Functions of organs/hormones

Hypothalamus

Releases/inhibits hormones and controls the pituitary gland.

Pituitary (anterior and posterior)

Major Hormones: GH, TSH, ACTH, LH, FSH, ADH, Oxytocin

Regulates other glands

Pineal Gland

Hormones: Melatonin

Regulated Circadian Rhythms

Thyroid (Neck)

Hormones: Produced T3, T4, Calcitonin

Regulated metabolism and calcium

Parathyroid (Neck)

Hormones: PTH

Increases blood calcium

Adrenal Glands (Above Kidneys)

Hormones: Cortisol, Adrenaline, Aldosterone

Works with stress, metabolism, and electrolyte balance

Pancreas (Abdomen)

Hormones: Insulin and Glucagon

Regulates blood glucose

Ovaries (Pelvis)

Hormones: Estrogen, Progesterone

Helps reproduction and secondary traits

Testes (Scrotum)

Hormones: Testosterone

Works with sperm production and secondary traits

Placenta (during pregnancy)

Hormones: Human chorionic gonadotropin (hCG), estrogen, and progesterone

Provides nutrients to the growing infant/fetus

Insulin (Pancreas)

Target: Liver, muscle, fat

Lowers blood glucose

Glucagon (Pancreas)

Target: Liver

Raises blood glucose

Thyroxine (T4) (Thyroid)

Target: Most body cells

Regulates metabolism (too little can cause hypothyroidism)

Triiodothyronine (T3) (Thyroid)

Target: Most body cells

Regulates metabolism (too much can cause high metabolic rate/hyperthyroidism)

Calcitonin (Thyroid)

Target: Bones

Regulates Lowers blood calcium

Parathyroid hormone (PTH) (Parathyroid)

Target: Bones/kidneys

Increases blood calcium

Cortisol (Adrenal Cortex)

Target: Liver and immune system

Works with stress response and glucose metabolism

Aldosterone (Adrenal Cortex)

Target: Kidneys

Increases sodium and water retention

Epinephrine (Adrenaline) (Adrenal Medulla)

Target: Heart, lungs, muscles

Fight or flight response

Growth Hormone (GH) (Anterior Pituitary)

Target: Bones/tissues

Stimulates growth

Prolactin (Anterior Pituitary)

Target: Mammary Glands/breasts

Stimulates milk production

Oxytocin (Posterior pituitary via hypothalamus)

Target: Uterus/breasts

Triggers contractions/milk release

Antidiuretic hormone (ADH) (Posterior pituitary via hypothalamus)

Target: Kidneys

Reduces urine output and retains water

Estrogen (Ovaries/placenta)

Target: Uterus, breasts, and brain

Female development and cycle regulation

Progesterone (Ovaries/placenta)

Target: Uterus

Prepares uterus for pregnancy

Testosterone (Testes)

Target: Muscle, bone, reproductive organs

Works on male development and sperm production

Melatonin (Pineal Gland)

Target: Brain

Regulates sleep/wake cycle

Erythropoietin (EPO)(Kidneys)

Target: Bone Marrow

Stimulates red blood cell production

Leptin (Adipose tissue)

Target: Brain

Inhibits hunger and regulates energy

Ghrelin (Stomach)

Target: Brain

Stimulates hunger

Gastrin (Stomach)

Target: Stomach

Stimulates acid secretion

Secretin (Duodenum (first part of small intestine))

Target: Pancreas/liver

Stimulates bicarbonate release (maintaining body’s pH balance)

Cholecystokinin (CCK) (small intestine)

Target: Gallbladder, pancreas

Stimulates bile and enzyme release

Somatostatin (Pancreas, GI tract)

Target: multiple targets

Inhibits GH, insulin, and GI hormones

Negative Feedback example (reduces hormone output to stabilize internal conditions/prevents overproduction)

Thyroid Regulation: The hypothalamus releases TRH → Pituitary releases TSH → Thyroid releases T3/T4. When T3/T4 levels rise, they inhibit TRH and TSH release

Positive feedback example (Amplifies hormone release for special events)

Childbirth (Oxytocin): Oxytocin causes uterine contractions → Stretching of the cervix triggers more oxytocin → Cycle continues until delivery.