Chapter 1 Terms Flashcards
Acclimatization
Environmentally induced improvement in functioning of a physiological system with no change in genetic endowment.
Acquired reflex
Behaviors that appear to be stereotypical and automatic, but which in fact result from considerable conscious effort to be learned. Also called learned reflex.
Adaptation
A biological characteristic that favors survival in a particular environment; (neural) decrease in action potential frequency in a neuron despite constant stimulus.
Afferent pathway
Component of reflex arc that transmits information from receptor to integrating center.
Autocrine agent
Chemical messenger secreted into extracellular fluid that acts upon cell that secreted it.
Basement membrane
Thin layer of extracellular proteinaceous material upon which epithelial and endothelial cell sit.
Cell
The simplest structural unit into which a complex multicellular organism can be divided and still retain the functions characteristic of life.
Circadian rhythm
Occurring in an approximately 24 hour cycle.
Collagen fiber
Strong, fibrous protein that functions as extracellular structural element in connective tissue.
Connective tissue
One of the four major categories of tissues in the body.p major component of extracellular matrices, cartilage, and bone.
Connective tissue cell
Cell specialized to form extracellular elements that connect, anchor, and support body structures.
Developmental acclimatization
Potentially irreversible change in structure or function of one or more organ systems that occurs during early life and favors survival in specific environments.
Effector
Cell or cell collection whose change in activity constitutes the response in a control system.
Dynamic constancy
A given variable may vary in the short term but is stable and predictable when averaged over the long term (e.g. blood glucose levels vary throughout the day but over time are predictable).
Elastin fiber
A protein with elastic or springlike properties; found in large arteries and in the airways.
Endocrine gland
Group of epithelial cells that secrete into the extracellular space hormones that then diffuse into bloodstream. Also called a ductless gland.
Entrainment
Adjusting biological rhythm to environmental cues.
Epithelial cell
Cell at surface of body or hollow organ; specialized to secrete or absorb ions and organic molecules; with other epithelial cells forms an epithelium.
Epithelial tissue
One of the four major tissue types in the body, comprised of aggregates of epithelial cells.
Equilibrium
No net change occurs in a system; requires no energy.
External environment
Environment surrounding external surface of an organism.
Extracellular fluid
Fluid outside cell, interstitial fluid and plasma.
Extracellular matrix
A complex consisting of a mixture of proteins interspersed with extracellular fluid.
Feedforward
Aspect of some control systems that allows system to anticipate changes in a regulated variable.
Free-running rhythm
Cyclical activity driven by biological clock in absence of environmental cues.
Homeostasis
Relatively stable condition of internal environment that results from regulatory system actions.
Hormone
Chemical messenger synthesized by specific endocrine cells in response to certain stimuli and secreted into the blood, which carries it to target cells.
Functional unit
Small, similar subunits each performing the function of the organ (e.g. the kidneys’ functional units are called nephrons).
Internal environment
Extracellular fluid (interstitial fluid and plasma)
Interstitial fluid
Extracellular fluid surrounding tissue cells; excludes plasma.
