hierarchy of structures in animals

• a hierarchy is an organizational structure with more complex things on top and simple below it
• Cell -> Tissue -> Organ -> Organ System -> Organism
• a tissue is a collection of similar cells that perform a particular but limited function
• animals have 4 major types of tissues:

  • epithelial
  • connective
  • muscle
  • nerve
• an organ is a structure composed of different tissues working together to perform a complex body function
• an organ system is a group of organs working together to perform a body function
• epithelial tissue are thin sheets of tightly packed cells that cover body surfaces and lines internal organs
• the main function of epithelial tissue is to protect from dehydration
• connective tissue is a specialized tissue that provides support and protection for various parts of the body
• main function of connective tissue is support and insulation
• examples of epithelial tissue: skin, lining of the stomach
• examples of connective tissue: bone, tendons, blood
• muscle tissue is a specialized tissue containing proteins that can contract and enable the body to move
• main function of muscle tissue is movement
• examples of muscle tissue: muscles that make bones move, heart
• nerve tissue is a specialized tissue that conducts electrical signals from one part of the body to another
• main function of nerve tissue is sensory, communicate within body, and to coordinate bodily functions
• examples of nerve tissue: brain, nerves in sensory organs