What does the Function of Bone tissue mean:

Storage

fat stored in the interior of the bones. Bone matrix serves as a storehouse for various minerals (calcium, phosphate)

What does the Function of Bone tissue mean:

Blood Cell Formation

hematopoiesis occurs within the marrow cavities of the bones.

Bones can be classified by the two types of osseous tissue.

compact & spongy bone

What is Compact bone?

dense and looks smooth and homogeneous

What is Spongy bone?

(cancellous bone) is composed of small needlelike or flat pieces of bone called trabeculae and has much open space. The trabeculae form an open network which is filled with bone marrow.

\What are the shape classifications for bone?

The shapes are long, short, flat, and irregular.

What are Long bones?

Long bones: Longer than they are wide. Reflects the elongated shape rather than the overall size. Consist of a shaft plus two ends and are constructed primarily of compact bone, but may contain substantial amounts of spongy bone. All bones of the limbs, except the patella, wrist and ankle bones, are long bones.

What are short bones?

Short bones: Roughly cubelike, containing mostly spongy bone. Comprise bones of the wrist and ankle. Vary in size and number in different individuals.

What are flat bones?

Flat bones: Thin, flattened, and usually a bit curved, they have two roughly parallel compact bone surfaces, with a layer of spongy bone (diploe) between. Examples include the sternum, ribs, and most of the skull bones.

What are irregular bones?

Irregular bones: Fit none of the previous classes. Include some skull bones, vertebrae, and hip bones. Have complicated shapes and consist mainly of spongy bone enclosed by thin layers of compact bone.

Where is Hematopoietic Tissue located?

Red marrow (blood forming tissue) is found in the trabecular cavities in long bones (especially the head of the femur and humerus) and in the diploe of flat bones (especially the sternum).

Diaphysis is?

"shaft" which constitutes the long axis of the bone. Constructed of a thick collar of compact bone that surrounds a cavity. The medulla cavity in adults contains fat (yellow marrow).

Epiphyses is?

"ends" or extremities. They are usually more expanded than the diaphyses. A thin layer of compact bone forms the exterior and the interior contains spongy bone.

Epiphyseal plate is?

In young bones, cartilage is present at the junction of the diaphysis and epiphysis. This is the growth area that allows bones to lengthen.

Epiphyseal line is?

remnant of the epiphyseal plate. After puberty the cartilage of the epiphyseal plate is converted to bone and no further growth is possible.

Periosteum is?

the outer surface of the diaphysis which is covered and protected by a double layered membrane. Provides an insertion or anchoring point for tendons and ligaments. It is secured to the bone by perforating (Sharpey’s) fibers which are made of collagen.

Endosteum is?

internal bone surfaces are covered with a delicate connective tissue membrane. Covers the trabeculae of spongy bone in the narrow cavities and lines the canals that pass through the compact bone.

Articular Cartilage is?

where long bones articulate at epiphyseal surfaces, the bony surfaces are covered with articular (hyaline) cartilage which cushions the bone ends and absorbs stress during joint movement.

Both of these membranes periosteum and endosteum are composed of which types of cells? (3)

osteogenic cells (give rise to osteoblasts), osteoblasts (bone forming cells), and osteoclasts (bone destroying cells)

Describe the design of all other bones besides long bones?

The other bones share a simple design. They consist of thin plates of periosteum-covered compact bone on the outside and endosteum covered spongy bone (diploe) within. They have no shaft or epiphyses.

What is the structural unit of compact bone is called the?

osteon or Haversian system.

What is a lamellae?

hollow tubes of bone matrix, one placed inside the next.

What are Interstitial lamellae?

incomplete ones

What are Circumferential lamellae and where are they found?

They are found next to the periosteum and extend around the entire circumference of the bone to help the bone resist twisting.

Running through the core of each osteon is a?

central or Haversian canal

Running a right angles to the long axis are?

perforating or Volkmann's canals

What is the purpose of Volkmann's canals?

They connect the vascular and nerve supplies of the periosteum to those in the central canals and medullary cavity.

What are lacunae?

hollowed-out spaces where osteocytes live

Canaliculi are?

little canals that interconnect the lacunae and the big canals and allow passage of nutrients through bone to get to the cells

Osteocytes function to?

maintain the bone matrix and to monitor stress on bones in order to direct bone remodeling

Describe spongy bone

Consists of trabeculae which are positioned where the bone is stressed. Only a few layers thick, the trabeculae contain irregularly arranged lamellae and osteocytes interconnected by canaliculi. No osteons are present.

Describe the chemical composition of bone.

Bone is made of both organic and inorganic components. The organic components consist of cells and the osteoid (organic part of the matrix, made of ground substance and collagen). The osteoid makes up 1/3 of the matrix, which contributes to the bone's structure, flexibility and tensile strength. The inorganic components consist of hydroxyapatites (mineral salts), largely calcium phosphate. Calcium salts are present in the form of tiny crystals, which accounts for bones hardness.

ossification is?

