Tag: science & technology

Red blood cells (erythrocytes) have an average lifespan of approximately 120 days in the human body. This precise figure is a standard medical fact taught in physiology courses. After this period, RBCs are removed from circulation by the spleen and liver, with new cells continuously produced in bone marrow.

Pupil dilation occurs in response to autonomic nervous system activation during intense emotions, both positive (love/attraction) and negative (hate/anger). This physiological response is mediated by the sympathetic nervous system and cannot be consciously controlled. The dilation happens due to increased adrenaline and other catecholamines released during emotional arousal.

While cerumen (earwax) production can increase with stress as part of the general fight-or-flight response, the claim that ears secrete 'more' earwax specifically when afraid is not well-established in medical literature. Earwax production is primarily continuous and varies by individual, not clearly documented to spike during fear states. This appears to be a common trivia claim rather than a rigorously verified medical fact.

Humans can survive after removal of significant portions of internal organs. Examples include living with one kidney (nephrectomy), parts of the liver (which regenerates), spleen, pancreas, stomach, and intestines. People can survive with one lung, portions of the brain, and even after removal of the entire stomach (though requiring adaptation). While obviously not all organs can be removed, the statement that 'a large part' can be removed with survival is accurate.

Dogs and humans are indeed among the few mammals with well-defined prostate glands. The prostate is present in most male mammals but varies considerably in size and structure between species. Canine prostates are anatomically and functionally similar to human prostates, which is why dogs are commonly used in prostate cancer research. While other mammals have prostate tissue, humans and dogs have the most prominent discrete prostate glands.

Stars are held together by gravitational force which counteracts the outward pressure from nuclear fusion. Without gravity's inward pull, stars would indeed explode from the immense thermal and radiation pressure within. This statement is fundamentally true.

The Moon recedes from Earth at approximately 3.8 cm per year, which rounds to 3 cm per year. This measured rate is based on lunar laser ranging experiments. Options 1, 2, and 4 cm don't match the actual measured recession rate.

The Milky Way galaxy spans approximately 100,000 light-years from edge to edge. This measurement includes the main galactic disk and its spiral arms. Options of 200,000, 300,000, and 400,000 light-years overestimate the galaxy's diameter.