The first line of defence (or outside defence system) includes physical and chemical barriers that are always ready and prepared to defend the body from infection. These include your skin, tears, mucus, cilia, stomach acid, urine flow, 'friendly' bacteria and white blood cells called neutrophils. Hope this helps.
Answer:
thomos is more likely to be bullied
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hope it helps
Answer:
i believe that the answer is D because the systemic circulation is based on the oxygenated blood
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could you add the choices please
