CHAPTER 6!!!!

Question 1

What types of tissues are found in the skeletal system?

Answer 1

• Bone tissue (osseous tissue) – main supportive tissue.
• Cartilage – flexible, smooth connective tissue.
• Dense connective tissue – forms ligaments and tendons.
• Nervous tissue – nerves that run through bones.
• Blood (vascular tissue) – inside bone marrow and vessels.

Question 2

What are the functions of cartilage, ligaments, and tendons in the skeletal system?

Answer 2

Cartilage: Cushions joints, reduces friction, and provides flexible support.

Ligaments: Connect bone to bone and stabilize joints.

Tendons: Connect muscle to bone and help move the skeleton.

Question 3

Know the functions of the skeleton.

Answer 3

a) Support – forms the body’s framework.

b) Protection – shields organs (skull → brain, ribs → lungs/heart).

c) Movement – muscles pull on bones.

d) Mineral storage – stores calcium and phosphorus.

e) Blood cell production
(hematopoiesis) – in bone marrow.

f) Fat storage – in yellow marrow

Question 4

What is the study of bone?

Answer 4

• Osteology

Question 5

Know and be able to describe the different shapes of bones.

Answer 5

1. Long bones: Longer than they are wide; support weight and movement (ex: femur).
2. Short bones: Cube-shaped; provide stability and little movement (ex: wrist bones).
3. Flat bones: Thin and flat; protect organs and provide surface for muscles (ex: skull, ribs).
4. Irregular bones: Odd-shaped; have special functions (ex: vertebrae).
5. Sesamoid bones: Small and round; protect tendons (ex: patella).

Question 6

identify the parts of a long bone.

Answer 6

Diaphysis: Shaft or middle part.

Epiphysis: Ends of the bone.

Metaphysis: Between diaphysis and epiphysis; growth plate area.

Articular cartilage: Covers ends; reduces friction.

Periosteum: Outer covering of the bone.

Medullary cavity: Hollow center with yellow marrow (fat).

Endosteum: Lining of the medullary cavity.

Red marrow: Found in spongy bone; makes blood cells.

Question 7

types of bone cells and the functions of each

Answer 7

1. Osteoblasts: Build new bone (bone-forming cells).
2. Osteocytes: Maintain bone tissue; mature bone cells.
3. Osteoclasts: Break down old bone (bone-resorbing cells).
4. Osteoprogenitor cells: Stem cells that become osteoblasts.

Question 8

Know where osteogenic cells can be found.

Answer 8

• In the periosteum (outer covering of bone) and endosteum (inner lining).

Question 9

What do osteoblasts and osteoclasts look like?

Answer 9

-Osteoblasts: small, cubelike cells found on bone surface (single layer).

-Osteoclasts: large, multinucleated cells with a ruffled border, look like “giant blobs”; dissolve bone.

Question 10

What is an osteon? What is the central canal?

Answer 10

• Osteon (Haversian system): the basic structural unit of compact bone; looks like a tree ring.
• Central (Haversian) canal: runs through the center of each osteon; contains blood vessels
  and nerves.

Question 11

What are spicules? What are trabeculae?

Answer 11

• Spicules: small, needle-like pieces of bone.
• Trabeculae: thin, branching plates of bone that form a web-like network.

Question 12

What is found in the spaces of spongy bone?

Answer 12

• Bone marrow (mostly red marrow, where blood cells are made).

Question 13

are there osteons in spongy bone?

Answer 13

no!

Question 14

What is the periosteum?

Answer 14

• Definition: Outer covering of a bone (except at joints)

Question 15

the structure and functions of the periosteum?

Answer 15

Structure:
▪ Outer fibrous layer: dense connective tissue; where tendons & ligaments attach.
▪ Inner cellular layer: has osteogenic cells → can form osteoblasts to grow or repair bone.

Functions:
▪ Nourishes bone (blood vessels run through it).
▪ Helps bone grow in thickness.
▪ Helps repair fractures.
▪ Serves as attachment for tendons & ligaments

Question 16

What is the endosteum? Where is it found and when is it active?

Answer 16

• Definition: Thin lining on the inside of bone surfaces (lines medullary cavity & trabeculae).
  o When active: During bone growth, repair, and remodeling.
  o Contains osteogenic cells, osteoblasts, and osteoclasts.

Question 17

In what places can bone marrow be found?

