Everyday Biology, Surprisingly Handy (Part 3)

[B] Goitre | Without iodine, your thyroid swells like a balloon trying to capture more from your blood. This is why table salt has iodine, preventing neck balloons since 1924.

[C] Allergies | Antihistamines block your body's overreaction to harmless things. They basically tell your immune system to calm down about pollen already.

[A] Vitamin K | Vitamin K got its name from the German word for clotting. Newborns get shots of it because they're born without enough, making birth literally bloody difficult.

[C] Leukemia | Leukemia makes white blood cells multiply like spam emails until they crowd out useful cells. Your blood becomes mostly immune cells that ironically can't protect you.

[B] Tendons | Tendons are stronger than steel cable of the same size. The Achilles tendon can withstand 1,000 pounds of force, though Greek mythology suggests avoiding arrows.

[D] Fungal infection | Ringworm isn't a worm at all, just fungus growing in circles. Medieval doctors named it wrong and we're still stuck with their mistake centuries later.

[A] Chromosomes | Your DNA would be 6 feet long if stretched out, so chromosomes pack it like the world's most important origami into every cell nucleus.

[A] Thalassemia | Thalassemia means "sea blood" because it was first found in Mediterranean people. It's genetic proof that evolution sometimes makes rough drafts.

[B] Night Blindness | Vitamin A helps make rhodopsin, the protein that lets you see in dim light. Without it, sunset basically means temporary blindness until morning.

[D] Pituitary gland | The pituitary is pea-sized but controls most other glands. It's basically your hormonal CEO making executive decisions from a tiny skull office.

[B] Bones | Your bones store 99% of your body's calcium like a mineral savings account. When blood calcium drops, bones make withdrawals automatically.

[D] Keratin | The same keratin in your nails makes rhino horns and bird beaks. Your fingernails grow 0.1mm daily, giving you rhino powers in extremely slow motion.

[A] Double helix | DNA's double helix is like a twisted ladder where the rungs spell out instructions for building you. Watson and Crick figured this out partly by stealing Rosalind Franklin's data.

[B] Neurons | You have 86 billion neurons making 100 trillion connections. That's more connections than stars in 1,000 Milky Ways, all fitting in your three-pound brain.

[C] Anemia | Anemia affects 2 billion people worldwide. Your blood basically becomes watered-down, making oxygen delivery as efficient as dial-up internet.

[A] Leukocytes | Leukocytes are your body's army with five different divisions. Each type has a specialty, from eating invaders to remembering enemies for decades.

[C] Oxygenated blood | Arteries carry oxygenated blood except the pulmonary artery, which is the rebel carrying the deoxygenated stuff. Biology loves its exceptions.

[D] Insulin | Insulin was first extracted from dog pancreases in 1921. Before that, Type 1 diabetes was a death sentence with a sugar-free diet that barely延长ed suffering.

[B] Dermis | You have 3 million sweat glands producing up to 3 gallons daily. They're your biological air conditioning system that unfortunately doesn't have an off switch.

[D] Brain | Your brain uses 20% of your oxygen and calories while being 2% of your weight. It's basically a very hungry, very complicated electrical potato.

[B] Bone Marrow | Bone marrow produces 2 million red blood cells per second. It's the fastest factory in your body, working harder than Amazon during Black Friday.

[A] Rickets | Rickets bends children's bones like overcooked spaghetti. Victorian England's smog blocked sunlight so badly that bendy children became depressingly common.

[C] Anatomy | Anatomy comes from Greek meaning "to cut up." Ancient anatomists were basically professional corpse dismantlers with really good drawing skills.

[B] Fluorine | Fluoride makes teeth harder than steel on the surface. Cities adding it to water saw cavity rates drop 25%, making dentists slightly less wealthy.

[B] Nostrils | Your nostrils take turns being dominant every few hours. You're basically breathing through one nostril at a time without noticing.

[C] Malacophily | Some plants are pollinated by snails, proving nature will try anything once. It's the slowest pollination method, but hey, it works.

[A] 33 | You start with 33 vertebrae but end up with 26 as some fuse together. Your spine literally gets shorter as you age, explaining grandpa's height stories.

[C] Wilhelm Johannsen | Johannsen coined "gene" in 1909 from the Greek for "birth." Before that, scientists just vaguely waved at heredity and mumbled about "factors."

[D] Biogeography | Biogeography explains why kangaroos are only in Australia and why island animals are often weird. Isolation makes evolution get creative.

[A] Iron | Each red blood cell contains 280 million hemoglobin molecules with iron centers. You're basically 4 grams of iron pretending to be a person.

[D] Paleontology | Paleontologists study things that died millions of years ago. It's basically CSI for creatures that turned into rocks.

[B] Endocrine system | The endocrine system sends chemical messages through blood at 2 mph. It's slower than nerves but lasts longer, like sending letters versus texts.

[D] Liver | Your liver stores about 100g of glycogen, enough energy for a 10-mile run. It's your body's emergency snack bar that opens during exercise.

[C] 7.40 | Blood pH must stay between 7.35-7.45 or you die. Your body maintains this better than any laboratory equipment, using lungs and kidneys as pH meters.

[C] Cerebral cortex | The motor cortex maps your body upside-down with huge areas for hands and mouth. Your brain thinks thumbs are more important than your entire back.

[D] Elephantiasis | Elephantiasis is caused by worms blocking lymph vessels. Your legs swell because fluid can't drain, turning limbs into water balloons nobody wants.

[D] 206 | Babies have 300 bones that fuse into 206 by adulthood. You literally lose 94 bones growing up, though unlike teeth, nobody puts money under your pillow.

[C] Aorta | Your aorta handles blood pressure that would explode normal pipes. It's an inch wide and curves like a candy cane, which is ironic given what candy does to arteries.

[A] Cognitive biology | Cognitive biology studies how organisms process information. It basically asks "what were they thinking?" but with actual science instead of gossip.

[A] Enlargement of Thyroid Gland | Your thyroid needs just 150 micrograms of iodine daily. That's less than a grain of sand, yet without it your neck becomes a balloon.