Topic of water represents four interconnected planes.

  1. Importance of water: Water in the human body performs many important and unique functions - for example, it is an essential component of cells, an important component of biochemical reactions, solvent of substances and further it serves to transmit the nutrients and other necessary substances (hormones, metabolites, antibodies, ...) or creates the systems equalizing the temperature of the body.
  2. Drinking water: As drinking water we can consider healthy water, which even through a continuous consumption does not cause diseases or ill health by the presence of microorganisms or substances affecting by acute, chronic or late effects the health of individuals and their offspring. In addition, its sensory properties and quality do not impede its use for drinking and sanitary needs of individuals. Currently, drinking water is obtained by treatment of surface water in waterworks or water from underground springs or wells.
  3. Absorption of water in the body: Water taken in beverages and food or formed in metabolic processes is absorbed in the small intestine, and a lesser portion also in the colon. This is done on the basis of different concentration, osmosis, in the presence of minerals of sodium and potassium. Unused, spent, water is excreted from the body through saliva, gastric or pancreatic juice, bile, intestinal secretions and faeces. The main dispensing of water is done through the urine, kidney filtration, vapour in breathing or evaporation and skin sweating.
  4. Haemodialysis: This method allows removing toxic waste products of metabolism and excess water from the blood using a special dialysis unit popularly known as "artificial kidney". Patients with kidney failure usually come to haemodialysis three times a week to the so-called dialysis centres.

The aim is that students gain a comprehensive view of water as an important component of the human body through practical tasks that require investigation thinking from students. The main topic of the unit is the production of drinking water and haemodialysis. Production of drinking water in the waterworks has several basic phases – sedimentation, trapping of impurities with the use of chemicals, filtration through a sand filter, disinfection. The principle of haemodialysis is the diffusion of solutes through a semipermeable membrane. Opposite direction flow is used when a sterile dialysis solution of mineral ions and glucose flows along the membrane in the direction opposite to blood flowing.