1. Bones & Skeletal (Osseous) Tissues

2. Functions of Bones
Support – hard framework that supports body & cradles soft organs
Protection – fused bones of skull, vertebrae, rib cage
Movement – skeletal muscles use bones as levers
Mineral Storage – calcium & phosphate
Blood Cell Formation (hematopoiesis) – RBC & WBC forms within red marrow cavities of certain bones

3. Classification of Bones
All bones contain external compact bone & internal spongy bone filled with red or yellow bone marrow

4. Can you classify these bones?

5. Classification of Bones
Classified according to shape:
Long Bones – has a shaft & 2 ends; made mostly of compact bone but may contain spongy bone in its interior
Ex. Femur, tibia, fibula, humerus, fingers of hand
Short Bones – cube-like & contain mostly spongy bone; compact bone provides thin surface layer
Ex. Bones of carpus (wrist) & tarsus (ankle)
Flat Bones – thin, flattened & usually a bit curved; have 2 relatively parallel compact bone surfaces
Ex. Sternum, ribs, skull
Irregular Bones – bones that do not fit above classification
Ex. Vertebrae & os coxa (pelvis)
Sutural Bones – small, flat, irregular shaped bones of skull
Sesamoid Bones – small, flat, shaped like sesame seed; develop in tendons located near joints
Ex. Knee cap

6. Why is Bone considered an Organ?
Bones are organs (organ level of organization) because they contain different types of tissue
Osseous
Nervous
Blood
Cartilage

7. Anatomy of Long Bones
Diaphysis (shaft) – composed of a thick collar of compact bone that surrounds a central medullary cavity (marrow cavity)
“dia” – passing through
Epiphyses – bone ends
Exterior made up of compact bone
Interior is spongy bone
Why are the exterior & interior regions of the epiphyses structured this way?
Joint surface of each epiphysis is covered with thin layer of articular cartilage (cushion)
“epi” – on top of

8. Anatomy of Long Bones Periosteum – outer surface of diaphysis
Richly supplied with nerve fibers & blood vessels
Endosteum – a delicate covering of internal bone structures
Why are there wrappings found within long bone structure?

9. Anatomy of Short, Irregular & Flat Bones
Thin plates of periosteum-covered compact bone on outside
Endosteum-covered spongy bone (called diploe in flat bones) on inside

10. Hematopoetic Tissue in Bones
Hematopoeisis: formation of blood cells
“hema” – blood
“poiesis” – production or formation of
Infants
Medullary cavity & all spongy bone contain red marrow
Adults
Diaphysis is usually filled with fatty (adipose) yellow marrow
Majority of hematopoiesis in long bones occurs in head of the femur & humerus
Most important blood production occurs in diploe of flat bones (sternum) & in some irregular bones (hip bone)

11. Bone Histology Now what level of organization are we talking about?
Bone contains specialized cells & a solid, sturdy matrix (calcium salts deposited around collagen protein fibers)
Osteocytes: mature bone cells that occupy a lacuna
“osteo” – bone
“cyte” - cell

12. Bone Histology
Bone cells are arranged in cylindrical patterns throughout bone around thin tubes called Haversian canals that contain nerves & blood vessels that nourish the osteocytes.
Tiny cytoplasmic extensions called canaliculi connect the osteocytes to one another & the Haversian canals.

13. Functions of Osteocytes
Maintain the protein & mineral content of the matrix
Secrete chemicals that dissolve old matrix & then stimulate the depositing of calcium crystals
Assist in the repair of damaged bone
If released from lacunae, osteocytes can become an osteoblast or an osteoprogenitor cell

14. Osteo-progenitor Cells
Osteoblasts
Perform osteogenesis
Make & release proteins & other parts of matrix
Before calcium salts are deposited the matrix is called osteoid
Osteoblasts elevate the level of calcium salts in matrix, thus converting osteoid to bone
Stem cells that undergo mitosis, producing daughter cells that differentiate into osteoblasts
Aid in repair of bone fractures
Located in the endosteum (which lines marrow cavities)

