Nutritional Sciences Lecture: Chemical, Biological, and Physiological Aspects

These flashcards provide vocabulary definitions based on the lecture notes covering levels of organization, cellular biology, transport mechanisms, the anatomy and physiology of the digestive system, and nutrient circulation.

Atoms

The smallest component of an element.

Molecules

Formed when chemical bonds join $2$ or more atoms together.

Complex molecules

Large molecules that are diverse in structure and function, such as carbohydrates.

Cells

The structural and functional units of living organisms.

Organelles

Structures that carry out specific functions within cells.

Tissues

Groups of cells that come together to carry out specific functions; there are four types in the human body.

Organs

Structures made of two or more different types of tissue; there are over $40$ in the human body.

Organ systems

Groups of several organs that together carry out a specific physiological function; there are $11$ in the human body.

Cations

Ions with a net positive charge resulting from the loss of an electron.

Anions

Ions with a net negative charge resulting from the gain of an electron.

Oxidation

The loss of electrons from a molecule.

Reduction

The gain of electrons by a molecule.

Redox reactions

Reduction-oxidation reactions involving the transfer of electrons from one molecule to another.

Glucose

A molecule formed by several atoms with the chemical formula $C_6H_{12}O_6$.

Major Body Elements

Six elements—Oxygen, Carbon, Hydrogen, Nitrogen, Calcium, and Phosphorus—that account for $99\%$ of total body weight.

Condensation

A chemical reaction that forms a bond to join molecules together, resulting in the release of a molecule of water ($H_2O$).

Hydrolysis

A chemical reaction that breaks chemical bonds by the addition of a molecule of water ($H_2O$).

pH scale

A scale where Acidic is $< 7$ (more $H^+$), Neutral is $7$ (equal $H^+$ and $OH^-$), and Basic/Alkaline is $> 7$ (more $OH^-$).

Buffers

Substances that enable fluids to resist changes in pH.

Passive transport mechanisms

Processes where substances move from high to low concentration without the requirement of energy.

Simple diffusion

A passive transport process where a substance crosses a cell membrane by moving from a higher to a lower concentration.

Facilitated diffusion

A passive transport process where a substance crosses a cell membrane with the assistance of a transport protein.

Osmosis

The net movement of water across cell membranes from a lower solute concentration to a higher solute concentration.

Active transport mechanisms

Processes requiring energy (ATP) and transport proteins to move substances from low to high concentration.

Endocytosis

A type of vesicular active transport where a portion of the cell membrane encloses particles to form a vesicle and bring them into the cell.

Exocytosis

A type of vesicular active transport where material packaged in a vesicle is released outside of the cell.

Cytoplasm

The gel-like substance inside cells containing organelles, proteins, electrolytes, and other molecules.

Nucleus

The organelle containing DNA, which provides coded instructions used for protein synthesis.

Mitochondrion

The organelle that produces most of the energy (ATP) used by cells.

Lysosome

An organelle containing digestive enzymes that break down proteins, lipids, and nucleic acids, and recycle waste.

Epithelial tissue

Tissue that covers and lines body surfaces, organs, and cavities.

Connective tissue

Tissue that provides structure to the body by binding and anchoring body parts.

Muscle tissue

Tissue that contracts and shortens when stimulated, playing a role in movement; includes skeletal, smooth, and cardiac types.

Neural tissue

Tissue that plays a role in communication by receiving and responding to stimuli.

Homeostasis

The state of internal stability maintained by organ systems working together.

Gastrointestinal (GI) tract

A hollow tube extending from the mouth to the anus.

Mucosa

The innermost layer of the GI tract made of epithelial tissue that produces and releases secretions needed for digestion.

Submucosa

A layer of the GI tract made of connective tissue containing blood vessels, lymphatic vessels, and nerves.

Muscularis

A layer of the GI tract consisting of longitudinal and circular smooth muscle responsible for motility.

Serosa

The outer cover of the GI tract that protects it and secretes lubricating fluid.

Segmentation

A GI motility process involving a 'chopping' motion by alternating circular muscle contractions to mix and slowly move food.

Peristalsis

A series of wavelike rhythmic contractions and relaxations of circular and longitudinal muscles that propels food forward.

Digestive enzymes

Biological catalysts that chemically break down foods.

Bile

A secretion made in the liver and stored in the gallbladder that enables lipid globules to disperse in water.

Pancreatic juice

An alkaline solution containing bicarbonate ($NaHCO_3$) and enzymes that neutralizes chyme and aids digestion.

Gastric juice

A secretion produced in gastric pits containing hydrochloric acid ($HCl$), enzymes, water, and intrinsic factor.

Intrinsic factor

A substance found in gastric juice needed for the absorption of vitamin $B_{12}$.

Gastrin

A hormone produced in the stomach that stimulates gastric motility and the secretion of gastric juice.

Secretin

A hormone produced in the small intestine that inhibits gastric motility and stimulates the release of pancreatic juice.

Cholecystokinin (CCK)

A hormone produced in the small intestine that stimulates the gallbladder to release bile and the pancreas to release enzymes.

Ghrelin

A hormone produced in the stomach and other tissues that stimulates hunger.

Cephalic phase

The first phase of digestion beginning with mastication and the mixing of food with saliva in the mouth.

Mastication

The mechanical breakdown and mixing of food with saliva; also known as chewing.

Epiglottis

The structure that covers the trachea during swallowing to block the opening to the lungs.

Gastroesophageal sphincter

The muscle that regulates the flow of food from the esophagus into the stomach.

Rugae

Folds in the lining of the stomach that flatten as the stomach fills, allowing it to expand.

Pyloric sphincter

The muscle that regulates the flow of chyme from the stomach into the small intestine.

Villi

Finger-like projections covering the circular folds (plica circulares) in the small intestine containing capillary networks and lacteals.

Enterocytes

Absorptive cells that make up the villi of the small intestine.

Microvilli

Small projections on enterocytic surfaces that make up the brush border where nutrient absorption takes place.

Pulmonary circulation

The circulation of oxygen-poor blood to the lungs and oxygen-rich blood back to the heart.

Systemic circulation

The circulation of blood that transports oxygen and nutrients to tissues and carries waste products away.

Nephrons

Specialized structures in the kidneys that remove waste products from the blood via filtration.

Microbiome

Microorganisms in the large intestine that break down undigested food residue and produce vitamin K and certain B vitamins.

Ileocecal sphincter

The structure that regulates the movement of undigested food residue from the ileum into the cecum.