Connective Tissues and Biological Classification

Comprehensive vocabulary flashcards reviewing the classification, cellular components, fiber types, ground substance, and specialized categories of connective tissues (proper, cartilage, bone, and blood), as well as associated classroom materials.

Mesenchyme

An embryonic tissue from which all connective tissues arise, serving as their common origin.

Extracellular Matrix (ECM)

Largely nonliving material composed of ground substance and fibers that separates living cells in connective tissue and provides support.

Ground Substance

The unstructured material filling the space between cells in connective tissue, composed of interstitial fluid, cell adhesion proteins, and proteoglycans.

Interstitial Fluid

Fluid present in large amounts within the ground substance that functions as a molecular sieve.

Cell Adhesion Proteins

Proteins in connective tissue that act as connective tissue glue, allowing connective tissue cells to attach to the extracellular matrix.

Proteoglycans

Molecules containing GAGs that trap water to create a gel-like matrix and control the physical state of the matrix between liquid and gel.

Collagen Fibers

Thick fibers secreted into extracellular spaces that provide high tensile strength to tissues.

Elastic Fibers

Long, thin fibers that form branching networks in the extracellular matrix to allow stretch and flexibility.

Reticular Fibers

Short, fine branching fibers similar to elastic fibers that provide a supportive framework (stroma) for soft tissue organs.

Fibroblasts

The fixed cell type responsible for producing the ground substance and fibers in connective tissue proper.

Chondroblasts

The immature, matrix-producing fixed cells found in cartilage.

Osteoblasts

The immature, matrix-producing fixed cells of bone that synthesize bone matrix and reside in lacunae.

Hemocytoblasts

The stem cells / fixed cells associated with the formation of blood cells.

-blast

A suffix referring to immature, actively secreting cells that are 'forming' matrix.

-cyte

A suffix designating a mature cell responsible for maintaining the matrix.

-clast

A suffix designating a cell that breaks down or destroys tissue matrix.

Macrophages

Large immune/lymphatic cells ('big eaters') that utilize phagocytosis, a type of active transport/endocytosis, to engulf bacteria and foreign material.

Mast Cells

Connective tissue cells that produce and release histamine, heparin, and proteases.

Histamine

A chemical produced by mast cells that makes capillaries and blood vessels leaky to promote inflammation.

Heparin

An anticoagulant chemical produced by mast cells that prevents blood clotting when in the matrix.

Protease

An enzyme produced by mast cells that breaks down foreign proteins.

Classification of Connective Tissue Criteria

The three characteristics used to classify connective tissues: 1. Fixed cell type present, 2. Fibers present in matrix, and 3. Arrangement of fibers.

Areolar Connective Tissue

A loose connective tissue proper featuring a gel-like matrix with spaces containing collagen, elastic, and reticular fibers; wraps and cushions organs, conveys tissue fluid, and aids in inflammation.

Adipose Connective Tissue

A highly vascular loose connective tissue proper consisting of packed modified adipocytes with all three fiber types; functions in preventing heat loss and supporting and protecting organs.

Reticular Connective Tissue

A loose connective tissue proper with a gel-like matrix containing solely reticular fibers; forms a supportive stroma for free blood cells in lymph nodes, the spleen, and bone marrow.

Dense Regular Connective Tissue

A poorly vascularized connective tissue proper with tightly packed parallel collagen fibers; withstands stress in one direction to attach muscles to bones or bones to bones.

Dense Irregular Connective Tissue

A poorly vascularized connective tissue proper with collagen fibers arranged without a fixed pattern; provides structural strength to withstand tension in multiple directions in the dermis and digestive tract.

Tendons

Dense regular connective tissue structures that attach muscle to bone.

Ligaments

Dense regular connective tissue structures that connect bone to bone.

Lacunae

Small cavities or chambers within the extracellular matrix where chondrocytes/chondroblasts in cartilage and osteocytes/osteoblasts in bone reside.

Hyaline Cartilage

An avascular cartilage with a glassy, transparent matrix and invisible collagen fibers; supports, reinforces, provides resilient cushioning, and covers ends of long bones, costal rib cartilages, nose, trachea, larynx, and epiphyseal plates.

Elastic Cartilage

Cartilage characterized by visible elastic fibers in the matrix; maintains shape and structure while permitting flexibility in the external ear (pinna) and epiglottis.

Fibrocartilage

Cartilage with a matrix less firm than hyaline cartilage packed with collagen fibers; provides tensile strength and absorbs compressive shock in intervertebral discs, the pubic symphysis, and knee menisci.

Bone (Osseous Tissue)

A highly vascularized specialized connective tissue with a hard, calcified matrix containing collagen fibers and osteoblasts in lacunae; functions in support, protection, hematopoiesis, acting as muscle levers, and mineral/fat storage.

Hematopoiesis

The process of blood cell formation that takes place within the bone marrow cavities.

Blood

A specialized connective tissue with a fluid matrix (plasma) and formed elements (WBCs, RBCs, platelets) that transports nutrients, waste, and respiratory gases ($O_2$) through blood vessels.

Plasma

The liquid extracellular matrix of blood that carries nutrients, wastes, gases, and formed elements.