Body Tissue Types

• There are four primary tissue types in the body with distinct structures and functions.

Epithelial Tissue

• This tissue covers or lines body surfaces and cavities.
• It consists of closely linked cells arranged in more than a flat, 1-3 column-shaped cell layer.

Connective Tissue

• This tissue provides support in the body and between cells.
• Its cells are separated by large amounts of intercellular material called matrix.

Muscular Tissue

• Muscle tissue cells, known as muscle fibers, are long, thin, and can contract.
• Skeletal muscles are attached to bones and are voluntary.
• Smooth muscles are found in the walls of organs like the stomach, intestines, blood vessels, iris, and uterus; they are involuntary.
• Cardiac muscle makes up most of the heart and is involuntary.

Nervous Tissue

• This tissue is composed of nerve cells called neurons.
• Neurons have long projections to carry messages.

Nutrients

• These are essential substances required for proper body function.

Carbohydrates

• Molecules made of carbon, hydrogen, and oxygen.
• Simple sugars (like glucose) are simple molecules.
• Carbohydrates are the body’s main energy source.

Proteins

• Molecules made of amino acid chains.
• They contain carbon, hydrogen, oxygen, and nitrogen.
• Amino acids are their simple molecule.

Lipids (Fats)

• Molecules made of glycerol and fatty acids.
• Lipids act as the body’s energy reserve.
• They are involved in immunity, make up the cell membrane, and include cholesterol.

Nucleic Acids

• Includes DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
• They contain sugar, a phosphate group, and a nitrogenous base.
• Nucleic acids store genetic information.

Minerals and Vitamins

• Minerals may be part of enzymes, enzyme co-factors, or other substances.
• Vitamins act as co-enzymes.

Water

• Acts as a solvent, dissolving other substances.
• Helps maintain balance of concentrations.

Enzymes

• Biological catalysts speed up reaction rates without being consumed.

Key Characteristics

• Provide a surface for reactions to occur.
• Act as catalysts to speed up reactions.
• Lower the activation energy needed for a reaction.
• Each enzyme is specific to a particular reaction.
• Enzymes are reusable.
• Substances reacting on an enzyme are called substrates.
• The active site is the surface on the enzyme where substrates meet.
• An enzyme-substrate complex forms when substances meet on an enzyme's active site.
• The lock and key model suggests enzymes' active site shape is complementary to its substrates.
• The induced fit model describes weak bonds forming when enzymes and substrates meet, causing slight shape change of the active site.

Factors Affecting Enzymes

• Enzymes function under specific conditions.

Temperature

• Enzyme activity increases with temperature.
• Excessive heat can denature the enzyme, misshaping the active site.

pH Level

• Enzymes operate within their specific pH range.

Concentration of Substrates

• Higher substrate concentration leads to a faster reaction rate (up to a saturation point).
• A saturation point is reached when all enzymes are being used, and an increase in substrate concentration will no longer increase the RR

Product Concentration

• Products must be constantly removed from enzymes, so they do not block incoming substrate from the active site.