Body Systems and Homeostasis

Body Systems

• Body systems include the digestive, respiratory, circulatory, immune, excretory, and muscular systems.

Digestive System

• Components include salivary glands, mouth, esophagus, stomach, pancreas, small intestine, appendix, rectum, and anus.
• The digestive system breaks down food for energy.

Homeostasis

• Homeostasis is the dynamic constancy of the internal environment.
• Organisms maintain internal consistency through sensors that measure internal conditions and relay information to a control center.
• The control center maintains a “set point” for each condition.
• The human body employs negative feedback loops to maintain homeostasis and correct deviations from set points.

Macromolecules

• Macromolecules are large organic compounds made up of C, H, O, N, and P.
• 4 main categories: carbohydrates, lipids, proteins, and nucleic acids.
• Many macromolecules are polymers, formed from smaller subunits (monomers).
• Macromolecules are formed through dehydration synthesis and broken down through hydrolysis.
• Examples include starch, cellulose, glycogen, fats, oils, phospholipids, steroids, proteins, and nucleic acids (DNA/RNA).

Carbohydrates

• Carbohydrates are produced by living things, consisting of C, H, and O atoms (ratio 1:2:1).
• Function: essential for short and long-term energy for organisms.
• Monosaccharides are the simplest form, produced by plants (examples: glucose, fructose, galactose — all with the formula C₆H₁₂O₆).
• Disaccharides are formed when two monosaccharides bond through dehydration synthesis (examples: sucrose, lactose, maltose).
• Polysaccharides are polymers of monosaccharides joined by dehydration synthesis. (examples: starch, glycogen, cellulose).

Lipids

• Lipids are molecules that build cell membranes, build steroids and hormones, and provide insulation.
• Lipids primarily consist of C, H, and O atoms.
• Most lipids are not soluble in water.
• Types include neutral fats and oils (made of glycerol and 3 fatty acid molecules forming a triglyceride), phospholipids (2 fatty acids and a phosphate attached to glycerol), steroids (needed to build parts of cells and hormones, examples: progesterone, cholesterol, testosterone, estrogen), and waxes (not soluble in water and used to waterproof feathers, fur, and leaves).

Proteins

• Proteins are the main material that makes up cell parts and perform many functions in the body.
• Proteins are complex molecules.
• The 3D shape determines the specific function of the protein.
• Proteins are important structural components (examples: hair, horns, feathers,spider webs, tendons, ligaments).
• Storage proteins provide a source of amino acids for developing plants and animals (example: seeds and eggs).
• Important transport proteins include hemoglobin which carries oxygen in the blood.
• Proteins such as, actin and myocin, play crucial roles in muscle contraction, movement, and cellular processes.
• Amino acids are made up of an amino group, a carbon chain, and a carboxyl group.
• Peptide bonds are formed by dehydration synthesis linking amino acids together, forming a polypeptide chain.
• Proteins can be denatured under unfavorable environmental condition — a disruption to the protein's shape affecting its normal shape.

Nucleic Acids

• Nucleic acids are heredity materials made up of nucleotides.
• Nucleotides are comprised of phosphate, a sugar (ribose or deoxyribose), and a nitrogenous base.
• Types include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

Enzymes

• Enzymes are proteins that act as catalysts to increase the rate of chemical reactions.
• They do this without being used up in the reaction.
• Enzymes have active sites to which specific substrates bind, changing the substrate's shape, making bonds possible, and forming new substances.
• Rate of enzyme activity can be affected by a variety of factors, including temperature, pH, and the concentration of substrate molecules.
• Cofactors (inorganic substances), and coenzymes (organic molecules) assist enzymes in functioning.
• Inhibitors (including competitive and non-competitive inhibitors) can also affect enzyme activity by interfering with the active site or inducing a shape change in the enzyme, leading to slower or even stopped reactions.

Lab Tests

• Lab tests can determine the presence of various biological molecules like starch and sugars or simple sugars.
• Different methods will use certain reactions to detect the presence of specific molecules.