Bones Chapter 23

Question 1

Bone

Answer 1

Most rigid of connective tissues. Dynamic tissue, constantly changing shape to deal with stresses. 206 bones. Enamel is the hardest substance in the body. Support and protection of internal organs.

Question 2

Bone serve as a reservoir for

Answer 2

Ca++, PO4-, Na+ and Mg++

Hemopoietic bone marrow.

Question 3

Bone type break

Answer 3

80% is cortical bone.
Dense compact bone, outer layer covered by periosteum. Collagenous connective tissue covering diaphysis of many bones.
20 is cancellous bone.
Spongy bone, found at the ends of long bones. Highly vascular. Space for bone marrow.
All bones contain cortical and cancellous elements but different %.

Question 4

Parts of bone

Answer 4

a) growth plates
b) Epiphysis- end of segment of long bone. Contains cartilaginous layer to allow grow.
c) Metaphysis - region of growth playe, columns of spongy tissue.
d) Diaphysis - body or shaft of bone

Question 5

Marrow cavity or medullary cavity

Answer 5

Where bone marrow residues, enclosed by cortical bone.

Question 6

Bones contain

Answer 6

Ca3(PO4)2 - calcium phosphate as well as hydroxyapatite crystals, an inorganic matrix. (99% of Ca++ in the body is stored in bone as hydroxyapatite crystals).
Organic mix is collagen and glycoproteins.

Question 7

Bones distinguishing feat

Answer 7

Is ground substance (glycoproteins) and its EcM of collagen.

Question 8

Axial Skeleton

Answer 8

Skull, ribs, vertebrae, sternum

Question 9

Appendicular skeleton

Answer 9

bones of pelvic and pectoral girdle like arms, legs, feet

Question 10

Ligaments

Answer 10

dense, regular connective tissues that connects bone to bone

Question 11

Tendons

Answer 11

dense, regular connective tissue that connects bone to muscle

Question 12

Joints

Answer 12

Area of contact or near contact between points

Question 13

Primary bone

Answer 13

Temporary bone usually replaced in adults- first bone to form during fetal development and during bone repair

Question 14

Secondary bone

Answer 14

bone usually found in adults

Question 15

Harversian System (Osteon)

Answer 15

Harversian canal, osteocytes lacunae, canaliculi, and concentric lamellae make up the osteon. Cortical bone/compact bone.

Question 16

Lamellae

Answer 16

Concentric rings of matrix surrounding haversian canals.

Question 17

Canaliculi

Answer 17

Cavities seen within bone matrix, serve as passages for substances between the blood vessels and bone cells.

Question 18

Lacunae

Answer 18

Spaces in bone occupied by bone cells called osteocytes.

Question 19

Volkmann’s Canals

Answer 19

Crossing canals that link haversian canals containing blood and lymph.

Question 20

Osteoblasts

Answer 20

Found at bone surface, mononucleated cells that build bone, Do not do mitosis. They make collagen, fibrolasts, growth factors, and synthesize much of the organic matrix of bone.

Question 21

Mesenchymal cells

Answer 21

Mesenchymal stem cells give rise to osteoblasts, myocytes, chondrocytes, and adipocytes. Mesenchyme is embryonic connective tissue derived from mesoderm.

Question 22

Osteoblasts

Answer 22

Monocyte/macropahge family. Break down bone (bone resorption). Often die by apoptosis afterwards.
Multinucleated cells have abundant lysosomes and mitochondria. Large and motile. Occupy shallow depressions called Howship’s lacunae. Gelatinase and collagenase are secreted by these cells which degrade the bone.

Question 23

Osteocyte

Answer 23

Trapped osteoblast embedded in bone matrix and isolated in a lacuna. This cell has projections called canaliculi and can communicate with other osteocytes.

Question 24

Cells that do not do mitosis

Answer 24

Osteocytes, osteoblasts, and osteoclasts

Question 25

Osteoprogenitor Cell

Answer 25

Derived from primitive stem cell and differentiates into osteoblasts and osteocytes.
Found in the marrow, periosteum, and marrow cavity.

Question 26

Bone development exceeds bone break down

Answer 26

In a young person. In adulthood, epiphyseal plates close and bone groth has been attained, a balance occurs between growth and breakdown.

Question 27

Coupling

Answer 27

Osteoclasts break down some bone to excavate the area to form absorption cavity. Osteoblasts build new bone (replacement).

Question 28

Acromegaly

Answer 28

Excess growth hormone causes increase in bone deposition without normal breakdown. Very thick bones.

Question 29

Osteoporosis

Answer 29

Decrease in bone mass, worse as estrogen levels decline. Osteoclastic activity exceeds bone deposition.

Question 30

Parathyroid gland and bones

Answer 30

When Ca++ levels decrease, parathyroid hormone is secreted. It activates receptors stopping osteoblasts from building more bone. Osteoclast stimulating factor produced by osteoblasts induce osteoclasts formation to break down bone and release Ca++.

Question 31

Thyroid and bones

Answer 31

Thyroid gland makes calcitonin, by decreasing Ca++ levels? When Ca++ increase, calcitonin activates receptors on osteoclasts, inhibiting them from breaking down bone. Osteoblastic activity occurs and Ca++ go into building bones.

Question 32

Cartilage

Answer 32

Specialized connective tissue. Does not contain blood vessels, nerves, or lymphatics. Gets nourishment from blood vessels of surrounding connective tissues by diffusion. 80% water, 20% collagen and proteoglycans.

Question 33

Perichondrium

Answer 33

Cartilage is surrounded by a dense, fibrous connective tissues. No blood supply means a slow rate of mitotic activity, if damaged it heals slowly.

Question 34

Hyaline

Answer 34

Most abundant type of cartilage. It’s in the nose, larynx, part of the ribs, trachea, bronchi, and epiphyseal plate. Reduces friction and is a shock absorber that aids with bone movement.

Question 35

Elastic cartilage

Answer 35

Pinna of ear

Question 36

Fibrocartilage

Answer 36

Intervertebral discs, can cause great pain because it compresses the lower spinal nerves.