Hormones and Endocrine System Review

Adrenal Gland Hormones

• Epinephrine

  • Also known as: Adrenaline (associated with the Epi-Pen).
  • Released by: Adrenal medulla.
  • Target organs: Heart, lungs, liver, and muscles.
  • Function: Expands the airway, raises the heart rate, and increases energy levels by raising glucose.
  • Trigger: Activation of the sympathetic nervous system, commonly known as the "fight or flight" response.

• Norepinephrine

  • Also known as: Nora-adrenaline.
  • Released by: Adrenal medulla.
  • Target organ: Blood vessels.
  • Function: Causes vasoconstriction of the blood vessels, raises blood pressure, and sharpens focus.

• Aldosterone

  • Mnemonic: Aldosterone stores salt.
  • Released by: Adrenal Cortex.
  • Target organ: Kidneys.
  • Function: Keeps water ($H_2O$) and sodium ($Na^+$) in the body, gets rid of potassium ($K^+$), and raises blood pressure.
  • Triggers: Low sodium ($Na^+$), high potassium ($K^+$), or low blood pressure and volume.

• Cortisol

  • Released by: Adrenal Cortex.
  • Function: Increases glucose, slows inflammation, and manages stress.
  • Trigger: Adenocorticotropic Hormone (ACTH) from the anterior pituitary.

• Gluconeogenesis

  • Process: A function involving cortisol where lipids and proteins are converted into glucose.
  • Trigger: Low glucose levels.

Pancreatic and Metabolic Control

• Glucagon

  • Purpose: Raises glucose.
  • Released by: Pancreas.
  • Target organ: Liver.
  • Function: Raises blood sugar by breaking down stored glycogen (stored glucose in the liver) into glucose.
  • Trigger: Low blood glucose.

• Insulin

  • Released by: Pancreas.
  • Target organs: Liver, muscles, and fat cells.
  • Function: Lowers blood glucose levels by taking glucose and storing it for later use.

• Leptin

  • Mnemonic: Lets put the fork down.
  • Made by: Fat (adipose tissue).
  • Target organ: Hypothalamus.
  • Function: Suppresses appetite, regulates food intake, and maintains energy balance.
  • Trigger: Increased fat storage.

• Somatostatin

  • Mnemonic: SOMATO-STOP_IN.
  • Made by: Hypothalamus and Pancreas.
  • Target organs: Pituitary gland and pancreas.
  • Function: Slows the secretion of Growth Hormone (GH), Thyroid Stimulating Hormone (TSH), insulin, and glucagon.

Hypothalamic and Pituitary Hormones

• Antidiuretic Hormone (ADH)

  • Origin: Made by the Hypothalamus; released by the Posterior Pituitary.
  • Target organ: Kidneys.
  • Function: Keeps water ($H_2O$) in the collecting duct, decreases urine output, and increases blood pressure.
  • Triggers: Dehydration and high blood osmolality.

• Oxytocin

  • Origin: Made by the Hypothalamus; released by the Posterior Pituitary.
  • Target organs: Uterus and mammary glands.
  • Function: Causes uterine contractions and forces milk into the milk ducts.

• Dopamine

  • Mnemonic: DOPAMINE DELIGHT.
  • Made by: Hypothalamus.
  • Released by: Adrenal medulla and the brain.
  • Target organs: Anterior pituitary and brain neurons.
  • Function: Slows down prolactin, regulates mood, motivation, and serves as the reward center.

• Releasing Hormones

  • Types: Gonadotropins RH, Corticotropin RH, Growth Hormone RH, and Thyrotropin RH.
  • Made by: Hypothalamus.
  • Target organ: Anterior pituitary.
  • Function: Stimulate the anterior pituitary to release specific hormones.

• Growth Hormone (GH)

  • Made by: Anterior pituitary.
  • Target organs: Liver, bones, and muscles.
  • Function: Facilitates the production of new proteins and stimulates cell growth.
  • Trigger: Growth Hormone Releasing Hormone (GHRH).

• Prolactin (PRL)

  • Made by: Anterior pituitary.
  • Target organ: Breasts.
  • Function: Stimulates milk production after giving birth.
  • Triggers: Nipple stimulation and low dopamine levels.

• Thyroid Stimulating Hormone (TSH)

  • Made by: Anterior pituitary.
  • Function: Stimulates the release of triiodothyronine ($T_3$) and thyroxine ($T_4$).
  • Trigger: Thyrotropin Releasing Hormone (TRH), which indicates low thyroid levels.

