NOTES PREPARED BY
ASHAQ HUSSAIN BHAT
TEACHER SCHOOL DEPARTMEN
EDUCATION DEPARTMENT
JAMMU AND KASHMIR
HOW DO ORGANISMS REPRODUCE
Life processes are primarily a means to end. i.e, reproduction. Biologically speaking, all other life functions are aimed at keeping the animal alive till it matures and reproduces. Reproduction alone determines the success in the evolutionary process, Humans, however should not consider life merely a waiting period for reproduction, but should have a higher goal than this, like Humanity, worship, work, charity and doing such activities which will ease the life of coming generation not only humans but for other species living with him like wild animals, birds, insects etc.
Meaning of Reproduction:- It is the ability of living organisms to produce a new generation of living individuals similar to themselves. It is one of the fundamental characteristics of life.
Purpose of Reproduction:-Reproduction is aimed at increasing population and perpetuation of the species. In other words, it provides group immortality by replacing the dead individuals with new ones. Reproduction may also lead to an increase in the number of species, if the conditions are suitable.
Basic features of Reproduction:-All organisms reproduce. But Modes of reproduction vary in different organisms. However: all modes have certain common basic features, these are
(1) Replication of DNA- This is the molecular basis of reproduction
(2) Cell division, only mitotic, or both mitotic and meiotic. This is Cytological basis of reproduction
(3) Formation of reproductive bodies or units.
(4) Development of reproductive bodies into offspring.
Forms of Reproduction:-Animals reproduce in a variety of ways. These are of two main types:
Asexual Reproduction
Sexual Reproduction
Asexual Reproduction:
Definition: Production of offspring by a single parent without the formation and fusion of gametes is called asexual reproduction. It is also known as gamogenesis or agamogeny . It is more primitive and hence, simpler than sexual reproduction. It involves mitotic cell division, and is also termed somatogenic reproduction. It ensures rapid increase in numbers. Asexual reproduction produces identical Offspring commonly referred as a Clone. The only genetic variation arises as a result of random mutation among the members of a Clone,
Occurance:- It occurs in protozoan and some lower animals such as coelenterates, certain worms, sponges. It is absent among the higher non-vertebrates and all vertebrates.
Sexual Reproduction:
Definition:-It is the production of offspring usually by two parents, male and female, involving four processes:
(1) Formation of special haploid cells, the gametes, by meiosis (gamesomeness )
(2) Fusion of the gametes in pairs, forming diploid cells, the zygotes (fertilization)
(3) Repeated mitotic division of the zygotes to form embryos.
(4) Growth of the embryos into new individuals. (Development) Sexual reproduction is also called Syngenesis (G. Syn=with, together; genesis =origin)
Occurrence:-It occurs nearly in all animals, including those which reproduce asexually. Some protozoa's, such as Amoeba, Euglena, lack sexual reproduction. In most animals there are two sexes, male and female and the difference between them is determined genetically.
Modes of Reproduction used by unicellular organisms
The unicellular organisms (Amoeba, Euglena etc) reproduce by different asexual methods. Some of the common methods are depicted below:-
Fission:-It is the division of the parent into two small, nearly equal-sized daughter
individuals. It is common in protozoans, but also occurs in certain flatworms such as Planarians. It has two types viz binary fission(in which parent cell is divided into two daughter cells) and multiple fission(in which parent cell is divided into more than the cells).
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| Binary Fission in Paramecium |
In several unicellular organisms when the individual cell is fully mature, it divides into two. This is called fission. The nucleus divides first and then the Cytoplasm. When two individuals are formed during fission, the process is called Binary Fission. Fig
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| Binary Fission in Amoeba |
(1) shows binary fission in Amoeba to produce daughter cells. Plane of the division of Cytoplasm is variable but is always at right angles to the elongated dividing nucleus.
Budding:-Formation of a daughter individual from a small projection, the bud, arising on the parent body is called budding.
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| Budding in yeast |
The parent body may form a single bud or many buds simultaneously. A bud grows and gradually assumes the form and size of the parent. In protozoans, the bud separates from the parent body and grows into an adult while leading an independent life. In animals, the bud develops into a new individual by drawing nourishment from the parent when full grown; the new individual may separate from the parent and become an independent animal as in Hydra.
Budding is of two types: External and internal with regards to the place where
buds arise.