15. Osteoclasts Cells that break down bone matrix
Large cells with approximately 50 nuclei
Dissolve matrix by secreting acids & certain enzymes
Dissolved minerals are reabsorbed in a process called osteolysis
“lysis” – loosen or dissolve

16. Osteoblast-Osteoclast- Osteoprogenitor Relationship

17. Osteoblast-Osteoclast Relationship
Osteoclasts are constantly destroying bone matrix & osteoblasts are always adding it
Remember…osteoblasts = building bone
Remember…osteoclasts = crush bone
When osteoclasts remove calcium salts faster than osteoblasts deposit them, bones weaken
The converse is also true
Stress body through exercise = strengthen muscle & bones
Declining muscular activity = reduction of bone mass at sites of muscle attachment

18. Bone Formation & Growth
Begins to form 6 weeks after fertilization
It is cartilaginous
Ossification occurs
Process by which cartilage is replaced by bone

19. Types of Cartilage Hyaline cartilage: Elastic cartilage:
translucent matrix
no prominent fibers
Reduces friction in joints
Elastic cartilage:
tightly packed elastic fibers
Flexible support
Fibrocartilage:
very dense collagen fibers
Resists compression

20. Bone Remodeling
Throughout adult life osteocytes, osteoclasts & osteoblasts remain active
In young adults, 1/5 of the adult skeleton is recycled & replaced each year
Regular exercise is essential in maintaining normal bone structure

21. Bone Fractures Fractures are cracks or breaks in bone
Most heal if components of blood supply survive
Due to
Extreme loads
Sudden impacts
Stresses from unusual directions

22. Bone Repair Process

23. Bone Repair Process

24. Examples of Fractures

25. Examples of Fractures

26. Effects of Hormones (Endocrine System) on Bone
Relationship between the Endocrine & Skeletal Systems
Calcitriol: essential for normal Ca & P ion absorption
Hormone GH (growth hormone): increases rate of mitosis of chondrocytes & osteoblasts, increases rate of protein synthesis (collagen & cartilage for cartilage & bone formation)
Parathyroid hormone: increases reabsorption of calcium from bones to the blood, raises blood Ca levels & increases absorption of Ca by small intestine & kidneys
Calcitonin: decreases the reabsorption of Ca from bones, lowering blood Ca levels
Estrogen or Testosterone: promotes closure of epiphyses of long bones (stops growth) & helps retain Ca in bones (maintaining strong bone matrix)

27. Effects of Nutrition on Bone
Body needs constant dietary supply of calcium, phosphate salts, magnesium, fluoride, iron & manganese
Vitamin A stimulates osteoblast activity
Vitamin C stimulates osteoblast development
Lack results in scurvy, a loss of bone mass & strength
Vitamins K & B12 make proteins (collagen) in bone

28. Effects of Nutrition on Bone
Vitamin D helps integrate Ca in bone tissue
If we do not replace Ca & P ions lost each day in urine, these ions will be released from bones
Makes bones weaker
Rickets (a form of osteomalacia) caused by inadequate exposure to sunlight
Bones become flexible & bow out
Ca is most abundant mineral in body
Helps bone growth
Neuromuscular activity

29. RUBBER BONES
Make sure you READ the directions & FOLLOW them CAREFULLY!
You MUST wear your SAFETY EQUIPMENT!
Acetic acid??? Chemical formula?
CH3COOH
Sodium oxalate??? Formula?
Na2C2O4
Answer all the Follow-Up Questions after each Part.
Clean your LAB STATIONS!

