Connective Tissues

What do all connective tissues have in common? Made up of 3 components: Specialized cells Protein fibers A fluid known as ground substance Protein fibers and ground substance= Matrix The matrix makes up most of the volume of connective tissues

3 Major Types of Connective Tissue: 1) Connective Tissue Proper 2) Fluid Connective Tissue 3) Supporting Connective Tissue

Cells of Connective Tissue Proper Fibroblasts: most abundant type; produce fibers and ground substance. Macrophages: these cells “eat” or phagocytize damaged cells or pathogens. Release chemicals that mobilize the immune system. Fat cells or adipocytes: contain large droplets of lipids (fat) Mast Cells: found near blood vessels; have vesicles filled with chemicals released to defend the body after injury/infection.

Connective Tissue Fibers: Collagen fibers: Most common type; long, straight, unbranched- Strong and flexible. Elastic fibers: contain protein Elastin. They are branched, wavy,and stretchy. Reticular fibers: least common type; thin, branched and interwoven like a web.

Ground Substance Fills the spaces between cells and surrounds the connective tissue fibers. Clear, colorless and has a maple-syrup consistency ( slows down pathogens)

Types of Connective Tissue Proper: Loose Connective Tissue Dense Connective Tissue

Loose Connective Tissue or “Areolar Tissue” “packing material of the body” Fill spaces between organs, provide cushioning, and support epithelia, anchor blood vessels and nerves, store lipids.

Adipose Tissue ( Fat) Loose connective tissue is called Adipose tissue if dominated by fat cells (adipocytes).

Dense Connective Tissues: Consists mostly of collagen fibers. Types: Tendons: attach skeletal muscles to bones Ligaments: connect bones to each other. Have some elastic fibers ( a little more stretchy than tendons).

Fluid Connective Tissues 2 Types: Blood and Lymph Contain cells in a watery matrix. Unlike other connective tissues, the proteins are dissolved in the matrix and do not form insoluble fibers.

Blood- A fluid Connective Tissue Consists of: Red blood cells: transport Oxygen(O2) White blood cells: fight infection Platelets: clot blood

Lymph- A fluid Connective Tissue Lymph: forms as interstitial fluid ( fluid within the body’s tissue) enters small passageways , or Lymphatic vessels that eventually return it to the cardiovascular system.

Supporting Connective Tissues: Includes: Cartilage and Bone Provide a strong framework that supports the body

Cartilage The matrix is a firm gel containing embedded fibers. Contains Chondrocytes: cartilage cells found within the matrix that live in small pockets called lacunae Is avascular Separated from surrounding tissues by perichondrium. 3 major types: Hyaline, Elastic, Fibrous

Hyaline Cartilage Most common type Matrix contains closely packed collagen fibers Tough but flexible. Found: between joints, connecting ribs to sternum, supporting the larynx and trachea.

Elastic Cartilage Matrix contains numerous elastic fibers Resilient and flexible Found: external flap of ear (auricle), the epiglottis, and airway to the middle ear.

Fibrous Cartilage or Fibrocartilage Matrix contains little ground substance and is dominated by collagen fibers that are densely interwoven. Tough and durable Found: pads between vertebrae, between pubic bones of pelvis.

Bone ( Osseus tissue) Matrix consists of little ground substance containing collagen fibers . It is calcified with calcium compounds Strong and resistant to shattering. Contain osteocytes( bone cells) found in lacunae Lacunae are found surrounding blood vessels . Cytoplasmic extensions from osteocytes reach blood vessels- form a network called the canaliculi

Bone Contain osteocytes( bone cells) found in lacunae Lacunae are found surrounding blood vessels . Cytoplasmic extensions from osteocytes reach blood vessels- form a network called the canaliculi (little canals) Outer layer of bone surrounded by a fibrous covering called periosteum