Skeletal System Flashcards
Skeletal system
An organ system
Consists of bones, cartilage, tendons( muscle to bone) and ligaments (bone to bone)
Functions of skeletal system
•Protection
•mineral storage and homeostasis
•Hematopoiesis (in red bone marrow) formation of blood cells
• Fat Storage( in yellow bone marrow)
• Movement
• support
Classifications of Bones by shape
Long, short, flat, irregular, Sesamoid
Long bone
Longer than wide; knobby ends
Found in arms & legs; fingers & toes
Short bone
About equal length & width; rock shaped
Found in wrists and ankles
Flat Bone
Thin, may be curved
Found in skull, rib cage & hips
Irregular bone
Comped shape; don’t fit other categories
Ex: vertebrae, ethmoid& sphenoid bones(skull)
Sesamoid bone
Looks like a short bone
Form in tendons in response to mechanical stress
Ex: patella (kneecap)
Diaphysis of long bone
Bone shaft (long middle part)
Epiphysis of long bone
Knobby ends
Articular Carttilage of long bone
Caps the ends
Epiphyseal line of long bone
Remnants of growth plate (epiphyseal plate)
Bone texture of long bone
Compact/ solid
Spongy
Medullary cavity of long bone
Hollow middle; contains red bone marrow (children) or yellow bone marrow (adults)
Endosteum of long bone
Inner lining of bone
Periosteum of long bone
Tough outer covering of bone
Bone remodeling
20% of skeleton is replaced each year
In healthy adult bone, osteoblasts and osteoclast work at the same rate.
Conditions that tip the balance of bone remodeling
Mechanical stress, hormones, and diet
Bone cells
Osteoblasts, osteocytes, osteoclastS
Osteoblast
Build bone- becomes trapped➡️ become osteocytes
Osteocytes
Mature bone cells
Formally osteoblasts
Osteoclasts
Breakdown bone
Osteon
Basic unit of compact bone
Looks like tree trunk
Central canal
How’s his blood vessels and nerves: parallel to length of bone
Lamellae
Layers of solid bone around central canal
Looks like rings of tree truck
Osteocytes
Mature bone cells
Looks like roaches
Lacunae
Pockets that the osteocytes sit in
Canaliculi
Canals that the osteocytes project cellular extensions (“arms”) through for communication and diffusion of nutrients.
Perforating Canal
Houses, blood vessels and nerves perpendicular to the length of the bone
Spongy bone structure
No osteons
Trabeculae structure; trabecular= solid part of “sponge”
Still has osteocytes in lacunae
Bone marrow fills open space in “sponge”
Always surrounds around the compact bone
Cartilage CT Components
- Cells - chondroblasts(build cartilage) chondrocytes (mature cartilage cells)
- Protein fibers: collagen &/or elastic
- Ground substance: rubbery
Hyaline cartilage
(Firm/strong)
Articular cartilage (end of long bones)
Costal cartilage (rib cage)
Fetal skeleton and growth plates
Nose
Trachea (windpipes)
Fibrocartilage
(Weight bearing)
Intervertebral discs
Pubic symphysis
Meniscus (knee)
Elastic Cartilage
(Springy)
Ear
Epiglottis (part of voice box)
Bone formation
Called Ossification or osteogenesis
Begins in embryo @8-12 wks
Completed by age 7
Two types of ossification
Intramembranous ossification- forms flat bones of skull &clavicle
Endochondral ossification- forms all bones below head (expect clavicle)
Interstitial Growth
Bone growth in length
- epiphyseal plates (childhood)
Appositional growth
Bone growth in width (adulthood)
Influenced by several factors.
