Skeletal System and Bone Tissue Flashcards
The skeletal system consists of:
- Bone
- Cartilage
- Ligaments
- Tendons
5 functions of the Skeletal System
- SUPPORT the body
- PROTECT soft organs
- MOVEMENT
- **STORAGE **of minerals and fats
- **BLOOD **cell formation
of bones in the skeleton
206
Axial skeleton consists of:
Skull, vertebral column, and rib cage
Appendicular skeleton consists of:
- Bones of the upper and lower limbs
- Pectoral and pelvic girdles
5 classifications of bone shape
- Long
- Short
- Flat
- Irregular
- Sesamoid
Bones longer than they are wide (e.g. femur)
Long bones
Bones about as long as they are wide (e.g. carpals)
Short bones
Bones which are slightly curved and flattened (e.g. scapula)
Flat bones
Bones whose shapes don’t fit into other categories (e.g. vertebrae)
Irregular bones
Bones surrounded by connective tissue; no bone-to-bone connection (e.g. patella)
Sesamoid bones
- Long shaft of a long bone
- Contains medullary cavity
- Made up entirely of compact bone
Diaphysis
- Broadened end of a long bone
- Made of cancellous (spongy) bone covered by compact bone
- Covered in hyaline cartilage to form the surface of joints
Epiphysis
Red bone marrow is located in the proximal _________
Epiphysis
- Space in the middle of a long bone
- In adults is filled with yellow marrow (fat)
Medullary cavity
Covers the epiphyses of long bones to form the surface of joints
Hyaline cartilage
Produces all types of blood cells
Red marrow
- Site of bone elongation
- Consists of hyaline cartilage
Epiphyseal plate (a.k.a. growth plate)
- Remnant of epiphyseal plate after skeletal maturity
- Dividing line between the epiphysis and diaphysis
Epiphyseal line
As long as this is present you still have the potential to grow taller
Epiphyseal plate
Occurs roughly around the ages of 18-21
Skeletal maturity
Osteogenic
Bone producing (bone generating)
- Double-layered membrane on the outside of living bone
- Supplied with nerves + blood vessels and lymph vessels
Periosteum
Consists of a fibrous outer layer made up of dense irregular connective tissue, and an osteogenic inner layer made up mainly of osteoblasts
Periosteum
- Internal bone membrane
- Lines medullary cavities and honeycombs of spongy bone
- Contains osteoblasts and osteoclasts
Endosteum
Cells who produce bone matrix
Osteoblasts
Cells who break down bone matrix
Osteoclasts
The structural unit of a compact bone
Osteon (Haversian system)
Concentric layers of hardened bone matrix circling a central canal
Lamallae
- Canal running lengthwise
- Contains blood vessels and nerves
- Lined by endosteum
Central or Haversian canal
- Canals running perpendicular to the Haversian canals
- Connects Haversian canal and medullary cavity to the periosteum
Volkmann’s canals (a.k.a. perforating canals)
- Mature bone cells
- Spider-shaped
- Responsible for maintenance of bone matrix
- Contained in lacunae
Osteocytes
- Hair-like canals containing projections of adjacent osteocytes
- Allow for diffusion of nutrients and waste between cells
Canaliculi
Name for the organic portion of a bone’s matrix
Osteoid
Ratio of organic to inorganic components in healthy bone matrix
~35% organic to ~65% inorganic
Organic ingrediant of bone matrix that gives bone flexibility and tensile strength
Collagen
Inorganic component of bone matrix that gives bone its hardness
Hydroxyapatite (made up of calcium and phosphate)
Ossification
- Bone formation by osteoblasts
- Begins in utero and continues until skeletal maturity
Bone formation that begins on a collagen membrane that is formed during embryonic development
Intramembranous ossification
Bone formation that begins at a primary ossification center in the middle of a hyaline cartilage template
Endochondral ossification
Responsible for the formation of flat bones and clavicles and some irregular bones of the skull
Intramembranous ossification
Responsible for the formation of the bones at the base of the skull and most of the skeleton
Endochondral ossification
The name for the middle of the hyaline cartilage template where endochondral ossification begins
Primary ossification center
Fat soluble vitamin necessary for calcium absorption from the intestines
Vitamin D
Necessary for normal collagen formation and mineralization of matrix
Vitamin C
Acts on epiphyseal plate to stimulate growth
Growth hormone
- Hormones active at puberty which stimulate bone growth
- Same hormones later send signal to ossify growth plates and end growth
Sex hormones (estrogen and testosterone)
- Bone disease in children caused by vitamin D deficiency
- Reduced mineralization makes bones “bendy”
- Can cause bowed legs and inflamed joints
Rickets
- Bone disease in adults involving softening of the bones due to calcium depletion
- Can be transient (e.g. in pregnant women)
Osteomalacia
- Porous bone resulting from bone depletion
- 2.5 x more common in women
- Caused by drop off in estrogen
Osteoporosis
A sex hormone which inhibits the stimulation of osteoclasts
Estrogen
Causes of osteoporosis
- Decrease in estrogen
- Inadequate calcium and vitamin C
- Inadequate absorption of calcium in the intestines
- Inadequate weight-bearing exercise
Hormone sometimes prescribed to postmenopausal women
Estrogen
Bone inflammation caused by bacterial infection
Osteomyelitis
Tiny cavities that osteocytes live in
Lacunae
Hyperplasia
Growth of tissue by increasing the number of cells (i.e. by cell division)
