Ch 7: Skeletal System

Question 1

What are the functions are skeletal system?

Answer 1

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

Question 2

Examples of bone tissue

Answer 2

1. spongy bone/. cancellous bone

2. compact bone

Question 3

spongy bone

Answer 3

network of bony shafts or trabeculae, surrounded by bone marrow

Question 4

compact bone

Answer 4

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)

Question 5

structure of a limb bone

Answer 5

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

Question 6

periosteum

Answer 6

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

Question 7

endosteum

Answer 7

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

Question 8

bone development

Answer 8

1. intramembranous ossification

2. endochondral ossification

Question 9

intramembranous ossification

Answer 9

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

Question 10

intramembranous mechanism

Answer 10

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

Question 11

endochondral ossification

Answer 11

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

Question 12

endochonral mechanism

Answer 12

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

Question 13

zones in metaphysis

Answer 13

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

Question 14

zone of reserve cartilage

Answer 14

farthest from Marrow Cavity; consists of typical Hyaline Cartilage

Question 15

zone of cell proliferation

Answer 15

chondrocytes multiply and arrange themselves into longitudinal columns of flattened lacunae

Question 16

zone of cell hypertrophy

Answer 16

chondrocytes cease to divide and begin to hypertrophy (enlarge)

Question 17

zone of calcification

Answer 17

minerals are deposited in the matrix and calcify the cartilage

Question 18

zone of bone deposition

Answer 18

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

Question 19

what are other factors that affect bone development

Answer 19

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

Question 20

calcitonin

Answer 20

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

Question 21

parathormone

Answer 21

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

Question 22

types of fractures

Answer 22

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

Question 23

compound (open) fracture

Answer 23

skin broken

Question 24

simple (closed) fracture

Answer 24

skin is not broken

Question 25

complete fracture

Answer 25

bone broken all the way through; completely

Question 26

incomplete fracture

Answer 26

bone is not broken all the way through; partial

Question 27

comminuted fracture

Answer 27

bone shatters; fragmented

Question 28

greenstick fracture

Answer 28

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

Question 29

pathological fracture

Answer 29

bone fractures due to disease

Question 30

rickets (child)/ osteomalacia (adult)

Answer 30

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

Question 31

osteomyelitis

Answer 31

rare today; serious bacterial or fungal infection; can affect bone and bone marrow

Question 32

osteoporosis

Answer 32

severe reduction in bone mass; possible causes include, hyperparathyroidism; hypothyroidism; vitamin C deficiency; decrease in estrogen (menopause); prolonged bed rest; heredity; and vitamin D and calcium deficiencies; can lessen effects with exercise, calcium and vitamin D supplements, and estrogen if female