[Nutrition of crews of long-term missions on the International Space Station]

Thousands of artificial satellites orbit the Earth every day at various distances from the Earth. Satellites that orbit the Earth below an altitude of 1,600 km are considered to be orbiting in low-Earth orbit (LEO). Research satellites and Earth observation satellites are usually placed in LEO, and mostly orbit the Earth in elliptical orbits. Navigation satellites are placed in medium-Earth orbit (MEO), ranging from 2,000 km to 36,000 km from the surface of the Earth. Meanwhile, communication...

During the initial hours of fasting, the body uses up its glycogen stores as an energy source. Once these glycogen reserves are depleted, the body begins breaking down stored triglycerides and structural proteins. During this stage, glycerol becomes a key substrate for gluconeogenesis, while free fatty acids undergo beta-oxidation to provide energy for tissues, such as skeletal muscle. In the fasting state, the body spares protein breakdown as much as possible to conserve muscle and structural...

Enteral nutrition delivers nutrients directly to the stomach or small intestine through a tube. This method is appropriate for patients who cannot eat but still have a functioning digestive system. It is also beneficial for individuals with swallowing difficulties, anorexia, malabsorption, or those who have undergone gastrointestinal (GI) surgery.
Orogastric (OG) and nasogastric (NG) feeding are two standard methods used for enteral nutrition. Enteral nutrition is often preferred over...

Enteral nutrition encompasses various methods of delivering nutrition directly to the gastrointestinal (GI) tract, bypassing traditional oral intake. It is particularly beneficial for patients who cannot eat by mouth but have a functioning digestive system. Key methods include nasointestinal feeding, gastrostomy, and jejunostomy, each suited to different clinical scenarios based on the patient's needs and condition.
Nasointestinal Feeding
Nasointestinal feeding involves placing a tube through...

Absorption refers to taking dietary nutrients from the intestinal lumen for transportation throughout the body. After digestion in the small intestine, carbohydrates, proteins, and fats are broken down into simpler forms. These essential macronutrients and other vital substances, such as vitamins, minerals, and water, are then prepared for absorption into the bloodstream.
Enterocytes, which are specialized polar epithelial cells, line the mucosa of the small intestinal walls. These cells...

Microorganisms exhibit diverse oxygen requirements and growth patterns driven by their metabolic strategies and environmental adaptations. Oxygen, while essential for many organisms, can also be toxic under certain conditions, shaping how microorganisms grow and survive.Oxygen Requirements of MicroorganismsMicroorganisms are classified based on their ability to use or tolerate oxygen:● Obligate aerobes like Mycobacterium tuberculosis need oxygen for energy production, as it serves as the...