1. The Skeletal System: Bone Tissue Lecture Outline
Chapter 6
The Skeletal System: Bone Tissue
Lecture Outline

2. INTRODUCTION
Bone is made up of several different tissues working together.
Each individual bone is an organ; the bones, along with their cartilages, make up the skeletal system.
The study of bone structure and the treatment of bone disorders is called osteology.
Principles of Human Anatomy and Physiology, 11e

3. Functions of Bone
Supporting soft tissues, providing an attachment site for tendons and muscles
Protects internal organs from injury
Work with muscles to produce movement
Storage of minerals like calcium & phosphate
Blood cell production occurs in red bone marrow
Energy storage (triglycerides) in yellow bone marrow
Principles of Human Anatomy and Physiology, 11e

4. Bone Anatomy A long bone is one that has greater length than width.
Principles of Human Anatomy and Physiology, 11e

5. Anatomy of a Long Bone
Diaphysis = shaft: the long, cylindrical main portion of the bone
Epiphysis = either end of a long bone
Metaphyses are the areas between the epiphysis and diaphysis
Principles of Human Anatomy and Physiology, 11e

6. Anatomy of a Long Bone
Articular cartilage is a thin layer of cartilage that forms a joint where two bones connect.
Periosteum is a tough connective tissue covering that surrounds a bone.
Principles of Human Anatomy and Physiology, 11e

7. Anatomy of a Long Bone
The medullary cavity or marrow cavity is the space in the diaphysis that stores yellow bone marrow.
The endosteum is a thin membrane that lines the medullary cavity.
Principles of Human Anatomy and Physiology, 11e

8. HISTOLOGY OF BONE TISSUE
Bone (osseous) tissue consists of widely separated cells surrounded by large amounts of matrix.
The matrix of bone is made up of water, collagen, and salts.
These salts are used to form new bone tissue, which is called calcification.
Principles of Human Anatomy and Physiology, 11e

9. Bone Marrow
Red bone marrow produces red blood cells, white blood cells, and platelets
Yellow bone marrow stores triglycerides (fats) which are used for energy
Principles of Human Anatomy and Physiology, 11e

10. Bone Cells (4)
Osteogenic cells are stem cells that can undergo cell division and become other bone cells.
Osteoblasts are bone-building cells.
Osteocytes are mature bone cells and the principal cells of bone tissue. They maintain bone metabolism, and exchange nutrients and wastes with the blood.
Osteoclasts are large cells that are used for bone development, growth, maintenance, and repair
Principles of Human Anatomy and Physiology, 11e

11. Types of Bone 80% of your skeleton is made of compact bone.
20% is spongy bone.
Principles of Human Anatomy and Physiology, 11e

12. Compact Bone
Compact bone contains few spaces and is the strongest type of bone.
It makes up the bulk of long bones
It provides protection and support, and resists the stresses of weight and movement
It is made of osteons, hard rings of material
Principles of Human Anatomy and Physiology, 11e

13. Spongy Bone
Spongy bone does not contain osteons. It consists of thin columns of bone with many red marrow filled spaces.
It forms most of the structure of short, flat, and irregular bones, and the epiphyses of long bones.
Spongy bone tissue is light and supports and protects the red bone marrow.
Hip bones, rib bones, the breastbone, vertebrae are types of spongy bones
Principles of Human Anatomy and Physiology, 11e

14. Bone Scan A bone scan is a diagnostic technique for viewing bones.
A radioactive tracer is injected through an IV
A scanner measures blood flow to areas of the bone
Dark areas (more blood flow) may indicate cancer
Light areas (less blood) may indicate arthritis or bone loss.
Principles of Human Anatomy and Physiology, 11e

15. Diseases and Disorders of the Bone
Submit a 1-2 page, TYPED report, due FRIDAY.
1. Describe the disease/disorder.
2. What causes this to happen?
3. Are there certain groups more at risk than others?
4. What are some treatments? Cures?
5. Describe the impact on the life of someone affected.
6. Are there support groups?
7. REFERENCES!!!!
Bone Fractures (last name A  B)
Paget’s Disease (last name C  D)
Osteoporosis (last name E  H)
Cleft Palate (last name J  L)
Herniated Disc (last name M)
Scoliosis (last name N  P)
Aplastic Anemia (last name Q)
Hip Fracture (last name R)
Lymphoma (last name S)
Arthritis (last name T)
Rickets (last name W)
Principles of Human Anatomy and Physiology, 11e

16. Blood and Nerve Supply of Bone
Periosteal arteries
supply periosteum (outer part of bone)
Nutrient arteries
Supplies inner bone and red marrow
Veins carry blood away from the bone and back to the heart.
All bones have sensory nerves attached to them.
Principles of Human Anatomy and Physiology, 11e

17. BONE FORMATION Bone formation is termed osteogenesis or ossification
Two types of ossification occur.
Intramembranous ossification
Endochondrial ossification
Principles of Human Anatomy and Physiology, 11e

18. Intramembranous Ossification
The flat bones of the skull and the jaw are formed this way.
This pathway is simpler.
1. A cluster of cells, called the ossification center, and form osteoblasts.
2. Osteoblasts become osteocytes, and harden (calcify)
3. Blood vessels grow into place.
4. The periosteum (membrane) grows over the bone.
Principles of Human Anatomy and Physiology, 11e

19. Endochondral Ossification
Endochondral ossification is the replacement of cartilage by bone. Most bones in the body form this way.
1. Cartilage forms in the shape of the bone.
2. An ossification center forms, and begins to grow osteoblasts.
3. The marrow cavity forms.
4. New ossification centers form at each epiphysis, so bones can continue to elongate.
Principles of Human Anatomy and Physiology, 11e

