Influence of the environment on embryonic development
The embryo is sensitive to the environment and the mother’s condition; harmful factors can cause defects, especially during organogenesis. Alcohol, nicotine and narcotic drugs pass through the mother’s blood to the foetus and disturb its growth and brain development; so a pregnant woman should avoid them and consult a doctor about certain infections and medicines. Homeostasis is the relative constancy of an organism’s internal environment (body temperature, blood composition, acidity); it keeps development stable. Regeneration is the restoration of lost or damaged parts and tissues: a lizard’s tail, the body of Hydra and planaria, and in humans the skin and liver. Anabiosis is a temporary state in which life processes almost stop, occurring in unfavourable conditions (cold, drought): bacterial spores, simple animals and some seeds survive this way. Acceleration is the speeding up of physical development and puberty in children and adolescents over the last hundred years, linked to better nutrition and living conditions.
“Which concept?”. The class reads 6 situations (steady blood sugar, a cut piece of Hydra regrowing, a spore surviving cold, children’s height increasing, etc.); name the concept for each.