Connective Tissue

What are the three basic components of connective tissue?

Specialized cells, extracellular protein fibers, and ground substance.

What are the three types of loose connective tissue?

Areolar, adipose, and reticular.

What are the three types of dense connective tissue?

Dense regular, dense irregular, and elastic.

What are the three types of cartilage?

Hyaline, elastic, and fibrocartilage.

What is the structure of areolar connective tissue?

Loose mesh of collagen, elastic, and reticular fibers, ground substance, fibroblasts, and immune cells.

What are the characteristics of areolar tissue?

Soft, flexible, well vascularized, with spaces between fibers.

What are the functions of areolar tissue?

Holds tissues together, cushions organs, supports vessels and nerves, and helps defend against infection.

Where is areolar connective tissue found?

Under skin, around organs, blood vessels and nerves, and between muscles.

Which tissue allows blood vessels and nerves to pass through?

Areolar connective tissue.

What is the structure of adipose tissue?

Tightly packed adipocytes with lipid droplets that push the nucleus toward the edge.

What are the main characteristics of adipose tissue?

Tightly packed cells and a rich blood supply.

What are the three functions of adipose tissue?

Stores energy as triglycerides, cushions organs, and insulates the body.

Where is adipose tissue found?

Under skin, around heart and kidneys, abdomen, neck, chest, and bone marrow.

What is white adipose tissue?

Most common fat tissue; one large lipid droplet per cell; stores energy.

What is brown adipose tissue?

Fat tissue with many small lipid droplets and mitochondria; produces heat.

What is beige adipose tissue?

White-like fat cells that can develop heat-producing properties under certain stimuli.

What does unilocular mean?

One large lipid droplet inside a cell.

What does multilocular mean?

Many small lipid droplets inside a cell.

What is the structure of reticular connective tissue?

Thin branching reticular fibers and reticular cells forming a supportive mesh.

What are the characteristics of reticular tissue?

Delicate, interwoven fibers forming a netlike structure.

What are the functions of reticular connective tissue?

Supports soft organs, forms their framework, and helps trap foreign particles.

Where is reticular connective tissue found?

Lymph nodes, spleen, bone marrow, and liver.

What is the stroma?

The supportive framework of cells and fibers inside an organ.

What is dense connective tissue?

Connective tissue with densely packed fibers providing strength and support.

What is the structure of dense regular tissue?

Thick, parallel collagen fibers with fibroblasts squeezed between them.

What is the main function of dense regular tissue?

Resists pulling forces in one direction and forms strong connections.

Where is dense regular connective tissue found?

Tendons and ligaments.

What is the difference between tendons and ligaments?

Tendons connect muscle to bone; ligaments connect bone to bone.

Why does dense regular tissue heal slowly?

It is poorly vascularized, meaning it has a limited blood supply.

What is the structure of dense irregular tissue?

Thick collagen bundles arranged in many directions with scattered fibroblasts.

What is the function of dense irregular tissue?

Resists stress from many directions and forms protective organ capsules.

Where is dense irregular connective tissue found?

Dermis of skin and capsules around kidneys, liver, and spleen.

How do dense regular and dense irregular tissue differ?

Regular has parallel fibers resisting pulling in one direction; irregular has fibers arranged in many directions.

What is the structure of elastic connective tissue?

Long branching elastin fibers with fibroblasts scattered throughout.

What are the functions of elastic connective tissue?

Allows stretching, recoil, and repeated expansion and contraction.

Where is elastic connective tissue found?

Large arteries, especially the aorta, and certain elastic structures of the respiratory tract and vocal cords.

What does recoil mean?

Returning to the original shape after stretching.

What are the general characteristics of cartilage?

Firm but flexible, avascular, with chondrocytes surrounded by matrix.

Why does cartilage heal slowly?

It is avascular, meaning it has no blood vessels.

What are chondrocytes?

The living cells found in cartilage.

What are lacunae?

Small spaces in the matrix that contain cartilage or bone cells.

What are the characteristics of hyaline cartilage?

Smooth, glassy matrix, fine collagen fibers, and chondrocytes in lacunae.

What are the functions of hyaline cartilage?

Reduces joint friction, absorbs shock, supports airways, and helps bone growth.

Where is hyaline cartilage found?

Ends of bones at joints, rib connections, trachea, larynx, and growth plates.

What is articular cartilage?

Hyaline cartilage covering bone ends at joints to reduce friction.

What is costal cartilage?