(1) External Budding:-Buds arise from the surface of the parent's body as in Hydra
(2) Internal Budding:-Buds are formed within the parent's body. These consist of small groups of cells enclosed by a resistant protective coat. The Internal buds are found in freshwater sponges and are called gemmules. A gemmule germinates into a new sponge under favourable conditions.
Fragmentation.-It is the breaking up of an animal's body into two or more pieces, each of which grows into a new individual. It occurs in the flatworm Microstomum Large sponge and coelenterate colonies may breakup into fragments by wave action, animal activity, or death and decay of old parts. Each fragment develops into a new colony in due course of time. It also occurs in Spirogyra.
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| Fragmentation in Planaria |
Spore formation or sporulation:- This method of asexual reproduction is very common in the plants which do not produce seeds. e.g; Algae, fungi, ferns, bryophytes etc.
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| Spore formation in Rhyzopus |
These plants produce very small-sized, light weighed spores which are covered over by thick walls to withstand the unfavorable environmental conditions. When conditions become favorable, the thick resistant covering is dissolved and each spore develops into the complete plant. In certain plants spores are produced in specialized organs called sporangia. In higher plants spores are enclosed in capsules.
VEGETATIVE PROPAGATION
It is that reproduction in wKich detached part or portion of a plant regenerates or grows into a new and independent plant. Plants belonging to this category propagate by a part of their body other than a seed. The structural unit that is employed in place of seed is called propagule. It is of two types namely natural and artificial.
Natural :-Natural vegetative reproduction takes place by different plant parts viz; root, stem, leaves etc.
(a) By-Roots:-Modified food storing tuberous roots of Sweet potato, Yam, Dahlia can be propagated vegetatively when planted in soil. The buds present on the roots grow into leafy shoots above ground (slips) and adventitious roots at their bases. Each slips gives rise to a new plant.
(b) By-Stems: - Underground modified stems such as rhizomes (in ginger) corms, bulbs possess buds which grow into new plants and help in vegetative propagation
(c) By-Leaves: - Some plants develop adventitious buds on their leaves which get detached and develop new plants. Leaves of Bryophyllum develop small plantlets with adventitious roots along their margins.
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| Bryophyllum leaf showing adventitious buds |
Artificial:-Several methods of vegetative propagation are man-made and developed by plant growers and Horticulturists for commercial production of crops. They are called artificial methods. Some of the artificial methods are:-
(a) Cuttings:- The small piece of any plant organ (stem, root or leaf) used for propagation is called cutling. Leaf cutting are used to propagate Begonia, Bryophyllum etc. Root cuttings are used to propagate 'Tamarind'. Ștem cuttings are mostly used for propagation. Sometimes the stem cutting, are reated with rooting -hormone (IBA) for proper development of roots.
(b) Layering:-In this method, roots are artificially induced on the stem branches before they are detached from the parent plant for propagation. There are two common types of layering:
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| Vegetative propagation by layering |
Mould layering:-It is the most common method of propagating herbaceous plants. In this method, the lower branch of stem is bent down and partially defoliated. An injury is made in the defoliated portion. The injured and defoliated portion is covered with a light layer of moist soil in which such a way that the growing tip of the branch remains above the soil surface. After a few days the pegged portion develops adventitious roots. The rooted branch is then cut, separated from parent plant and grown into a new plant.e.g Jasmine, Grapevine, Strawberry, Cherry.
Air layering:- (or Gootee) This method is commonly employed in case of shrubs and trees which do not possess branches near the ground. In this method, a ring of bark is removed.(girdled) The girdled portion is then covered with moist mass or grafting clay and wrapped with a polyethene sheet. The wrapped portion is gootee. The girdled portion of the branch inside the gootee develops roots within a period of a month or two. Now the branch is cut and planted in the soil after removing the polyethene. This method is used in vegetative propagation of orange, lemon.
(C) Propagation by plant' Tissue culture Or Micro-Propagation: This method includes propagation of plants by culturing the cells, tissues and organs, called 'tissue culture'. Initially, the culturing of cells or tissues results in the formation of an undifferentiated mass of cells called callus, which later differentiates to produce a large number of plantlets. These plantlets are then transferred to separate pots of nursery buds to obtain a large number of plants. Tissue-culture technique is useful in obtaining virus free plants, disease free plants and in commercial propagation or orchids, Chrysan theikum and other ornamental plants. This method is also employed for quick multiplication of plants.
