Biology (4)



We take it for granted that we are born with hinged bones to provide low-friction articulations, eye protectors (eyelids), tears secreted by the lachrymal glands to lubricate the eyes so that they don't feel scratchy, and an optic nerve to transmit electrical impulses to the brain to decode visual cues so that we can know where we are. We shrug off as unremarkable the fact that broken bones will, unlike broken vases, mend, or the fact that minor wounds will heal by the process to which medical people refer with a complacent lack of affect as "bodily regeneration."Taking Leave of Darwin, 113-114


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We should therefore be more appreciative of nature's ingenuity and the sheer ease with which we see, hear, talk, eat, drink, make love, and reproduce our kind. Such should be the central core of school biology lessons, promoting a sense of wonder in the young mind at the very fact of existence. The reason that it does not form that core is that scientists and the educational establishment subscribe to the materialistic-mechanistic model of human functioning, and therefore tend not to "do" wonder.Taking Leave of Darwin, 113


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Faced with the onslaught of microbes, how does the normal human body defend itself and stay healthy? To begin with, it keeps out as many potential pathogens as possible with barriers such as the skin and other non-specific defences. The skin, which is waterproof, is impenetrable to most invaders, and it provides fatty acids that many microorganisms find toxic. Areas not covered by the skin, such as the eyes, mouth, lungs and digestive tract, are more vulnerable, but they have alternative defences. Tears, saliva, urine and other body secretions contain lysozyme, an enzyme that can kill certain types of bacteria by splitting the molecules found in their cell walls. Mucus in the nose and the airways engulfs bacteria and stops them penetrating the membranes. Cilia - tiny beating "hairs"- then push the mucus out of the airways into the throat, where it is swallowed. In the stomach, acid kills most of the microorganisms in food, as well as starting the process of digrestion.


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