Human Anatomy and Physiology I - Topic 2: Cells and Tissues (Page 1)

Vocabulary flashcards covering key terms from Topic 2: Cells and Tissues (A&P I)

Extracellular environment

The environment outside cells, including interstitial fluid, plasma, and the extracellular matrix, that surrounds cells and supports signaling and exchange.

Interstitial fluid

The fluid in tissue spaces that bathes and surrounds cells; part of the extracellular environment.

Plasma

The liquid component of blood in which cells and platelets are suspended; part of the extracellular environment.

Extracellular matrix

A network of proteins and polysaccharides outside cells that provides structural support and biochemical cues for cell behavior.

Basement membrane

A thin extracellular layer under epithelial sheets and around some tissues, anchoring epithelium to underlying connective tissue.

Cell adhesion

The process by which cells attach to each other or to the extracellular matrix via adhesion molecules and receptors.

Cell junctions

Structures that connect neighboring cells or connect cells to the extracellular matrix, enabling adhesion and communication.

Tight junctions

Junctions that seal adjacent cells together to prevent paracellular passage of substances.

Desmosomes

Anchoring junctions that link adjacent cells mechanically via intermediate filaments, providing tensile strength.

Gap junctions

Intercellular channels that allow direct passage of ions and small molecules between neighboring cells for rapid communication.

Cadherins

Calcium-dependent adhesion proteins that mediate cell–cell adhesion at adherens junctions and desmosomes.

Integrins

Transmembrane receptors that mediate cell–ECM adhesion and connect ECM to the cytoskeleton via linker proteins.

Contact signaling

Direct cell-to-cell communication through membrane-bound signals and receptors at the cell surface.

Chemical signaling

Communication via secreted ligands (hormones, growth factors, cytokines) acting on receptors on target cells.

Electrical signaling

Communication through changes in membrane potential, such as nerve impulses or gap junction–mediated signals.

Tissue

A group of similar cells plus their extracellular matrix performing a common function.

Histology

The study of tissues, including their structure and organization.

Four tissue categories

Epithelial, connective, muscle, and nervous tissues.

Epithelial tissue

Tissues that line surfaces and cavities, form glands, are usually avascular, and exhibit polarity and regeneration.

Simple squamous epithelium

One cell layer of flat cells; functions in diffusion and filtration; lines vessels and air sacs.

Simple cuboidal epithelium

One cell layer of cube-shaped cells; functions in secretion and absorption; lines kidney tubules and glands.

Simple columnar epithelium

One cell layer of tall, column-like cells; often with microvilli; functions in absorption and secretion; lines GI tract.

Pseudostratified columnar epithelium

Appears multi-layered but all cells touch the basement membrane; often ciliated; functions in secretion and propulsion.

Stratified squamous epithelium

Multiple layers of flat cells; protects underlying tissues; keratinized in skin, nonkeratinized in mouth/esophagus.

Stratified cuboidal epithelium

Two or more layers of cube-shaped cells; protective; lines some ducts.

Stratified columnar epithelium

Several cell layers; relatively rare; functions in absorption and secretion; found in some large ducts.

Transitional epithelium

Stratified, highly adaptable epithelium that stretches; lines urinary bladder and ureters.

Gland

A cell or group of cells that produces a secretory product (mucus, enzymes, hormones).

Exocrine glands

Glands that secrete onto surfaces or into ducts (e.g., sweat, salivary) rather than into blood.

Endocrine glands

Glands that secrete hormones directly into the bloodstream.

Multicellular exocrine glands (structural classifications)

Structural categories include simple vs compound ducts and tubular vs acinar (alveolar) secretory units.

Secretory mechanisms (secretory modes)

Merocrine, apocrine, and holocrine modes describe how glands release their secretions.

Mesenchyme

Embryonic connective tissue from which all connective tissues originate.

Loose connective tissue

Areolar, adipose, and reticular tissues; function in packing, insulation, and energy storage (adipose).

Dense connective tissue

Dense regular, dense irregular, and elastic tissues; provide strong connections and elasticity (e.g., tendons, dermis, elastic arteries).

Hyaline cartilage

Glass-like cartilage with a firm matrix; provides support with flexibility; found at articular surfaces and respiratory passages.

Elastic cartilage

Cartilage with many elastic fibers; maintains shape while allowing flexibility (ears, epiglottis).

Fibrocartilage

Cartilage with dense collagen fibers; resists compression; found in intervertebral discs and knee menisci.

Serous membranes

Membranes lining closed body cavities that secrete serous fluid to reduce friction (pleura, pericardium, peritoneum).

Mucous membranes

Membranes lining cavities open to the exterior; secrete mucus; line respiratory, digestive, and reproductive tracts.

Inflammation

Protective tissue response to injury, with redness, heat, swelling, and pain, aiming to remove injurious stimuli and begin healing.

Growth factor

Proteins that stimulate cell growth, proliferation, and differentiation during tissue repair.

Organization

Early repair phase in which granulation tissue forms and the wound is reorganized and prepared for regeneration or fibrosis.

Regeneration

Repair that restores the original tissue architecture and function, when possible.

Fibrosis

Repair by scar formation with dense connective tissue, often resulting in reduced function.

Repair outcome determinants

Factors such as injury size, nutrition, blood supply, age, and infection that influence healing outcomes.