Merits (Significance) and De-merits of vegetative propagation
Significance :( Merits)
(1). It is the only method of reproduction in plants. Which are seedless. Which have low seed-out put. The seeds are non-viable. The seed which have along dormancy period. e.g banana, seedless-grapes, oranges, rose, pone-apple, tulips etc.
(2) This method is easy and cheap method. e.g a lily seed produces a plant which flowers after 5 years to 10 years. But a plant of lily obtained through vegetative methods flowers within one to two year.
(3). There are cent-percent results through vegetative-multiplication. i.e; all plants can survive raised through this means.
(4). Due to vegetative methods we are able to raise plants in the areas which are unfit for seed-germination.
(5). Due to vegetative-propagation we get a uniform population of daughter plants. These plants are similar to the parent plant in all respects. Such a uniform population of plants is called a Clone,
De-Merits:-
(1) A superior character can neither be introduced nor an inferior character can be eliminated by this method ( in case of natural methods)
(2) If the parent is diseased all the daughter plants will also be diseased.
(3) Due to this vigor and viability is lost generation after generation.
(4) As there are no variations the daughter plants fail to cope up with the changed environment.
(5) Parts which are responsible for vegetative reproduction are not dispersed by the agents like, water, wind, birds etc.
Sexual Reproduction in plants
In Angiosperms, flowers are the modified vegetative shoots meant for sexual reproduction. Thus, it is through flowers that sexual reproduction takes place in these plants.
A lower is generally hermaphrodite. (Bisexual) Its male reproductive part is 'stamen' while 'carpel ' (pistil) is the female reproductive part. A stamen consists of thin thread like filament and a swoolen bilobed anther as its free end. An anther has four pollen sacs and each pollen sac consists of numerous microscopic structures called pollen-grains. The pollen grains produce the male gametes.
A carpel or pistil is flask shaped. Its basal swoolen end is called 'ovary' and a long thin part as 'style'. The free tip of style is blunt and sticky and is called 'stigma'. It is in the ovary that one or many ovules are present. Each ovule contains an egg within it.
The pollen grains from the anther of a flower are carried to the stigma of the same or other flower through different agencies like wind, insects, water, birds etc. This process of transference of pollen grains on to the stigma of the carpel is called pollination
The pollen grains on falling on the stigma of the carpel, germinate forming a tube like structure called pollen tube that penetrates style and ovary and enters the ovule. Two male gametes found at the tip of the pollen tubes, fuse with the ovum of the ovule causing fertilization. The zygote is formed. It gradually develops into an embryo which consists of a ridicule, plumule and cotyledons. Ovule gives rise to the seed which on germination develops into a new plant
Flower And Its Functions?
A flower is a modified condensed shoot specialized to carry out sexual reproduction in higher plants,
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| A typical flower showing floral parts |
Functions -
(1) Flowers are modifications of shoot to perform the function of sexual reproduction. The fertile leaves become microscopic (carpels) which bear anthers and ovules respectively. The anthers produce pollen grains and the ovules possess eggs.
(2) Flowers of most of the angiosperms are shaped variously to help diverse modes of pollination.
(3) Flowers provide seat for germination of pollen, development of pollen tube, formation of gametes and fertilization.
(4) The ovary part of the carpel gets transformed into fruit and the ovules are transformed into seeds after fertilization.
Pollination and its types?
The transferal of pollen grains from the opened receptive stigma of the carpel is called pollination. It is of two types:
Self pollination and cross pollination
Self-pollination:- involves the transfer of pollen grains from the anther of a flower to the stigma of the same flower or genetically similar flower. It is of two types:
(A) Autogamy: (GK. autos=self, gamos=marriage) It is a kind of pollination in which the pollen grains from the anthers of a flower are transferred to the stigma of the same flower. It occurs by three methods:
(1) Cleistogamy: (GK.Kleisto=closed, gamos=marriage) Some plants never open to ensure complete self-pollination. This condition is called cleistogamy, e.g; Oxalis, Viola etc. The cleistogamous flowers are bisexual, small, colourless and do not secrete nectar.
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| Fertilization in a flowering plant |
(2) Homogamy: Anthers and stigma of the bisexual flowers of some plants mature at the same time. They are brought close to each other by growth, bending or folding to ensure self-pollination. This condition is called homogamy e.g; Mirabilis (four O'clock) potato, sunflower etc.
