Nursing Entrance Exam

Nursing Preparation Study Guide • Cilia: Motile microtubule-containing structures of eukaryotes. • Cytoplasm: The contents of the main fluid-filled space inside cells. • Cytoskeleton: Protein filaments inside cells. • Endoplasmic reticulum: The major site of membrane protein synthesis. • Flagella: Motile structures of bacteria, archaea, and eukaryotes. • Golgi apparatus: The site of protein glycosylation in the endomembrane system. • Lipid bilayer: The fundamental organizational structure of cell membranes. • Lysosome: Breaks down cellular waste products and debris into simple compounds in animal cells. • Mitochondrion: Major energy-producing organelle (by generating and releasing ATP). • Nucleus: Holds most of the DNA of eukaryotic cells and controls all cellular activities. • Mitosis: DNA replication and nuclear division of somatic cells. • Meiosis: Cell division that results in gamete production. • Organelle: Major subcellular structures. • Ribosome: A particle made up of RNA and proteins, and is required for protein synthesis in cells. • Vesicle: Small, membrane-bounded spheres inside cells. 6.1.2 Homeostasis Homeostasis , a term coined by American physiologist Walter Bradford Cannon in 1962, is the concept for maintaining the stability of an internal environment. The survival of an organism is dependent on homeostasis; lack of it can lead to illness or death. Physiological systems have evolved to maintain homeostasis in an environment that is often inconsistent, unpredictable, and potentially dangerous. Essentially, homeostasis is the body’s way of preserving its internal state in an ever- changing external environment. Autoregulation and extrinsic regulation are two mechanisms involved in homeostasis. For example, in humans, the body will start sweating on a hot day in attempt to cool off and maintain an internal temperature of 98.6 degrees Fahrenheit. Negative feedback and positive feedback loops assist with maintaining homeostasis. Negative feedback is a corrective mechanism involving an action that directly opposes a variation from normal limits. In positive feedback, an initial stimulus produces a response that enhances the change in the original conditions and creates a positive feedback loop. 6.2 Electrolytes Electrolytes in the body play an important role inmaintaining homeostasis. Most of these electrolytes are responsible for maintaining the balance of fluids between the intracellular (inside the cell) and extracellular (outside the cell) environments. Electrolyte balance is vitally important for the body to maintain normal function, such as hydration, nerve impulses, muscle function, and pH levels.

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