Definition of Skeletal System

Skeletal systems form the scaffolding and shape of the body, as well as being the structural support for muscles and organs. There are two types of skeletal systems: the exoskeleton, where there is an external frame, such as in insects and the endoskeletons, which are internal structures and form the bone skeletons, typical of the vertebrates.

The skeleton is made up mainly of bones, which are rigid and resistant organs, but it is also made up of bone cells and a complex network of tissues and muscles that work in harmony to allow us to move and maintain ourselves upright

The bones

Bones are the building blocks of the skeletal system. At first glance, they may appear to be just hard, dry structures, but they are actually living and dynamic organs. Bones grow to keep up with the growth of the body. Bone cells, which are the cells in the bones, can make or break bone, and use that ability to repair injuries such as breaks and fissures.

He bone tissue is a type of connective tissue

, but it is characterized by having a rigid and mineralized extracellular matrix. Matrix is ​​the substance that surrounds cells. In the rest of the connective tissues, the matrix has a more or less gelatinous consistency, but in bone, it is impregnated with minerals of calcium and phosphorus, which gives it hardness and resistance.

The matrix also contains proteins that give it elasticity and resistance to mechanical stress.

Bone tissue has several types of bone cells, each with specific functions.

Osteocytes are the main cells of bone tissue and are responsible for the daily maintenance of bone, regulate mineral metabolism and respond to mechanical forces. The osteoblasts they are responsible for the formation of new matrix, while osteoclasts are dedicated to bone resorption. The combined action of osteoclasts and osteoblasts allows bone to be remodeled for life.

Through the bones circulate blood vessels and nerves, which are essential to nourish and maintain bone cells. Blood vessels carry oxygen and nutrients, while nerves carry signals and contribute to bone sensitivity. Bones are not insensitive structures, and a bone lesion is usually very painful.

Functions of the bones

Although one of the most obvious functions of the bones is to provide support and support our body, they have other important functions:

• Bones form rigid structures that act as protective cages for vital organs. For example, the skull protects the brain, the ribs and sternum protect the lungs and heart, and the vertebral column protects the spinal cord.

• Bones act as a mineral store, storing mainly calcium and phosphorus. When the body needs those minerals, osteoclasts dissolve the bone matrix to release those minerals, which pass into the blood and are available to other cells in the body. When there is a surplus of minerals in the blood, it is deposited in the bone matrix and stored.

• Inside certain bones, such as the femur and sternum, is the bone marrow. This is where blood cells are produced, including the Red blood cells, responsible for the transport of oxygen, the white blood cells, fundamental components of the immune system, and the platelets, which are responsible for forming a "plug" in the broken blood vessels to seal the leak and prevent blood loss. The bone marrow is an essential tissue for the functioning of two vital systems: the circulatory system and the immune system.

Movement and the musculoskeletal system

the bones are articulated with each other and together with the muscles, ligaments and tendons, form a mechanical system that allows movement and locomotion. Without this solid and articulated structure, movement would be impossible.

Muscles are soft tissues capable of contracting and exerting directed forces and are attached or anchored to bone by tendons, which are like strong ropes. When a muscle contracts, it pulls on the bone to which it is attached, causing movement in the joints. For example, when we flex our arm to lift an object, the biceps muscle of the arm contracts and pulls on the arm bone, generating the flexion movement, very similar to the operation of a lever. At the same time, the triceps muscle on the back of the arm relaxes to allow movement.

When instead of flexing the arm, what we want is to extend it, the game of forces is the inverse: this time, the muscle that contracts and pulls on the bone is the triceps, while the biceps remains relaxed so as not to exert a force in the opposite direction. contrary.

The muscles, especially those linked to voluntary movements, they work in opposite pairs. When one muscle contracts, the opposite muscle relaxes to allow movement in the desired direction. This balance is essential for efficient and precise mobility. In addition to allowing movement, muscles also play a role in stabilizing the body.

The postural muscles, which are the buttocks, abdominals, and back muscles, are responsible for maintaining an upright posture and stabilizing the body. skeleton during movements such as walking, jogging or lifting heavy objects or holding a position for a long time while standing or sitting. These muscles perform, unconsciously and controlled by the cerebellum., an organ of the central nervous system, adjusts the forces necessary to maintain the posture according to the position of the body. During dizziness, the cerebellum cannot determine the position of the body (which is called loss of balance). By not having precise orders, the muscles cannot maintain the posture and sometimes, dizziness can cause falls.

The skeletal systems are complex structures that provide support, protection and movement to the body of the animals with internal skeletons, and the interaction of the bones with the muscles is what allows movements.

Muscles cannot work without bones, and the skeleton without musculature would only be an immobile scaffold. For this reason, the organ system, which allows movement, is called musculoskeletal system, with three fundamental components: bones, joints and muscles.

References

Photos: iStock - Nikola Nastasic / ZU_09