Essentials of Human Anatomy & Physiology: Cells and Tissues

Vocabulary flashcards covering cellular anatomy, membrane transport, protein synthesis, cell division, and tissue types based on the Chapter 3 lecture transcript.

Cell Theory

The concept that a cell is the basic structural and functional unit of living organisms, and that the activity of an organism depends on the collective activities of its cells.

Principle of Complementarity

The biochemical activities of cells are dictated by their structure ($\text{anatomy}$), which determines their function ($\text{physiology}$).

Four Key Elements of Cells

Most cells are composed of $\text{Carbon}$ ($C$), $\text{Hydrogen}$ ($H$), $\text{Oxygen}$ ($O$), and $\text{Nitrogen}$ ($N$).

Water Content in Cells

Cells are approximately $60\%$ water.

Nucleus

The control center of the cell that contains genetic material known as $\text{deoxyribonucleic acid}$ ($DNA$).

Nuclear Envelope

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

Nucleolus

The site within the nucleus where ribosome assembly occurs.

Chromatin

Granular, threadlike material composed of $DNA$ and histone proteins; it condenses into rodlike chromosomes during cell division.

Plasma Membrane

A transparent barrier that contains cell contents and separates them from the surrounding environment; described by the fluid mosaic model.

Hydrophilic Heads

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

Hydrophobic Tails

The 'water fearing' nonpolar parts of phospholipid molecules that form the interior of the plasma membrane.

Tight Junctions

Impermeable junctions that bind cells together into leakproof sheets to prevent substances from passing through extracellular space.

Desmosomes

Anchoring junctions that prevent cells from being pulled apart as a result of mechanical stress.

Gap Junctions

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

Cytosol

The semitransparent fluid that suspends other elements within the cytoplasm and contains nutrients and electrolytes.

Organelles

The 'little organs' or metabolic machinery of the cell that perform specific specialized functions.

Mitochondria

The 'powerhouses' of the cell where oxygen is used to break down food into $ATP$ molecules.

Ribosomes

Dual-subunit particles made of protein and ribosomal $RNA$ ($rRNA$) that serve as the site of protein synthesis.

Rough Endoplasmic Reticulum

A system of fluid-filled tunnels studded with ribosomes that synthesizes and transports proteins.

Smooth Endoplasmic Reticulum

A series of tunnels lacking ribosomes that 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.

Lysosomes

Membranous bags containing powerful digestive enzymes that dispose of bacteria and worn-out cell structures.

Peroxisomes

Membranous sacs of oxidase and catalase enzymes that detoxify harmful substances and break down highly reactive free radicals.

Cytoskeleton

A network of protein structures—including microfilaments, intermediate filaments, and microtubules—that provides an internal framework for the cell.

Centrioles

Paired cylindrical bodies made of nine triplets of microtubules that direct the formation of the mitotic spindle.

Cilia

Whip-like cellular extensions that move materials across the cell surface.

Microvilli

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

Solvent

The dissolving medium present in the larger quantity in a solution; water is the body's main solvent.

Diffusion

The movement of molecules from an area of higher concentration to an area of lower concentration along a concentration gradient.

Osmosis

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

Isotonic Solutions

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

Hypertonic Solutions

Solutions containing more solutes than the cell, causing water to leave the cell and the cell to shrink.

Hypotonic Solutions

Solutions containing fewer solutes than the cell, causing water to enter the cell and the cell to plump or burst.

Filtration

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

Active Transport

A transport process that requires energy ($ATP$) to move substances across a membrane via protein carriers or solute pumps.

Exocytosis

A vesicular transport process where cells actively secrete hormones, mucus, or other products using membranous sacs.

Phagocytosis

A type of endocytosis commonly called 'cell eating' where the cell engulfs large particles like bacteria.

Pinocytosis

A type of endocytosis known as 'cell drinking' where the cell gulps droplets of extracellular fluid containing dissolved proteins or fats.

Interphase

The metabolic phase of the cell life cycle during which the cell grows and replicates its $DNA$.

Mitosis

The division of the cell nucleus, consisting of four stages: prophase, metaphase, anaphase, and telophase.

Mitotic Spindle

A structure composed of microtubules that provides scaffolding for the attachment and movement of chromosomes during mitosis.

Cytokinesis

The division of the cytoplasm, which begins during late anaphase and results in the formation of two daughter cells.

Gene

A segment of a $DNA$ molecule that carries the instructions for building one protein or polypeptide chain.

Transcription

The phase of protein synthesis where information is transferred from $DNA$'s base sequence to messenger $RNA$ ($mRNA$).

Translation

The phase of protein synthesis where the base sequence of nucleic acid is translated into an amino acid sequence.

Base Pairing Rules ($DNA$)

$\text{Adenine}$ ($A$) always bonds with $\text{Thymine}$ ($T$), and $\text{Guanine}$ ($G$) always bonds with $\text{Cytosine}$ ($C$).

Epithelial Tissue

The lining, covering, and glandular tissue of the body characterized by an apical surface, a basement membrane, and lack of blood supply ($\text{avascular}$).

Connective Tissue

The most abundant and widely distributed tissue type, consisting of living cells surrounded by a nonliving extracellular matrix.

Regeneration

The replacement of destroyed tissue by the same kind of cells during wound healing.

Fibrosis

Tissue repair by dense connective tissue, which results in the formation of scar tissue.

Hyperplasia

An increase in the size of a tissue or organ that occurs when it is strongly stimulated or irritated.

Atrophy

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