pcb 3703 lec 7

What are the primary organs of the skeletal system?

Bones.

What the components of the skeletal system?

Bones of skeleton, Cartilage, Ligaments , Other CT

What percentage of bone mass does compact bone make up?

80 percent.

What is another name for compact bone?

Dense or cortical bone.

What percentage of bone mass does spongy bone make up?

20 percent.

What is another name for spongy bone?

Cancellous or trabecular bone.

Where is spongy bone located relative to compact bone?

Internal to compact bone.

How does spongy bone appear structurally?

Porous.

What type of connective tissue is cartilage?

Semirigid connective tissue that is more flexible than bone.

What are the primary types of cartilage mentioned in the text?

Hyaline cartilage and fibrocartilage.

Where is hyaline cartilage found in the body?

Attaching ribs to the sternum, covering bone ends, within growth plates, and as a model for bone formation.

What is the main characteristic of fibrocartilage?

It is a weight-bearing cartilage that withstands compression.

Where are intervertebral discs, pubic symphysis, and menisci of the knee located?

They are structures composed of fibrocartilage.

What connects bone to bone?

Ligaments.

What connects muscle to bone?

Tendons.

What type of connective tissue forms ligaments and tendons?

Dense regular connective tissue.

What are the basic functions of bones?

Support and protection, levers for movement, hematopoiesis, and storage of mineral and energy reserves.

Where does hematopoiesis occur?

In red bone marrow connective tissue.

What blood cells are produced during hematopoiesis?

Blood cells.

What minerals are stored in bones?

Calcium and phosphate.

How many classes of bone are determined by shape?

Four classes.

What defines a long bone?

Greater in length than width.

Give two examples of long bones.

Femur and humerus.

What defines a short bone?

Length nearly equal to width.

Give two examples of short bones.

Carpals and tarsals.

What are the structural features of flat bones?

Flat, thin surfaces that may be slightly curved.

Give an example of flat bones.

Cranial bones.

What defines irregular bones?

Elaborate, sometimes complex shapes.

Give an example of an irregular bone.

Vertebrae.

What is the diaphysis of a long bone?

The elongated, usually cylindrical shaft.

What are the functions of the diaphysis?

Provides leverage and weight support.

What is the medullary cavity?

A hollow, cylindrical space within the diaphysis.

What does the medullary cavity contain in children?

Red bone marrow.

What does the medullary cavity contain in adults?

Yellow bone marrow.

What is the epiphysis?

The knobby region at each end of a long bone.

What is the proximal epiphysis?

The end of the bone closest to the body trunk.

What is the distal epiphysis?

The end farthest from the trunk.

What composes the outer layer of the epiphysis?

An outer thin layer of compact bone.

What composes the inner region of the epiphysis?

An inner region of spongy bone.

What covers the joint surface of an epiphysis?

Articular cartilage.

What type of cartilage is articular cartilage?

A thin layer of hyaline cartilage.

What are the functions of articular cartilage?

Reduces friction and absorbs shock in moveable joints.

What is the metaphysis?

The region where bone widens and transfers weight between the diaphysis and epiphysis.

What is located within the metaphysis for lengthwise bone growth?

The epiphyseal plate.

What is another name for the epiphyseal plate?

Growth plate.

What is the epiphyseal line?

The adult remnant of the epiphyseal plate.

What is the periosteum?

A tough sheath covering the outer surface of bone.

What tissue forms the outer fibrous layer of the periosteum?

Dense irregular connective tissue.

What are the functions of the periosteum?

Protects bone, anchors blood vessels and nerves, and serves as an attachment site for ligaments and tendons.

What cells are found in the inner cellular layer of the periosteum?

Osteoprogenitor cells, osteoblasts, and osteoclasts.

How is the periosteum attached to the bone?

By numerous collagen fibers called perforating fibers.

What is the endosteum?

A thin layer of connective tissue covering all internal surfaces of bone within the medullary cavity.

What cells are found in the endosteum?

Osteoprogenitor cells, osteoblasts, and osteoclasts.

How do short, flat, and irregular bones differ structurally from long bones?

