Topic 2: Cells and Tissues (Vocabulary Flashcards)

A vocabulary-style set of flashcards covering key terms and concepts from the topic on Cells and Tissues (including extracellular environment, cell adhesion, signaling, epithelial and connective tissues, glands, membranes, and tissue repair).

Extracellular environment

The region outside cells that includes interstitial fluid and other body fluids in which cells reside and interact.

Intracellular material

Material found inside cells, including cytoplasm, organelles, and inclusions.

Extracellular material

Material found outside cells, between cells or in body cavities; also called intercellular material.

Interstitial fluid (IF)

Fluid surrounding cells in tissues that nourishes and bathes them.

Plasma

The fluid component of blood that carries cells and dissolved substances.

Synovial fluid

Viscous, non-Newtonian fluid in joint cavities that lubricates and nourishes joints.

Cerebrospinal fluid (CSF)

Clear fluid surrounding brain and spinal cord.

Matrix (extracellular matrix, ECM)

Proteins and polysaccharides secreted by cells that determine tissue properties and function.

Proteoglycans

Large molecules with a protein core and attached glycosaminoglycans; contribute to ECM structure and hydration.

Fibers

ECM components including collagen (ten­sile strength), elastic (stretch), and reticular (supportive nets).

Attachment proteins

Proteins such as fibronectin and laminin that connect cells to the ECM.

Fibronectin

ECM glycoprotein that binds to integrins and other ECM components to help attach cells.

Laminin

ECM glycoprotein that anchors cells to the basement membrane.

Basement membrane

Thin, noncellular layer between epithelium and connective tissue, composed of basal lamina and reticular lamina; supports and filters.

Basal lamina

Glycoprotein-rich layer secreted by epithelial cells; forms part of the basement membrane.

Reticular lamina

Layer secreted by connective tissue; part of the basement membrane providing support.

Basal surface

Bottom surface of epithelial cells that faces the underlying connective tissue.

Apical surface

Top surface of epithelial cells facing the lumen or exterior.

Lumen

Inside space of a tubular structure or organ.

Avascular

Lacking blood vessels.

Innervated

Supplied with nerves.

Regenerates well

Tissues that readily replace damaged cells (e.g., many epithelia and some connective tissues).

Tight junctions

Junctions where adjacent cells fuse to form a seal, preventing leakage of substances; occludins/claudins are key proteins.

Desmosomes

Anchoring junctions that rivet cells together, providing strong adhesion in tissues under mechanical stress; cadherins link to plaques and cytoskeleton.

Gap junctions

Intercellular channels formed by connexins/connexons that allow passage of small molecules and ions between neighboring cells.

Connexons

A pair of connexons forming a gap junction channel between adjacent cells.

Cadherins

Calcium-dependent cell–cell adhesion molecules essential for desmosomes and adherent junctions.

Integrins

Transmembrane receptors that mediate cell–ECM adhesion and signaling.

Selectins

CAMs that mediate transient cell–cell adhesion in the bloodstream.

CAMs (cell adhesion molecules)

Membrane proteins (e.g., cadherins, integrins, selectins) that mediate cell–cell and cell–ECM adhesion.

Contact signaling

Signaling where ligands are bound to the surface of a signaling cell and interact with receptors on an adjacent cell.

Chemical signaling

Extracellular signaling by soluble ligands (paracrine, neurotransmitter, hormonal) binding to receptors on target cells.

Electrical signaling

Signal transmission via electrical changes (often via gap junctions or membrane potentials) between cells.

Tissue

A group of cells and their extracellular matrix organized to perform a specific function.

Histology

Microscopic study of tissues.

Epithelial tissue

Tissue that covers body surfaces, lines cavities, and forms glands; derived from germ layers; avascular and innervated.

Connective tissue

Tissue that supports, binds, protects, and reinforces; derived from mesoderm; has a substantial extracellular matrix.

Muscle tissue

Tissue that contracts to produce movement; generates force and heat.

Nervous tissue

Tissue that initiates and transmits electrical impulses to coordinate body activities.

Germ layers

Three primary embryonic layers from which tissues develop: ectoderm, mesoderm, endoderm.

Ectoderm

Outer germ layer; gives rise to epidermis and nervous system components.

Mesoderm

Middle germ layer; gives rise to connective tissue, muscle, bone, and the circulatory system.

Endoderm

Inner germ layer; gives rise to the epithelium of GI and respiratory tracts and associated glands.

Basement membrane components

Noncellular boundary consisting of basal lamina (epithelial) and reticular lamina (connective).