• Follicle Stimulating Hormone (FSH)

  • Made by: Anterior pituitary.
  • Target organs: Ovaries and testes.
  • Function: Egg and follicle maturation in females and sperm production in males.
  • Trigger: Gonadotropin Releasing Hormone (GnRH).

• Luteinizing Hormone (LH)

  • Made by: Anterior pituitary.
  • Target organs: Ovaries and testes.
  • Function: Triggers ovulation in females and the production of testosterone in males.
  • Trigger: Gonadotropin Releasing Hormone (GnRH).

• Adenocorticotropic Hormone (ACTH)

  • Made by: Anterior pituitary.
  • Target organ: Adrenal Cortex.
  • Function: Stimulates the release of cortisol to manage stress levels.

Thyroid, Parathyroid, and Pineal Hormones

• Thyroxine ($T_4$) and Triiodothyronine ($T_3$)

  • Mnemonic: "Turns up the thermostat."
  • Made by: Thyroid gland.
  • Released by: Triggered by Thyroid Stimulating Hormone (TSH).
  • Function: Increases the metabolic rate and energy use.

• Calcitonin

  • Mnemonic: TONES DOWN THE CALCIUM.
  • Made by: Thyroid gland.
  • Target organs: Bones and kidneys.
  • Function: Lowers blood calcium levels.
  • Trigger: High calcium levels.

• Parathyroid Hormone (PTH)

  • Mnemonic: PTH PUSHES IT UP.
  • Made by: Parathyroid glands.
  • Target organs: Bones, kidneys, and intestines.
  • Function: Raises blood calcium levels, promotes calcium retention, and activates Vitamin D.
  • Trigger: Low blood calcium levels.

• Melatonin

  • Mnemonic: MOON HORMONE.
  • Made by: Pineal gland.
  • Target organs: Brain and various body tissues.
  • Function: Promotes sleep.
  • Trigger: Darkness.

Digestive Hormones

• Gastrin

  • Secreted by: G-cells located in the stomach.
  • Target organ: Parietal cells in the stomach.
  • Function: Encourages the secretion of gastric acid.
  • Trigger: Neural activity.

• Cholecystokinin (CCK)

  • Mnemonic: Contracts the cholecyst (gallbladder).
  • Made by: Small intestine (specifically the duodenum).
  • Target organs: Gallbladder, pancreas, and brain.
  • Function: Stimulates the release of bile and pancreatic enzymes.
  • Trigger: Presence of fat and protein in the chyme.

• Secretin

  • Mnemonic: BICARBONATE SECRETION.
  • Made by: Small intestine (specifically S-cells).
  • Target organs: Pancreas, liver, and stomach.
  • Function: Signals the pancreas to release bicarbonate, which neutralizes stomach acid from food as it enters the small intestine.
  • Trigger: Acidic chyme entering the duodenum.

• Ghrelin

  • Mnemonic: GROWLIN TUMMY HORMONE.
  • Made by: Stomach.
  • Target organ: Hypothalamus.
  • Function: Increases appetite and stimulates the release of growth hormone.
  • Trigger: Fasting or an empty stomach.

Reproductive Hormones and Miscellaneous Factors

• Estrogen

  • Made by: Ovaries.
  • Target organs: Uterus, breasts, bones, and brains.
  • Function: Assists in the development of breasts and reproductive organs, regulates the menstrual cycle, and builds the uterine lining.

• Progesterone

  • Mnemonic: PRO-GESTATION.
  • Released from: Ovaries.
  • Target organs: Uterus and breasts.
  • Function: Keeps the uterine lining thick during pregnancy to prevent miscarriage and prevents uterine contractions.
  • Triggers: Luteinizing Hormone (LH) stimulation and post-ovulation phases.

• Testosterone

  • Released by: Testes.
  • Target organs: Muscles, bones, and testes.
  • Function: Supports sperm production, builds muscle mass, and helps develop male reproductive organs.

• Thymosin

  • Source: Thymus.
  • Target: T-lymphocytes.
  • Function: Trains T-cells for immune response.

• Erythropoietin (EPO)

  • Released by: Kidneys.
  • Target organ: Bone Marrow.
  • Function: The kidneys signal the bone marrow to produce more red blood cells.

• Erythrocytes

  • Origin: Bone Marrow.
  • Function: Carry oxygen to tissues and organs (release oxygen).