A & P I: Ch 6 Notes

Front 1

What are the 6 functions of the skeletal system?

Back 1

support
storage of minerals (calcium/phosphate)
storage of lipids (yellow marrow)
blood cell production (red marrow)
Protection
Leverage (force of motion)

Front 2

What are the 3 ways bones are classified?

Back 2

Shape
Internal tissue organization
Bone markings (surface features)

Front 3

What are the 6 shapes of bones?

Back 3

Long bones - long & thin, found in arms, legs, hands, feet, fingers and toes
Flat bones - thin w parallel surfaces, found in skull, sternum, ribs and scapulae
Sutural bones- small irregular bones, found between flat bones of the skull
Irregular bones - complex shape, spinal vertebrae & pelvic bones
Short bones - small & thick, ankle & wrist bones
Sesamoid bones - small & flat, inside tendons, near joints of knees hands and feet (patella)

Front 4

What are canaliculi?

Back 4

- pathways for blood vessels
- exchange nutrients and wastes
- extend off of lacunae

Front 5

What is the periosteum?

Back 5

- covers outer surfaces of bones (on top of cortex)
- consists of outer fibrous and inner cellular layers

Front 6

Describe osteocytes and list their functions

Back 6

- mature bone cells
- between lamellae (layers of matrix)
- connect by cytoplasmic extensions thru canaliculi in lamellae
- do NOT divide
- FCNS: maintain protein/mineral content of matrix & help repair damaged bone

Front 7

What are the 4 types of cells in osseous tissue?

Back 7

- osteocytes
- osteoblasts
- osteoclasts
- osteoperogenitor

Front 8

Describe osteoblasts and list their functions

Back 8

- immature bone cells that secrete matrix compounds (this is known as osteogenesis)
- osteoid is the matrix produced by osteoblasts, but not yet calcified to form bone
- osteoblasts that become surrounded by bone (calcified osteoid) turn into osteocytes

Front 9

Describe osteoprogenitor cells and list their function

Back 9

- mesenchymal stem cells that divide to produce osteoblasts
- located in endosteum (inner cellular layer of periosteum)
- assist in fracture repair

Front 10

Describe osteoclasts and list their functions

Back 10

- giant, multinucleate cells
- derived from stem cells that produce macrophages
- dissolves bone matrix to release stored minerals (this is known as osteolysis)
- secrete acids and protein-digesting enzymes

Front 11

How do bones maintain homeostasis?

Back 11

Build bone (osteogenesis) with osteoblasts and recycle bone (osteolysis) with osteoclasts but must maintain a balance (when there's more breakdown - bones become weak)
- exercise (weight-bearing) causes osteoblasts to build bone

Front 12

Describe the structure of compact bone

Back 12

- osteon is the basic unit
- osteocytes are arranged in concentric lamellae around a central canal (contains blood vessels)
-circumferential lamellae -> wrap around the long bone and bind osteons together
- perforating canals: are perpendicular to the central canal and carries blood vessels into bone and marrow
- interstitial lamellae: spaces btwn osteons in compact bone, remnants of osteons whose matrix components have been almost completely recycled by osteoclasts

Front 13

Describe structure of spongy bone

Back 13

- does not have osteons
- matrix forms an open network of trabeculae (which have no blood vessels)
- space btwn the trabecule is filled with red bonemarrow (has blood vessels, forms red/white blood cells, supplies nutrients to osteocytes) or yellow marrow (stores fat)

Front 14

What are perforating fibers of the periosteum?

Back 14

- collagen fibers of the periosteum that connect with collagen fibers in bone and with fibers of joint capsules to attach tendons and ligaments

Front 15

What are the functions of the periosteum?

Back 15

- isolates bone from surrounding tissues
- route for circulatory and nervous supply
- participates in bone growth and repair

Front 16

Where is the endosteum? What are its functions?

Back 16

- lines medullary cavity, covers trabeculae of spongy bone, lines central canals of e/osteon,
- active in bone growth and repair
- contains osteoblasts, osteprogenitor, cells and osteoclasts

Front 17

What is osteogenesis?

Back 17

Bone formation

Front 18

What is ossification? And what are the two main forms of ossification?