(3) Bud pollination: Anthers and stigma of the bisexual flowers of some plants mature before the opening of the buds to ensure self-pollination. e.g; wheat, rice, etc.
(B) Geitonogamv:-(GK gelton=neighbour, gamos-marriage) It is a kind of pollination in which ht pollen grains from the anther of one flower are transferred to the stigma of another flower borne on the same plant. It usually occurs in plants which show monoecious condition (unisexual, male and female flowers are borne on the same plant)
Advantages of Self-Pollination:
Self pollination maintains purity of the race and avoids mixing .It needs not to produce a large number of pollen grains. Flowers need not to possess devices such as large and showy petals, presence of scent and nectar to attract pollinators.
Disadvantages:
Progeny continuously gets weaker after every generation. Less chances of the production of new species and varieties. Cross-pollination (Xenogamy, Allogamy) It involves the transfer of pollen grains from the flower of one plant to the stigma of the flower of another plant. It is also called xenogam (GK.allos= other,gamos=marriage ) Or allogamy (GK.allos-other ,gamos-marriage )
The main foral characteristics which facilitate cross pollination are:
(1) Herkogamy: Flowers possess some mechanical barrier on their stigma surface to avoid self pollination.
(2) Dichogamy: pollen and stigma of the flower mature different times to avoid self pollination :
(3) Self-incompatibility: In some time plants, the mature pollen fall on the receptive stigma of the same flower but fail to bring about self- pollination. It is called self-incompatibility. Under such conditions the cross pollination is the only option.
(4) Heterostyly: The flowers of some plants have different lengths of stamens and styles SO that self pollination is not possible e.g; Linum, Primula The agents responsible for cross pollination in
angiosperms are both abiotic (wind, water) and biotic (animal pollinators)
Sexual reproduction in Humans
Man is unisexual. There is a distinct sexual dimorphism. Males visibly differ from females in physical standards, external genital organs and accessory sex characters.
Name of primary and secondary sex organs in human beings.
The primary sex organs are gonads which produce gametes (sex cells) and secrete sex hormones. The gonads of the male are called testes which produce male gametes- sperms and the male hormone-testosterone. The gonads of the female are ovaries which produce female gametes-ova and female hormone- estrogen and progesterone. The secondary sex organs include the genital ducts and glands which help in transportation of gametes and reproductive processes. These do not produce gametes or secrete hormones.
Define puberty. When is it attained?
Puberty is the age of human males and females at which the reproductive organs become functional, gonads start producing gametes and sex hormones and the boys and the girls become sexually mature.
It is attained between the age of 13-14 years in males and is triggered by the production of testosterone. While it is attained between 10-12 yrs in females and is triggered by the production of oestrogen.
What are the changes seen in boys at the time of puberty?
The changes seen in boys at the time of puberty are:
i) Enlargement of penis and scrotum.
ii) Broadening of shoulders and increased muscle development. Enlargement of larynx and thickening of vocal cords producing deepening of voice. Growth of pubic hair and extra hair on the face, in the arm pits and on the chest.
v) Changes in behaviour associated with courtship and mating.
vi) Increase in height.
Male reproductive System:-
The male reproductive system consists of a scrotum, a pair of testes, a pair of epididymis, vas deferens, a pair of ejaculatory ducts, a urethra, a penis and certain glands.
Scrotum:- The scrotum is a pouch of pigmented skin arising from the lower abdominal wall and hanging between the legs. A scar like raphe marks the position of the septum is. externally. The testes originate in the abdominal cavity but later, during the seventh month of development, descend permanently into the respective scrotal sacs through termed inguinal canals. The scrotum acts as a thermo- regulator, maintaining the testes at a temperature 2 degree lower than that of the body. This protects the sperms against relatively high body temperature. Failure of the testi6 to descend into the scrotum causes sterility because sperm formation does not occur at the abdominal temperature.
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| Human male reproductive system |
Testis:- The testis are the primary sex organs. They are soft, smooth, pinkish, oval organs, about 4-5cm long, 2.5cm wide and 3cm thick. They are suspended in the scrotal sacs by spermatic cords.
Epididymes:-The epididymis is a long tube which is greatly coiled and tightly packed to form an elongated, flattened body attached to the testes. It shows three regions: upper wider head or caput epididymis, middle narrower body or corpus epididymis, and lower also wider tail or cauda epididymis.
