Cell Structures, Functions, and Tissues

Comprehensive vocabulary flashcards covering cell structure, organelles, membrane transport, mitosis, gene expression, and tissue types based on Seeley’s Anatomy & Physiology.

Cell

The basic unit of life in all organisms which can be specialized to perform specific functions.

Cell Metabolism

The chemical reactions occurring within a cell that release energy for activities such as synthesis, muscle contraction, and heat production.

Cell Membrane

Also known as the plasma membrane, it forms the outer boundary of the cell, encloses cytoplasm, and is primarily composed of phospholipids and proteins.

Fluid-Mosaic Model

A description of the cell membrane consisting of a phospholipid bilayer in which proteins float.

Hydrophilic

Water-loving; describes the polar, phosphate-containing heads of the cell membrane that face the extracellular fluid and cytoplasm.

Hydrophobic

Water-fearing; describes the nonpolar fatty acid tails of the cell membrane that point inward away from surrounding fluid.

Cholesterol (in membrane)

A molecule in the phospholipid membrane that adds strength and stability by restricting phospholipid movement.

Selectively Permeable

The property of cell membranes that allows some substances to enter or leave while restricting others.

Diffusion

The movement of a solute from an area of higher concentration to an area of lower concentration within a solvent.

Concentration Gradient

The difference in solute concentration between two points in a solvent divided by the distance between them.

Osmosis

The diffusion of water across a selectively permeable membrane from a region of higher water concentration to one of lower water concentration.

Osmotic Pressure

The force needed to stop water from moving across a selectively permeable membrane.

Hypotonic Solution

A solution with a lower solute concentration and higher water concentration than the cell's cytoplasm, causing water to move into the cell.

Isotonic Solution

A solution with the same solute and water concentrations as the cytoplasm, resulting in no cell swelling or shrinking.

Hypertonic Solution

A solution with a higher solute concentration and lower water concentration than the cytoplasm, causing water to move out and the cell to undergo crenation.

Facilitated Diffusion

A mediated transport process involving channel or carrier proteins that moves substances from higher to lower concentration without expending $ATP$.

Active Membrane Transport

A process using membrane proteins and energy in the form of $ATP$ to move substances against a concentration gradient.

Sodium-Potassium Pump

An active transport mechanism that moves $Na^+$ out of the cell and $K^+$ into the cell.

Secondary Active Transport

Occurs when the active transport of one substance, such as $Na^+$, creates a concentration gradient that provides energy to move another substance.

Endocytosis

The process by which materials enter the cell through the formation of a vesicle.

Phagocytosis

A type of endocytosis that involves taking in solid particles.

Pinocytosis

A type of endocytosis that involves taking in small amounts of fluid and dissolved substances.

Exocytosis

The release of substances from the cell through the fusion of a vesicle with the cell membrane.

Nucleus

The organelle containing genetic material organized into 23 chromosomes; it acts as the hereditary material and controls cell activities.

Chromatin

The collective term for DNA and proteins when chromosomes are loosely coiled within the nucleus.

Nucleoli

Diffuse bodies within the nucleus consisting of RNA and proteins; they are the sites of ribosomal subunit assembly.

Ribosomes

Organelles composed of one large and one small subunit that serve as the site of protein synthesis.

Rough Endoplasmic Reticulum

A series of membranes with ribosomes attached; it is a major site of protein synthesis for export from the cell.

Smooth Endoplasmic Reticulum

Membrane sacs/tubules without ribosomes that facilitate lipid synthesis, detoxification, and $Ca^{2+}$ storage in skeletal muscle.

Golgi Apparatus

Closely packed membrane sacs that collect, modify, package, and distribute proteins and lipids from the ER.

Lysosomes

Membrane-bound sacs containing enzymes that function as intracellular digestive systems to break down phagocytized material.

Peroxisomes

Organelles that break down fatty acids, amino acids, and the toxic byproduct hydrogen peroxide ($H_2O_2$).

Mitochondria

The major sites for the production of adenosine triphosphate ($ATP$) through aerobic respiration; they contain their own DNA ($mtDNA$).

