Tag: Human physiology

The human body absorbs approximately 90% of all ingested water and electrolytes in the small intestine, highlighting its role as the primary site for nutrient uptake. This process, detailing what nutrients are absorbed, is a sophisticated physiological journey that ensures your cells receive the fuel they need to function, grow, and repair.

Approximately 99% of the body's calcium is stored in our bones and teeth, making it the most abundant mineral in the human body. Can humans live without calcium? The unequivocal answer is no, as this mineral is essential for a wide array of critical physiological functions beyond just supporting the skeletal structure.

Sweat is about 99% water, but many people wonder what else is in it and what is the nutritional value of sweat. This article explores the minimal nutritional content of perspiration, focusing on the essential electrolytes and minerals lost during physical activity and why replenishment is key.

An astonishing 30% of starch digestion can occur in the mouth, initiated by the enzyme known as salivary amylase. This enzyme acts on polysaccharides in the mouth, beginning the crucial chemical breakdown of complex carbohydrates during the process of mastication.

While once mistakenly considered a simple waste product causing muscle fatigue, recent scientific understanding has completely reshaped the perspective on what being lactate means. Modern research now shows lactate is a dynamic and multifunctional molecule, playing a key role in energy production, cellular signaling, and even fueling the brain and heart. The 'burn' during intense exercise is not a result of lactate itself but other metabolic factors.

Glucose is the most common respiratory substrate used by the body's cells to produce energy. This simple carbohydrate is favored due to its efficiency and readily available energy source for vital cellular processes, though other substrates can be utilized.

Over 45% of deaths among children under 5 years are linked to undernutrition, highlighting the critical role of proper nutrient intake. So, how do humans receive nutrients to fuel their growth, repair tissues, and perform essential functions? The process is a complex journey involving digestion, absorption, and transport.

For an average-weight 70 kg individual, a significant energy reserve of approximately 400,000 kJ (around 95,000 kcal) is stored in the form of triacylglycerols (fats), far exceeding the capacity of other energy stores like glycogen. This reveals that a person's total 'calorific value' is not a fixed number but a complex calculation of their body's energy potential.

In 1965, a 27-year-old Scottish man named Angus Barbieri began a medically supervised fast that would extend to an astonishing 382 days. This extreme dietary measure, undertaken to combat his severe obesity, resulted in a dramatic weight loss of 276 pounds and made him the man who never ate for a year, setting a record for the longest medically documented fast in history.

Digestion starts long before food reaches the stomach, with a sophisticated process beginning the moment a starchy food touches your tongue. This initial breakdown is the primary role of the salivary gland to break down carbohydrates, utilizing a key enzyme to initiate the chemical conversion of complex sugars.