Week 1 A&P lecture notes
Week 1 A&P lecture notes HS 220
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This 5 page Class Notes was uploaded by Annie Estes on Thursday September 22, 2016. The Class Notes belongs to HS 220 at Whitworth University taught by Ulbright in Fall 2016. Since its upload, it has received 6 views. For similar materials see Anatomy and Physiology in Health Sciences at Whitworth University.
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Date Created: 09/22/16
CHEMICAL LEVEL OF ORGANIZATION Chemicals compose your body and all body activities are chemical in nature, therefore, it is important to become familiar with some basic language and fundamental concepts of chemistry. Chemical Reactions: The Foundation of All Life Processes • A chemical reaction occurs when new bonds are formed or old bonds break between atoms o Reactants: the initial substances involved in a chemical reaction o Products: the final substances from a chemical reaction NOTE: Total mass of reactants = Total mass of products o Metabolism: all of the chemical reactions that occur in an organism Body structures are built and body functions are carried out • Forms of energy and chemical reactions o Energy: the capacity to do work Potential energy: energy stored by matter (e.g. battery, dam) Kinetic energy: energy released / associated with matter in motion (e.g. inertia of a falling baseball) Chemical energy: a form of potential energy stored in the bonds of compounds or molecules (e.g. ATP, glucose) • Energy transfer in chemical reactions o Breaking chemical bonds releases energy and forming new bonds requires energy. Exergonic reaction: one in which the bond being broken has more energy than the one formed so that extra energy is released, usually as heat (occurs during catabolism of food) Endergonic reaction: one that requires energy, usually from a molecule called ATP, to form a bond, as in bonding amino acid molecules together to form proteins NOTE: In the body, exergonic and endergonic reactions are usually coupled so that an endergonic reaction uses the energy from an exergonic reaction. o Activation energy: the initial energy needed to start a reaction. In reality, this is the collision energy needed to break chemical bonds in the reactants Factors that influence the chance that a collision will occur and cause a chemical reaction include: • Concentration: many people small room, few people big room • Temperature: increased temp increases activity and speed of collisions o Catalysts: chemical compounds that speed up reactions by lowering the activation energy needed for a reaction to occur. Most important catalysts are enzymes A catalyst does not alter the difference in potential energy between reactants and products. It only lowers the amount of energy needed to get the reaction started A catalyst helps to properly orient the colliding particles of matter so that a reaction can occur The catalyst itself is unchanged at the end of the reaction. o Types of chemical reactions Synthesis reactions: when two or more atoms, ions, or molecules combine to form new and larger molecules. These are anabolic meaning that bonds are formed (e.g. forming ATP) Decomposition reactions: a molecule is broken down into smaller parts. These are catabolic meaning that chemical bonds are broken in the process (e.g. glucose breakdown to pyruvate) Exchange reactions: reactants are shuffled around to produce an equal amount of new products. Reversible reactions: reactions that can proceed in either direction. Most of the reactions in the human body are reversible. Inorganic Compounds and Solutions • Inorganic compounds usually lack C and are simple molecules. • A mixture is a combo of elements or compounds that are physically blended together but are not bound by chemical bonds. Three common mixtures are: o Solution: a substance called a solvent dissolves another substance called the solute. Usually there is more solvent than solute in a solution (e.g. water and salt = sweat) o Colloid: a solution with larger particles, which are large enough to scatter light (e.g. milk, colloid cyst). o Suspension: larger particles, usually visible to the naked eye, mixed into a liquid or suspending medium for some time, but will eventually settle out (e.g. paint, blood) • Water: All living organisms are made mostly of water (approx. 65% of body mass, and 70-90% of cell composition). Water is the most important and abundant inorganic compound in all living systems. It is the substance that makes life as we know it possible. o Water as a solvent Water is the ideal medium for most chemical reactions in the body and participates as a reactant or product in certain reactions. Often called the universal solvent because it will stick to almost any molecule that it can form an H bond with. That is why some things dissolve in water and some things don’t. • Sugar can form H bonds (hydrophilic) with water and thus dissolves in water. • Vegetable oil cannot form H bonds (hydrophobic) with water and therefore cannot dissolve in water. Water also used to flush dissolved waste and eliminate it from the body. o Water in chemical reactions Hydrolysis: breaks large molecules down into simpler ones by adding a molecule of water. This is necessary for the breakdown of nutrients. Dehydration synthesis: occurs when two simple molecules join together, eliminating a molecule of water in the process. o Thermal properties of water Water has a high heat capacity. It can absorb or release a relatively large amount of heat with only a modest change in its own temperature. + • This property is due to the large number of H ions in water. When H bonds are broken, heat is given off. Water has a high heat of vaporization. It requires a large amount of heat to change from a liquid to a gas. Evaporation can cool body surfaces by removing heat. o Water as a lubricant Water is a major part of mucus and other lubricating fluids (e.g. synovial fluid and serous membranes) It is found wherever friction needs to be reduced or where particles need to be eliminated (e.g. synovial fluid, bursae, tears, snot). o Water is sticky The H bonds that link water molecules to one another give water considerable cohesion, the tendency of like particles to stay together. Water also sticks to other molecules, a property called adhesion. The adhesion of water molecules creates a high surface tension, a measure of the difficulty of stretching or breaking the surface of a liquid (e.g. fluid between pleural cavity and lungs, water overfilling a glass, water droplets on a leaf). Acids, Bases, and pH • Acid: any solute that dissociates in solution and releases H ions. • Base: any solute that dissociates in solution and release OH ions. + • pH: the negative logarithm of the H concentration in a solution. pH within the body often dictates whether or not chemical reactions can take place. o A solution with pH of 7 is neutral o A solution with pH < 7 is acidic (lots of H present) o A solution with pH > 7 is basic (lots of OH present) • Bu+fers: compounds —hat stabilize the pH of a solution by removing or replacing H ions (e.g. HCO 3 , NaHCO )3 Organic Compounds • Organic compounds always contain C and H, usually contain O, and always have covalent bonds. They comprise approximately 40% of body mass and carry out complex functions. • Carbon and its functional groups o The C that organic compounds always contain has several properties that make it particularly useful to living organisms. It can react with one to several hundred other C atoms to form large molecules of many different shapes. Some C compounds do not dissolve easily in water, making them useful materials for building body structures (non-polar). However, C compounds are mostly or entirely held together by covalent bonds and tend to decompose easily. This means that organic compounds are a good source of energy. • Carbohydrates (CHO): contain C, H, and O; provide most of the energy needed for life. o Some CHOs are converted to other substances, which are used to immediately build structures or generate ATP (e.g. glucose) o Other CHOs function as energy reserves (i.e. glycogen in muscle or liver) o CHOs are divided into three major groups based on their size: Monosaccharides: the main energy-supplying compound of the body (e.g. glucose, fructose, and galactose) Disaccharides: formed by two monosaccharides: they can be split back into simple sugars by hydrolysis (e.g. maltose, sucrose, and lactose) Polysaccharides: large chains of monosaccharides (e.g. glycogen, fiber, and starch). • Lipids: also contain C, H, and O, but unlike CHOs in that they… o Have fewer polar covalent bonds and thus are mostly insoluble in polar solvents such as water (they are hydrophobic) o Triglycerides: composed of a glycerol backbone and three fatty acids; provide protection, insulation, and energy At room temperature, triglycerides may be either solid (fats) or liquid (oils) Triglycerides provide more than twice as much energy (9 kcal/g) as either CHOs or PRO (4 kcal/g). Triglyceride storage is virtually unlimited Excess dietary CHO, PRO, fats and oils will be deposited in adipose tissue as triglycerides. The type of covalent bonds found in fatty acids determines whether a triglyceride is saturated, monounsaturated, or polyunsaturated. o Phospholipids: important membrane components There are amphipathic, with both polar and nonpolar regions o Steroids: include sex hormones and cholesterol, with cholesterol serving as an important component of cell membranes and as starting material for synthesizing other steroids. o Eicosanoids and other lipids: Prostaglandins: modify responses to hormones, contribute to inflammatory responses, prevent stomach ulcers, dilate airways to the lungs, regulate body temperature, and influence blood clots, among other things Leukotrienes: participate in allergic and inflammatory responses Body lipids also include fatty acids, fat-soluble vitamins such as beta-carotenes (vision), Vitamins E (wound healing) and K (blood clotting) and lipoproteins (carry cholesterol). • Proteins: give structure to the body, regulate processes, provide protection (immune system), help muscles to contract (contractile), transport substances, and serve as enzymes (catalytic). o Amino acids and polypeptides: the building blocks of the body that contain C, H, O, and N. AA are joined together with peptide bonds; resulting polypeptide chains may contain 10 to 2,000 AA. o Enzymes: act as catalysts in living cells by speeding up chemical reactions via lowering the activation energy and properly orienting molecules for collision. Names of enzymes typically end in the suffix –ase, usually named after the type of chemical reaction they catalyze • Oxidase – adds O • Kinase – adds Pi • Dehydrogenase – removes H • Anhydrase – removes H O 2 • Protease – splits PRO • Lipase – breaks down fats • ATPase – splits ATP Enzymes catalyze select reactions with great efficiency (can interact with multiple substrate molecules) and with many built-in controls (such as pH). Enzymes are highly specific in terms of the substrate with which they react. o Nucleic acids: huge organic molecules that contain chains of C, H, O, N, and P. Deoxyribonucleic Acid (DNA): forms the genetic code inside each cell and regulates most cellular activities throughout a lifetime. Ribonucleic acid (RNA): relays instructions from the genes in the cell’s nucleus to guide ribosome assembly of AA into proteins. o Adenosine Triphosphate (ATP): the principal energy-storing/releasing molecule in the body. ATP consists of three Pi groups attached to an adenosine unit composed of adenine and a 5-C sugar ring called ribose. • When energy is liberated from ATP, it is decomposed to adenosine diphosphate (ADP) and phosphate (Pi). • ATP is manufactured from ADP and Pi using the energy supplied by various decomposition reactions, particularly that of glucose. Cellular activities for which ATP provides energy include muscular contractions, chromosome movement during cell division, membrane transport processes, and synthesis reactions.
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