Question

Explain briefly: [5 MARKS]
(i) The oviducal funnel is lined with cilia.
(ii) The mother's blood does not circulate through the embryo.
(iii) The umbilical cord is the life line of the foetus.
(iv) The foetus respires but does not breathe.
(v) Chances of pregnancy to occur are most favourable around the 14-15th day of the menstrual cycle.

Answer 1

Each Part: 1 Mark

(i) The oviducal funnel is lined with cilia so as to pitch up and push the released ovum into the oviduct.
(ii) The mother's blood does not circulate through the embryo because if this happens, then the relatively high pressure of mother's blood would seriously damage the delicate tissues of the foetus.
(iii) The umbilical cord is a tough structure that serves as the blood vascular connection between the foetus and uterine wall. The maternal blood carries nutrients, oxygen, hormones and water to the placenta, where they are absorbed and passed on to the embryo through the blood vessels of the umbilical cord. Therefore, it is the lifeline of the foetus.
(iv) The full-grown human embryo (foetus) respires because the dissolved oxygen in the mother's blood diffuses into the foetus and is used in the oxidation of glucose in the cells with the liberation of energy. However, there are no breathing movements as the lungs lie collapsed in the foetus and only function after the foetus is expelled from the mother's body. There is, therefore, no breathing movements in the embryo as it receives oxygen by diffusion of gases.
(v) On about 13th or 14th day of the menstrual cycle, the follicle ruptures (ovulation) and the released egg travels down the oviduct. Therefore, chances of pregnancy to occur are most favourable around the 14-15th day of the menstrual cycle.