Endocrine and Musculoskeletal Systems: Functions and Anatomy

The Endocrine System

The endocrine system is a set of organs and tissues responsible for secreting hormones. It is distributed throughout the body, similar to the nervous system. However, the endocrine system uses chemical substances instead of nerve impulses.

Types of Hormones and Glands

• Pituitary: Located in the head.
  • Growth hormone: Stimulates the growth of all body tissues, especially the skeleton.
  • Thyroid-stimulating hormone: Regulates the production of thyroid hormones.
• Testes: Male gonads.
  • Testosterone: Stimulates the production of sperm and the development of secondary sexual characteristics.
• Thyroid: Located in the neck, in front of the trachea.
  • T3 and T4: Increase cell metabolism, oxygen consumption, protein synthesis, and glucose utilization.
• Parathyroid: Located at the back of the thyroid.
  • Parathyroid hormone: Increases the amount of calcium in the blood.
• Adrenal glands: Situated above the kidneys.
  • Medulla: Secretes adrenaline.
• Pancreas: Located behind the stomach.
  • Insulin: Reduces the amount of glucose in the blood.
  • Glucagon: Increases the amount of glucose in the blood.
• Ovaries: Female gonads.
  • Estrogens: Stimulate the development of secondary sexual characteristics.
  • Progesterone: Prepares the uterus for pregnancy.

Bones

• Short bones: Provide support and stability and serve as insertion points for muscles.
• Long bones: Provide support and enable movement.
• Flat bones: Provide protection, as in the case of the skull bones.

Joints

• Slightly movable joints: In addition to the bones, ligaments and cartilage are present, limiting the mobility of the vertebrae.
• Intervertebral disc: Located between two vertebrae, absorbing the impact when pressure is exerted on the spinal column.
• Immovable joints: Completely solid because the edges fit together like pieces of a puzzle. For example, the cranial bones are held together by fixed joints called sutures.

The Musculoskeletal System: Lever Classes

• First class: The lever that the head forms with the spinal column and the splenius muscle.
  • Resistance (R): The weight of the head.
  • Effort (E): From the muscle.
  • Fulcrum (F): The spinal column.
• Second class: The lever formed by the ankle joint and the gastrocnemius muscles. This raises the body and rests the weight on the leg bones.
• Third class: The lever that raises the forearm over the arm.
  • R: The weight of the hand.
  • F: The elbow.
  • E: The contraction of the biceps.