This week, listener Rick emailed us to ask "Why do we acquire lifelong immunity against some pathogens but not others?" Sally Le Page asked author and infectious disease researcher at Imperial College, London, John Tregoning, to jog our memories... Like this podcast? Please help us by supporting the Naked Scientists

Margaret got in touch to ask The Naked Scientists: "Science has now identified actual nerve endings that humans and other mammals have that send that itchy feeling to the brain. Do snakes and other amphibians have these same nerve types? Have frogs been seen scratching an itch?"Harry Lewis dived deep to find an answer and Gerhard Schlosser from the National University of Ireland Galway was on hand to tell him more... Like this podcast? Please help us by supporting the Naked Scientists

Listener Mark was curious to know: "Since the Universe is expanding, and light coming across it stretches as it does so, becoming more red, what happens to the lost energy when the shorter wavelength, higher energy light towards the blue end of the spectrum is shifted into lower energy, red wavelengths?" Cameron Voisey went off to figure it out... Like this podcast? Please help us by supporting the Naked Scientists

Listener Martin wanted to know: "How long does it take the food I eat to become part of me?" Eva Higginbotham set off to find out the answer... Like this podcast? Please help us by supporting the Naked Scientists

Dave got in touch with The Naked Scientists to ask, "How much of the brain is memory?" This week Harrison Lewis only just remembered to get in touch with Amy Milton from the University of Cambridge. Thank goodness he did, as Amy has extensive experience wrapping her head around this brain teaser... Like this podcast? Please help us by supporting the Naked Scientists

Listener Ruomei wrote in to ask "Why do ladybugs have different numbers of spots on their backs?"Eva Higginbotham spoke with ladybird enthusiast Helen Roy from the Uk Centre for Ecology and Hydrology... Like this podcast? Please help us by supporting the Naked Scientists

Listener Henk wrote in to ask "Is lava wet?" Sally Le Page spoke with magmanimous geologist Brooke Johnson from the University of Oxford... Like this podcast? Please help us by supporting the Naked Scientists

Beth wrote in to ask "My dog is always licking her fur but never gets a hairball. Why don't dogs get hairballs?" Sally Le Page spoke to three animal aficionados: Nick Sutton, Science Communications Advisor at The Kennel Club; Justine Shotton, Junior Vice President at the British Veterinary Association; and Ann Hohenhaus, Staff Doctor at NYC's Animal Medical Center for the answer... Like this podcast? Please help us by supporting the Naked Scientists

Wayne got in touch to ask: "We've always learned that heat rises but it's normally cooler in the mountains. Shouldn't their higher elevation make it warmer there?" Sally Le Page reached out to atmospheric physicist Simon Clark for the answer... Like this podcast? Please help us by supporting the Naked Scientists

Paul got in touch to ask "If one is recovering or has recovered from covid, would playing bagpipes help to expand the lungs and be beneficial or detrimental?". Adam Murphy reached out to John Dickinson from the University of Kent and Michael Steiner from the University of Leicester for the answer... Like this podcast? Please help us by supporting the Naked Scientists