Vas Deferens:- The vas deferens is a continuation of the cauda epididymis. It is about 40cm long and is slightly coiled at first but becomes straight as it enters the abdominal cavity. Here, it passes over the urinary bladder, curves round the urethra and joins the duct of seminal vesicle to form an ejaculatory duct near its end, the vas deferens is enlarged to form a spindle-like ampulla for the temporary storage of spermatozoa( sperms)
Urethra:-It is the urinary duct leading from the bladder. It is joined by ejaculatory ducts and carries urine as well as spermatozoa and secretions urethra is some 20cm long and passes through the penis.
Penis;- The penis is an external intermittent organ through which the urethra runs. It contains three columns of Spongy-tissue. The spongy tissue has abundant blood sinuses that are normally empty and collapsed and help in excreting the penis. The tip of the penis is covered with a soft and highly sensitive skin e.g; glans penis. It is covered by the prepuce or fore-skin. The urethra opens at the tip of the penis.
Semen and its functions
The secretions of accessory sex glands and mucus are added to the sperms to form seminal fluid or semen. The secretions have many functions.
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| Flow chart showing path of sperm and role of different glands in male reproductive system |
(1) They provide a fluid medium for the transmission of sperms into the vagina of the female.
(2) They nourish and activate the sperms to keeps them viable and motile.
(3) They neutralize the acidity of the urine in the urethra of the male and vagina of the female to protect the sperms. The semen has a pH of 7.35 to 7.5
Test for Rape
"Fructose, which is present in the seminal fluid and is not produced anywhere else in the body, provides a forensic test for rape. It is present in the female genital-tract confirms sexual intercourse".
Female reproductive system
The female reproductive system consists of a pair of ovaries, a pair of fallopian tubes (oviducts), uterus, vagina, and external genitalia or vulva.
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| Human female Reproductive system |
Ovaries:- The ovaries are the primary sex organs of the female. The ovaries are about the size and shape of an almond. They are about 3cm long, 2cm wide and I cm thick. The ovaries contain 2 million or more eggs six months before a human female is born, about a million at the time of birth, and only about 400,000 by the time of puberty.
Fallopian tube:-A fallopian tube is about 10 to 12 cm long muscular tube. It conveys the eggs from the ovary to the uterus and also provides the appropriate environment for its fertilization
Uterus: - The uterus (womb) is a large, highly elastic median sac specialized for the development of the embryo. It is located between the urinary bladder and rectum. It varies in size In a nulliparous woman ( who has not born any child it is about 8cm long, 5cm wide and 2cm thick. It is some what larger in a multiparous woman.
Vagina:-The vagina is a larger, elastic muscular tube about 7.5cm long. It extends forward and downward and opens out at its lower end into the vestibule by vaginal orifice. The vagina is adopted for:
(i). Receiving the male penis during copulation
(ii) . Allowing menstrual flow.
(iii) . Serving as the birth canal during parturition.
Vulva:-There is a depression, the vestibule, in front of the anus. It is flanked by two pairs of fleshy folds of skin: the inner small, thin, moist, labia minora and outer layer, hair covered labia majora, urethra and vagina open by separate apertures into the vulva.
Menstrual Cycle
The gamete formation in females in a cyclic process that takes about 28 days and involves changes in the structure and function of the entire reproductive system. It is called Menstrual Cycle. The menstrual cycle in humans lasts 28days. The days are numbered from the first day of blood flow in the menstrual period. The cycle consists of three phases:
(a) Follicular Phase - This phase lasts for about 14 days it comprises the following events:-
(i) The anterior pituitary lobe secretes FSH hormone which stimulates the growth of the selected primary ovarian follicle and maturation of the primary oocyte in this follicle,
(ii). The FSH stimulates the follicle cells to secrete estradiol, a female sex hormone which inhibits the secretion of FSH and stimulates the secretion of LH.
(iii) . The LH induces the mature Graafian follicle to burst and eject its egg into the fallopian tube. This is called ovulation. It occurs after about 14days.
(IV) . The estradiol stimulates the uterus to prepare for the implantation and nourishment of the foetus likely to arrive after ovulation. The
wall of the uterus becomes progressively thick. The blood vessels become long and coiled.
(b) Leutal phase:- This phase lasts for 10days and involves the following events.
