The Skeletal System Chapters 6, 7 & 8

A set of vocabulary flashcards covering the key terms and concepts from the Skeletal System lectures.

Skeletal System

• the body system consisting of bones, cartilage, and ligaments that provide support and protection.

Bone

• A connective tissue with a hard, mineralized extracellular matrix that supports, protects, aids in movement, stores minerals, and houses bone marrow.

• support

• protection

• assistance in movements

• mineral homeostasis

• blood cell production (hemopoiesis)

• triglyceride storage

Functions of the Skeletal System:

support & assistance in movements 

• structural framework of the body - soft tissues & attachment issues

protection

• internal organs - skull-brain & ribs-thoracic organs

Mineral Homeostasis

• The process by which bones store calcium and phosphorus and release minerals into the bloodstream.

Blood Cell Production (Hemopoiesis)

• red bone marrow produces RBC’s, WBC’s, platelets

Triglyceride Storage

• yellow bone marrow fat for energy

• Diaphysis

• Epiphyses

• Metaphyses

• Articular Cartilage

• Periosteum

• Medullary Cavity

• Endosteum

Structure of Bone - Long Bone Anatomy: 

Diaphysis

• bone shaft, long, cylindrical portion

Epiphyses

• proximal & distal ends of long bones 

Metaphyses

• region between diaphysis & epiphysis

• contains Epiphyseal state (growth plate) in growing bones

• Epiphyseal line in adults

Articular Cartilage

• Hyaline cartiage covering epiphysis at joints

• reduces friction & absorb shock

periosteum

• tough connective tissue sheath covering bone

• protects bone

• allows appositional growth & attachment point

• perforating fibers or sharpey’s fibers

medullary cavity

• hollow, cylindrical space in diaphysis

• contains yellow bone marrow

endosteum

• thin membrane lining medullary cavity

• osteogenic cells “producing”

• osteoblasts

• osteocytes

• osteoclasts

Histology of Bone Tissue: Bone Cells

Osteogenic Cells “producing”

• stem cells derived from mesenchyme

• only bone cells that undergo cell division

• bone-building

• secrete collagen fibers

• initiate calcification

Osteoblasts

• Bone-building cells that secrete collagen fibers and initiate the calcification process in bone.

Osteoclasts

• Cells responsible for the breakdown of bone (resorption) and the regulation of blood calcium levels.

osteoBlasts Build bone, while osteoClasts Carve out bone

• mnemonic: “BBCC”

extracellular matrix

• water (15%), collagen fibers (30%), crystallize mineral salts (55%)

collagen fibers

• provide tensile strength 

crystallize mineral salts

• mainly calcium phosphate → hydroxyapatite

• provide hardness

Compact Bone Tissue

• contains osteons (Haversian systems)

• composes of central cancal, concentric lamellae, lacunae, and canaliculi

• strongest form of bone

• makes up: diaphyses of long bone & outer layer of all bones 

Spongy Bone

• Also known as trabecular or cancellous bone tissue

• it contains trabeculae

• houses red bone marrow

• no osteons

• found in: epiphyses of long bones & flat bones (sternum, hip bone)

1. initial formation of bones in an embryo and fetus

2. growth of bones during infancy, childhood, and adolescence

3. remodeling of bone

4. repair of fractures

• 4 principal situations in ossification:

• intramembranous ossification

• endochondrial ossification

initial formation of bones in an embryo & fetus:

Intramembranous Ossification

• simpler of two methods

• occurs in: flat skull bones, mandible & clavicle

1. development of ossification center

2. calcification

3. formation of trabeculae

steps of Intramembranous Ossification:

Endochondrial Ossification

The method of bone formation that involves the replacement of cartilage with bone.

Hemopoiesis

The production of blood cells, primarily in the red bone marrow.

Calcium Homeostasis

The regulation of calcium levels in the body, primarily through hormones such as parathyroid hormone and calcitonin.

Fracture

Any break in a bone, classified into types such as open, closed, comminuted, and greenstick fractures.

Appositional Growth

Growth in thickness, where osteoblasts in the periosteum deposit new bone on the outer surface.

Hyoid Bone

A U-shaped bone in the neck that supports the tongue and is unique as it does not articulate directly with other bones.

Vertebral Column

The spine consisting of 26 vertebrae that provides support and protection for the spinal cord.

Axial Skeleton

The part of the skeletal system that forms the longitudinal axis of the body, comprising 80 bones.

Appendicular Skeleton

The portion of the skeletal system consisting of the bones of the upper and lower limbs, as well as the girdles.

Sutures

Immovable joints that hold most skull bones together, providing a protective structure for the brain.

Fontanels

Soft spots on an infant's skull where the cranial bones have not yet fused.

Pelvic Girdle

The structure formed by the hip bones that connects the vertebral column to the lower limbs.

Long Bones

Bones that are longer than they are wide, containing a diaphysis and epiphyses.