Thus, in negative feedback, the variant condition is canceled, or negated, so that conditions are returned to normal. When the control center determines that conditions have returned to normal, corrective action is discontinued. Conditions are constantly monitored by receptors and evaluated by the control center. A control center, or integrator (often the brain), evaluates the change and activates a second mechanism (an effector) to correct the condition for example, cells that either remove or add glucose to the blood in an effort to maintain homeostasis are effectors. In negative feedback,Р’В a sensing mechanism (a receptor) detects a change in conditions beyond specific limits. In many cases, stable conditions are maintained by negative feedback.

An organismР’В is a system possessing the characteristics of living things-the ability to obtain and process energy, the ability to respond to environmental changes, and the ability to reproduce.Р”Р„ characteristic of all living systems is homeostasis,Р’В or the maintenance of stable, internal conditions within specific limits.

The digestive system, for example, involves the coordinated activities of many organs, including the mouth, stomach, small and large intestines, pancreas, and liver.

An organ systemР’В is two or more organs working together to accomplish a particular task.

The heart is an organ composed of muscle, nervous, connective, and epithelial tissues.

An organР’В is a group of different kinds of tissues working together to perform a particular activity.Muscle tissue, for example, consists of muscle cells. A tissueР’В is a group of similar cells performing a common function.Thus, there are nerve cells, bone cells, and muscle cells. OrganellesР’В within the cell are specialized bodies performing specific cellular functions. The cellР’В is the smallest unit of life.At the chemical level, atoms,Р’В moleculesР’В (combinations of atoms), and the chemical bonds between atoms provide the framework upon which all living activity is based.Each perspective provides information about how or why a living system functions: Living systemsР’В can be defined from various perspectives, from the broad (looking at the entire earth) to the minute (individual atoms). NeurophysiologyР’В is the study of how the nervous system functions.CytologyР’В is the study of cells at the microscopic level.HistologyР’В is the study of tissues at the microscopic level.Gross (macroscopic) anatomyР’В is the study of body parts visible to the naked eye, such as the heart or bones.Some specializations within each of these sciences follow: PhysiologyР’В is the study of the function of body parts and the body as a whole. What Is Anatomy and Physiology? AnatomyР’В is the study of the structure and relationship between body parts. Quiz: Regulation of Urine Concentration.Quiz: Structure of the Digestive Tract Wall.Quiz: Function of the Respiratory System.Quiz: Structure of the Respiratory System.Quiz: Supplements to the Immune Response.Quiz: Humoral and Cell-Mediated Immune Responses.Humoral and Cell-Mediated Immune Responses.Quiz: Specific Defense (The Immune System).The Immune System and Other Body Defenses.Quiz: Functions of the Cardiovascular System.

Quiz: The Hypothalamus and Pituitary Glands.Quiz: The Ventricles and Cerebrospinal Fluid.Quiz: Muscle Size and Arrangement of Muscle Fascicles.Muscle Size and Arrangement of Muscle Fascicles.Quiz: Structure of Cardiac and Smooth Muscle.Quiz: Connective Tissue Associated with Muscle Tissue.Connective Tissue Associated with Muscle Tissue.Quiz: Chemical Reactions in Metabolic Processes.Chemical Reactions in Metabolic Processes.Quiz: Atoms, Molecules, Ions, and Bonds.

Essential anatomy vs visible body app