Step 1: Understanding the Concept:
IUDs are devices inserted by doctors in the uterus through the vagina. Copper-releasing IUDs utilize the chemical properties of copper ions to prevent conception.
Step 2: Detailed Explanation:
1. Examples: Two common copper-releasing IUDs are CuT (Copper T), Cu7, and Multiload 375.
2. Effectiveness Reasons:
- Suppression of Sperm Motility: The copper ions released by these devices suppress the motility and the fertilizing capacity of the sperms, ensuring they cannot reach the ovum.
- Phagocytosis: The presence of the IUD increases the phagocytosis (cell-eating) of sperms within the uterus, reducing the number of viable sperms.
Step 3: Final Answer:
Two IUDs are CuT and Multiload 375. They are effective because they suppress sperm motility and increase sperm phagocytosis in the uterus.