1. Class #2

2. Your Skeleton has five major functions. It provides shape and support. It enables movement. It protects internal organs. It produces blood cells. It stores minerals and other materials.

3. Structure of Bones A bone is an organ composed of living tissue.

4. Structure of Bones There are two main types of bone tissue: compact and spongy.

5. Structure of Bones A bone also contains other types of tissue, as you can see in the arm bone shown in Figure 3.

6. Compact Bone Tissue The hard, outer portions of bones are made of compact bone tissue.

7. Compact Bone Tissue Compact bone tissue is a dense web of fibers. A long bone, like the arm bone shown in Figure 3, is made mostly of compact bone tissue.

8. Compact Bone Tissue However, in its ends, a long bone contains a different kind of tissue called spongy bone tissue.

9. Spongy Bone Tissue The small holes in spongy bone tissue make it look like a sponge. Because of these holes, spongy bone is less dense than compact bone. A short bone, like the one in your wrist, is mostly spongy bone tissue.

10. Bone Marrow The insides of most bones contain a soft tissue called bone marrow. There are two types of bone marrow.

11. Bone Marrow Red bone marrow is the tissue where red blood cells are made. It is found in the spongy ends of long bones and in some flat bones, such as ribs.

12. Bone Marrow Yellow bone marrow stores fat and is found inside the longest part of long bones.

13. Cartilage Have you ever fallen on a hard floor made of tiles or concrete? Falling on a hard surface is usually more painful than falling on a soft surface like a carpet, which cushions your fall.

14. Cartilage A special tissue in your body acts like a carpet to protect the skeletal system. Cartilage is a strong, flexible tissue that covers the ends of bones.

15. Cartilage Cartilage, shown in Figure 4, prevents the surfaces of bones from rubbing against each other and reduces friction.

16. Periosteum The parts of a bone that are not covered in cartilage are covered with the periosteum. The periosteum is a membrane that surrounds bone.

17. Periosteum This thin tissue contains blood vessels and nerves as well as cells that produce new bone tissue.

18. Periosteum Periosteum nourishes bones and helps them function and grow properly, as well as heal after injury.

19. Formation of Bones Before you were born, your skeleton was made mostly of cartilage. During your infancy and childhood, the cartilage was gradually replaced by bone, as shown in Figure 5.

20. Formation of Bones The long bones in children and young teens have regions of bone growth that produces new bone cells. These regions are called growth plates.

21. Formation of Bones A growth plate produces cartilage that is then replaced by bone tissue. A growth plate, shown in figure 5, is the weakest part of an adolescent bone.

22. Formation of Bones Growth is continuous until adulthood, when most of the cartilage has turned to bone.

23. Homework Compact Bone Tissue:_______ Web of Fibers:_____________ Spongy Bone Tissue:________ Less Dense than:___________ Wrist:____________________ Bone Marrow:_____________ Red Bone Marrow:_________ Ribs:_____________________ Yellow Bone Marrow:_______ Long Bones:_______________ Cartilage:_________________ Hard Surface:______________ Translate the words into Chinese and then send me a WeChat message saying the words in English Name:____________ Cushion:____________________ Cushion your fall:_____________ Spongy Bone Tissue:________ Less Dense than:___________ Rubbing against each other:___ __________________________ Friction:____________________ Periosteum:_________________ Membrane:_________________ Nourishes:__________________ Formation of Bones:__________ Infancy:___________________ Childhood:_________________ Gradually:__________________

24. Fill in the blanks with the correct response. 1. The hard outer portions of bones are made of ____________ 2. Compact bone tissue is a __________ web of fibers. 3. Yellow bone marrow stores ____ and is found inside the longest part of long bones. 4. A special ______ in your body acts like a carpet to protect the skeletal system. 5. The periosteum is a _________ that surrounds bones. 6. _________ nourishes bones and helps them function and grow properly. 7. Before you were ______, your skeleton was made mostly of cartilage. 8. ________ is continuous until adulthood, when most of the cartilage has turned to bone. Name: ____________ Dense Fat Periosteum Converting TissueMembrane Growth Compact Bone Tissue