Chapter 1 D efinit i ons Cardiovascular system - Organ system that distributes the blood to deliver nutrients and remove wastes. Positive feedback mechanisms - Feedback that tends to cause the level of a variable to change in the same direction as an initial change. Metabolism - Sum total of the chemical reactions occurring in the body cells. Homeostasis - A state of body equilibrium or stable internal environment of the body. Hypotonic - Below normal tone or tension. Oblique section - A cut made diagonally between the horizontal and vertical plane of the body or an organ. Axial - Relating to the head, neck, and trunk; one of the two major divisions of the body. Visceral serosa - The part of the double-layered membrane that lines the oter surfaces of organs with in the vental body cavity. Histology - Branch of anatomy dealing with the microscopic structure of tissues. Negative feedback mechanisms – The most common homeostatic control mechanism. The net effect is that the output of the system shuts off the original stimulus or reduces its intensity. Superficial – Located close to or on the body surface. Umbilicus – Navel; marks site where umbilical cord was attached in fetal stage. Insulin – A hormone that enhances the carrier-mediated diffusion of glucose into tissue cells, thus lowering blood glucose levels. Receptor – A cell or nerve ending of a sensory neuron specialized to respond to particular types of stimuli; protein that binds specifically with other molecules, e.g., neurotransmitters, hormones, paracrines , antigens. Atmospheric pressure – Force that sir exerts on the surface of the body (760 mm Hg at sea level). Excitability (responsiveness) – Ability to respond to stimuli. Tumor – An abnormal growth of cells; a swelling; may be cancerous. Sagittal plane – A longitudinal plane that divides the body or any of its parts into right and left portions. Complementarity of structure and function – The relationship between a structure and its function; I.e., structure determines function. Organism – The living animal (or plant), which represents the sum total of all its organ systems working together to maintain life; also applies to a microorganism. Effector – Muscle or gland capable of being activated by nerve endings. Parietal serosa – The part of the double-layered membrane that lines the walls of the ventral body cavity. Nutrients – Chemical substances taken in via the diet that are used for energy and cell building. Renal – Pertaining to the kidney. Inguinal – Pertaining to the groin region. Organ – A part of the body formed of two or more tissues and adapted to carry out a specific function; e.g., the stomach. Selectively permeable membrane – A membrane that allows certain substances to pass while restricting the movement of others; also called differentially permeable membrane. Frontal (coronal) plane – Longitudinal plane that divides the body or an organ into anterior and posterior parts. Dorsal – Pertaining to the back; posterior. Digestion – A series of catabolic steps in which complex food molecules are broken down to their building blocks by enzymes. Embryo – Developmental stage extending from fertilization to the end of the eighth week. Serosa (serous membrane) – The moist membrane found in closed ventral body cavities. Systemic – Pertaining to the whole body. Parietal – Pertaining to the walls of a cavity. Cross section – A cut running horizontally from right to left, dividing the body or an organ into superior and inferior parts. Parasagittal planes – All sagittal planes offset from the midline. Glucose – Principal blood sugar; a hexose. Anatomy – Study of the structure of living organisms. Distal – Away from the attached end of a limb or the oridin of a structure. Midsagittal (median) plane – Specific sagittal plane that lies exactly in the midline. Serous fluid – Clear, watery fluid secreted by cells of a serous membrane. Appendicular – Relating to the limbs; one of the two major divisions of the body. Excretion – Elimination of waste products from the body. Visceral organs (viscera) – A group of internal organs housed in the ventral body cavity. Organ system – A group of organs that work together to perform a vital body function; e.g., the nervous system. Pleural cavity – A potential space between the two laters of pleura; contains a thin film of serous fluid. Cell – Structural unit of all living things. Vertebral column (spine) – Formed of a number of individual bones called vertebrae and two composite bones (sacrum and coccyx). Transverse (horizontal) plane – A plane running from right to left, dividing the body or and organ into superior and inferior parts. Physiology – Study of the function of living organisms. Mediastinum – The medial cavity of the thorax containing the heart, great vessels, thymus, and parts of the trachea, bronchi, and esophagus.