Characteristics of the Living Organism

1. Characteristics of the Living Organism Lesson 3 Human Anatomy

2. Basic Life Processes • Metabolism • The sum of all chemical processes that occur in the body. • Anabolsim: the building of complex chemical substances from smaller, simpler components. • Catabolism: the breaking down of complex chemical substances into simpler components. • Responsiveness • The body’s ability to detect and respond to changes in the external and internal environments.

3. Movement • Motion of the whole body, individual organs, single cells, or even cellular organelles. • Growth • An increase in body size that results from an increase in cell size and/or number. • Differentiation • Development of a cell from an unspecialized to a specialized state. • Cells that divide and give rise to cells that undergo differentiation are called stem cells.

4. Reproduction • Refers to formation or new cells for tissue growth, repair, or replacement, or to the production of a new individual.

5. Homeostasis • The balance in the body’s internal environment due to the continual interaction of the body’s many regulatory processes. • The body’s systems constantly interact with one another to keep all body functions and chemical balances within a specific set of parameters – the normal limits.

6. Body Fluids • Body fluids are important to homeostasis because the interact within and between cells to help maintain cellular pH, glucose levels, amino acid levels, oxygen levels, and other materials needed for cell health. • Intercellular fluid: fluid within cells • Extracellular fluid: fluid outside of cells • Interstitial fluid: extracellular fluid that fills the spaces between the cells of tissues

7. Control of Homeostasis • Homeostasis is continually disturbed by the body’s external and internal environments. • Most of the time, the disruption is temporary and the body’s cells, tissues, and organs can quickly restore balance. • When the body cannot quickly restore balance, disease and death may result. • The body had many regulatory systems that usually bring the internal environment back into balance. Most of these systems are negative feedback systems.

8. Feedback Systems • A feedback system is a cycle of events in which the status of the body is constantly monitored, evaluated, changed, remonitored, reevaluated, and so on. • Each monitored variable is called a controlled condition and any change in a controlled condition is called a stimulus.

9. Parts of a Feedback System • There are three basic parts to a feedback system: • Receptor – a body structure that monitors changes in a controlled condition and sends input to a control center. • Control center – the brain sets the range of values within which a controlled condition should be maintained, evaluates the input it receives from receptors, and generates output commands when they are needed. • Effector – a body structure that receives output from the control center and produces a response that changes the controlled condition.

10. Types of Feedback Systems • A negative feedback system reverses a change in a controlled condition. • The action continues until the controlled condition returns to normal limits. • A positive feedback system tends to strengthen or reinforce a change in one of the body’s controlled conditions. This tends to increase the amount of change. • The action continues until it is interrupted by some mechanism.

11. Homeostatic Imbalances • If the homeostatic imbalance is moderate, a disorder or disease may result; if it is severe, death may occur. • A disorder is any abnormality of structure or function. • A disease is an illness characterized by a recognizable set of signs (observable and measurable changes: fever, rash) and symptoms (not apparent to an observer: nausea, headache). • A local disease affects one part of a limited region of the body. • A systemic disease affects either the entire body or several parts of it.