The process in which cartilage becomes bone

What cartilage remains after ossification?

hyaline cartilage (covers ends of bones at movable joints, connect ribs to sternum, forms larynx, supports external nose), elastic cartilage (external ear, epiglottis), and fibrocartilage (knee menisci, intervertebral disks).

What happens during Intramembranous Ossification?

• Bone develops from fibrous membranes
• Mostly in flat bones (cranial bones) and clavicle
• Osteoid is laid down in a random manner between embryonic blood vessels, giving rise to trabeculae
• Outer edges become compact bone

What happens during Endochondral Ossification?

• Bone develops by replacing hyaline cartilage
• First the perichondrium becomes periosteum.
• Next a bone collar forms around the hyaline cartilage model of the future bone in the area of the diaphysis.
• Then cartilage in the center calcifies and develops cavities.
• A periosteal bud (consists of artery, vein, lymphatic vessels, nerve fibers, red marrow, osteoblasts, and osteoclasts) invades the internal cavities and spongy bone forms.
• The diaphysis elongates and medullary cavity forms. Cartilage continues to be ossified.
• Secondary ossification centers formed in the epiphyses.
• Epiphyses then ossify. The only remaining hyaline cartilage is the epiphyseal plate and articular cartilage.

What is Interstitial Growth?

Growth of the bone at the epiphyseal plate. New hyaline cartilage is laid down on the epiphyseal-facing side and is subsequently ossified on the diaphysis-facing side.

What is Appositional Growth?

Osteoblasts beneath the periosteum secrete bone matrix on the external bone surface as osteoclasts on the endosteal surface remove bone (but more is built up than is broken down).

What do osteogenic cells do?

Give rise to osteoblasts

What do osteoblasts do?

Form bone cells

What do osteoclasts do?

destroy bone cells

Bone deposition happens when?

bone is injured or added strength is required. This osteoblast activity needs a diet containing protein, vitamins (C, D, A) and minerals (Ca, P, Mg, Mn).

Bone resorption happens when?

osteoclasts digest the organic matrix of bone and convert calcium salts into soluble form that passes easily into solution, eventually to the blood.

Describe these bone markings that are the site of muscle and ligament attachment:

Tuberosity,Crest, Trochanter:

Tuberosity: large rounded projection

Crest: narrow ridge of bone, usually prominent

Trochanter: very large, blunt, irregularly shaped process

Describe these bone markings that are the site of muscle and ligament attachment:

Tubercle, Epicondyle, Spine

Tubercle: small rounded projection or process

Epicondyle: raised area on or above a condyle

Spine: sharp, slender, often pointed projection

Describe these projections that help form joints:

Head, condyle, ramus

Head: bony expansion carried on a narrow neck

Condyle: rounded articular projection

Ramus: arm-like bar of bone

Describe these Depressions and openings:

Meatus, Sinus, Fossa,

Meatus: canal-like passageway

Sinus: cavity within a bone, filled with air and lined with mucous membrane

Fossa: shallow basin-like depression in a bone often serving as an articular surface

Describe these Depressions and openings:

Fissure, Foramen

Fissure: narrow, slit-like opening

Foramen: round or oval opening through a bone

Steps of fracture repair?

Hematoma Formation, fibrocartilaginous callus formation, Bony callous Formation, remodeling

Describe these types of fractures

simple, compound, comminuted, compression

simple - bone breaks cleanly, does not penetrate the skin

compound - broken ends of bone protrude through skin

comminuted - bone fragments into many pieces

compression - bone is crushed

Describe these types of fractures:

depressed, impacted, spiral, greenstick

depressed - broken bone portion is pressed inward

impacted - broken bone ends are forced into each other

spiral - ragged break occurring when excessive twisting forces are applied to bone

greenstick - bone breaks incompletely similar to a green twig

What happens during Hematoma formation?

A mass of clotted blood forms at fracture site. Bone cells begin to die and tissue becomes swollen, painful, and inflamed.

What happens during Fibrocartilaginous callus formation

Capillaries grow into the area and macrophages clean up debris. Fibroblasts and osteoblasts migrate to the area and begin reconstructing bone. Fibroblasts produce collagen fibers that begin to connect broken ends. Some fibroblasts become chondroblasts which make cartilage. Osteoblasts begin forming spongy bone. All of the repair tissue at this stage is called the fibrocartilage callus.

What happens during Bony callus formation?

The fibrocartilage callus is converted to a hard bony callus of spongy bone by the action of the osteoblasts and osteoclasts. This begins 3-4 weeks post injury and continues until a firm union forms 2-3 months later.

What happens during Remodeling?

During bony callus formation and the following several months remodeling occurs. Excess material outside the shaft is removed and compact bone is laid down to reconstruct the shaft. The final structure will resemble unbroken bone because it is under the same set of mechanical stimuli.