Connective Tissues and Joints

1. Connective tissues are essential for maintaining structural integrity and enabling movement.
2. Connective tissues provide support, movement, and protection
   1. Support: Connective tissues provide a framework that supports other tissues and organs in the body.
   2. Movement: They assist in the transmission of force from muscles to bones, enabling movement at the joints.
   3. Protection: Connective tissues like cartilage and bone protect internal organs from injury.
3. The body uses five connective tissues to make movement possible: bone, ligaments, cartilage, fascia, and tendons, each with a specific job.
4. All five share a common building plan: cells embedded in an extracellular matrix that contains protein fibres (mainly collagen) and a ground substance.
5. The proportions of cells, fibres, and ground substance change from tissue to tissue, which is why bone is hard, cartilage is springy, ligaments are tough, and fascia is sheet-like.

Role of Connective Tissues in Movement and Stability

1. Stability

1. Connective tissues such as ligaments and joint capsules help stabilize joints by limiting excessive motion and preventing injury.
2. The arrangement and composition of fibres in ligaments (mostly collagen) allow for the tensile strength necessary for joint stability.

2. Movement

1. Tendons, which attach muscles to bones, are crucial for facilitating movement.
2. When muscles contract, they pull on tendons, which in turn, pull on bones to create motion at the joints.

Cushioning and Reducing Friction

1. Cartilage acts as a cushion at joints, reducing friction and preventing the bones from grinding against each other during movement.
2. This helps protect the joint from wear and tear.

Bone structure and functions

The structure of bone is adapted to perform various functions efficiently, from providing leverage for muscles to housing the bone marrow where blood cells are produced.

Types of Bones

1. Long bones (e.g., femur, humerus)
2. Short bones (e.g., carpals, tarsals)
3. Flat bones (e.g., skull, sternum)
4. Irregular bones (e.g., vertebrae)

1. Bone tissue is a matrix of collagen fibres infused with mineral salts, mostly calcium and phosphorus.
2. The minerals crystallise around the collagen and make the tissue hard, while the collagen gives it tensile strength so it resists being stretched or torn.

Structure of Bone

1. Diaphysis (Shaft)

1. The diaphysis is the long, cylindrical portion of the bone.
2. It is the main shaft and serves as a lever for movement.
3. Composed mostly of compact bone that surrounds a central medullary cavity filled with bone marrow (used in blood cell production).

2. Epiphysis (Ends of the Bone)

1. The epiphysis is the rounded end of the bone, which articulates (forms a joint) with other bones.
2. It consists of spongy bone, which allows the bone to absorb shock and reduces the weight of the bone.

3. Periosteum

1. A fibrous membrane that covers the outer surface of the bone except at the joints.
2. Contains blood vessels and nerves that nourish the bone.
3. It also serves as an attachment point for tendons and ligaments.

4. Articular Cartilage

1. Hyaline cartilage that covers the surfaces of the epiphyses where the bone forms a joint.
2. It reduces friction and absorbs shock in the joints.

7. Medullary Cavity and Bone Marrow

1. The medullary cavity sits inside the diaphysis and holds yellow bone marrow, an energy store of triglycerides.
2. Red bone marrow sits inside spongy bone and produces red blood cells, white blood cells, and platelets.

5. Compact Bone

1. Compact bone is dense and forms the outer layer of bone. It is made up of tightly packed units called osteons, also known as Haversian systems. These cylindrical structures run parallel to the bone’s length.
2. Osteons consist of concentric rings of bone tissue surrounding a central canal that contains blood vessels and nerves.
3. This arrangement allows the bone to resist bending and torsion effectively.
4. Compact bone provides strength and rigidity, enabling bones to bear weight and withstand forces.
5. It also acts as a storage site for calcium and phosphorus, which are critical for muscle function and bone health.

6. Spongy Bone (Cancellous Bone)