United States University NURSING MSN 570 Study Guide CHAPTER 1 Cellular Biology

CHAPTER 1 Cellular Biology B) Cellular Permeability: • Is the ability of the cell to allow passage of some substances through the membrane, while not permitting others to enter or exit. • Some substances have free passage in and out of the cells, including enzymes, glucose, and electrolytes. Enzymes are proteins that facilitate chemical reactions in cells, while glucose is a sugar molecule that provides energy. Electrolytes are chemicals that are charged conductors when they are dissolved in water. Failure of these exchange mechanisms can lead to the development of disease. Diffusion - is the movement of solutes—that is, particles dissolved in a solvent—from an area of higher concentration to an area of lower concentration. Simple diffusion will occur until the concentration gradient, which is the difference in concentrations of substances on either side of the membrane, is equal on each side. Solution is made of a solvent and solutes. Solvents dissolve solutes. In the human body, the solvent is usually water, and the solutes are particles such as sodium, potassium, glucose, urea, and oxygen. Active Transport- is the movement of a substance from an area of lower concentration to an area of higher concentration, against a concentration gradient. This movement involves a carrier molecule, like facilitated diffusion, but energy, usually in the form of adenosine triphosphate (ATP), is required because of the effort necessary to go against the gradient. Endocytosis- is the process of bringing a substance into the cell that is too large to go by other mechanisms. Components of the immune system use endocytosis, particularly phagocytosis, to consume and destroy bacteria and other foreign material. Phagocytosis- or cell eating, occurs when this process involves solid particles. Pinocytosis- or cell drinking, takes place when this process involves a liquid. Osmosis- is the movement of water or any other solvent across the cellular membrane from an area of low solute concentration or high water to an area of high solute concentration or low water. Osmotic and hydrostatic pressure - help regulate fluid balance in the body; an example can be found in the functioning of the kidneys. Oncotic pressure- is created by plasma proteins—particularly albumin—and is similar to osmotic pressure as higher pressure draws water in. Hydrostatic pressure- is created by water pushing against the cellular membrane, forcing the water out, which is the opposite of osmotic pressure, which, when higher, draws water in. Osmolality -is the preferred term when referring to fluids inside the body. Measured with osmometer. Normal serum range is 282– 295. Osmolarity is best used to describe fluids outside the body.