ANATOMY AND PHYSIOLOGY NOTES: CELLS, TISSUES, EPITHELIUM, CONNECTIVE TISSUE, CARTILAGE, BONE, AND BLOOD

Vocabulary-style flashcards covering key terms from the notes on cells, tissues, epithelia, connective tissue, cartilage, bone, and blood.

Histology

The study of tissues under the microscope; the microscopic anatomy of life and how tissues look and function.

Tissue

A group of similar cells that work together to perform a specific function.

Matrix (connective tissue)

The extracellular framework composed of fibers and ground substance that surrounds cells in connective tissue.

Ground substance

A clear gel-like component of the extracellular matrix in connective tissue that fills spaces between fibers and cells.

Germ layers

Three primary embryonic tissue layers (ectoderm, mesoderm, endoderm) that give rise to all tissues and organs.

Ectoderm

The outer germ layer; forms skin, hair, nails, and the nervous system.

Mesoderm

The middle germ layer; forms muscle, bone, blood, cartilage, connective tissues, and the heart.

Endoderm

The inner germ layer; forms the lining of the digestive and respiratory tracts and associated glands.

Epithelial tissue

Covers surfaces, lines cavities and organs; one or more cell layers; avascular and nourished by underlying connective tissue.

Connective tissue

Binds, supports, and protects; cells are separated by an extracellular matrix and it is highly vascular.

Nervous tissue

Transmits electrical signals; makes up the brain, spinal cord, and nerves.

Muscle tissue

Contracts to produce movement; includes skeletal, smooth, and cardiac muscle.

Simple epithelium

One cell layer thick; named for cell shape; all cells contact the basement membrane.

Simple squamous

Thin, flat cells; permits rapid diffusion and may secrete serous fluid.

Simple cuboidal

Cube or square-shaped cells; involved in absorption and secretion (examples include liver, thyroid, glands, bronchioles, kidney tubules).

Simple columnar

Tall, narrow cells; absorption and secretion; often contains goblet cells and mucus; lines GI tract, uterus, kidneys, and uterine tubes.

Pseudostratified columnar epithelium

Appears multilayered but all cells touch the basement membrane; often with cilia and goblet cells; secretes and propels mucus; in the respiratory tract and parts of the male urethra.

Stratified epithelium

Multiple cell layers; deepest layer attaches to the basement membrane; named by the shape of the apical cells.

Stratified squamous

Several layers with surface cells that are flat; keratinized (skin) or nonkeratinized (mouth, esophagus, vagina).

Keratinized stratified squamous

Multiple layers with a superficial layer of dead cells filled with keratin; present on the skin; resistant to abrasion and water loss.

Nonkeratinized stratified squamous

Lacks a surface keratin layer; lines the tongue, oral mucosa, esophagus, and vagina.

Stratified cuboidal epithelium

Two or more layers; surface cells are square or round; found in sweat glands ducts and in ovarian follicles and seminiferous tubules.

Transitional epithelium

Multilayered; surface cells change shape from round to flat when stretched; lines the urinary tract (ureter and bladder).

Goblet cells

Mucus-secreting cells found in simple columnar and pseudostratified epithelia.

Basement membrane

Layer between epithelium and underlying connective tissue; anchors epithelium; contains collagen, laminin, fibronectin, and heparan sulfate.

Basal surface

Surface of an epithelial cell that faces the basement membrane.

Apical surface

Surface of an epithelial cell that faces away from the basement membrane.

Areolar tissue

Loose connective tissue with a gel-like ground substance, abundant blood vessels, and random fibers; cushions and nourishes epithelia.

Reticular tissue

Mesh of reticular fibers and fibroblasts; forms supportive stroma for lymphatic organs (lymph nodes, spleen, thymus, bone marrow).

Adipose tissue

Fat tissue dominated by adipocytes; stores triglycerides; provides insulation, cushioning, and energy storage.

White fat

Most common type in adults; stores energy as triglycerides and provides insulation.

Brown fat

Fat found in fetuses and infants that generates heat (thermogenesis).

Cartilage

Supportive connective tissue with a rubbery matrix; chondroblasts produce matrix; chondrocytes in lacunae; avascular; perichondrium; matrix rich in chondroitin sulfate.

Chondroblasts

Cartilage-forming cells that secrete cartilage matrix and become chondrocytes in lacunae.

Chondrocytes

Cartilage cells that reside in lacunae within the cartilage matrix.

Perichondrium

Dense irregular connective tissue surrounding cartilage (except articular cartilage); contains chondroblasts and supplies nutrients.

Chondroitin sulfate

A major glycosaminoglycan (GAG) in cartilage that contributes to its resilience and structure.

Hyaluronic acid

Viscous, slippery GAG that acts as a joint lubricant and is a major component of the vitreous body of the eye.

Proteoglycan

A large molecule that forms a gel-like ground substance; helps hold tissues together by binding cells and extracellular molecules.

Adhesive glycoproteins

Proteins that bind components of tissues together to form extracellular connections.

Bone tissue (osseous tissue)

Rigid connective tissue; supports body structure; two forms: spongy bone and compact bone.

Spongy bone

Cancellous bone with a porous, lattice-like structure (trabeculae); located at ends of long bones and inside flat bones.

Compact bone

Dense bone with a rigid, organized structure surrounding vertically oriented blood vessels (osteons).

Blood

Fluid connective tissue that transports cells and dissolved substances; composed of plasma and formed elements (erythrocytes, leukocytes, platelets).

Plasma

The liquid, non-cellular component of blood that carries nutrients, hormones, and proteins.

Erythrocytes

Red blood cells; transport oxygen and carbon dioxide.

Leukocytes

White blood cells; defend against infection and disease.

Platelets

Cell fragments involved in blood clotting and other processes.