13: Human Biology Last updated Save as PDF Page ID311 Contributed by CK12CK12 13.10: Muscle Contraction13.11: Skin13.12: Nails and Hair13.13: Neuron13.14: Nerve Impulse13.15: Central Nervous System13.16: Peripheral Nervous System13.17: Senses13.18: Drugs and the Nervous System13.19: Nervous System Diseases13.1: Human Body13.20: Endocrine Glands13.21: Hormone13.22: Hormone Regulation13.23: Endocrine System Diseases13.24: Heart13.25: Blood Vessels13.26: Circulatory System13.27: Cardiovascular Diseases13.28: Blood13.29: Respiratory System13.2: Homeostasis13.30: Respiratory System Organs13.31: Breathing13.32: Regulation of Breathing13.33: Respiratory System Disorders13.34: Digestive System Organs13.35: Digestive System13.36: Small Intestine13.37: Large Intestine13.38: Digestive System Diseases13.39: Food and Nutrients13.3: Skeletal System13.40: Balanced Eating13.41: Excretory System13.42: Urinary System13.43: Kidneys13.44: Excretory System Diseases13.45: Innate Immune System13.46: Inflammatory Response13.47: Lymphatic System13.48: Humoral Response13.49: Cell-Mediated Response13.4: Bones13.50: Immunity13.51: Allergies13.52: Autoimmune Disease13.53: Immunodeficiency13.54: HIV AIDS13.55: Carcinogens and Cancer13.56: Air Pollution and Illness13.57: Bioterrorism13.58: Male Reproductive Organs13.59: Male Reproductive Development13.5: Bone Growth13.60: Sperm13.61: Female Reproductive Organs13.62: Female Reproductive Development13.63: Egg Cells13.64: Menstrual Cycle13.65: Fertilization13.66: Embryo Growth13.67: Prenatal Development13.68: The Placenta13.69: Pregnancy13.6: Joints13.70: Birth to Adulthood13.71: Adulthood13.72: STIs13.73: Bacterial STIs13.74: Viral STIs13.7: Skeletal Diseases13.8: Muscles13.9: Skeletal Muscles