation: Renin-angiotensin-aldosterone system (RAAS) and high potassium levels
Hypersecretion (too much): Hypertension, low potassium
Hyposecretion (too little): Low blood pressure, dehydration, high potassium
Quick Memory Tip: Salt follows ALDO. Water follows salt.

DHEA

Dehydroepiandrosterone

Made by: Adrenal cortex (zona reticularis)
Target(s): Many tissues
Action(s): Weak androgen; precursor to testosterone and estrogen
Regulation: ACTH
Hypersecretion (too much): Excess body hair, acne, virilization
Hyposecretion (too little): Usually mild effects
Quick Memory Tip: DHEA = Hormone precursor.

MSH

MELANOCYTE-STIMULATING HORMONE

Made by: Pars intermedia of the pituitary (or anterior pituitary in humans)
Target(s): Melanocytes in the skin
Action(s): Increases melanin production (pigmentation)
Regulation: Hypothalamic signals (less significant in humans)
Hypersecretion (too much): Darkened skin pigmentation
Hyposecretion (too little): Little clinical effect
Quick Memory Tip: MSH Makes Skin darker.

TH

THYMIC HORMONES

Made by: Thymus
Target(s): T lymphocytes
Action(s): Promote maturation and differentiation of T cells for immune function
Regulation: Most active during childhood; decreases with age as the thymus involutes
Hypersecretion (too much): No well-defined disorder
Hyposecretion (too little): Impaired T-cell development and weakened immune response
Quick Memory Tip: TH = Thymus Helps T cells.

Diabetes Mellitus

Cause: Too little insulin or the body's cells don't respond properly to insulin
Hormone(s) involved: Insulin
Key Signs/Symptoms: High blood sugar, excessive urination, excessive thirst, increased hunger, fatigue
Quick Memory Tip: Diabetes Mellitus = Sugar problem.

Diabetes Insipidus

Cause: Too little ADH or kidneys don't respond to ADH
Hormone(s) involved: ADH
Key Signs/Symptoms: Large amounts of dilute urine, excessive thirst, dehydration
Quick Memory Tip: Diabetes Insipidus = Water problem.

Hyperthyroidism

Cause: Excess thyroid hormone production
Hormone(s) involved: T3, T4
Key Signs/Symptoms: Weight loss, heat intolerance, rapid heart rate, nervousness, increased metabolism
Quick Memory Tip: Hyper = Everything speeds UP.

Hypothyroidism

Cause: Too little thyroid hormone production
Hormone(s) involved: T3, T4
Key Signs/Symptoms: Weight gain, fatigue, cold intolerance, slow heart rate, decreased metabolism
Quick Memory Tip: Hypo = Everything slows DOWN.

Graves Disease

Cause: Autoimmune disorder causing hyperthyroidism
Hormone(s) involved: T3, T4
Key Signs/Symptoms: Hyperthyroidism symptoms plus bulging eyes (exophthalmos) and goiter
Quick Memory Tip: Graves = Grave eyes (bulging eyes).

Cushing Syndrome

Cause: Too much cortisol (from any cause)
Hormone(s) involved: Cortisol
Key Signs/Symptoms: Moon face, buffalo hump, central obesity, muscle weakness, high blood glucose, high blood pressure
Quick Memory Tip: Cushing = Cushioned with fat.

Addison Disease

Cause: Adrenal cortex doesn't produce enough cortisol (and often aldosterone)
Hormone(s) involved: Cortisol, Aldosterone
Key Signs/Symptoms: Fatigue, weight loss, low blood pressure, dehydration, skin darkening (hyperpigmentation)
Quick Memory Tip: Addison = Add salt (low aldosterone).

Hyperparathyroidism

Cause: Too much PTH
Hormone(s) involved: PTH
Key Signs/Symptoms: High blood calcium, weak bones, kidney stones, muscle weakness
Quick Memory Tip: Too much PTH pulls calcium OUT of bones.

Hypoparathyroidism

Cause: Too little PTH
Hormone(s) involved: PTH
Key Signs/Symptoms: Low blood calcium, muscle cramps, tingling, tetany (muscle spasms)
Quick Memory Tip: Too little PTH = Tight muscles (tetany).

Gigantism

Cause: Excess GH before growth plates close (childhood)
Hormone(s) involved: GH
Key Signs/Symptoms: Extremely tall height, enlarged bones and tissues
Quick Memory Tip: Child + GH = Giant.

Acromegaly

Cause: Excess GH after growth plates close (adulthood)
Hormone(s) involved: GH
Key Signs/Symptoms: Enlarged hands, feet, jaw, and facial bones
Quick Memory Tip: Adult + GH = AcrOmegaly = Overgrown extremities.

Pituitary Dwarfism

Cause: Too little GH during childhood
Hormone(s) involved: GH
Key Signs/Symptoms: Short stature with normal body proportions
Quick Memory Tip: Too little GH = Doesn't grow.

Goiter

Cause: Enlargement of the thyroid gland (can occur with hyperthyroidism, hypothyroidism, or iodine deficiency)
Hormone(s) involved: Usually TSH, T3, and T4
Key Signs/Symptoms: Enlarged thyroid, visible neck swelling, possible difficulty swallowing
Quick Memory Tip: Goiter = Big thyroid.

Water-Soluble Hormones

Includes: Most peptide/protein hormones and catecholamines (insulin, glucagon, GH, ADH, epinephrine, etc.)
Receptor: Cell membrane
Mechanism: Uses second messengers (like cAMP)
Quick Memory Tip: Water = Membrane receptor.

Lipid-Soluble Hormones

Includes: Steroid hormones and thyroid hormones (T3/T4)
Receptor: Inside the cell (cytoplasm or nucleus)
Mechanism: Changes gene expression by affecting DNA transcription
Quick Memory Tip: Lipid = Goes through the membrane.

Up-Regulation

Definition: Cells increase the number of hormone receptors, making them more sensitive to a hormone.

Quick Memory Tip: Up = More receptors.

Down-Regulation

Definition: Cells decrease the number of hormone receptors, making them less sensitive to a hormone.

Quick Memory Tip: Down = Fewer receptors.

Target Cell

Definition: A cell that has receptors for a specific hormone and can respond to it.

Quick Memory Tip: No receptor = No response.

Female Masculinization (Androgenital Syndrome)

Cause: Excess adrenal androgen production (usually adrenal cortex)

Hormone(s): Androgens/DHEA

Signs: Excess facial/body hair, deep voice, enlarged clitoris, irregular periods

Quick Memory Tip: Too many adrenal androgens = Masculinization.

Glucocorticoid Drugs

Cause: Long-term use of steroid medications (prednisone, etc.)

Hormone: Cortisol-like drugs

Signs: Same as Cushing syndrome (moon face, buffalo hump, high blood sugar)

Quick Memory Tip: Too many steroids = Cushing-like symptoms.

Type 1 Diabetes Mellitus

Cause: Autoimmune destruction of pancreatic beta cells

Hormone: No insulin produced

Signs: Usually begins in childhood; requires insulin injections

Quick Memory Tip: Type 1 = No insulin.

Type 2 Diabetes Mellitus

Cause: Cells become resistant to insulin

Hormone: Insulin present but doesn't work well

Signs: Usually develops in adults; associated with obesity; high blood sugar

Quick Memory Tip: Type 2 = Insulin resistance.

Endocrine System Function

Maintains homeostasis by secreting hormones into the bloodstream to regulate growth, metabolism, reproduction, stress response, fluid balance, and blood glucose.