BIOL 203 - Topic 2: Cells and Tissues

Vocabulary flashcards covering key concepts from the Cells and Tissues notes.

Intracellular materials

Materials found within cells; includes cytoplasm, organelles and inclusions (fat, hemoglobin, glycogen, keratin, etc.).

Extracellular materials

Materials found between cells or outside of cells; in tissues or body cavities (saliva, serous fluid, synovial fluid); also called intercellular material.

Interstitial fluid

The fluid found between cells in a tissue.

Plasma

The extracellular fluid of blood.

Matrix

Proteins and polysaccharides secreted by cells of a tissue that determine tissue properties and regulate cell behavior (stabilize structure, control division, migration, shape, function).

Fibers (collagen)

Collagen fibers: strong fibers that provide tensile strength in many connective tissues.

Fibers (elastic)

Elastic fibers: fibers that provide elasticity, allowing tissues to stretch and recoil.

Fibers (reticular)

Reticular fibers: thin fibers forming supportive networks in organs like lymph nodes and bone marrow.

Attachment proteins

Noncollagen proteins that organize the matrix and help cells attach to it.

Cell adhesion molecules (CAMs)

Membrane proteins that mediate cell–cell and cell–matrix adhesion and signaling.

Tight junctions

Junctions where membranes of adjacent cells fuse to form an impermeable barrier.

Desmosome

Junction with intercellular space bridged by linker proteins connected to plaques and keratin; resists pulling forces.

Cadherin

Cadherin: a cell adhesion molecule involved in desmosomes; linked to cytoplasmic plaques and intermediate filaments.

Pemphigus

Skin disease in which antibodies target desmosomal proteins, causing layers of skin to separate.

Gap junction

Small intercellular space bridged by connexons (membrane channels) allowing direct chemical and electrical coupling between cells.

Connexon

Constituent of a gap junction; a membrane channel formed by connexin proteins.

Basal lamina

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

Reticular lamina

Collagen-rich layer of the basement membrane secreted by connective tissue cells.

Basement membrane

Composite structure of basal lamina and reticular lamina that anchors epithelium to connective tissue.

Apical surface

The exposed surface of an epithelial cell facing the body exterior or lumen.

Basal surface

The opposite side of an epithelial cell facing the underlying connective tissue.

Polarity (apical vs basal)

Epithelial cells exhibit apical (top) and basal (bottom) surfaces with distinct features and roles.

Avascular

Epithelia lack blood vessels; receive nutrients by diffusion from underlying tissues.

Innervated

Epithelia have a nerve supply.

Keratin

Major cytoskeletal protein in epithelial cells; contributes to structural stability.

Ectoderm origin

Epithelial tissues can be derived from the ectoderm (surface epithelia, nervous system).

Simple squamous epithelium

Single layer of flattened cells; allows diffusion and filtration; found in kidney glomeruli, lung alveoli, lining of vessels and serosae.

Simple cuboidal epithelium

Single layer of cube-shaped cells; functions in secretion and absorption; lines kidney tubules, gland ducts, and ovaries.

Simple columnar epithelium

Single layer of tall cells; absorption and secretion; may have goblet cells and microvilli; lines most of the digestive tract.

Pseudostratified columnar epithelium

Single layer of cells of varying heights; nuclei at different levels; often ciliated and mucus-secreting.

Stratified squamous epithelium

Several cell layers; surface cells are flat; protects underlying tissues; keratinized (skin) vs nonkeratinized (oral, esophagus, vagina).

Stratified cuboidal epithelium

Two or more cell layers; provides protection and conduit in ducts.

Stratified columnar epithelium

Multiple cell layers with a tall apical layer; provides protection and secretion.

Transitional epithelium

Stratified epithelium that stretches (urinary bladder, ureters, part of urethra); surface cells dome-shaped when relaxed.

Goblet cell

Mucus-secreting unicellular gland found in simple columnar and pseudostratified epithelia.

Brush border

Microvilli-covered surfaces (often on absorptive epithelia) that increase surface area for absorption.

Microvilli

Fingerlike extensions on the apical surface that expand surface area for absorption.

Cilia

Hairlike projections on the apical surface that move mucus and cells; used for propulsion.

Keratinized epithelium

Surface cells filled with keratin and dead; provides a dry, protective layer (e.g., skin).

Nonkeratinized epithelium

Moist epithelial surface lacking keratin; found in esophagus, mouth, vagina.

Basement membrane (general)

Thin layer attaching epithelium to underlying connective tissue.

Basement membrane components: basal lamina

Basal lamina: glycoprotein-rich layer secreted by epithelial cells.

Basement membrane components: reticular lamina

Reticular lamina: collagen-rich layer secreted by connective tissue cells.