Answer 17

• In children: In almost all bones.
• In adults:
  Red marrow: In skull, ribs, sternum, vertebrae, pelvis, and ends of long bones.
  Yellow marrow: In medullary cavities of long bones (mostly fat).

Question 18

Which type of bone marrow forms blood?

Answer 18

− Red bone marrow (hematopoietic tissue).

Question 19

What is ossification?

Answer 19

− The process of bone formation.

Question 20

What two processes form bone?

Answer 20

• Intramembranous ossification
• Endochondral ossification

Question 21

What kind of bones are formed from intramembranous ossification?

Answer 21

• Bones formed: Flat bones of skull, clavicle, and parts of mandible.
• Process: Bone develops directly from mesenchymal (embryonic) tissue, no cartilage model.

Question 22

Which type of bone formation develops from a hyaline cartilage model?

Answer 22

• Bones formed: Most bones of the body (especially long bones).
• Process: Bone develops from a hyaline cartilage model.
• Begins: Around the 6th week of fetal development.
• Ends: When growth plates close at about age 20–25.

Question 23

When does endochondral ossification begin? When does it end?

Answer 23

• Bones formed: Most bones of the body (especially long bones).
• Process: Bone develops from a hyaline cartilage model.
• Begins: Around the 6th week of fetal development.
• Ends: When growth plates close at about age 20–25.

Question 24

Compare the two processes that form bone.

Answer 24

1. Intramembranous ossification:
   -Bone forms directly from connective tissue.
   -Makes flat bones (like skull and clavicle).
2. Endochondral ossification:
   -Bone forms by replacing cartilage.
   -Makes most bones, especially long bones.

Question 25

What is appositional bone growth? How does it happen?

Answer 25

* Definition: Growth in width (diameter) of bones. How: Osteoblasts in the periosteum lay new bone on the outside while osteoclasts widen the medullary cavity inside.

Question 26

what happens in each zone of bone elongation.

Answer 26

1. Zone of reserve cartilage: Resting cartilage, anchors plate to bone. 2. Zone of cell proliferation: Chondrocytes divide and stack up in columns. 3. Zone of cell hypertrophy: Chondrocytes enlarge. 4. Zone of calcification: Matrix hardens; chondrocytes die. 5. Zone of bone deposition: Osteoblasts replace cartilage with bone tissue.

Question 27

What is bone remodeling? What does Wolff’s Law of Bone say?

Answer 27

* Definition: Continuous process of breaking down old bone and building new bone. * Wolff’s Law of Bone: Bone grows or remodels in response to the stresses placed on it (e.g., weightlifting strengthens bone).

Question 28

Where do blood vessels enter and exit bones?

Answer 28

− Through nutrient foramina (small holes in the bone surface).

Question 29

What type of nerves innervates bones?

Answer 29

* Sensory nerves that detect pain, injury, and pressure. * Found mostly in periosteum.

Question 30

What factors affect bone growth and health? *Know what the hormones that affect bone growth and health do*

Answer 30

* Nutrition – calcium, vitamin D, and protein are essential. oHormones: ▪ Growth hormone: Stimulates bone growth in children. ▪ Thyroid hormone: Controls metabolism, supports bone growth. ▪ Sex hormones (estrogen/testosterone): Speed up bone growth at puberty, then close growth plates. ▪ Parathyroid hormone (PTH): Raises blood calcium by stimulating osteoclasts. * Calcitonin: Lowers blood calcium by stimulating osteoblasts. * Vitamin D: Helps calcium absorption from food. * Physical stress: Exercise strengthens bones.

Question 31

What is osteopenia? What does it lead to? When does it typically begin to take effect?

Answer 31

* Definition: Loss of bone density * Leads to: Osteoporosis if it worsens. -Begins: Usually around age 30–40 when bone resorption outpaces formation.

Question 32

the difference between stress fractures and pathological fractures.

Answer 32

Stress fracture: Small crack in bone from repeated stress or overuse. Pathological fracture: Break caused by disease or weakness in the bone (like osteoporosis or cancer).

Question 33

What is osteoporosis? What does it cause?

Answer 33

* Definition: Severe bone density loss → bones become brittle and fracture easily. - Causes: Aging, low estrogen (especially after menopause), lack of exercise, poor diet. - Results in: Curved spine, hip and vertebral fractures, height loss.

Question 34

What is orthopedics?

Answer 34

− Definition: Medical branch that studies and treats bone, joint, and muscle disorders.