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Animal Body Organization and Systems



The animal body is a complex system that relies on a myriad of processes in order for activities such as feeding, reproduction, and homeostasis to be performed. Each of these processes involves cells that carry out specific functions. Specialized cells combine to form tissues. Organs are assemblages of two or more tissue types that perform specific functions within the body. Multiple organs form an organ system, which has a larger role in the body. All the organ systems function together within an organism.

At A Glance

  • The body is a complex organized system: cells make up the tissues, tissues make up the organs, organs form the individual body systems, and multiple body systems form the organism.
  • There are four basic types of tissue in the animal body: muscle, nervous, epithelial, and connective.
  • The cardiopulmonary system moves gases, nutrients, and waste to the appropriate places in the body.
  • The cardiovascular system consists of the heart, blood vessels, and blood, which circulates materials around the body.
  • The heart and lungs work together to circulate oxygen to the cells of the body and remove waste carbon dioxide.
  • The respiratory system exchanges oxygen and waste carbon dioxide between the blood and the environment.
  • Breathing brings needed oxygen into the body and eliminates waste carbon dioxide.
  • The reproductive system is involved in the development and growth of offspring. Sexual reproduction results in offspring with unique sets of traits. Asexual reproduction results in offspring identical to the parent.
  • The digestive system processes food into nutrients for cells, while the excretory system removes unwanted waste products from the body.
  • Digestion involves mechanical and chemical processes to break food down into constituent nutrients for absorption, transport, and use by the body.
  • The excretory system controls the solute and water balance of the blood.
  • The nervous and endocrine systems are the body's means of communicating internal and external conditions, processing information, and controlling the body's responses.
  • The endocrine system uses chemical communication via hormones to control many body functions.
  • The nervous system transmits information through neurons, processes the information in the central nervous system, and controls body responses. There are several divisions within the nervous system for different types of signals or responses.
  • Nerves transmit information to and from the brain through electrical signals along individual nerves and chemical signals between nerves.
  • The immune system protects the body against pathogens. Some parts of the immune system are nonspecific, while others are specific to the pathogen.
  • The muscular and skeletal systems allow the body to move, allow the organs to function, and protect internal organs from external forces.