They have an external surface of compact bone covered by periosteum and an interior of spongy bone without a medullary cavity.

What is the term for spongy bone in the flat bone of the skull?

Diploë.

What is a nutrient foramen?

A small opening or hole in bone for artery entrance and vein exit.

What type of nerves mainly supply bone?

Sensory nerves that accompany blood vessels.

What is another name for red bone marrow?

Myeloid tissue.

What type of tissue is red bone marrow?

Reticular connective tissue containing developing blood cells and adipocytes.

Where is red bone marrow located in children?

Spongy bone and medullary cavities of long bones.

Where is red bone marrow located in adults?

Selected areas of the axial skeleton like the skull, vertebrae, ribs, sternum, ossa coxae, and proximal epiphyses of the humerus and femur.

What is yellow bone marrow?

A fatty substance that is a product of red bone marrow degeneration.

When can yellow bone marrow convert back to red bone marrow?

During severe anemia.

What is bone connective tissue also known as?

Osseous connective tissue.

What are the four types of cells found in bone connective tissue?

Osteoprogenitor cells, osteoblasts, osteocytes, and osteoclasts.

What are osteoprogenitor cells derived from?

Mesenchyme stem cells.

Where are osteoprogenitor cells located?

In the periosteum and endosteum.

What cell type do osteoprogenitor cells mature to become?

Osteoblasts.

What do osteoblasts synthesize and secrete?

Osteoid.

What is osteoid?

The initial semisolid organic form of bone matrix.

What cell type do osteoblasts become when entrapped in the matrix?

Osteocytes.

What is the primary function of osteocytes?

To detect stress on bone and trigger new bone formation.

Where are osteocytes located?

In lacunae between concentric lamellae.

What are osteoclasts?

Large, multinuclear, phagocytic cells involved in bone resorption.

What are osteoclasts derived from?

Fused bone marrow cells.

What structural feature increases the surface area of osteoclasts exposed to bone?

A ruffled border.

Where are osteoclasts located during bone breakdown?

Within or adjacent to a resorption lacuna on the bone surface.

What organic component gives bone tensile strength and flexibility?

Collagen protein within the osteoid.

What inorganic salt crystals are the primary component of the bone matrix?

Calcium phosphate.

What crystal is formed when calcium phosphate interacts with calcium hydroxide?

Hydroxyapatite.

What substances account for the rigidity and hardness of bones?

Hydroxyapatite crystals deposited around collagen fibers.

What vitamin enhances calcium absorption from the gastrointestinal tract during bone formation?

Vitamin D.

What vitamin is required for collagen formation during bone production?

Vitamin C.

How do osteoclasts destroy the organic matrix during bone resorption?

By releasing proteolytic enzymes from lysosomes.

How do osteoclasts dissolve calcium and phosphate in bone matrix?

By releasing hydrochloric acid.

When does bone resorption occur in the body?

When blood calcium levels are low.

What is the basic functional and structural unit of mature compact bone?

An osteon or Haversian system.

What is found at the center of an osteon running parallel to it?

The central or Haversian canal.

What extends through the central canal of an osteon?

Blood vessels and nerves.

What are concentric lamellae?

Rings of bone connective tissue surrounding the central canal.

What are canaliculi?

Tiny, interconnecting channels within bone connective tissue that house osteocyte projections.

What is the function of canaliculi?

To allow exchange of nutrients, minerals, gases, and wastes between blood vessels and osteocytes.

What canals connect central canals of different osteons perpendicularly?

Perforating or Volkmann canals.

What are interstitial lamellae?

Components of compact bone located between osteons or as partially resorbed osteons.

What are trabeculae in spongy bone?

An open lattice of narrow rods and plates of bone.

What fills the spaces between trabeculae in spongy bone?

Bone marrow.

What cells produce the cartilage matrix?

Chondroblasts.

What are chondrocytes?

Chondroblasts encased within the cartilage matrix occupying lacunae.

What is the perichondrium?

A dense irregular connective tissue covering cartilage and helping maintain its shape.

Is hyaline cartilage vascular or avascular?

Avascular.