1. Chapter 12 Human Biology Stage 3 Unit 3B – Body systems
The skeleton
Chapter 12
Human Biology Stage 3
Unit 3B – Body systems

2. Keywords Connective tissue Matrix Long bone Diaphysis Epiphysis
Articulate cartilage
Compact bone
Haversian system
Spongy bone
Bone marrow
Cartilage
Chondrin
Collagen
Hyaline cartilage
Elastic cartilage
Fibrocartilage
Joints
Fibrous
Cartilaginous
Synovial
Synovial joints
Hinge
Ball & socket
Pivot
Saddle
Movement
Adduction
Abduction
Flexion
Extension
Rotation

3. The skeletal system
The skeletal system consists of the bones, joints, ligaments and cartilage.
All the components of the skeletal system are classified as connective tissue
The function of the skeletal system is to:
Support
Protect
Facilitate movement
Act as storage organs
Produce blood cells

4. Bones

5. Structure of bone
Bone is made up of a mineralised matrix and includes blood vessels, cells, nerves, collagen and bone marrow.
A long bone consists of:
A shaft, called the diaphysis
The ends, called the epiphyses. A thin layer of articular cartilage cover each epiphysis
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6. Bone There are two types of bone:
compact bone, which is very hard and dense
spongy bone, which is porous and consists of a network of small bony plates.
Compact bone
Spongy bone
Medical Art Services, Munich, Wellcome Images

7. Compact bone Compact bone consists of Haversian systems.
A Haversian system comprises of circular layers of bone tissue (lamellae) surrounding a central Haversian canal, which carries blood and lymph vessels.
Within the Haversian system are osteocytes. These are mature bone cells and are contained within spaces called lacunae

8. Compact bone

9. Compact bone

10. Haversian systems Haversian system Haversian canal Concentric lamellae
Lacuna with mature osteocyte
M I Walker, Wellcome Images

11. Spongy bone Spongy bone is found in the epiphyses of long bones
It is more porous than compact bone
The spaces in spongy bone are filled with bone marrow
In some spongy bone, the spaces are filled with red bone marrow. This is where blood cell production takes place

12. Articulating cartilage
Growth cartilage
Spongy or cancellous bone
Epiphysis
Marrow cavity
Periosteum
Diaphysis
Compact or dense bone
The Miles Kelly Art library, Wellcome Images

13. Cartilage

14. Cartilage
Cartilage contains fibres made of protein called collagen. These fibres are embedded in a matrix of a protein-carbohydrate complex called chondrin
This firm matrix gives cartilage its strength but still allows for flexibility
Function
Support & structure
eg. ear, nose, trachea
Protection
stops joint bones from rubbing against each other
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15. Microscopic structure of cartilage
Within the matrix are spaces that contain cartilage cells called chondroblasts
The chondroblasts produce matrix until they are surrounded and trapped in small spaces called lacunae. When this occurs the cell is considered mature and now called a chondrocyte
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16. Types of cartilage Type Characteristics Example Hyaline
Collagen fibres are fine and closely packed
End of bones to form moveable joints
Rings of trachea & bronchi
Elastic
Contains elastic fibres.
Collagen fibres not as closely packed as in hyaline.
External ear
Fibrocartilage
Contains thick bundles of collagen fibres which provide cushioning
Invertebral discs in spinal column
Knee joints
Pelvis
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17. Joints

18. Joints
The site at which two or more bones come together is called a joint
There are many types of joints
Joints are classified according to their range of movement, this is called a functional classification.
Joints may also be classified structurally according to the connective tissue that binds the bones together.
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19. Joint classification
Joints can be classified by their structure and the amount of movement they allow.
Structure
Joint cavity
Movement
Fibrous
None
Cartilaginous
None or slight
Synovial
Present
Freely movable

20. Movable synovial joint
Types of joints
Movable synovial joint
Wellcome Photo Library

21. Immovable or fibrous joints
When no movement occurs between the bones concerned, the joint is described as immovable.
The bones are held in place by fibrous connective tissue .
It is very difficult to damage this type of joint, as it is so strong.
Immovable fibrous joint
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22. Slightly movable or cartilaginous joints
Slightly movable cartilaginous joint
These joints are held in place by cartilage to allow slight movement to occur.
Found:
between the 2 pelvic bones
between adjacent vertebrae
between the ribs and the sternum.
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23. Freely movable or synovial joints
Most of the joints in the body are freely moveable, the amount of movement possible being limited my ligaments, muscles, tendons and adjoining bones.
These joints are known as synovial joints
They occur at the shoulder, elbow, wrist, fingers, hip, knee.
They have a synovial cavity between the articulating surfaces of the bone.
A synovial membrane surrounds the synovial cavity and there is articular cartilage on the bone surfaces.
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24. The structure of a synovial joint
Fibrous capsule
Synovial membrane
Bursa
Joint cavity
Articulating cartilage
Wellcome Photo Library

25. Movement at a joint Flexion or bending i.e. bending the knee
Extension or straightening, usually increases the angle between the articulating bones i.e. straightening the arm or leg after flexion.
Abduction which is a movement away from the body’s midline
Adduction is movement towards the body’s midline
Rotation is the movement of bone around its long axis i.e. rotation of the humerus.
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26. Movement at a joint Type Explanation Example Flexion Bending
Bending the knee
Extension
Straightening
Increases the angle between the articulating bones
Straightening the leg after bending at the knee
Abduction
movement away from the body’s midline
Lifting arm up to the side
Adduction
movement towards the body’s midline
Bringing arm back down
Rotation
movement of bone around its long axis
Rotating the arm - rotates the humerus

27. Synovial joints Types of synovial joints: Hinge joint
Ball & socket joint
Pivot joint
Saddle joint

28. Hinge joint Ball & socket joint Pivot joint Extension Flexion Rotation
Abduction
Ball & socket joint
Rotation
Adduction
Rotation
Pivot joint

29. Hinge joint
Mariana Ruiz Villarreal

30. Ball and socket joint
Mariana Ruiz Villarreal

31. Pivot joint
Mariana Ruiz Villarreal

32. Saddle joint
Mariana Ruiz Villarreal

33. Trauma injuries to skeleton
For the following topics (on the next slide) you need to answer the research questions:
What is it?
How is it caused?
How can it be treated?
Can it be cured?
Can it be prevented?
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34. Topics Spinal injuries Broken bones Ligament damage Arthritis
Osteoporosis
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