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Biology 2nd Baccalaureate

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10.1. The skeleton

The skeleton

As you already know, a living being is any individual who is capable of nurturing, reproducing and relating.

Living things are related when they respond to stimuli. stimulus is a change that occurs in the environment that surrounds the living being that is captured by sensory receptors. The information collected is processed by the Central Nervous System and, it elaborates a response that is transmitted to the effector organ.

The stimuli can be very varied, such as a caress or the noise of the engine of a car that is approaching us. Stimuli are captured by one or more sensory receptors, the information of which is transmitted to the Central Nervous System, where it is integrated and a response is produced. If we feel a caress, our body will relax and we will feel a pleasant sensation, and if we hear the sound of a car approaching, we will prepare ourselves in case it is a dangerous situation and it is necessary to have to run so that it does not run over us. In both cases, the locomotor system is in charge of executing the response.

The locomotor system or musculoskeletal system is responsible for the movement of our body. The locomotor system is made up of:

  • Skeletal systemformed by the bones, the joints and ligaments (fibers connective tissue that connects bones to each other). Its main functions are:
    • Intervene in the movement of the organism.
    • It has a skeletal function, as it shapes and supports the body.
    • Protection of internal organs, such as the encephalon and spinal cord.
    • They store calcium and phosphorus, which can be released into the blood.
    • The bone marrow makes blood cells.
  • Muscular systemformed by skeletal muscles, which are attached to bones by tendons (connective tissue fibers).

The skeletal system

The skeleton of an adult human is made up of 206 bones. When we are born we have some more bones but they are welded later.


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Biology and Geology teaching materials for Compulsory Secondary Education (ESO) and Baccalaureate students.