Introduction to Human Anatomy Chapter 4: Connective Tissues

Three Types of Connective Tissue found after birth

1) Connective tissue proper 2) Supporting connective tissue 3) Fluid connective tissue

The two types of Connective Tissue found only in Embryos

1) Mesenchyme: The source of all adult connective tissue 2) Mucous: Found in umbilical cord

Mast Cells

A type of wandering cell that contains a granule-filled cytoplasm; Usually found close to blood vessels; They secrete heparin to inhibit blood clotting, and histamine to dilate blood vessels and increase blood flow

Ground Substance

A mixture of proteins and carbohydrates with variable amounts of salts and water

Fibroblast

Large, relatively flat cells with tapered ends. They are the most abundant resident cells in connective tissue proper. They produce the fibers and ground substance components of the extracellular matrix

Adipocyte

Also called fat cells; Often appears in small clusters within some types of connective tissue proper. If a larger cluster of these cells dominates an area, the connective tissue is called adipose connective tissue

Connective Tissue

The most diverse, abundant, widely distributed, and microscopically variable of the tissues

Compact Bone

Appears solid but is in fact perforated by a number of vascular canals; usually forms the hard outer shell of the bone

Plasma Cells

B-lymphocytes which have matured due to activation of immune response; small "factories" that synthesize antibodies; usually found in intestinal walls, spleen, and lymph nodes

Wandering Cells

Cells that move throughout the connective tissue and are involved in immune protection and repair of damaged extracellular matrix

Mesenchymal Cells (Stem Cells)

Cells which support the repair of the tissue following damage or injury

Three Basic components of Connective Tissue

Cells, protein fibers, and ground substance are basic components of THIS tissue

FLUID CONNECTIVE TISSUE (BLOOD)

Composed in part of cells and cell fragments called formed elements: Erythrocytes (Red Blood Cells), Leukocytes (White Blood Cells), and Thrombocytes (Platelets); dissolved protein fibers in watery ground substance forms a matrix called plasma

Adipose Connective Tissue ("Fat")

Composed primarily of cells called adipocytes; Serves as packing around structures and provides padding, cushion shocks and acts as an insulator to slow heat loss through the skin

Dense Connective Tissue

Composed primarily of protein fibers and has proportionately less ground substance than does loose connective tissue; sometimes called collagenous tissue because collagen fibers are the dominant fiber type

Loose Connective Tissue

Connective Tissue Proper which contains relatively fewer cells and protein fibers than Dense Connective Tissue; The protein fibers in it are loosely arranged rather than tightly packed together; Supports and overlying epithelia and provides cushioning around organs; Supports and surrounds blood vessels and nerves, stores lipids, and provides a medium for the diffusion of materials

Bone (Connective Tissue)

More solid than cartilage and provides greater support; almost all surfaces are covered by a dense irregular connective tissue called periosteum; provides levers for movement when muscles attached to them contract, and they protect soft tissues and vital body organs

Reticular Connective Tissue

Contains a meshwork of reticular fibers, fibroblasts, and leukocytes

Cartilage

Features a firm, gel-like extracellular matrix composed of both protein fibers and ground substance; Mature cells are called chondrocytes; they occupy small spaces called lacunae within extracellular matrix; Usually has a covering called perichondrium

Elastic Connective Tissue

Features branching elastic fibers and more fibroblasts than loose connective tissue in addition to packed collagen fibers; they provide resilience and the ability to deform and then return to normal shape. Examples are vocal cords, suspensory ligament of the penis, some ligaments of the spinal column; also present as wavy sheets in the walls of large and medium arteries

Dense Regular Connective Tissue

Features collagen fibers which are packed tightly and aligned parallel to a an applied force; This tissue type is found in tendons and ligaments, where stress is applied in a single direction; has few blood vessels, and thus takes a long time to heal from an injury

Dense Irregular Connective Tissue

Features individual bundles of collagen fibers which extend in all directions in a scattered meshwork; these bundles of collagen fibers appear in clumps throughout the tissue; provides support and resistance to stress in multiple directions

Fibrocartilage

Features numerous coarse, readily visible fibers in its extracellular matrix; fibers are arranged as irregular bundles between large chondrocytes; There is only a sparse amount of ground substance, and chondrocytes are often arranged in parallel rows; densely interwoven collagen fibers contribute to the extreme durability of this type of cartilage; found in intervertebral discs, the pubic symphysis (a pad of cartilage between the anterior parts of the pelvic bones), and the menisci (C-shaped cartilage pads) of the knee joint

Elastic Cartilage

Features numerous elastic fibers in its matrix; chondrocytes are typically closely packed and surrounded by only a small amount of extracellular matrix; fibers ensure that elastic cartilage is extremely resilient and flexible; found in epiglottis and external ear

Protein Fibers

Fibers throughout connective tissue that provide strength and support;

CONNECTIVE TISSUE PROPER

Includes those types of connective tissue that exhibit a variable mixture of both connective tissue cell types and extracellular protein fibers suspended with a viscous ground substance

Spongy Bone

Located within the interior of a bone; contains spaces, and the bone connective tissue forms a latticework structure that is very strong, yet very lightweight

Areolar Connective Tissue

Loosely organized array of collagen and elastic fibers and an abundant distribution of blood vessels; Contains all cell types but predominant cell is the fibroblast; viscous ground substance cushions shocks and loosely organized fibers ensures this type of tissue can be distorted without damage; elastic properties of it promote independent movements

The source of all Adult Connective Tissue

Mesenchyme (Stem Cells)

Elastic Fibers

Protein Fibers which are flexible and resilient; Think ____ rubber bands

Collagen Fibers

Protein Fibers which are strong and stretch-resistant; think lip injections

Reticular Fibers

Protein Fibers which form an interwoven framework; Think squiggly lines throughout

Macrophages (Fixed)

Relatively large, irregular-shaped cells with numerous surface folds and projections; the are derived from one type of leukocyte [white blood cell] (monocyte) and dispersed throughout the extracellular matrix

Resident Cells

Stationary cells that help support, maintain, and repair the extracellular matrix; examples include fibroblasts, adipocytes, fixed macrophages, and mesenchymal cells

Extracellular Matrix

The combination of the ground substance and protein fibers; with a relatively small proportion of cells

Hyaline Cartilage

The most common type of cartilage and also the weakest; the chondrocytes within their lacunae are irregularly scattered throughout the extracellular matrix; surrounded by a perichondrium; forms most of the fetal skeleton and is a model for most future bone growth; found in nose, trachea, most of the larnyx, costal cartilage (attached to the ribs), and articular ends of long bones

Connective Tissue

This tissue type includes: Tendons, ligaments, fat, bones, cartilage, and blood

SUPPORTING CONNECTIVE TISSUE

Tissues that form a strong, durable framework that protects and supports the soft body tissues; The extracellular matrix contains many protein fibers and a ground substance that ranges from solid to semisolid; in general cartilage has a semisolid extracellular matrix and bone has a solid extracellular matrix