Essentials of Human Anatomy & Physiology: Chapter 3 - Cells and Tissues

These vocabulary flashcards cover the primary concepts of Chapter 3, including cell anatomy, organelle function, membrane transport mechanisms, cell division, protein synthesis, and the classification of human body tissues.

Cell Theory

The scientific principle stating that the cell is the basic structural and functional unit of living organisms, and that an organism's activity depends on the collective activities of its cells.

Principle of Complementarity

A biological concept stating that the biochemical activities of cells are dictated by their specific structure (anatomy), which in turn determines their functions (physiology).

Generalized Cell Elements

The four main elements composing most cells, which include Carbon ($C$), Hydrogen ($H$), Oxygen ($O$), and Nitrogen ($N$).

Nucleus

The control center of the cell containing genetic material known as deoxyribonucleic acid, or $DNA$, which provides instructions for building proteins and cell reproduction.

Nuclear Envelope

A double membrane that bounds the nucleus and contains nuclear pores for the exchange of material with the cytoplasm.

Nucleolus

Dark-staining sites within the nucleus where ribosomes are assembled.

Chromatin

A granular material composed of $DNA$ wound around histone proteins, which condenses into chromosomes during cell division.

Plasma Membrane

A transparent barrier for cell contents constructed using a fluid mosaic model consisting of two layers of phospholipids arranged tail-to-tail.

Hydrophilic

The 'water loving' polar heads of phospholipid molecules located on the inner and outer surfaces of the plasma membrane.

Hydrophobic

The 'water fearing' nonpolar tails of phospholipid molecules that form the relatively impermeable center of the plasma membrane.

Tight Junctions

Impermeable junctions that fuse plasma membranes like a zipper to prevent substances from passing through the extracellular space between cells.

Desmosomes

Anchoring junctions that act like rivets to prevent cells from being pulled apart when subjected to mechanical stress.

Gap Junctions

Communicating junctions composed of hollow cylinders of proteins called connexons that allow molecules to travel directly between cells.

Cytoplasm

The cellular material outside the nucleus and inside the plasma membrane, containing cytosol, inclusions, and organelles.

Cytosol

The semitransparent fluid of the cytoplasm that suspends otras elements and contains nutrients and electrolytes.

Mitochondria

Known as the cell's 'powerhouses,' these organelles use oxygen to break down food into $ATP$ molecules via aerobic respiration.

Ribosomes

Small structures made of protein and ribosomal $RNA$ ($rRNA$) that serve as the actual sites of protein synthesis.

Rough Endoplasmic Reticulum

A membranous canal system studded with ribosomes used for protein synthesis and transport within the cell.

Smooth Endoplasmic Reticulum

A system of fluid-filled tunnels that lacks ribosomes and functions in lipid metabolism and the detoxification of drugs and pesticides.

Golgi Apparatus

A stack of flattened membranes that modifies and packages proteins arriving from the rough endoplasmic reticulum via transport vesicles.

Lysosomes

Membranous sacs containing powerful digestive enzymes (acid hydrolases) used to digest worn-out cell structures and bacteria.

Peroxisomes

Membranous sacs containing oxidase and catalase enzymes that detoxify harmful substances and break down free radicals into water.

Cytoskeleton

An internal framework of proteins extending throughout the cytoplasm, consisting of microfilaments, intermediate filaments, and microtubules.

Centrioles

Rod-shaped bodies composed of nine triplets of microtubules that direct the formation of the mitotic spindle during mitosis.

Cilia

Cell surface extensions used to move materials, such as mucus in the respiratory system, across the cell's surface.

Flagella

Long cell surface extensions used for propulsion; the only flagellated cell in the human body is the sperm cell.

Microvilli

Tiny, fingerlike extensions of the plasma membrane that increase surface area for more efficient absorption.

Diffusion

The passive transport of molecules from an area of high concentration to an area of low concentration down a gradient.

Osmosis

The simple diffusion of water through a selectively permeable membrane using specific channel proteins called aquaporins.

Isotonic

Solutions that have the same solute and water concentrations as the cell, resulting in no change in cell volume.

Hypertonic

Solutions with a higher solute concentration than the cell, causing the cell to shrink as water leaves.

Hypotonic

Solutions with a lower solute concentration than the cell, causing the cell to swell or plump as water enters.

Facilitated Diffusion

A passive transport process that uses protein membrane channels or carrier molecules to move lipid-insoluble or large substances.

Filtration

A passive process where water and solutes are forced through a membrane or capillary wall by hydrostatic pressure.

Active Transport

The movement of substances across a membrane against a concentration gradient using metabolic energy ($ATP$) and solute pumps.

Sodium-Potassium Pump

An active transport mechanism essential for nerve impulses that pumps sodium out of the cell and potassium into the cell.

Exocytosis

A vesicular transport process where docking proteins bind to the plasma membrane to release material like hormones or mucus to the cell exterior.

Endocytosis

The process by which cells take in extracellular substance by engulfing them in a membranous vesicle.

Phagocytosis

Known as 'cell eating,' a protective process where the cell uses pseudopods to engulf large particles such as bacteria.

Pinocytosis

Known as 'cell drinking,' a routine cellular activity where the cell gulps droplets of extracellular fluid containing dissolved fats or proteins.

Receptor-Mediated Endocytosis

A highly selective process where receptor proteins on the membrane surface bind specific target molecules like iron or cholesterol.

Interphase

The longer phase of the cell cycle where the cell grows, carries on metabolic processes, and replicates its $DNA$.

Mitosis

The process of nuclear division consisting of prophase, metaphase, anaphase, and telophase.

Cytokinesis

The division of the cytoplasm resulting in two separate daughter cells, occurring during late anaphase and telophase of the cell cycle.

Transcription

The phase of protein synthesis where genetic information is transferred from $DNA$ triplets to complementary $mRNA$ codons.

Translation

The phase of protein synthesis occurring in the cytoplasm where the $mRNA$ sequence is decoded by $tRNA$ and used to build an amino acid chain.

Epithelial Tissue

Tissue types that form body coverings, linings, and glands, characterized by an apical surface, a basement membrane, and lack of blood supply (avascularity).

Connective Tissue

The most widely distributed tissue type, used for support and protection, containing a nonliving extracellular matrix of ground substance and fibers.

Osseous Tissue

Commonly called bone, it consists of osteocytes sitting in lacunae within a hard matrix of calcium salts and collagen fibers.

Areolar Tissue

A soft, pliable loose connective tissue that acts as a universal packing material and 'glue' to hold internal organs in their proper positions.

Adipose Tissue

A soft tissue dominated by fat cells used for insulation, organ protection, and fuel storage.

Skeletal Muscle

Voluntarily controlled muscle tissue characterized by long, cylindrical, multinucleate cells with visible striations.

Cardiac Muscle

Involuntarily controlled striated muscle found only in the heart, featuring branching cells connected by intercalated discs.

Smooth Muscle

Involuntary, non-striated muscle with spindle-shaped cells found in the walls of hollow organs like the stomach and blood vessels.

Regeneration

A method of tissue repair where destroyed tissue is replaced by the same kind of cells.

Fibrosis

A method of tissue repair where destroyed tissue is replaced by dense connective tissue, forming a scar.

Hyperplasia

An increase in the size of a tissue or organ that occurs as a result of strong stimulation or irritation.

Atrophy

A decrease in the size of a tissue or organ that occurs when the organ is no longer stimulated normally.