Human Body Systems Summary

Circulatory System

  • Function: Moves blood, oxygen, nutrients, and waste.
  • Main Parts: Heart, blood vessels, blood.

Respiratory System

  • Function: Brings in oxygen, removes carbon dioxide.
  • Main Parts: Lungs, trachea, bronchi, nose, mouth.

Digestive System

  • Function: Breaks down food into nutrients.
  • Main Parts: Mouth, esophagus, stomach, small and large intestines, liver, pancreas.

Nervous System

  • Function: Controls body, communicates between body parts.
  • Main Parts: Brain, spinal cord, nerves.

Muscular System

  • Function: Allows movement, helps with posture, generates heat.
  • Main Parts: Skeletal, smooth, and cardiac muscles.

Skeletal System

  • Function: Supports the body, protects organs, allows movement.
  • Main Parts: Bones, joints, cartilage.

Endocrine System

  • Function: Produces hormones to regulate body processes.
  • Main Parts: Glands (pituitary, thyroid, adrenal), pancreas, hormones.

Hypothalamus

  • Connects nervous and endocrine systems.
  • Hormones: Releasing (e.g., TRH), inhibiting hormones.

Pituitary Gland

  • Controls other glands, regulates growth.
  • Hormones: GH, TSH, ACTH, LH, FSH, Prolactin, ADH, Oxytocin.

Thyroid Gland

  • Regulates metabolism and energy use.
  • Hormones: T3, T4, Calcitonin.

Parathyroid Glands

  • Regulates calcium levels.
  • Hormone: PTH.

Adrenal Glands

  • Manages stress, blood pressure, and metabolism.
  • Hormones: Cortisol, Adrenaline, Aldosterone.

Pancreas

  • Regulates blood sugar.
  • Hormones: Insulin, Glucagon.

Ovaries

  • Regulates blood sugar
  • Hormones: Estrogen, Progesterone.

Testes

  • Controls male reproduction.
  • Hormone: Testosterone.

Pineal Gland

  • Regulates sleep.
  • Hormone: Melatonin.

Thymus

  • Helps develop the immune system.
  • Hormone: Thymosin.
  • Stress Response Example: Hypothalamus -> CRH, Pituitary -> ACTH, Adrenal -> Cortisol.

Immune System

  • Function: Defends against diseases.
  • Main Parts: White blood cells, lymph nodes, spleen, tonsils.

Lymphatic System

  • Function: Returns fluids to bloodstream, helps fight infection.
  • Main Parts: Lymph, lymph vessels, lymph nodes.

Urinary (Excretory) System

  • Function: Removes waste, balances water and salt.
  • Main Parts: Kidneys, ureters, bladder, urethra.

Reproductive System

  • Function: Produces offspring.
  • Main Parts: Male (testes, penis, prostate), female (ovaries, uterus, vagina).

Integumentary System

  • Function: Protects the body, regulates temperature, senses the environment.
  • Main Parts: Skin, hair, nails.

System Interactions

  • Nervous + Muscular: Nervous system signals muscles to contract or relax.
  • Muscular + Skeletal: Muscles pull on the skeletal system for movement.