(i) LH tighter with prolaction hormone stimulates the follicular cells of the empty Graafian follicle to form a yellow body called corpus luteum. The corpus luteum secretes another ovarian hormone named progesterone
(ii) . Progesterone is also necessary for the proper implantation of the fetus in the uterine wall.
(c) Menstrual or Bleeding phase:-
Or what happens if the egg is not fertilized?
This phase lasts for about occur 4days.It involves the following events:-
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| Flow chart showing path of sperm and ova in female reproductive system in human |
If the fertilization does not occur, the secondary oocyte undergoes autolysis and progesterone inhibits the release of LH from pituitary.
Reduction of LH level causes regression of corpus lutuem by autolysis and a consequent fall in the progesterone level in the blood. The uterine lining dies to deficiency of progesterone and is sloughed off. Blood vessels rupture, causing bleeding. The lining of the fallopian tubes breaks down. The cast off uterine and fallopian tube tissues, blood that oozes from the ruptured blood vessels and tissue fluid from the endometrial surface pass out through the vaginal opening. This process is called Menstruation or Menstrual flow. It occurs after about 25days and continuous for 3-5days. Menstruation is often described as "funeral of unfertilized egg" or weeping of uterus for the lost of Ovum.
Define Menarche and Menopause.
At puberty, the commencement of menstruation is termed menarche. It marks the beginning of the reproductive life of human female. The reproductive cycles continue to occur till the age of 50 (45-55). After this age, the menstruation stops. Cessation of cycle of events in ovary and uterus around the age of 50 years and stoppage of menstrual flow is termed menopause.
POPULATION CONTROL
Having pregnancies too frequently and giving child birth at quick succession reduce mother's health and vitality and cause mental strain. Large families are also a cause of tension. They also add to our regarding advantages of small families, keeping sufficient spacing between successive birth and prevention exploding human population. Thus, there is an urgent need to have a general awareness in our society of unwanted pregnancies.
The regulation of conception by preventive measures or devices to control the number of
off springs is called birth control. A number of preventive methods or devices have been developed for birth control. The methods of devices of birth control which deliberately prevent fertilisation (i.e., fusion of male gamete with the female gamete) are referred to as contraception. These methods help woman to avoid unwanted pregnancies. These methods are broadly categorised as follows:
(1). Barrier methods
(2). Chemical methods
(3). Intrauterine Contraceptive Device (IUCD)
(4). Natural methods
(5). Surgical methods
These methods are as follows:
(1). Barrier methods. These are physical devices to prevent the entry of sperm in the female genital tract during copulation. They also protect against sexually transmitted diseases. Some common barrier methods are :
(i) Condoms. These are thin, strong rubber sheaths used by man to cover the erect penis. It is simple but effective and widely used contraceptive that has no side effects. It checks pregnancy by preventing deposition of semen in the vagina. This method gives best results when used regularly and put on before starting coital activities.
(ii) Femidom. It is not a common contraceptive method. A femidon is a thin rubber or polyurethane tube which fits inside vagina. It is used by female just before starting coital activities.
(iii) Diaphragm (Cervical cap). It is a flexible rubber/plastic cover that is fitted over the cervix in the female's vagina. It checks the entry of sperms into the uterus. These are smeared with a spermicidal jelly or cream and must be kept fitted for at least six hours after sexual intercourse.
2. Chemical methods. Foam tablets, jellies, pastes, creams and spermicides are some common chemicals used by females. These are placed in vagina. These chemicals adhere to the mucous membrane and immobilise and kill the sperms. Oral pills are also used to check ovulation. These are mainly hormonal preparations and contain estrogen and progesteron. These prevent development of egg and ovulation by inhibiting secretion of FSH. The oral pills act on hypothalamus, pituitary and the ovaries. They are called oral contraceptives (OCs). Vaginal pills are drug preparations which contain spermicides. They are used before copulation by women.
3. Intrauterine Contraceptive Device (IUCD). These are contraceptive devices made of copper,
plastic or stainless steel. A copper-T is inserted into uterus by a practising doctor or a skilled nurse and left in place. It prevents implantation in the uterus. The other intrauterine contraceptive devices are loop, spiral ring, bow and shield. These can be placed for long periods (up to 5 years). The drawbacks with these devices are bleeding and discomfort. IUCD may come out even without the women's knowledge.