Basal lamina

Basement membrane layer secreted by epithelial cells; provides support and filtration.

Reticular lamina

Basement membrane layer secreted by connective tissue; provides structural support.

Apical vs basal polarity

Asymmetry of epithelial cells: apical faces lumen; basal faces connective tissue.

Cilia

Hair-like projections from the cell surface that move substances along the surface.

Microvilli

Finger-like extensions increasing surface area for absorption; supported by actin.

Keratin

Fibrous protein in hair, nails, and epidermis providing strength and waterproofing.

Pseudostratified epithelium

Epithelium that appears multi-layered but is a single layer; nuclei at different levels; often with cilia.

Simple squamous

One cell layer of flat cells; diffusion and filtration; lines vessels and membranes.

Simple cuboidal

One cell layer of cube-shaped cells; secretion and absorption; lines kidneys, glands, ovaries.

Simple columnar

One cell layer of tall, column-shaped cells; secretion and absorption; often with microvilli or cilia.

Pseudostratified columnar

Epithelium with appears layered; usually ciliated; often involved in secretion and movement.

Stratified epithelia

Two or more cell layers; provide protection; named by apical cell shape.

Stratified squamous

Multiple cell layers with flat apical cells; provides protection; non-keratinized (mouth, esophagus) and keratinized (skin).

Stratified cuboidal

Rare multilayered epithelium; protective; ducts of sweat and mammary glands.

Stratified columnar

Rare multilayered epithelium with basal cells cuboidal and apical cells columnar; protection and secretion.

Transitional epithelium

Stratified, distensible epithelium found in urinary system (bladder, ureters).

Gland

A single cell or group of cells that produce and secrete a product.

Exocrine gland

Gland that secretes onto a body surface or lumen through a duct (e.g., sweat, mucus).

Endocrine gland

Gland that releases hormones directly into the blood or lymph without ducts.

Unicellular glands

Glands consisting of a single cell (e.g., goblet cell) that secretes mucus.

Multicellular glands

Glands formed by many cells; classified by duct structure and secretory portion.

Duct

Part of a gland that conveys secretions to the surface or lumen.

Secretory portion

Part of a gland that produces the secretion; may be tubular or alveolar.

Merocrine

Secretions released by exocytosis; no loss of cell cytoplasm.

Apocrine

Secretions accumulate at the apical portion; part of cell pinches off.

Holocrine

Secretions accumulate as the entire cell disintegrates—cell rupture to release product.

Simple tubular

Gland with a single unbranched duct and tubular secretory portion.

Simple alveolar (acinar)

Gland with a tubular duct and sac-like alveolar secretory portions.

Compound tubular

Gland with branching ducts and tubular secretory portions.

Cartilage types (general)

Hyaline, elastic, and fibrocartilage—types of connective tissue cartilage with distinct properties.

Areolar connective tissue

Loose connective tissue; loose arrangement of fibers and cells; underlies epithelia and supports organs.

Adipose tissue (white)

Loose connective tissue; adipocytes store fat; insulation and energy storage.

Adipose tissue (brown)

Fat tissue rich in mitochondria; generates heat in infants and hibernating animals.

Dense connective tissue (types)

Dense regular (tendons/ligaments in one direction), dense irregular (dermis), elastic (arteries, lungs).

Hyaline cartilage

Most common cartilage with glassy matrix; supports and cushions joints and developing skeleton.

Elastic cartilage

Cartilage with abundant elastic fibers; maintains shape while allowing flexibility (e.g., ear, epiglottis).

Fibrocartilage

Cartilage with thick collagen fibers; resists compression (intervertebral discs, menisci).

Bone

Rigid connective tissue that provides support, protection, and hematopoiesis; mineralized matrix.

Blood

Fluid connective tissue with plasma as the matrix; transports nutrients, wastes, hormones.

Lacunae

Small spaces in cartilage and bone that house chondrocytes and osteocytes.

Mucous membranes

Membranes with mucous epithelium and lamina propria; lines passages that open to exterior.

Serous membranes

Membranes that line closed body cavities and secrete serous fluid; include pleura, pericardium, peritoneum.

Cutaneous membrane

Skin; a dry membrane consisting of keratinized epithelium and underlying connective tissue.

Tissue repair: inflammation

Initial, non-specific response to injury involving vasodilation, permeability, and immune cell migration.

Tissue repair: organization

Replacement of clot with granulation tissue and reestablishment of blood supply; forms scar.

Regeneration vs fibrosis

Regeneration restores original tissue; fibrosis replaces with scar tissue; functional recovery depends on tissue type.