HOMEOSTASIS OLEH FATURRAHMAN

Intro to Homeostasis HomeostasisHomeostasis can be defined as the maintenance of physiological conditions required to maintain the life of the organism. Homeostasis Homeostasis is the property of an closed system, especially living organisms, to regulate its internal environment to maintain a stable, constant condition, by means of multiple dynamic equilibrium adjustments, controlled by interrelated regulation mechanisms. closed systemorganismsdynamic equilibriumclosed systemorganismsdynamic equilibrium The term was coined in 1932 by Walter Cannon from the Greek homo (same, like) and stasis (to stand, posture). 1932Walter CannonGreek1932Walter CannonGreek

The term is most often used in the sense of biological homeostasis. Multicellular organisms require a homeostatic internal environment, in order to live biologicalMulticellular organisms environmentlivebiologicalMulticellular organisms environmentlive Complex systemsComplex systems, such as a human body, must have homeostasis to maintain stability and to survive. These systems do not only have to endure to survive; they must adapt themselves and evolve to modifications of the environment. Complex systems

Properties of homeostasis : They are ultrastable: the system is capable of testing which way its variables should be adjusted.ultrastable Their whole organization (internal, structural, and functional) contributes to the maintenance of equilibrium.organization equilibrium They are unpredictable: the resulting effect of a precise action often has the opposite effect to what was expected.

Internal System of homeostasis: Blood pH (controlled by both nervous and endocrine system) Water potential (controlled by the endocrine system, kidney and ADH) Oxygen and CO 2 concentrations (controlled by the nervous system, ventilation rate etc) Blood glucose (controlled by the endocrine system, glucagon and insulin) Body temperature (controlled by the nervous and endocrine systems)

Mechanisms of homeostasis : feedback  Negative feedback control mechanisms (used by most of the body's systems) are called negative because the information caused by the feedback causes a reverse of the response. TSH is an example: blood levels of TSH serve as feedback for production of TSH. Negative feedback control mechanisms Negative feedback control mechanisms

 Positive feedback control is used in some cases. Input increases or accelerates the response. During uterine contractions, oxytocin is produced. Oxytocin causes an increase in frequency and strength of uterine contractions. This in turn causes further production of oxytocin, etc. Positive feedback control oxytocin Positive feedback control oxytocin

Examples : ► Thermoregulation Thermoregulation  The skeletal muscles can shiver to produce heat if the body temperature is too low. skeletal musclesshiverskeletal musclesshiver  Non-shivering thermogenesis involves the decomposition of fat to produce heat. Non-shivering thermogenesisfat Non-shivering thermogenesisfat  Sweating cools the body with the use of evaporation. Sweatingevaporation Sweatingevaporation ► Chemical regulation Chemical regulation Chemical regulation  The pancreas produces insulin and glucagon to control blood-sugar concentration. pancreasinsulinglucagonpancreasinsulinglucagon  The lungs take in oxygen and give off carbon dioxide. lungsoxygencarbon dioxidelungsoxygencarbon dioxide  The kidneys remove urea, and adjust the concentrations of water and a wide variety of ions. kidneysureawaterionskidneysureawaterions

 Homeostasis depends on the action and interaction of a number of body systems to maintain a range of conditions within which the body can best operate.  Eleven major organ systems are present within animals : 1.Muscular System allows movement and locomotion. The muscular system produces body movements, body heat, maintains posture, and supports the body Muscular SystemMuscular System 2.Skeletal System provides support and protection, and attachment points for muscles. Skeletal SystemSkeletal System

3. Skin or Integument is the outermost protective layer. It prevents water loss from and invasion of foreign microorganisms and viruses into the body. Skin or IntegumentSkin or Integument 4. Respiratory System moves oxygen from the external environment into the internal environment; also removes carbon dioxide. Respiratory System Respiratory System 5. Digestive System digests and absorbs food into nutrient molecules by chemical and mechanical breakdown; eliminates solid wastes into the environment. Digestive SystemDigestive System 6. Circulatory System transports oxygen, carbon dioxide, nutrients, waste products, immune components, and hormones. Circulatory SystemCirculatory System 7. Immune System defends the internal environment from invading microorganisms and viruses, as well as cancerous cell growth. Immune SystemImmune System

8. Excretory System regulates volume of internal body fluids as well as eliminates metabolic wastes from the internal environment. Excretory SystemExcretory System 9. Nervous System coordinates and controls actions of internal organs and body systems. Nervous SystemNervous System 10. Endocrine System works with the nervous system to control the activity internal organs as well as coordinating long-range response to external stimuli. Endocrine SystemEndocrine System 11. Reproductive System is mostly controlled by the endocrine system, and is responsible for survival and perpetuation of the species. Reproductive SystemReproductive System