External Barrier

The external barrier is the general name for morphological structures that protect the body from the adverse effects of the external environment. External barriers include the skin, respiratory system, digestive system, liver, kidneys, and reticuloendothelial system. These structures perform many functions, such as protection against infections, toxins and other harmful substances, regulation of body temperature, maintaining homeostasis, etc.

The skin is the first external barrier that protects the body from external influences. It consists of several layers, including the epidermis, dermis and subcutaneous fat. The epidermis consists of stratified squamous epithelium, which contains keratinocytes, melanocytes and other cells. The dermis contains collagen, elastin and other proteins that provide strength and elasticity to the skin. Subcutaneous fatty tissue provides additional protection from cold and injury.

The respiratory apparatus is also an external barrier. The lungs and bronchi provide gas exchange between the external environment and the blood. The lungs are made up of many alveoli, which are small air sacs surrounded by capillaries. The bronchi connect the lungs to the trachea, which in turn connects to the larynx. The trachea and larynx are important organs for breathing and voice.

The digestive system is also an external barrier as it protects the body from pathogens and toxins. The digestive tract begins in the mouth and ends in the anus. It consists of a number of organs, including the esophagus, stomach, small intestine, colon, and rectum. Each of these organs performs different functions, such as digesting food, absorbing nutrients, and removing waste.

The liver and kidneys are also extrinsic barriers as they perform important functions in maintaining homeostasis. The liver processes toxins, hormones and other substances that can be harmful to the body.

The external barrier is the general name for the morphological structures of the body that protect it from unfavorable environmental factors. External barriers include the skin, respiratory and digestive systems, as well as the liver and kidneys and reticuloendothelial tissue. The skin is the very first barrier, protecting the body from germs, toxins and other harmful substances