30. RUBBER BONES INTRODUCTION: What makes bones strong?
Some say you should drink milk when your bones are developing. Is this logical?
Using your knowledge of osseous tissue, perform the following lab & answer the Conclusion & Application questions.
PART ONE: GOGGLES ARE REQUIRED FOR THIS LAB!!
Take an uncooked chicken bone & break it in half.
Take one side & pour the contents of the marrow cavity onto a slide and create a wet mount using bromothymol blue dye (make sure the slide contents are VERY thin!).
Look at the wet mount under the microscope using medium and/or high power. DRAW WHAT YOU SEE (using your correct format for microscope drawings) & label properly.
ANSWER the FOLLOW-UP QUESTIONS

31. RUBBER BONES
PART TWO:
Take one half of the chicken bone & break it in half again.
Place one half of the new broken bone into a test tube containing distilled water & the remaining half place into a test tube of acetic acid (vinegar).
Using masking tape & a pen, identify each test tube as ACID & WATER.
Place the test tubes into a holder for hours.
MAKE A PREDICTION: What do you think the effect of each liquid will be on the bones?
The End

32. RUBBER BONES PART THREE: PUT YOUR GOGGLES ON!!!
Must be completed hours after Part Two!
Mark two clean test tubes as ACID & WATER with a piece of masking tape & a pen.
Remove 3-4 milliliters of solution from each test tube into the correct clean test tube. DO NOT USE THE SAME PIPET FOR EACH TUBE!!!
Add 2-3 drops of 1% sodium oxalate into each of the NEW test tubes filled with solution. Watch what happens…DESCRIBE IT!
ANSWER the FOLLOW-UP QUESTIONS.

33. RUBBER BONES PART FOUR: POSITIVE CONTROL TEST
Add 1.5 grams of calcium carbonate powder into a beaker.
Add 6 ml of acetic acid, stir well allowing the gas to evolve. Let any remaining solid settle to the bottom.
Filter the top portion of the liquid located in the beaker into a clean test tube. This solution should be CLEAR.
Add 3 drops of 1% sodium oxalate solution to the test tube of filtered liquid.
ANSWER the FOLLOW-UP QUESTIONS.

34. RUBBER BONES PART FIVE: Hardness, Color, Texture Tests
Using a set of tweezers, extract each of the bones, wash them off & check for hardness, using the tweezers. WRITE DOWN YOUR OBSERVATIONS.
Using the magnifying glass, observe the color & texture of the bones. WRITE DOWN YOUR OBSERVATIONS.
Place the bones back into their original solutions & store in the classroom for another hours. You may need to add more vinegar or water to your test tubes.
REPEAT steps 1-2 after the hour period is up.
ANSWER the FOLLOW-UP QUESTIONS.
The End

35. Rubber Bones Lab Abstract
Title Page
Title of lab, Name, Date & Period
Data & Observations
Part 1: Bone Marrow Extraction
Label the layers of the bone cross-section & the contents found within each regions.
Part 2 & 5: Acid & Water Bones
Draw & label your Acid & Water beaker set-up.
Describe, compare & contrast the observations made for hardness, color & texture of the bones in each beaker & before & after letting them soak.
Part 4: Positive Control Test
Draw & label your Positive Control Test set-up.
Include necessary chemicals (include formula) & precipitate found.

36. Rubber Bones Lab Abstract
Conclusions & Applications
In paragraph format, answer the following Conclusion & Application questions.
State your prediction for the experiment. Was it supported or not? Explain.
What makes bones strong? Some say you should drink milk when your bones are developing. Is this logical? Explain your answer using ideas investigated in this lab.
What is a positive control test & why is such a test performed? Describe the precipitate found at the bottom of the test tube. Why was it there? What did its presence confirm?

37. Conclusion & Application Questions (cont)
What is typical/healthy pH of blood? Is this acidic or basic? Why is blood pH important to understand when talking about the health of bone tissue?
Think about one of the most common staples of the American diet – soda. What is the pH of soda? Is it acidic or basic? What in the soda gives it this pH?
What effect could drinking a high quantity soda each day have on the health of bone? What is the chemical reaction that takes place? Explain your answer using examples from this lab.
What other body parts are made from/of a high proportion of calcium? Describe one other application of this lab to another part of the body other than bone.