Ch 7: Skeletal System Flashcards Preview

A&P I Exam 2 > Ch 7: Skeletal System > Flashcards

Flashcards in Ch 7: Skeletal System Deck (32)
Loading flashcards...

What are the functions are skeletal system?

support; protection; blood cell production; storage; and motion


Examples of bone tissue

1. spongy bone/. cancellous bone
2. compact bone


spongy bone

network of bony shafts or trabeculae, surrounded by bone marrow


compact bone

highly organized; composed of repeating osteons; composed of a central Haversian Canal (passage of blood vessels); lamellae (rings of matrix); lacunae (small holes in matrix where bone cells are located); osteocytes (bone cells); and canaliculi (cytoplasmic extensions of osteocytes, which travel from cell to cell and transport nutrients and wastes)


structure of a limb bone

2 epiphyses (broad ends; contain spongy bone); 1 diaphysis (shaft; compact bone on outer part, and spongy bone lines the marrow cavity)



covers outer surface of bone; isolates bone from surrounding soft tissue; passage of blood vessels and nerves; growth and repair; becomes continuous with tendons



lines marrow cavity; active during bone growth; contains giant osteoclasts, which are multinucleated (50), and eat the bone matrix to attack invaders, remove damaged cells, and release calcium


bone development

1. intramembranous ossification
2. endochondral ossification


intramembranous ossification

occurs in flat, short, and irregular bones, known as dermal bones; osteoblasts form from C.T.; roof of jaw; clavicle; mandible


intramembranous mechanism

a)Condensation of mesenchyme into soft sheet permeated with blood capillaries

b)Deposition of osteoid tissue by osteoblasts on mesenchymal surface; entrapment of first osteocytes; formation of periosteum

c)Honeycomb of bony trabeculae formed by continued mineral deposition; creation of spongy bone

d)Surface bone filled in by bone deposition, converting spongy bone to compact bone; persistence of spongy bone in the middle layer


endochondral ossification

occurs in limb bones; osteoblasts form from cartilage; metaphysic region (metaphysis ) in limb bone, which is between epiphysis and diaphysis; known as growth plate, or epiphyseal plate; as mitosis occurs, limb bone lengthens; process ends around age 16 to 18 years


endochonral mechanism

a)Mesenchyme develops into a body of hyaline cartilage, covered with a fibrous perichondrium; the perichondrium produces chondrocytes and the cartilage model grows in thickness

b)The perichondrium stops producing chondrocytes and begins producing osteoblasts; formation of bony collar around middle of cartilage; perichondrium converts into periosteum; formation of the Primary Ossification Center (area of chondrocyte enlargement in diaphysis)

c)Blood vessels penetrate the bony collar and invade the primary ossification center; formation of primary marrow cavity; formation of Secondary Ossification Center

d)Formation of secondary marrow cavity in the epiphyses


zones in metaphysis

1. zone of reserve cartilage
2. zone of cell proliferation
3. zone of cell hypertrophy
4. zone of calcification
5. zone of bone deposition


zone of reserve cartilage

farthest from Marrow Cavity; consists of typical Hyaline Cartilage


zone of cell proliferation

chondrocytes multiply and arrange themselves into longitudinal columns of flattened lacunae


zone of cell hypertrophy

chondrocytes cease to divide and begin to hypertrophy (enlarge)


zone of calcification

minerals are deposited in the matrix and calcify the cartilage


zone of bone deposition

chondrocytes die; osteoblasts form and begin to lay down bone matrix; closest to marrow cavity


what are other factors that affect bone development

growth hormone (pituitary) and thyroxine (thyroid) target growth plate; vitamin D (absorbs calcium) and calcium are needed for health of bone tissue



thyroid hormone; released when blood calcium levels are elevated; functions to lower blood calcium levels; a) inhibits osteoclasts; b) decreases intestinal absorption of calcium; and c) increases calcium loss at the kidneys



parathyroid hormone; released when blood calcium levels are decreased; functions to raise blood calcium levels; a) stimulates osteoclasts; b) increases intestinal absorption of calcium; and c) decreases calcium loss at the kidneys


types of fractures

1. compound (open)
2. simple (closed)
3. complete
4. incomplete
5. comminuted
6. greenstick
7. pathological


compound (open) fracture

skin broken


simple (closed) fracture

skin is not broken


complete fracture

bone broken all the way through; completely


incomplete fracture

bone is not broken all the way through; partial


comminuted fracture

bone shatters; fragmented


greenstick fracture

common in children; bone broken on one side and bent on the other side


pathological fracture

bone fractures due to disease


rickets (child)/ osteomalacia (adult)

both due to vitamin D deficiency; bones become weak and softening of bone; in rickets can have bowing of the femurs; bone can fracture easily in both