Ground substance

Amorphous matrix between cells in connective tissue that supports diffusion of nutrients and wastes.

Proteoglycans

Core protein with glycosaminoglycans (e.g., chondroitin sulfate, hyaluronic acid) forming a major part of ground substance.

Fibers (connective tissue)

Collagen fibers (strength), elastic fibers (elasticity), reticular fibers (support networks).

Fibroblast

Very active connective tissue cell that synthesizes ground substance and fibers.

Fibrocyte

Mature fibroblast that maintains the connective tissue matrix.

Chondroblast

Cell that secretes the ground substance for cartilage.

Osteoblast

Cell that secretes the bone matrix.

Osteocyte

Mature bone cell embedded in bone matrix.

Adipocyte

Fat cell that stores fat and can secrete leptin; nucleus pushed to the side (signet-ring appearance).

Plasma cell

Cell that secretes antibodies; derived from B lymphocytes.

Mast cell

Cell that secretes histamine, heparin, and proteases during inflammation.

Macrophage

Phagocytic cell that engulfs pathogens and debris; part of the immune system.

Hematopoietic stem cell

Stem cell that differentiates into red blood cells, white blood cells, and platelets.

Areolar connective tissue

Loose connective tissue with a gel-like matrix; contains fibroblasts, macrophages, mast cells; cushions and surrounds organs.

Adipose tissue

Loose connective tissue with sparse matrix; adipocytes store fat and insulate; lipid droplets push nuclei to the periphery.

Reticular connective tissue

Loose connective tissue with reticular fibers forming a supporting stroma in lymphoid organs.

Dense regular connective tissue

Dense tissue with parallel collagen fibers; fibroblasts; resists tension in one direction (tendons and ligaments).

Dense irregular connective tissue

Dense tissue with irregularly arranged collagen fibers; resists tension in many directions (dermis, capsules).

Hyaline cartilage

Firm, amorphous matrix with sparse collagen; chondroblasts produce matrix; chondrocytes in lacunae.

Elastic cartilage

Cartilage with many elastic fibers; maintains shape with flexibility (external ear, epiglottis).

Fibrocartilage

Cartilage with thick collagen fibers; strong and absorbs shock (intervertebral discs, pubic symphysis).

Bone (osseous tissue)

Connective tissue with mineralized matrix; osteoblasts build bone, osteocytes maintain it.

Blood

Fluid connective tissue with plasma as extracellular matrix; cells (RBCs, WBCs, platelets) suspended in plasma.

Mesenchyme

Embryonic connective tissue; gel-like ground substance with star-shaped cells; gives rise to all other connective tissues.

Glandular epithelium

Epithelium that forms glands for secretion (unicellular or multicellular).

Exocrine gland

Gland that secretes products onto a body surface or into ducts that lead to a body cavity.

Endocrine gland

Gland that secretes hormones into the bloodstream, with target organs throughout the body.

Structure classification of multicellular exocrine glands

Simple vs compound glands; tubular vs acinar (alveolar); describes duct and secretory portion architecture.

Merocrine secretion

Glandular secretion by exocytosis without cell rupture.

Holocrine secretion

Glandular secretion where the whole cell disintegrates to release product.

Apocrine secretion

Glandular secretion where the apex of the cell pinches off to release product.

Connective tissue proper vs specialized connective tissue

Connective tissue types include loose (areolar, adipose, reticular) and dense; specialized CT includes cartilage, bone, blood.

Epithelial membranes

Membranes formed by epithelia with underlying connective tissue: serous, mucous, and cutaneous (skin).

Serous membrane

Membrane of simple squamous epithelium (mesothelium) plus areolar tissue; secretes lubricating serous fluid (pleura, peritoneum, pericardium).

Mucous membrane

Epithelium with lamina propria; secretes mucus to lubricate and protect surfaces (respiratory, digestive, urinary, reproductive tracts).

Cutaneous membrane

Skin; stratified squamous epithelium (epidermis) plus underlying connective tissue.

Tissue repair (general)

Response to injury with regeneration or fibrosis; depends on tissue type and conditions.

Regeneration

Replacement of damaged tissue with the same type of tissue, restoring function.

Fibrosis

Replacement of damaged tissue with fibrous connective tissue (scar tissue).

Inflammation stage

First repair stage; phagocytes migrate, blood vessels dilate, clot forms to stop bleeding and isolate area.

Organization stage

Reestablishes blood supply; granulation tissue forms; capillaries, macrophages, and fibroblasts present.

Regeneration and fibrosis outcome

Outcome depends on tissue type, blood supply, nutrition, and age; may fully regenerate or leave scar.