Classwork Series And Exercises {Biology – SS1}: Human Reproductive System

 

 

Human Reproductive System

Introduction

The reproductive system or genital system is a system of sex organs within an organism which work together for the purpose of reproduction. Reproduction is a process involving coming to life of new organisms either from one parent or a pair of parent organisms. Reproduction allows continuity of life. It may be sexual or asexual.

·         Sexual reproduction involves the fusion of two different sex cells which usually come together from two different parents to produce an offspring. Gametes are formed by a kind of cell division called meiosis.

·         Asexual reproduction involves only one parent. An individual produces an offspring by itself. There is no fusion of nuclei, and the cells which give rise to the offspring usually divide by means of mitosis.

Structure and Functions of Female Reproductive System

 

The female reproductive system is designed to carry out several functions. It produces the female egg cells called the ova for reproduction. The system is designed to transport the ova to the site of fertilization. The fertilization of an egg by a sperm normally occurs in the fallopian tubes. The fertilized egg is implanted into the walls of the uterus (womb), beginning the initial stages of pregnancy. If fertilization and/or implantation do not take place, the system is designed to menstruate. In addition, the female reproductive system produces female sex hormones that maintain the reproductive cycle. The human female reproductive system contains three main parts: the vagina, which leads from the vulva, the vaginal opening, to the uterus; the uterus, which holds the developing fetus; and the ovaries, which produce the female’s ova.

I.      Vagina: The vagina is a canal that joins the cervix (the lower part of uterus) to the outside of the body. It also is known as the birth canal.

II.      Uterus (womb): The uterus is a hollow, pear-shaped organ that is the home to a developing fetus. The uterus is divided into two parts: the cervix, which is the lower part that opens into the vagina, and the main body of the uterus, called the corpus. The corpus can easily expand to hold a developing baby. A channel through the cervix allows sperm to enter and menstrual blood to exit.

III.      Ovaries: The ovaries are small, oval-shaped glands that are located on either side of the uterus. The ovaries produce eggs and hormones.

IV.      Fallopian tubes or oviduct: These are narrow tubes that are attached to the upper part of the uterus and serve as tunnels for the ova (egg cells) to travel from the ovaries to the uterus. In conception, the fertilization of an egg by a sperm normally occurs in the fallopian tubes. The fertilized egg then moves to the uterus, where it implants into the lining of the uterine wall.

Structure and Functions of Male Reproductive System

 

The male reproductive system includes the scrotum, testes, spermatic ducts, sex glands, and penis. These organs work together to produce sperm, the male gamete, and the other components of semen. These organs also work together to deliver semen out of the body and into the vagina where it can fertilize egg cells to produce offspring. 

I.          Testes: are two oval-shaped organs present in the lower part of the abdomen.  The 2 testes, also known as testicles, are responsible for the production of sperm and the male sex hormone, testosterone.

II.          Scrotum: This is a sac-like organ made of skin and muscles that houses the testes. It protects the testes and epididymis.

III.          Epididymis: It is a long (6m) coiled tube on the outside of testes. It is for the temporary storage of sperm after production until when matured.

IV.          Sperm duct or vas deferens: is a narrow tube which leads from the epididymis to the seminal vesicle. They join with the tube from the bladder to form the urethra. It carries urine or sperms though cannot carry both together.

V.          Prostate gland, Seminal vesicle and Cowper’s gland: are along the sperm tubes and urethra. They secrete fluid (seminal fluid) containing food and enzymes to activate the sperms as well as make them mobile (fluid + sperm = semen).

VI.          Penis: is an intromittent organ for introducing sperms into the female reproductive organ (vagina). The penis contains spongy tissues which can be filled with blood and become erected. It introduces the sperm into the vagina of the female and for urination.

VII.          Urethra: is a narrow tube which prolongs into the penis. The urethra is urinogenital in function, that is, it serves as a means of reproduction as well as excretion. It aids the passage of sperm into vagina and the passage of urine out of the body.

 

Sex cells

The reproductive sex cells are also known as gametes. The formation of gametes called gametogenesis takes place in the gonads (Testes and Ovaries)

·         Male Gametes or Sex Cells called sperms are produced in the testes by a process called spermatogenesis. The gamete is unicellular in nature. The sperm consists of a head which contains the nucleus, a middle piece and a whip-like tail or flagellum.

Parts and Functions of Sperm Cell

I.        Acrosome: is located at the posterior end of the head which contain lytic enzymes used to dissolve the egg membrane and enhances the penetration of the egg during fertilization.

II.        Middle piece: it contains numerous mitochondria which generate the energy used by the sperm to swim towards the egg.

III.        Nucleus: is found in the head of the sperm cell and contains the genetic materials which fuse with the nucleus of the egg or ovum.

IV.        Long whip-like tail or flagellum: it helps to move the sperm cell.

 

·         Female Sex Cells or Gametes: also called the eggs or ova are produced in the ovaries by a process called oogenesis. The human female gametes are larger than the sperm. It consists of the cytoplasm, a nucleus in the centre, granules and yolk droplet. The yolk provides a source of nourishment for the embryo, especially at the early stages of development. The nuclei of the sperm and ovum contain chromosomes (thread-like materials) which carries the genes. The genes are the transmittable character from parents to offspring.

TESTS AND QUESTION

1.    After sperm are produced, they are delivered first to the (a) vas deferens (b) urethra (c) Epididymis (d) seminal vesicle  Answer: Epididymis

2.    What is the name of the vesicle at the tip of a sperm cell that contains enzymes that will help the sperm cell penetrate an egg cell it encounters? (a) scrotum (b) nucleus (c) mitochondria (d) acrosome  Answer: Acrosome

3.    In humans, fertilization of egg normally takes place when the egg and sperm unite in the (a) vagina (b) fallopian tube (c) uterus (d) ovaries.  Fallopian tube

4.    The duct that transport sperm into the urethra is_____________ (a) vas deferens (b) epididymal duct (c) ureter (d) none of the above  Answer: Vas deferens

5.    The production of ova is called ________________ (a) spermatogenesis (b) oogenesis (c) ovanogenesis (d) all of the above  Answer: Oogenesis