Human has no control on his heart muscles. It is a unique muscle that keeps on contracting and expansion for the whole life without taking rest. It is found only in heart walls. By inactiveness of muscles, poison is gathered inside our body slowly and later it becomes as a dangerous disease. Therefore, we should take work from this muscle regularly for keeping it strong and active.
The skin is a flexible covering of our body that protects it from harmful bacteria. It also gives sensation of our surroundings. Additions to them, it also controls our body temperature. Our skin is divided in to two layers. The layer outside of our body is called outer skin and those present inside our body is called internal skin. The skin we can see with our naked eyes is called outer skin and formed with dead cells. In these dead cells, 2 important elements- keratin and melanin are found. They provide toughness and glow to our skin. Internal skin is present beneath outer skin having nerves, blood vessels, hairs roots, oily glands and white glands that secretes sweat.
Importance of muscular system-
- It is responsible for body movement.
- It gives shape to our body.
- It produces energy (heat).
On the both ends of muscles, kandrain is located that remains attached with bones joints. These muscles get impulses through motor nerves for contraction and expansion. It can be also known as nerve. The place where muscle is connected with nerve end is called neuro muscles joints. When impulse starts in the nervous system, motor neuron secretes a special type of chemical that gives order to the muscular cell for contracting and expanding.
A motor neuron that is connected with muscular cells is called motor unit. This type of contraction and expansion provide movement to our bones. The skeletal muscles stop functioning when the nervous system does not get impulses and paralysis attacks take place. Due to which, many muscles and tissues are become tough and affects the spinal cord and brain too. It is responsible for muscular paralysis. Sometimes, hands and legs start trembling, body becomes unbalanced, eyelids start blinking with motions and a person feels difficulty in proper pronunciation of words during talk. It is also known as the disease of motor neuron.