Cristae

Numerous folds of the inner mitochondrial membrane that project into the interior matrix.

Cytoskeleton

A support system for cytoplasm and organelles composed of microtubules, microfilaments, and intermediate filaments.

Transcription

The process where a gene's DNA nucleotide sequence determines the nucleotide sequence of $mRNA$.

Translation

The process at ribosomes where $mRNA$ codons are used to produce proteins with the help of $tRNA$ anticodons.

Codon

A three-nucleotide sequence in $mRNA$ that specifies a particular amino acid.

Cell Cycle

A series of events for growth and tissue repair consisting of interphase and cell division.

Interphase

The time between cell divisions where DNA replication occurs during the S phase.

Prophase

The first stage of mitosis where chromatin condenses into chromosomes and the nuclear envelope disappears.

Metaphase

The mitosis stage where chromosomes align at the center of the cell.

Anaphase

The mitosis stage where chromatids separate at the centromere and migrate to opposite poles.

Telophase

The final stage of mitosis where two new nuclei form and cell division is completed.

Differentiation

The process resulting from selective DNA activation by which cells develop specialized structures and functions.

Apoptosis

Programmed cell death used to regulate the number of cells within body tissues.

Histology

The microscopic study of tissues to identify abnormalities, including cancer.

Epithelial Tissue

Tissue consisting almost entirely of cells with little extracellular matrix; it forms coverings and linings of body surfaces.

Simple Epithelium

A single layer of cells where each cell extends from the basement membrane to the free surface.

Stratified Epithelium

Consists of more than one layer of cells, but only the deepest layer attaches to the basement membrane.

Pseudostratified Columnar Epithelium

A single layer of cells that appears stratified because some cells are tall and reach the surface while others are short.

Squamous Cells

Epithelial cells that are flat or scalelike.

Cuboidal Cells

Epithelial cells that are cube-shaped, approximately as wide as they are tall.

Columnar Cells

Epithelial cells that are taller than they are wide.

Tight Junctions

Structures that bind adjacent cells together to form a permeability barrier.

Gap Junctions

Cell junctions that allow intercellular communication.

Endocrine Glands

Ductless glands that produce hormones transported by the blood.

Exocrine Glands

Glands with ducts that transport secretions like saliva or sweat to the epithelial surface.

Merocrine Secretion

The most common mode of secretion where products are released through exocytosis.

Apocrine Secretion

Secretion where a portion of the epithelial cell's free surface pinches off to release contents.

Holocrine Secretion

Secretion characterized by the release of products through the shedding of entire cells.

Connective Tissue

A diverse tissue type where cells are separated by an abundant extracellular matrix.

Fibroblasts

Specialized connective tissue cells that form protein fibers.

Extracellular Matrix Components

Composed of protein fibers (collagen, reticular, elastic), ground substance (hyaluronic acid, proteoglycans), and fluid.

Areolar Connective Tissue

The 'packing material' of the body that fills spaces between organs.

Adipose Tissue

Fat tissue that stores energy, pads/protects the body, and acts as a thermal insulator.

Hyaline Cartilage

The most abundant cartilage type; it provides smooth surfaces at joints and forms respiratory tract rings.

Fibrocartilage

Cartilage with visible collagen bundles that resists compression and tearing; found in intervertebral discs.

Skeletal Muscle

Voluntary, striated muscle with long, cylindrical, multinucleated cells used for body movement.

Cardiac Muscle

Involuntary, striated muscle of the heart featuring branched cells and intercalated discs.

Smooth Muscle

Involuntary, nonstriated, spindle-shaped cells found in hollow organs, skin, and eyes.

Glial Cells

Supporting cells of the nervous system that nourish, protect, and insulate neurons.

Serous Membranes

Internal membranes lining trunk cavities (pleural, pericardial, peritoneal) that secrete serous fluid.

Inflammation Symptoms

Redness (rubor), heat (calor), swelling (tumor), pain (dolor), and disturbance of function.

Regeneration

A form of tissue repair where stem cells replace destroyed cells with new cells of the same type.

Fibrosis

A form of tissue repair where destroyed cells are replaced by different cell types, resulting in scar formation.