Introduction -

Sexual reproduction is a mode of reproduction in which an offspring is formed by two parents. In human beings sexual reproduction is the only mode of reproduction. 


  • It is the condition of being or the period of becoming first capable of reproducing sexually that is brought on by the production of hormones and the maturing of the reproductive organs (such as the testes and ovaries ).¬†
  • The age at which puberty occurs often construed legally as 14 in boys and 12 in girls.
  • The changes in your body during puberty are caused by hormones which are chemicals produced in your body these hormones are like chemical messengers that cause the testicles or the ovaries to release other hormones.
  • All these hormones work together to start the changes in puberty.

Changes occur during puberty

In females 

  • During puberty, your body will start to produce two hormones. oestrogen and progesterone.
  • Oestrogen causes your breast to grow.
  • Oestrogen and progesterone control your menstrual cycle or period.
  • Thick hair growth under armpits and genital are a in voice.

In males 

  • The hormone testosterone is the hormone that starts development from boy to man.¬†
  • Testosterone is the major male sex hormone and it is produced in the testes.
  • Testosterone starts the production of sperm, cause the chest and shoulders to broaden and cause facial hair to grow.

Processes Involved in Sexual Reproduction

    • 1.Gametogenesis- formation of gametes that is sperm in male and ovum in the females.
    • 2.Gamete transfer- now once the gametes are form they need to meet in order to get fuse.
    • 3.Fertilisation -process of fusion of sperm with an ovum.
    • 4.Embryo growth- development of embryo from the zygote.

Male reproductive Part

The purpose of the organs of the male reproductive system is to :-

  • To produce, maintain and transport the sperm ( the male reproductive cells) and protective fluid (semen).
  • To discharge sperm within the female reproductive during gamete transfer.
  • To secrete and produce hormones which is responsible the male reproductive system.

Male reproductive Part

The male reproductive system is located in the pelvic region.

It includes

i )  Pair of testes 

ii)  Accessory duct

iii) Glands

iv) External genitalia


    • 1. The testes are situated outside the abdominal¬† cavity within a pouch called scrotum.¬†
    • 2. Scrotum helps in maintaining the low temperature of the testes which is lower than the normal body temperature and necessary for the spermatogenesis.¬†
    • 3. In adults, each testis is oval in shape with a length of about 4 to 5 cm .
    • 4. Each testis has about 250 compartments called testicular lobules.¬†
    • 5. These compartments contains highly coiled tubules called seminiferous tubules.¬†
    • 6. Each lobule contain 1 to 3 seminiferous seminiferous tubules in which the sperms are produced.¬†
    • 7. Each seminiferous tubule is lined on its inside by two types of cells called male germ cells (spermatogonia) and sertoli cells.
    • 8. Germ cells (spermatogonia)¬† give rise to spermatozoa.
    • 9. Sertoli cells or sustentacular or nurse cells are present which provide¬†
    • Testes :-

      Testes are present outside the abdominal cavity in pairs. 

      Scrotum :-

      Testes are situated outside the abdominal cavity with in a pouch called scrotum. 

      Vasa efferentia :-

      It start with aduct from each testies. 

      Epididymis :-

      10 to 12 vasa efferentia confluent to form a folded and coiled tube called epididymis. 

      Vasa deferens :-

      Epididymis store the sperm temporarily from epididymis ,partially coiled tube called vas deferens ascend into the abdomen and passes over the urinary bladder. 

      Urethra :-

      Male urethra provides a common pathway for the flow of urine and semen larger in males than in females.

      Penis( External genitalia) :-

      It is the copulatory organ of man. It is cylindrical , erectile, pendulous organ suspended from the pubic region. The extended part of penis is enlarged, forming a bulging, conical structure called glans penis. The loose skin of penis becomes folded form a loose, rectractile skin covering.

Extra Testicular Duct System

  • It consists of tubes which conduct sperm from the testes to the outside.

