WEEK 6: REPRODUCTIVE SYSTEM IN MAMAMALS

 TOPIC: Reproductive system in mammals
MAIN AIM: To help the learners understand the reproductive system in mammals
SUBSIDIARY AIM: By the end of the lesson, learner should be able to;

1. Explain the male reproductive system
2. Explain the female reproductive system

PERSONAL AIM: To keep strictly to time allotted to  each stage of the lesson
PREVIOUS KNOWLEDGE: The learners learnt reproductive system in their previous lesson
TEACHING AIDS: Research work from the internet, pictures
PROCEDURE: The teacher present the lesson with the following steps
STEP ONE: THE MALE REPRODUCTIVE SYSTEMS 

Reproductive systems in different mammals are very similar and some parts of their reproductive systems are found outside the body. These parts are called external genitals.
Reproductive System of Man: Male reproductive system of man is made up of primary sex organs and the secondary sex organs. The primary sex organs are the two testes (singular—testis) while the secondary or accessory sex organs include the vas deferens (sperm duct), epididymis, urethra, penis, the external sacs bearing the testes called the scrotal sacs or scrotum and  the three accessory glands---seminal vesicle, prostate gland and Cowper’s gland.
Primary sex organs: These are the testes. The testes are two ovoid shaped structures found outside the abdominal cavity in sacs called scrotal sacs. In a young male, the testes are found in the lower part of the abdomen. At puberty, they descend into the scrotal sacs for the production of spermatozoa and the male sex hormone, testosterone. The two testes are separated from each other by the scrotal septum.  The two major functions of the testes are

1. They produce spermatozoa
2. They also produce/secrete hormones like androgens and testosterone for the appearance of secondary sexual characteristics.

Secondary or accessory sex organs: The secondary sex organs in human male are all other organs associated with reproduction apart from the testes. These organs include vas deferens, urethra, seminal vesicle, prostate gland, Cowper’s gland, penis and the skin pouch called scrotum.
Epididymis: This is a highly coiled tube which stores spermatozoa temporarily before they are moved through the vas deferens/ sperm duct to the seminal vesicle.
Penis: This is the only erectile organ in the male reproductive system. It is used for introducing spermatozoa into the vagina of the female during copulation.
Urethra: This is the tube or opening in the penis which used for the passage of urine and spermatozoa into the exterior. Therefore , it is urogenital in function.
Vas deferens: Also called sperm duct transports sperm cells from the epididymis to the seminal vesicle.
Seminal vesicles are sac-like glands which produce a sticky alkaline fluid called semen or seminal fluid. The sperm cells are embedded in this fluid.
Prostate gland: This gland secretes part of the seminal fluid and enzymes to activate the sperm cells.
Cowper’s gland: It also secretes part of the seminal fluid and enzymes that activate the sperm cells.    
Scrotum (scrotal sac): There are two scrotal sacs in man. These sacs house the testes and protect it. They also help in maintaining the temperature of the testis (about 350C) to enhance sperm production.

STEP TWO:  FEMALE REPRODUCTIVE SYSTEM IN HUMANS

The female reproductive system is also made up of primary sex organs and secondary sex organs.
Primary sex organs: The primary sex organs in female mammals are the two ovaries. They are ovoid shaped structures found in the lower part of the abdomen of females and are attached to the uterus by the ovarian ligaments. The major functions of the ovaries are

1. They produce eggs.
2. They also produce female sex hormones such as progesterone and estrogen.

Secondary sex organs in the female reproductive system include the oviduct or fallopian tubes, uterus or womb, cervix, vagina and clitoris.
Oviduct or fallopian tubes are two tubes that open at the ovaries and extend towards the uterus. They are funnel shaped and perform these performs;

1. They provide sites for fertilization of ovum (egg).
2. They carry ovum from the ovary to the uterus by peristalsis.
3. They also assist in the nourishment of the zygote during the early stage of fertilization.

Uterus (womb): This is a muscular tube where the zygote is implanted. Development of embryo and foetus occurs here. It also plays a role in childbirth by the contraction and relaxation of the uterine wall.
Vagina: This is a muscular canal that extends from the uterus to the vulva. The functions of vagina include;

1. It acts as a canal for the expulsion of fetus.
2. It provides site for the deposition of semen.
3. It allows menstrual flow.
4. It produces lactic acid (by its mucous epithelium) which kills germs in the vagina.

Clitoris: This is the erectile organ found in the vulva. It becomes erect during coitus.
Vulva: This is the external part of the female reproductive system in man. It is made up of the clitoris, labia minora and labia majora.

EVALUATION:

1. Explain the male reproductive system
2. Explain the female reproductive system

CONCLUSION: The teacher concludes the lesson by summarizing the topic from the beginning and give assignment to the learner.