Connective Tissue Types

Prominent Cell Types of Connective Tissue

1. Chondrocytes/Chondroblasts: cartilage cells, only in the matrix of the lacunae chamber. 2. Osteocytes: bone cells, also in the lacunae, can communicate with blood vessels using the canaliculi. 3. Blood Cells: Erythrocytes: red blood cells. Leukocytes: white blood cells. 4. Fibroblasts: most common in connective tissue. Secretions form extracellular matrix and forms collagen. ALSO: 5. Adipocyte: fat cells, huge lipid droplet, nucleus, organelles, cytoplasm pushed aside. 6. Lymphocytes: migratory cell, uses blood stream for transport, increase when damage occurs, type of white blood cell. 7. Plasma Cell: produce antibodies (proteins involving in defending the body). 8. Mast Cell: small, mobile connective tissue, responsible for inflammation in allergic response, can see histimine. 9. Melanocyte: synthesize and store pigment melanin. Common in epithelium. 10. Macrophages: large phagocytic cells, scattered, scavangers, the frontline of defense. Rally around the pathogen, alert the immune system of intruder. 11. Mesenchymal Cells: stem cells, respond to injury/infection by dividing the produce differentiated daughter cells. Give rise to all other connective tissues.

Cartilage: Hyaline

Amorphous but firm matrix, collagen fibers form an imperceptible network, chondroblasts produce the matrix and when mature, chondrocytes lie in lacunae. Function: Supports and reinforces, serves as resilient cushion, resists compressive stress. Location: Forms most of embryonic skeleton, covers the ends of long bones in joint cavaties, forms costal cartilages of the ribs, cartilages of nose, trachea, and larynx.

Connective Tissue

Binds, supports, and connects the others (cardiac, skeletal, muscle). Organs contain all four types of tissue (connective, muscle, nervous, and epithelium).

Dense Connective Tissue Elastic

Dense regular connective tissue containing a high proportion of elastic fibers. Function: Allow recoil of tissue following stretching, maintains pulsatile flow of blood through arteries, aids in passive recoil of lungs and following inspiration. Location: Walls of large arteries, with in certain ligaments associated with the vertebral column, within the walls of the bronchial tubes.

Mesenchymal

Embryonic connective tissue, gel-like ground substance containing fibers , star shaped mesenchymal cells. Function: Give rise to all other connective tissues. Location: Embryo.

Ground Substance

Fluid, gel-like jelly that surrounds cells, in between fibers and cells.

Loose Connective Tissue Areolar

Gel-like matrix with all three fiber types. Cell types: fibroblasts, macrophages, mast cells, some white blood cells. Function: Wraps and cushions organs, plays role in inflammation, holds tissue fluid. Location: Widely distributed under epithelium, packages organs, surrounds capillaries.

Osseous Tissue: Bones

Hard, calcified matrix containing many collagen fibers, osteocytes lie in lacunae. Very well vascularized. Function: Bone supports and protects (by enclosing), provides levers for the muscles to act on, stores calcium and other minerals and fat, marrow inside bones is the site for blood cell formation (hematopoiesis). Location: Ya bones.

Cartilage: Fibrocartilage

Matrix similar to but less firm than that of hyaline cartilage, thick collagen fibers predominate. Function: Tensile strength with the ability to absorb compressive shock. Location: Intervertebral discs, pubic symphysis, discs of knee joint.

Loose Connective Tissue Reticular

Network of reticular fibers in typical loose ground substance, reticular cells lie on the network. Function: Fibers form a soft internal skeleton (stroma) that supports other cell types (white blood cells, mast cells, and macrophages). Location: Lymphoid organs (nodes, bone marrow, and spleen).

Dense Connective Tissue Irregular

Primarily irregularly arranged collagen fibers, some elastic fibers, major cell type is fibroblast. Function: Able to withstand tension exerted in many directions, provides structural strength. Location: Fibrous capsules of organs and of joints, dermis of skin, submucosa of digestive tract.

Dense Connective Tissue Regular

Primarily parallel collagen fibers, few elastic fibers, major cell type is fibroblast. Function: Attaches muscle to bone or muscle to muscule, attaches bone to bone, withstands great tensile stress while pulling force is applied in one direction. Location: Tendon, most ligament, aponeuroses (whatever that is.).

Blood

Red and white blood cells in a fluid matrix (plasma). Function: Transport of respiratory gases, nutrients, wastes, and other substances. Location: Contained within blood vessels.

Cartilage: Elastic

Similar to hyaline cartilage, but more elastic fibers in matrix. Function: Maintains the shape of a structure while allowing great flexibility. Location: Supports external ear (auricle), epiglottis.

Loose Connective Tissue Adipose

Sparse matrix, closely packed adipocytes (fat cell), nucleus pushed aside by large fat vacuole. Function: Provides reserve fuel, insulates against heat loss, supports and protects organs. Location: Under skin, around kidneys and eyeballs, with in abdomen, in breasts (duh!)