    1. The seminiferous tubules open into the vasa efferentia through testes.
    2. Several vasa efferentia open into the epididymis and carry sperm outside the testes.
    3. Epididymis is a long, coiled tube present along the posterior surface of each testes. It continues as the vas deferens and ascends into the loop over the urinary bladder. Epididymis temporarily stores non motile and immature sperms.
    4. The duct from seminal vesicle and vas deferens together from the ejaculatory duct. They pass through the prostate gland and join the urethra. They carry secretions of seminal vesicle and sperms from the testes to the outside through urethra.
    5. Urethra originates from the urinary bladdar and extends through the penis to its external opening called urethral meatus. It carries urine from the bladder and sperms from the vas deferens through the peins.

Accessory Glands Of Male

      1. Seminal vesical –

       These are paired, tubular, coiled gland situated behind the bladder. They secrete viscous fluid which constitute the main part of ejaculate, seminal fluid contains fructose which provides energy to the sperms.

      1. Prostrate glands –

      The prostrate gland is a chestnut shaped gland it contributes an alkaline component of the semen. This secretion contains citric acid, lipids and enzymes. The alkaline secretion of prostate glands nourishes and activates the spermatozoa to swim.

      1. Bulbourethral glands or Cowper‚Äôs glands –

      These are attached to the urethra below the prostate gland. They secrete mucus fluid for the lubrication of the penis.

The Female Reproductive System

  1. Primary sex organ: ovary 
  2. Sexcondary sex organ:

                Accessory ducts : pair of oviducts (fallopian tubes),uterus, cervix and vagina

                 Accessory gland : mammary gland.

iii. External genitalia : vulva

  1.  Ovaries

    The ovary is the primary female sex hormones, estrogen and progestrones which are responsible for the development of seconected female sex characteristics. The human ovaries are small almond like flattened bodies, about 2 to 4 cm in length and is connected to pelvic wall and uterus by ligaments.

    1. Location :-  

    Ovaries are located near kidney and remain attached to the lower abdominal cavity through mesovarian tube. 

     2 . Structure :- 

    The outmost layer of simple epithelium, known as the germinal epithelium, forms a soft, smooth covering fothe ovary. The tunica aldugines is a thick band of tough fibrous connective tissue just below the germinal epithelium . 

    It supports and protects the delicate underlying tissues. Deep to the tunica albuginea is the ovarian cortex, which contains follicles and their supporting connective tissues.

    The follicles contain oocytes that mature into ova throughout a woman’s reproductive years. The innermost layer, the ovarian medulla, contains most of the vascular tissue that supports the other layers of the ovary.

Ovarian Follicle :-

The ovaries follicle contain a lage, centrally placed ovum ,surrounded by several layers of granular cells, it is suspended in small cavity antrum. Antrum is filled with a fluid knawn as liquor follicle.

The secondary oocyte in the tertiary also forms a new membrane called zona pellucida. The follicle bulges onto the surface of the ovary such a follicle is called the mature graffian follicle.

Corpus luteum :-

The ovum is shed from the ovary by rupture of the follicle. The shedding of the ovum is called ovulation and occurs nearly 14 days before the onset of the next menstrual cycle. After the extrusion of the graafian follicle is called corpus lutein.

The cytoplasm of the corpus luteum is filled with a yellow pigment called lutein.

The corpus luteum grows for a few days and if the ovum is fertilised and pregnancy result it continuous to grow.

But if the ovum is not fertilised ,the corpus luteum persist only for about 14 days and it secretes progesterone and small amount of estrogen.

DUCTS - Fallopian Tubes (Oviduct)

  • The are one pair of long (10 to 12 cm) ciliated, muscular and tubular structure, which extend from the periphery of each ovary to the uterus.

    Infundibulum :-

    The part of oviduct close to the ovary is the funnel shaped infundibulum. The edge of infundibulum poses finger – like projections called fimbriae.fimbriae help in collection of the ovum after ovulation. Infundibulum opens into the abdominal cavity by an aperture called ostium.

    Ampulla :-

    The infundibulum leads to a wider part of the oviduct called ampulla.

    Isthmus –

    It is the last and narrow part having narrow lumen that links to the uterus.

