Comprehensive Biology and Anatomy Lecture Review

Flashcards covering introductory chemistry, biochemistry, cell biology, histology, and the integumentary, skeletal, muscular, and nervous systems based on lecture units 1-17.

Chemical element

A pure substance that cannot be further divided by ordinary chemical means, composed of atoms with a specific number of protons.

Atomic number

The number of protons an atom has, which defines its chemical element and determines many of its properties.

Isotope

An atom that has a different neutron count than that element's usual form, changing the mass number but not the atomic number.

Anion

A negatively charged ion that has gained one or more electrons.

Cation

A positively charged ion that has lost one or more electrons.

Octet rule

The principle stating that atoms without a certain amount of electrons in their valence shell (generally eight) are reactive and prone to giving, taking, or sharing electrons.

Compound

A specific type of molecule composed of atoms of more than one element.

Organic molecules

Molecules distinguished by the presence of bonded carbon and hydrogen, often forming large complex structures.

Hydrolysis

A chemical reaction that breaks up a molecule by adding $H_2O$, which attaches to the new smaller molecules as an $H$ and a hydroxyl group.

Dehydration synthesis

A reaction where two molecules bind into one larger molecule following the departure of an $H$ and an $OH$, which leave as a molecule of water.

pH scale

A 0 to 14 scale measuring grams of hydrogen per liter of solution; 0 is most acidic, 7 is neutral ($H_2O$), and 14 is most basic.

Buffer

A solution of a weak acid and its conjugate base used to maintain pH homeostasis by binding excesses of hydrogen or hydroxyl ions.

Monosaccharide

A single monomer of carbohydrate, such as glucose, fructose, or galactose.

Glycogen

A polysaccharide assembled by the human body to store glucose in the liver and muscle cells.

Triglyceride

A lipid formed by a glycerol attached to three fatty acid chains; used as a major fuel source and compact energy storage.

Phospholipid

An amphipathic molecule with a polar phosphate head and nonpolar fatty acid tails, forming the bulk of cell membranes.

ATP (Adenosine Triphosphate)

The primary energy molecule of the body, composed of adenine, ribose, and three phosphate groups joined by high-energy covalent bonds.

Cell differentiation

The process by which a single genome produces specialized cell types expressing only the genes needed for specific functions.

Fluid mosaic model

A model describing the cell membrane as a fluid bilayer of phospholipids studded with proteins, cholesterol, and glycoproteins.

Osmosis

The passage of water from areas of lower solute concentration to areas of higher solute concentration across a membrane.

Active transport

Methods of moving molecules through cell membranes that require the use of energy in the form of $ATP$.

Epithelial tissue

Avascular tissue characterized by cellularity and polarity that lines body surfaces, hollow organs, and glands.

Connective tissue

A diverse group of tissues with mesenchymal origins characterized by extracellular matrix (ground substance and fibers) and matrix-producing cells.

Homeostasis

The body's maintenance of ideal set points for gas/nutrient concentration, temperature (approximately $37^{\circ}C$), and pressure.

Negative feedback

A feedback loop that works to return a physiological level to its established set point.

Stratum basale

The deepest layer of the epidermis, made of cuboidal epithelial cells, containing stem cells, melanocytes, and Merkel cells.

Osteon

The structural unit of compact bone consisting of concentric lamellae arranged around a central Haversian canal.

Endochondral ossification

The process of bone formation where a hyaline cartilage template is replaced by bone tissue.

Synarthrosis

A functional class of joints that are immobile and protective, such as skull sutures.

Agonist

Also known as the prime mover, it is the principal muscle responsible for a specific movement.

Sarcomere

The functional unit of a myofibril containing sliding filaments of actin and myosin bounded by Z-lines.

Slow oxidative fibers

Red muscle fibers fueled by aerobic respiration, rich in myoglobin and mitochondria, and built for long-term endurance.

Intercalated discs

Specialized junctions between cardiac muscle cells containing desmosomes for structural unity and gap junctions for electrical coupling.

Cerebrum

The largest part of the brain responsible for higher functions like reasoning, divided into frontal, parietal, temporal, and occipital lobes.

Meninges

The three-layer protective covering of the central nervous system consisting of the dura mater, arachnoid mater, and pia mater.

Resting membrane potential

The charge differential of approximately $-70\,mV$ maintained at a neuron's membrane by the sodium-potassium pump and leakage channels.

Action potential

An "all or none" depolarization that travels down an axon once the membrane reaches a threshold of $-55\,mV$.

Saltatory conduction

The process in myelinated axons where the depolarization jump from one node of Ranvier to the next, speeding up signal transmission.

Ionotropic receptor

A membrane receptor that acts as a ligand-gated ion channel, opening directly when a neurotransmitter binds.

Metabotropic receptor

A receptor that, when bound by a ligand, activates a G protein and second messengers to produce a cellular effect.