Back 18

process of replacing other tissues with bone
- intramembranous ossification
endochondral ossification

Front 19

What is calcification?

Back 19

process of depositing calcium salts - this occurs during bone ossification

Front 20

Describe endochondral ossification and the 6 steps of endochondral ossification

Back 20

- ossifies bone that originates as hyaline cartilage (most bones originate as hyaline cartilage)
1) chondrocytes move near center, enlarge, then die and disintegrate leaving cavities w/i cartilage
2) blood vessels begin to grow, cells convert to osteoblasts and shaft of cartilage -> ensheathed in a superficial layer of bone
3) blood vessels enter cartilage framework, fribroblasts become osteoblasts in center of cavity to begin producing spongy bone (primary ossification center) which spreads twds ends
4) medullary cavity is formed, bone shaft becomes thicker as growth continues
5) capillaries/osteoblasts migrate to epiphyses creating secondary ossification centers
6) epiphyses are filled w spongy bone except for an outer layer of articular cartilage

Front 21

What is the epiphyseal line?

Back 21

Used to be epiphyseal cartilage (while growing like in children) aka metaphysis which separates epiphysis from diaphysis

Front 22

What is intramembranous ossification? What are the 3 main steps?

Back 22

-aka dermal ossification
- occurs in the dermis
- produces dermal bones such as mandible and clavicle
1) mesenchymal cells become osteoblasts -> bone expans as spicules (sm branches of calcifying fibers)
2) spicules interconnect and trap blood vessels into bone
3) thru time becomes spongy bone - thru remodeling over time may become compact bone

Front 23

What is appositional growth?

Back 23

when compact bone thickens and strengthens (long bones) w layers of circumferential lamellae

Front 24

What are the three major sets of blood supply to mature bones?

Back 24

1) Nutrient artery and vein - enters diaphysis thru nutrient foramen (femur has more than 1 pair)
2) Metaphyseal vessels- supply epiphyseal cartilage where bone growth occurs
3) Periosteal vessels: blood to superficial osteons and secondary ossification centers

Front 25

Which nutritional factors and hormones affect bone growth?

Back 25

To strengthen bone matrix:
- calcium and phosphate salts
- sm amts of magnesium, fluoride, iron and manganese
For collagen synthesis and stimulation of osteoblast differentiation
- vitamin C
To stimulate osteoblast activity
- Vitamin A
To help synthesize bone proteins
- Vitamins K and B12
To stimulate bone growth
- growth hormone and thyroxine
To stimulate osteoblasts
- estrogens and androgens

Front 26

What does the parathyroid hormone do in the hormonal control of calcium?

Back 26

- stimulates osteoclats in bones to release calcium
- intestines then enhance the calcitriol effects and increase calcium absorption
- kidneys increase release of hormone calcitriol which causes calcium reabsorption in kidneys

Front 27

What does the hormone Calcitonin do in the hormonal control of calcium?

Back 27

- bone: decreases osteoclast activity and stimulates osteoblasts
- intestines: decreased absorption with decreasing PTH and calcitrol
- kidneys: inhibits calcitrol release and calcium reabsorption

Front 28

What is a comminuted fracture?

Back 28

splintering/shattering of the bone into multiple pieces

Front 29

What is a transverse fracture?

Back 29

break across the long axis of a bone (nondisplaced fracture)

Front 30

What is a spiral fractures?

Back 30

fracture due to a twisting force - spread along the length of the bone

Front 31

Describe a Displaced fracture

Back 31

produces new and abnormal bone fractures

Front 32

Describe a Colles fracture

Back 32

break in the distal portion of the radius

Front 33

Describe a greenstick fracture

Back 33

only in kids, one side breaks and the other side bends

Front 34

Describe an epiphyseal fracture

Back 34

occurs in children, fracture goes thru epiphyseal plate, bone may not grow properly after

Front 35

Describe a compression fracture

Back 35

occurs in vertebrae - vertebral bodies are flattened

Front 36

Describe osteopenia

Back 36

bones becoming thinner w age, lose a lot of spongy bone -> epiphyses, vertebrae and jaw are most affected

Front 37

Describe osteoporosis

Back 37

severe bone loss that affects normal function

Front 38

Describe a pott fracture

Back 38

both bones of leg are affected at the ankle joint