Organ (biology)

Definition

In a multicellular organism, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a function. Tissues of different types combine to form an organ which has a specific function. The intestinal wall for example is formed by epithelial tissue and smooth muscle tissue. Two or more organs working together in the execution of a specific body function form an organ system, also called a biological system or body system.

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Abdominal cavity Adenoid Adrenal Adrenal gland Analogy (biology)Anatomical terminology Anatomy Ancient Greek Ancillary Animal Anus Appendix (anatomy)Aristotle Artery Artificial organ Asexual reproduction Augur Bilateria Biliary tract Biocoenosis Biological organisation Biological organization Biological system Biome Biomolecule Biosphere Bird Bladder Blood Blood stream Blood vessel Body cavity Bone Bone marrow Brain Breast Breathing Bronchi Bronchus Cardiovascular system Carpal bones Cartilage Cartilaginous joint Cell (biology)Chinese traditional medicine Chordate Circulatory system Classical planets Clavicle Clonal colony Cnidaria Colon (anatomy)Conifer cone Connective tissue Ctenophora Digestion Disease Distributive justice Ear Ecosystem Electrolyte Embryology Endocrine gland Endocrine system Epiphyte Epithelial tissue Equisetum telmateia Esophagus Eukaryotes Excretory system Feather Female reproductive system Femur Fibrous joint Fibula Fish Flatworm Flower Flowering plant Foundational Model of Anatomy Fruit Function (biology)Gallbladder Gastrointestinal tract Genitourinary system Germ layer Gland Glymphatic system Graft-versus-host disease Gynoecium Haematopoietic system Hair Haruspices Heart Hermaphroditic (botany)Hermetic Qabalah Hibiscus Hippocratic corpus Hormone Human anatomy Human anus Human body Human brain Human digestive system Human eye Human mouth Human musculoskeletal system Human nose Human penis Human reproductive system Human skeleton Human skin Human tooth Humerus Hypothalamus Immune system Immunosuppression Innervation of the pelvic viscera Integumentary system Intestine Intestines Joint Kidney Kidney (vertebrates)Large intestine Larynx Latin Leaf Leukocyte Ligament Lip List of organs of the human body List of pelvic organs Liver Lung Lycopodiophyta Lymph Lymph node Lymph vessel Lymphatic system Lymphatic vessel Lymphocyte Macromolecular assembly Macromolecule Male reproductive system Mammal Mammary gland Mandible Mesentery Metabolism Metacarpal bones Metatarsal bones Mollusca Moss Multicellular Muscle Muscular system Musculoskeletal system Myeloid Nail (anatomy)Nerve Nerve tissue Nervous system Nervous tissue Neuroendocrine system Online Etymology Dictionary Organ-on-a-chip Organ (music)Organ donation Organ system Organ transplant Organ transplantation Organelle Organism Organoid Organon Organs (disambiguation)Ossicles Ovary Oviduct Pancreas Pancreatic islets Paracelsus Parathyroid Parathyroid gland Parenchyma Patella Pelvic cavity Pelvis Penis Phalanx bone Pharynx Photosynthesis Phylum Pineal body Pineal gland Pinophyta Pituitary Pituitary gland Placenta Placozoa Plant Plant anatomy Plant morphology Plant physiology Plant sexuality Plant stem Population (biology)Porifera Priest Prostate Radius (bone)Rectum Reproductive system Reptile Respiratory system Respiratory tract Rib Rome Root Salivary gland San jiao Scale (anatomy)Scrotum Seed Seminal vesicle Sensory system Sex organ Sheep Situs inversus Skeletal system Skeleton Skin Skull Small intestine Smooth muscle tissue Somatic nervous system Spinal cord Splanchnic Splanchnology Spleen Stamen Sternum Stomach Strobili Stroma (tissue)Subcutaneous tissue Synovial joint Tarsus (skeleton)Taxon Tendon Testicle Thoracic cavity Thoracic diaphragm Thymus Thyroid Tibia Tissue (biology)Tissue engineering Tongue Tonsil Trachea Transplant rejection Ulna Unicellular organism Ureter Urethra Urinary bladder Urinary system Urine Uterus Vagina Vasa deferentia Vegetative reproduction Vein Vertebral column Vertebrate trachea Viscera (disambiguation)Vulva Wuxing (Chinese philosophy)Xenotransplant Yin and yang

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