20. Growth in Length
Bones grow only at the epiphyseal plate which is located in the metaphysis of a growing bone.
Between ages 18 to 25, epiphyseal plates close.
Growth in length stops at age 25
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21. Growth in Thickness
Bone can increase in diameter through appositional growth.
Osteoblasts grow outward and form hardened ridges
These ridges fold over and become osteons (rings)
The marrow cavity enlarges.
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22. Bone Remodeling
Remodeling is the ongoing replacement of old bone tissue by new bone tissue.
Old bone is constantly destroyed by osteoclasts (bone resorption), whereas new bone is constructed by osteoblasts (bone deposition).
20% of spongy bone and 4% of compact bone is remodeled each year!
This can be triggered by exercise, diet, or lack of exercise.
Principles of Human Anatomy and Physiology, 11e

23. Braces In orthodontics teeth are moved by braces.
This places stress on bone in the sockets causing osteoclasts and osteoblasts to remodel the sockets so that the teeth can be properly aligned.
Principles of Human Anatomy and Physiology, 11e

24. Factors Affecting Bone Growth
Nutrition
adequate levels of minerals and vitamins
calcium and phosphorus for bone growth
vitamin C for collagen formation, Vitamin A for osteoblasts
vitamins K and B12 for protein synthesis
Principles of Human Anatomy and Physiology, 11e

25. Factors affecting Bone Growth
Sufficient levels of specific hormones
during childhood need insulinlike growth factor (IGF)
Human Growth Hormone (too much=gigantism, not enough=pituitary dwarfism)
sex steroids at puberty
At puberty the sex hormones, estrogen and testosterone, stimulate sudden growth and modifications of the skeleton to create the male and female forms (wider pelvis).
Principles of Human Anatomy and Physiology, 11e

26. Fracture and Repair of Bone
A fracture is any break in a bone.
Fractures are named according to their severity, the shape of the fracture, or the physician who first described fractures.
Principles of Human Anatomy and Physiology, 11e

27. Common Fractures Open Fracture: Broken bones protrude through skin
Closed Fracture: Broken bones do NOT show through
Comminuted fracture: Bone splinters at site of impact
Greenstick Fracture: One side of the bone breaks, the other bends (only occurs in children)
Impacted fracture: One bone is driven into another
Pott’s fracture: fracture of the fibula (leg bone)
Colles’ fracture: fracture of the forearm bone
Stress fracture: Microscopic fissures but no broken bones
Results from repeated, strenuous activity like running, jumping, or dancing
Principles of Human Anatomy and Physiology, 11e

28. Fracture & Repair of Bone
Healing is faster in bone than in cartilage since bones have better blood supplies
Healing of bone is still slow process due to vessel damage
Clinical treatment:
closed reduction = restore pieces to normal position by manipulation
open reduction = realignment during surgery
Both are followed by immobilization in a cast, sling, or bandage
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29. Repair of a Fracture 1. Formation of fracture hematoma
Damaged blood vessels produce a clot
2. Formation of fibrocartilagenous callus
Collagen and cartilage fibers span the break
Principles of Human Anatomy and Physiology, 11e

30. Repair of a Fracture 3. Formation of bony callus
osteoblasts secrete spongy bone
lasts 3-4 months
4. Bone remodeling
compact bone replaces the spongy in the bony callus
surface is remodeled back to normal shape
Principles of Human Anatomy and Physiology, 11e

31. Calcium Homeostasis & Bone Tissue
Skeleton is a reservoir of Calcium & Phosphate
Calcium ions involved with many body systems
nerve & muscle cell function
blood clotting
enzyme function in many biochemical reactions
Small changes in blood levels of Ca+2 can be deadly
cardiac arrest if too high
respiratory arrest if too low
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32. EXERCISE AND BONE TISSUE
Within limits, bone has the ability to alter its strength in response to mechanical stress by increasing deposition of mineral salts and production of collagen fibers.
Removal of mechanical stress leads to weakening of bone through demineralization (loss of bone minerals) and collagen reduction.
reduced activity while in a cast
astronauts in weightless environment
bedridden person
Weight-bearing activities, such as walking or moderate weightlifting, help build and retain bone mass.
Principles of Human Anatomy and Physiology, 11e

33. AGING AND BONE TISSUE
Loss of calcium which may result in osteoporosis.
very rapid in women as estrogens levels decrease
in males, begins after age 60
Decreased rate of protein synthesis
decrease in collagen production which gives bone its tensile strength
decrease in growth hormone
bone becomes brittle & susceptible to fracture
Principles of Human Anatomy and Physiology, 11e

34. Osteoporosis Decreased bone mass resulting in porous bones
Those at risk
white, thin menopausal, smoking, drinking female with family history
athletes who are not menstruating due to decreased body fat & decreased estrogen levels
people allergic to milk or with eating disorders whose intake of calcium is too low
Prevention or decrease in severity
adequate diet, weight-bearing exercise, & estrogen replacement therapy (for menopausal women)
behavior when young may be most important factor
Principles of Human Anatomy and Physiology, 11e

35. Disorders of Bone Ossification
Rickets
calcium salts are not deposited properly
bones of growing children are soft
bowed legs, skull, rib cage, and pelvic deformities result
Osteomalacia
new adult bone produced during remodeling fails to ossify
hip fractures are common
Principles of Human Anatomy and Physiology, 11e