Ch.6 - The Skeletal System: Bone Tissue

Question 1

Bone Remodeling

Answer 1

Building of new bone tissue and breaking down of old bone tissue.

Question 2

Bone is an organ made up of several different tissues:

Answer 2

bone (osseous tissue), cartilage, dense connective tissue, epithelium, blood, adipose tissue, and nervous tissue.

Question 3

Bones along with their cartilage make up the

Answer 3

Skeletal System

Question 4

Osteology

Answer 4

the study of bone structure and treatment of bone disorders

Question 5

There are 6 functions of the skeletal system

Answer 5

1. Support - serves as the structural framework for the body by supporting soft tissues and providing attachment points for the tendons of most skeletal muscles
2. Protection - protects internal organs from injury
3. Assistance in movement most skeletal muscles attach to bones, so when they contract, they pull on bones to produce movement
4. Mineral Homeostasis (storage and release) - bone tissue makes up about 18% of human body weight; stores several minerals (calcium, phosphorus); stores about 99% of the body’s calcium
5. Blood cell production - RBC, WBC, and platelets are produced by Red Bone Marrow through a process called hemopoiesis
6. Triglyceride storage - Yellow Bone Marrow consists mainly of adipose cells, which store triglycerides ( they are a potential chemical energy reserve)

Question 6

Structure of Bone

Answer 6

1. Diaphysis - The shaft of the long bone; the main portion
2. Epiphyses - The ends of the bone that articulate with adjacent bones
3. Articular Cartilage or Hyaline Cartilage - At the ends of bones that reduce friction and absorb shock at freely moveable joints; repair of damage is limited due to a lack of perichondrium and blood vessels
4. Metaphyses - The areas between the epiphyses and diaphysis; include an epiphyseal plate, which is the site of bone elongation in growing bones
5. Periosteum - A connective tissue covering (sheath) of the surface pf the Bonne which contains osteogenic cells which promotes bone growth in width, assists in fracture repair, helps nourish the bone, and serves as attachment point for tendons and ligaments
6. Medullary Cavity - The space within the diaphysis; contains yellow bone marrow or adipose connective tissue
7. Endosteum - Lining of the medullary cavity; composed of osteoclasts, osteoblasts, and connective tissue.

Question 7

There are 4 types of bone cells:

Answer 7

1. Osteogenic - undergo cell division
2. Osteoblasts - bone-building cells that promote bone deposition
3. Osteocytes - derived from osteoblasts mature bone cells that maintain bone tissue
4. Osteoclasts - derived from monocytes (white blood cells) and serve to break down/resorb bone tissue to release calcium salts

Question 8

Calcification or Mineralization

Answer 8

As these (hydroxyapatite, calcium carbonate, magnesium, fluoride, potassium, and sulfate) mineral salts are deposited in the framework formed by collagen fibers of the extracellular matrix, they crystalize and the tissue hardens.

a. This process only occurs in the presence of collagen fibers.
b. Mineral salts confer hardness on bone while collagen fibers give bone its great tensile strength.

Question 9

Compact vs. Spongy Bone

Answer 9

Compact bone

• contains only a few spaces & is the strongest type of bone
• arranged in unites called Osteons & is found on the outside of bones
• Osteons contain blood vessels, lymphatic vessels, nerves, and osteoclasts along with calcified matrix
• Osteons are aligned in the same direction along the lines of stress

Spongy Bone

• DO NOT contain osteons, but instead consist of trabeculae surrounding many red marrow filled spaces
• forms the interior structure of short, flat, and irregular bones and the epiphyses of long bones
• spongy bone tissue is light, and provides open spaces and support for red bone marrow, and is the site of hemopoiesis
• always protected by a layer of compact bone

Question 10

Blood and Nerve Supply of Bone

Answer 10

A. Bone is richly supplied with blood

B. The arterial supply to the bone involves several vessels

Question 11

Bone Formation occurs in 4 principal situations:

Answer 11

1. Initial formation of bones in an embryo and fetus
2. The growth of bones during infancy, childhood, and adolescence until their adult sizes are reached
3. The remodeling of bone
4. Repair of fractures

Question 12

Bone formation is termed

Answer 12

Osteogenesis or Ossification and begins when embryonic mesenchymal cells provide the template for subsequent ossification in two types:

1. Intramembranous Ossification - The formation of bone directly from or within fibrous connective tissue membranes
2. Endochondral Ossification - The replacement of cartilage by bone and forms most of the bones in the body

Question 13

Bone Growth in Length

Answer 13

The epiphyseal plate or epiphyseal cartilage is a layer of hyaline cartilage in the metaphysics of growing bone that consists of four zones:

1. Zone of resting cartilage
2. Zone of proliferating cartilage
3. Zone of hypertrophic cartilage
4. Zone of calcified cartilage