Class notes SCIENCE LESSON NOTES - 2020

Specific Objectives By the end of this topic, the learner should be able to: • Identify some of the reproductive systems • Describe physical changes during adolescence • Identify parts of the circulatory system • Describe the components of blood and their functions • Identify the types of blood vessels and their functions • Describe the structure of and functions of the heart • Explain fertilization, development of foetus and birth process • Identify the main excretory organs and their waste products Revision Notes 1 1.1 Reproductive System This part presents two kinds of reproductive system, namely female and male reproductive systems. a) Female Reproductive System The system by which human beings are enabled to produce young ones is called reproductive system. As shown by Figure 1.1, the system consists of different parts. These include: Vagina, Cervix, Uterus, Ovaries and Fallopian tubes. Ovary: There are two ovaries in the female body. There are several eggs in each ovary called ova. At puberty, that is 12-16 years the ova mature monthly and set free from the ovary into the oviduct. This is called ovulation. Notes distributed electronically by Schools Net Kenya | Order your copy online at |Email: | Mobile: 2 Figure 1.1: Parts of a Female Reproductive System Oviduct/fallopian tube: The tube from ovary to the uterus. There are two types one from each ovary. Ovum is released into this. Uterus: The walls develop a thick lining every month. Fertilized ovum attaches its self in this lining and grows into an embryo. The lining sheds off if there is non fertilization and flows off with the unfertilized ovum via the virginal. This is called menstruation. Vagina: this is canal from the outside. The sperms are deposited here in the time of sexual intercourse. At birth the baby passes out through here b) Parts of Male Reproductive System Male Reproductive System consists of various parts. These include penis, testis, urethra, prostrate and bladder. Penis: tube like structure through which sperms are released. Also in this structure urine is passed outside the body. Testis: Male human beings have two testes they are called testis in plural. They are enclosed in a bag called scrotum. Urethra: a tube passing through the centre of penis. The sperms and urine pass through her