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

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

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

Bones

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 4/27/2017 3AB HBS

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

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

Compact bone

Compact bone

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

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

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

Cartilage

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 http://www.ivy-rose.co.uk/HumanBody/Tissue/Tissue_Cartilage-Tissue.htm 4/27/2017 3AB HBS

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 4/27/2017 3AB HBS

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 4/27/2017 3AB HBS

Joints

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. 4/27/2017 3AB HBS

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

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

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 4/27/2017 3AB HBS

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. 4/27/2017 3AB HBS

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. 4/27/2017 3AB HBS

The structure of a synovial joint Fibrous capsule Synovial membrane Bursa Joint cavity Articulating cartilage Wellcome Photo Library

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. 4/27/2017 3AB HBS

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

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

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

Hinge joint Mariana Ruiz Villarreal

Ball and socket joint Mariana Ruiz Villarreal

Pivot joint Mariana Ruiz Villarreal

Saddle joint Mariana Ruiz Villarreal

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? 4/27/2017 3AB HBS

Topics Spinal injuries Broken bones Ligament damage Arthritis Osteoporosis 4/27/2017 3AB HBS