Biology

• Bones: Made up of minerals such as phosphates and calcium carbonates, as well as water and some fibers.
• Cortical (Compact) bones: The compact tissue forms the tubular structure of the bone through which the bone marrow passes.
• Cancellous bones: There is an interconnected network of plates called bony trabeculae, which gives it a poroues, spongy like appearance. The spaces are filled with red bone marrrow that contains blood stem cells, which can give rise to eythrocytes, leukocytes or platelets
• Bone marrow: Soft, spongy substance that functions as connective tissue. All blood cells are produced in the bone marrow in a controlled manner, as the body need them.
• Cartilage: Made up of collagen fibres for toughness and elastin for flexibility.
• Chondrocyte: Chondrocyte is a particular type of cell located in the cartilage, these cells are responsable for synthesising the collagen and structural macromolecules that will give its biomechanical characteristics
• Ligaments: Made up of a dense tissue, which is made of tightly packed collagen fibres that are always oriented in the same direction
• Ligaments: Its function is to connect bone to bone, straightening the joints and allowing the bones to move.
• Joints: Junction between two or more bones. The configuration of a joint determines the degree and direction of movement possible
• Synarthrosis: These are joints that do not move, made up of two bony ends and a connecting tissue, which maintains rigidity between the bony parts.
• Amphiarthrosis: These joints allow subtle movements, where the bone ends are joined by a disc of fibrocartilaginous tissue.
• Synovial Joints: These are those with the most significant movement, whose difference lies in the presence of a synovia.
• Muscle system: This system is primarily responsible for every movement of our body.

  Muscles are critical in digestive functions and in regulating blood pressure.
• Skeletal muscle: This type of tissue is what we think of when we talk about a muscle. It is so called because tendons connect it to the bones of the body.
• Smooth muscle: Muscular tissue made up of much smaller cells than skeletal muscle and has a smooth appearance. It is an elongated ovoid, where each cell has a single nucleus in the centre.
• Cardiac muscle: Cardiac muscle is found only in the heart and consists of branched muscle cells with one or two nuclei. Cardiac muscle contracts involuntarily, and its shape is more branched than skeletal muscle cells.
• Filaments: Filaments are made up of two contractile proteins, actin and myosin, and are organised within the myofibril into small compartments called sarcomeres.
• Epidermis: Epidermal cells are constantly being replaced, their cells constantly emerging from the bottom of the epidermal layer and pushing old cells to the surface.
• Melanocytes: In the deepest layer of the epidermis are cells called melanocytes, which produce a dark brown pigment called melanin.
• Keratinocytes: These are the most common and numerous cells inside the epidermis; they produce a relatively rigid and waterproof protein called keratin, which helps the skin surface have these same properties.
• Langerhans: Langerhans cells are phagocytes that consume unhealthy bacteria, which often attack the skin and alert the immune system.
• Merkel: These cells are located in the deepest layer of the epidermis, where they make contact with sensitive nerve endings; these cells are responsible for signalling different aspects of tactile sensations to the brain.
• Dermis: The dermis is mainly dense tissue made up of collagen and elastic fibers. This layer contains blood vessels, nerve endings, sweat, sebaceous glands and follicles.
• Sebaceous glands: Produce an oily substance that releases secretions that trap and eliminate harmful bacteria and naturally lubricate and soften our skin and hair
• Sweat glands: These are used to lubricate parts of the body such as pals of the hand and soles of the feet.
• The skin is the largest organ in our body; the boundary separates the organism from the outside world.