The major external body parts and anatomical points of a dog in lateral view.

• Muzzle: The projecting part of the head including the jaws and nose.
• Nose: The moist, pigmented olfactory organ at the tip of the muzzle.
• Stop: The step-down or indentation between the forehead and the muzzle.
• Skull: The upper part of the head between the ears and forehead.
• Ear: The external auditory flap or pinna.
• Neck: The segment connecting the head to the torso.
• Withers: The highest point of the shoulder blades, used to measure a dog's height.
• Back: The dorsal region extending from behind the withers to the loin.
• Loin: The region of the back between the ribcage and the pelvis.
• Croup: The dorsal surface of the pelvis sloping down toward the base of the tail.
• Tail: The flexible caudal appendage extending from the rear of the spine.
• Chest: The deep ventral part of the torso enclosing the heart and lungs.
• Shoulder: The upper forequarter area overlying the scapula.
• Elbow: The joint connecting the upper arm and forearm on the forelimb.
• Pastern: The lower part of the leg between the wrist/carpus and the paw.
• Forepaw: The front foot including digits and pads.
• Abdomen: The ventral underside of the dog between the chest and the pelvis (tuck-up).
• Flank: The fleshy side of the body between the ribs and the hip.
• Stifle: The true knee joint of the hind leg, located between the thigh and shin.
• Hock: The tarsal joint of the hind leg, analogous to the human ankle.
• Hindpaw: The rear foot including digits and pads.

The major functional groups in organic chemistry shown as skeletal chemical structures.

• Alkane: A saturated hydrocarbon containing only single covalent carbon-carbon and carbon-hydrogen bonds.
• Alkene: An unsaturated hydrocarbon containing at least one carbon-carbon double bond.
• Alkyne: An unsaturated hydrocarbon containing at least one carbon-carbon triple bond.
• Arene (Phenyl): An aromatic hydrocarbon ring with alternating single and double bonds or a delocalized pi-electron ring.
• Haloalkane (Alkyl Halide): A compound where one or more hydrogen atoms in an alkane have been replaced by halogen atoms.
• Alcohol: An organic compound containing a hydroxyl (-OH) functional group covalently bonded to a saturated carbon atom.
• Ether: A compound containing an oxygen atom connected to two alkyl or aryl groups.
• Epoxide: A cyclic ether consisting of a three-membered ring containing two carbon atoms and one oxygen atom.
• Thiol: An organosulfur compound containing a sulfhydryl (-SH) group bonded to a carbon atom.
• Sulfide (Thioether): An organosulfur compound containing a sulfur atom bonded to two distinct organic groups.
• Aldehyde: A carbonyl compound with the carbonyl carbon bonded to at least one hydrogen atom at the end of a chain.
• Ketone: A carbonyl compound where the carbonyl carbon is bonded internally to two other carbon atoms.
• Carboxylic Acid: An organic acid containing a carboxyl group consisting of a carbonyl group bonded directly to a hydroxyl group.
• Ester: A derivative of a carboxylic acid where the hydroxyl hydrogen is replaced by an alkyl or aryl group.
• Acyl Halide (Acid Halide): A carboxylic acid derivative where the hydroxyl group is replaced by a halogen atom.
• Acid Anhydride: A compound formed from two acyl groups linked by a bridging oxygen atom.
• Amine: A compound containing a basic nitrogen atom with a lone pair, derived from ammonia by replacing hydrogens with alkyl or aryl groups.
• Amide: A compound containing a carbonyl group linked directly to a nitrogen atom.
• Nitrile: An organic compound containing a cyano group with a carbon atom triple-bonded to a nitrogen atom.
• Imine: A functional group containing a carbon-nitrogen double bond, with the nitrogen attached to a hydrogen or organic group.
• Nitro Compound: An organic compound containing one or more nitro functional groups (-NO2) bonded to a carbon backbone.

The major organelles and structural components of a eukaryotic animal cell.

• Nucleus: Membrane-bound organelle that stores genetic material and controls cellular activities.
• Nucleolus: Dense region inside the nucleus responsible for ribosome synthesis.
• Nuclear envelope: Double membrane perforated by pores that encloses the nucleus.
• Rough endoplasmic reticulum: Network of folded membranes studded with ribosomes involved in protein processing.
• Smooth endoplasmic reticulum: Tubular membrane system that synthesizes lipids, metabolizes carbohydrates, and detoxifies chemicals.
• Golgi apparatus: Stack of flattened cisternae that modifies, sorts, and packages proteins for secretion or delivery.
• Mitochondrion: Organelle that generates most of the chemical energy needed to power cellular reactions through aerobic respiration.
• Lysosome: Membrane-bound vesicle containing digestive enzymes to break down waste and cellular debris.
• Peroxisome: Metabolic organelle that breaks down fatty acids and neutralizes hydrogen peroxide.
• Centrosome: Microtubule-organizing center containing a pair of centrioles involved in cell division.
• Ribosomes: Complexes of RNA and protein that synthesize polypeptides.
• Cytoskeleton: Network of protein filaments and tubules that maintains cell shape and enables internal transport.
• Cytoplasm: Gel-like fluid and suspended components occupying the interior of the cell outside the nucleus.
• Plasma membrane: Phospholipid bilayer that encloses the cell and regulates the movement of substances in and out.
• Vacuole: Small membrane-bound sac used for temporary storage and transport of materials.