Topic 5: Bones and Skeletal Tissues

What is the skeletal system made up of?

Bones, Cartilages, and Jooint

What does the bone provide?

Support of shape to body, attachment sites for muscles, and a storage depot for essential minerals

What is Cartilage

It is a component of joints, and it aids in support and movement by cushioning connecting bone surfaces

Define Perichondrium

A type of dense irregular CT that holds back the bulging when articulation is compressed

Define Hyaline Cartilage

It is a thick sugary ground substance that holds lots of water

Define Fibrocartilage

It is a cartilage that resists both strong compression and strong tension forces, ground substance is thick collagen fibers

How does cartilaginous structures grow?

Two ways; Appositional growth, Interstitial growth

What is Appositional growth?

It is when chondroblasts in perichondrium produce new cartilage material by actively secreting matrix

What is Interstitial growth?

It is when chondrocytes in cartilage divide and secrete new matrix

What are some of the following functions that bones do?

Support, Movement, Protection, Mineral Storage, Blood cell formation and energy storage, Energy metabolism

What are the different types of bones (shapes)?

Long Bones, Short Bones, Flat Bones, Irregular bones

What are the internal types that makes up every bone in the skeleton?

Compact bone and Spongey bone

What is compact bone?

The dense outer layer of most bones; looks smooth and solid to the naked eye

What is Spongey bone?

internal layer of most bones; open spaces between network of trabeculae are filled with red or yellow bone marrow

Define trabeculae

Honeycomb of small needle-like or flat pieces of bone

What is the general structure of long bones?

Diaphysis, Epiphyses, Articular cartilage, and Epiphyseal line, Medullary cavity (filled with yellow bone marrow)

What is the membrane that is covering the typical long bone called?

Periosteum

What does long bones contain within the bone?

Osteoblasts and osteoclasts

What is the membrane that covers the inner surfaces of the long bone?

Endosteum

Within the compact bone what is it compromised of?

Osteons, Lamella, central canal, perforating canals, osteocytes, circumferential lamellae

What are Osteons?

Long, cylindrical structures parallel to long axis of the bone (think oval shaped)

What is a lamella?

A group of concentric tubes

What is the central canal?

It is canal that contains blood vessels and nerves (lined with endosteum)

What are perforating canals?

It is a canal that connects blood flow between central canals, and periosteum and inner bone (canal within)

What are osteocytes?

They are within the small cavities of the solid matrix that is connected by a canaliculi

What is the circumferential lamellae?

It wraps around the entire outer surface of the bone (additional large cylinder layers)

What does the spongey bone contain from inside the bone?

Bone marrow, has no medullary cavity

What is a projection?

Attachment sites for muscle and ligaments

What is a surface that form joints?

Articulating surfaces

What are depressions and openings?

Passageway of vessels and nerves

What are two ways that bone can develop?

Intramembranous ossification and endochondral ossification

What is intramembranous ossification?

It is when the skull bones and clavicles develop in a layer of fibrous CT with mesenchyme cells that directly convert into bone cells

Skull bones and clavicles are mostly what?

They are mostly spongey bone that is surrounded by compact bone

What is Endochondral ossification?

Other bones in the body develop in a scaffold of hyaline cartilage

What also results from the endochondral ossification too?

Articular cartilages and epiphyseal plates

What are the “zones” of the epiphyseal plate?

Resting Zone, Proliferation Zone, Hypertrophic Zone, Calcification Zone, and Ossification Zone

What happens in the Proliferation zone of the epiphyseal plate?

Cartilage cells undergo mitosis (chondrocytes)

What happens in the Hypertrophic zone of the epiphyseal plate?

Older cartilage cells enlarge

What happens in the Calcification zone of the epiphyseal plate?

It is when Matrix becomes calcified; cartilage cells die; matrix begins deteriorating

What happens in the Ossification zone of the epiphyseal plate?

New bone is forming

Which cells are being removed and replaced in bone remodeling?

Osteoclasts and Osteoblasts (within the endosteum)

What are the different types of bone fractures?

Simple and compound fractures

Explain Simple fractures

It is when bone breaks cleanly but does not penetrate skin

Explain Compound fractures

It is when broken ends of bone puncture through skin

Explain the repair of bone fractures

It is when blood vessels break and the bone releases blood that clots which forms a hematoma, then fibrocartilaginous callus forms, then the bony callus forms and finally bone remolding occurs.

What is Endochondral ossification?

It is when new spongey bone is formed within cartilage

What are Joints or Articulations

Rigid ends of skeletal bones meeting at sites

What are the functional classifications of joints?

Synarthroses, Amphiarthroses, Diarthroses

What is the Structural classification of joints?

Fibrous, Cartilaginous, Synovial

What is Synarthroses?

They are immovable joints

What is Amphiarthroses?

They are slightly movable joints

What are diarthroses?

They are freely moveable joints

What are fibrous joints?

They are bones that are connected by Dense Reg. CT (have no joint cavity, and most are immovable or slightly movable)

What are some examples of fibrous joints?

Sutures, and ligament bindings

What are cartilaginous joints?

They are bines connected by cartilage CT (no joint cavity present, and NOT highly movable)

What are some examples of Cartilaginous joints?

Epiphyseal plate, rib-sternum cartilage, intervertebral discs

What are Synovial joints?

They are the MOST moveable type of joint, and contains a synovial fluid

What is the synovial fluid called?

Joint Cavity

What is articular capsule

It is a cavity bound by articular cartilage of bone ends, and by layers of tissue that forms

What are Synovial joints doing?

They are innervated, so the nerves detect pain on injury, but also signal stretching of joint