Human Physiology and Anatomy

When you sweat, you lose water, which decreases blood volume. Since the total amount of salts in your blood remains constant while blood volume decreases, the concentration of salts increases. This is why staying hydrated during exercise is crucial.

Hemoglobin is a protein in red blood cells that binds to oxygen in the lungs and transports it to tissues throughout the body. Each hemoglobin molecule can carry four oxygen molecules. The other options are incorrect - hemoglobin does not destroy bacteria (white blood cells do), prevent anemia (it causes anemia when deficient), or utilize energy directly.

The kidney's primary function is filtering blood to remove waste products and excess substances, excreting them as urine. Each kidney contains about one million nephrons that perform this filtration. While kidneys also help regulate blood pressure and produce hormones, waste removal is their MAIN function. The other options describe functions of other systems (circulatory, nervous, digestive).

Stomach's function is digestion (organ-function relationship). Muscles' primary function is movement. Breathe involves lungs, run and lift are specific movements but not the fundamental function.

The kidney's primary function is filtering blood and removing metabolic waste products like urea, creatinine, and excess salts through urine formation. While kidneys do help regulate blood pressure (via renin-angiotensin system), this is not their main function. Temperature regulation is managed by the skin and hypothalamus, and digestion involves the gastrointestinal tract.

Haemoglobin is a protein in red blood cells that binds to oxygen in the lungs and carries it to tissues throughout the body. Each haemoglobin molecule can carry up to four oxygen molecules.

ICU stands for Intensive Care Unit, a hospital department providing critical care to seriously ill patients with 24/7 monitoring. It is not related to computers, children specifically, or circuits. The term reflects the intensive nature of medical care provided.

The middle finger's nail grows fastest due to increased blood circulation and longer growth period before injury. Nail growth rates vary across fingers - the dominant hand's nails also grow slightly faster. On average, fingernails grow about 3mm per month.

The human body contains approximately 40-42 liters (10-11 gallons) of water in an average adult. The 10-gallon figure is approximately correct. This tests basic knowledge of human biology and body composition.

Men typically have about 60% water by body weight, while women have about 55%. This difference is because women generally have more body fat, which contains less water than lean tissue. Therefore, men's bodies contain a higher percentage of water.

The brain is approximately 80% water. This high water content is necessary for proper brain function, as water is essential for neural transmission, maintaining cellular structure, and removing waste products from brain tissue.

The respiratory system performs multiple vital functions. Ventilation moves air in and out of lungs. Gas exchange transfers oxygen into blood and removes carbon dioxide. The system also eliminates water vapor and helps regulate blood pH by controlling carbon dioxide levels.

The kidney's primary function is filtering blood and removing waste products like urea, creatinine, and excess salts through urine. It does regulate blood pressure indirectly, but waste removal is its main role.

Hemoglobin is the red pigment in red blood cells that binds to oxygen in the lungs and transports it to body tissues. It does not destroy bacteria, prevent anemia, or directly utilize energy.