4. Natural methods. These methods include abstinence (avoid copulation), rhythm method (avoid copulation around the time of ovulation) and coitus interruptus (withdrawal of penis before ejaculation).
5. Surgical methods. Surgical methods are safe in the long run but they may cause infections and other problems if not done properly. These methods include -
(i) Vasectomy and
(ii) Tubectomy.
(1) Vasectomy. This is a small surgical operation performed in males. It involves removal of a small portion of the sperm duct (or vas deferens) by surgical operation. The two cut ends are then ligated (tied) with threads. This prevents the sperms from coming out.
(ii) Tubectomy. This is a surgical operation performed in females. It involves removal of a small portion of the fallopian tubes (or oviducts) by surgical operation. The cut ends are then ligated (tied) with threads. It prevents the egg (ovum) to enter the fallopian tube. Both vasectomy and tubectomy are also known as methods of sterilization. These do not affect the normal sexual life. Surgery can also be used for abortion. Abortion the medical termination of pregnancy (MTP) before the foetus becomes viable. However, this method is widely misused by people who do not want a female child. It is illegal (the prenatal sex determination has been prohibited by law). Moreover, the female- male sex ratio must be maintained to have a healthy society. Before using contraceptives, particularly oral pills, vaginal pills and copper-T etc., one must be aware of their side effects and take regular medical advise.
REPRODUCTIVE HEALTH AND SEXUALLY TRANSMITTED DISEASES (STDs)
We know, the diseases are caused by bacteria, viruses, protozoans, fungi, mycoplasmas and many other kinds of pathogens. These are called infectious diseases. Some other kinds of diseases are caused by physiological disorders. These are not infectious. The infectious diseases are spread by means of air, water and food. Similarly, some infectious diseases concerned with the reproductive parts are transmitted through sex. These are sexually transmitted diseases (STDs). These diseases are also known as venereal diseases (VD). The infectious (communicable) diseases, which are spread from an infected person to a healthy person by sexual contact, are called sexually transmitted diseases. Human beings suffer from over 30 different kinds of sexually transmitted diseases (STDs). They are usually caused by bacteria, protozoa and viruses. The common among them are :
1. Gonorrhea. Gonorrhoea is caused by a bacterium Neisseria gonorrhoeae, The victim feels burning sensation and pain during urination. The disease causes inflammation of the mucous membrane of the urinogenital tract, rectum, throat and eye. There may be pus from the penis and excessive secretion of vagina. It spreads by sexual contact and through infested clothes. The disease is easily curable with antibiotics.
2. Syphilis. Syphilis is caused by spirochaete bacterium, Treponema pallidum. The disease is a chronic illness which affects the mucous membrane in genital, rectal and oral regions, and causes lesions. Infection occurs by sexual inter course, and occasionally by kissing or close body contact. Syphilis is easily cured with antibiotics,
3. HIV (Human Immunodeficiency Virus)/AIDS (Acquired Immunodeficiency Syndrome
disease AIDS is caused by a virus, called HIV. It is a fast spreading incurable disease which weaken the body's immune system. The virus (HIV) was discovered in 1984 by an American Scientist, named Robert Gallo and a French Scientist - Luc Montagnier, independently. It now seems that the disease -
AIDS may have passed into humans from chimpanzees by eating butchered chimps. The first case of AIDS was noticed in U.S.A. in 1981. In India, the first case of AIDS was reported in Chennai prostitute in 1986. The disease can manifest in two major ways :
(i) malignant tumours in connective tissue, and
(ii) viral, bacterial, protozoan and fungal infections of any system of the body.
The main symptoms of the disease are damage to brain, unexplained fever, unexplained loss of appetite, unexplained loss of weight over a short time, chronic diarrhoea, cough, night sweats, shortness of breath and severe weakness. In people with AIDS, infections diseases neurologic damage and physiological wasting lead to death.
Spread of disease : AIDS is transmitted A only by a contact of infected cells-containing blood of a
patient with the blood of a healthy person as in -
(i) Unprotected (without condom) sex with an infected partner if there is tissue injury to permit blood contact ;
(ii) Use of contaminated needles and syringes to inject drugs or vaccines;
(iii) Use of contaminated razors for shaving ;
(iv) Transfusion of infected blood or blood products.
Prevention (control) : People, particularly those in high-risk group, should be educated about AIDS transmission, advantage of using condom, danger of sharing needles and virtue of monogamy,
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