Hyaline cartilage connecting ribs to the sternum.

What are the characteristics of elastic cartilage?

Many elastic fibers, chondrocytes in lacunae, and a flexible matrix.

What are the functions of elastic cartilage?

Provides flexible support, bends without breaking, and returns to its shape.

Where is elastic cartilage found?

External ear (pinna) and epiglottis.

What does the epiglottis do?

Helps keep food and liquid out of the airway during swallowing.

What are the characteristics of fibrocartilage?

Thick collagen fibers, chondrocytes in rows, and a strong matrix.

What are the functions of fibrocartilage?

Absorbs shock and resists compression, tension, and pulling.

Where is fibrocartilage found?

Intervertebral discs, pubic symphysis, and knee menisci.

Which type of cartilage is the strongest?

Fibrocartilage.

Which cartilage is the most common?

Hyaline cartilage.

Which cartilage is the most flexible?

Elastic cartilage.

What is bone (osseous) tissue?

Specialized, living connective tissue with a hard mineralized matrix.

What are the main characteristics of bone tissue?

Hard, strong, living, vascular, and constantly renewed.

What are the six main functions of bone?

Support, fat storage, protection, movement, blood cell production, and mineral storage.

What is the structure of bone tissue?

Bone cells surrounded by a matrix of collagen fibers and mineral crystals.

What are osteoblasts?

Bone-building cells that produce new bone matrix.

Where are osteoblasts found?

On bone surfaces where new bone is being formed.

What are osteocytes?

Mature bone cells that maintain bone tissue and sense stress.

Where are osteocytes found?

Inside lacunae within the bone matrix.

What are osteoclasts?

Cells that break down and resorb bone during remodeling.

Where are osteoclasts found?

On bone surfaces where bone is being broken down.

What are bone lining cells?

Cells covering inactive bone surfaces and helping regulate the surface.

What is the bone matrix?

Material surrounding bone cells, made of organic and inorganic components.

What is the organic part of bone matrix?

Collagen fibers and proteins that provide flexibility and resist pulling.

What is the inorganic part of bone matrix?

Minerals, especially hydroxyapatite, providing hardness and strength.

What is hydroxyapatite?

Calcium-phosphate mineral crystals that harden bone.

What is the difference between collagen and minerals in bone?

Collagen adds flexibility; minerals add hardness.

What is compact bone?

Dense, solid bone organized into osteons, providing strength and protection.

Where is compact bone located?

Outer layer of bones and much of the shaft of long bones.

What are osteons?

Cylinder-shaped structural units of compact bone.

What is spongy bone?

Lightweight, porous bone made of trabeculae with open spaces.

Where is spongy bone located?

Inside bones, including the ends of long bones.

What are trabeculae?

Thin plates or rods forming the framework of spongy bone.

What is the difference between compact and spongy bone?

Compact is dense and solid; spongy is porous and lightweight.

What is the function of red bone marrow?

Produces red blood cells, white blood cells, and platelets.

What is the function of yellow bone marrow?

Stores fat.

What is ossification (osteogenesis)?

The process of forming bone tissue.

What does vascular mean?

Having a blood supply.

What does avascular mean?

Having no blood vessels.

Which connective tissue has parallel collagen fibers?

Dense regular connective tissue.

Which connective tissue resists stress in multiple directions?

Dense irregular connective tissue.

Which connective tissue forms a supportive net in soft organs?

Reticular connective tissue.

Which connective tissue allows the aorta to stretch and recoil?

Elastic connective tissue.

Which connective tissue cushions organs and stores triglycerides?

Adipose connective tissue.

Which cartilage is found in intervertebral discs?

Fibrocartilage.

Which cartilage is found in the external ear?

Elastic cartilage.

Which cartilage covers the ends of bones at joints?

Hyaline cartilage.

What are fibroblasts?

Cells that produce fibers and ground substance in connective tissue proper.

What are adipocytes?

Fat-storing cells found in adipose tissue.

What are the three types of connective tissue fibers?

Collagen, elastic, and reticular fibers.

What is the function of collagen fibers?

Provide strength and resist pulling forces.

What is the function of elastic fibers?

Allow tissues to stretch and recoil.

What is the function of reticular fibers?

Form a delicate supporting network in soft organs.

What is ground substance?

Gel-like material filling spaces between connective tissue cells and fibers.

Why is areolar tissue called packing material?

It wraps and cushions organs and holds tissue fluid.