    The tube is involved in conduction of the ovum or zygote towards the uterus by peristalsis and ciliary is also the site of fertilization .

     ( fertilisation occur at the junction of ampulla and isthmus)

    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..

    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, vagina is covered partially by a membrane diaphragm called hymen. Hymen is often ruptured during the first coitus however, it can also be broken by a sudden fall or joints, active participation in in some sport like horseback riding, cyling etc.

    In some women the hymen persists even after the coitus, Infact the presence or absence of hymen is not reliable indicator of virginity or experience.

Based on the type of immune cell acting against the antigens, immunity can be classified into two types –

Humoral immunity –

Cell-mediated immunity-

The immunity which is mediated by T-lymphocytes by directly attaching themselves to the antigens is called cell mediated immunity.

During organ transplantation tissue matching and blood group matching are essential before undertaking any graft/transplant and even after this patient has to take immuno-suppresants all his/her life because the body is able to differentiate ‚Äėself‚Äô abd ‚Äėnonself and the cell -mediated immune¬† response is responsible for the graft rejection.


Based On Nature Of Antibodies, Immunity is Divided Into Two Types -:

    • Active immunity- When a host is exposed to antigens, which may be in the form of living or dead microbes or other proteins, antibodies are produced in the host body, this type of immunity is called active immunity.

    Example – antibody produced when any microorganism enters the body.

    • Passive immunity- When ready- made antibodies are directly given to protect the body against foreign agents this type of immunity is called passive immunity¬†

    Example – the yellowish fluid colostrum secreted by mother during the initial days of lactation has abundant antibodies (lg,A) to protect the infant.


  • Vaccination is the process of introduction of vaccines into the body to produce antibodies against the antigens to neutralize the effect of pathogens during actual infection.

    > Vaccines are the dead or weakened pathogens introduced into the body.

    > The dead or weakened pathogen leads to the production of antibodies which neutralizes the pathogenic agents during actual infection with the same pathogen.

    > immunization is the process where performed antibodies against the toxin are introduced into the body.

    Example – performed antibody injection against snake venom.

    > Using recombinant DNA technology antigenic polypeptides of pathogens in bacteria or yeast.

    Example – hepatitis B vaccine produced from yeast.


The exaggerated response of the immune system to certain antigens present in the environment is called allergy.

The substances to which immune is produced are called allergens.

Common examples of allergens are mites in dust, pollens, animal dander etc.

Allergy is due to the release of chemicals like histamine and serotonin from the mast cells.

The antibodies produced to these are of lgE type.

Symptoms of allergic include sneezing, watery eyes, running nose and difficulty is breathing.

The patient is diagnosed by injecting or exposing the patient to very small doses of allergens.

Drugs like anti-histamine, adrenalin and steroids quickly reduce the symptoms of allergy.

What Is An Autoimmune Disease? 

An autoimmune disease is a condition in which your immune system mistakenly attacks your body.

Due to genetic and other unknow reasons, the body attacks self-cell which results in damage to the body and is called auto-immune disease.

The immune system normally guards against germs like bacteria and viruses. When it senses these foreign invaders, it sends out an army of fighter cells to attack them.

Normally, the immune system can tell the difference between foreign cells and your own cells.

In a autoimmune disease, the immune system mistakes part of your body – like your joints or skin- as foregn. It releases proteins called autoantibodies that attack healthy cells.

Rheumatoid arthritis (RA)

In rheumatoid arthritis (RA), the immune system attacks the joints.

This attack causes redness, warmth, soreness, and stiffness in the joints.


Immune system consists of-

  • Lymphoid organs
  • Lymphoid tissues
  • B-cell and T- cells
  • Antibodies 

Primary Lymphoid Organs :

In primary lymphoid organs, immature lymphocytes differentiate to mature ones into an antigen sensitive lymphocytes and after maturation, lymphocytes migrate to secondary lymphoid organs.

These are of two types :

  1. Bone marrow
  2. Thymus

Bone marrow :

It is the main lymphoid organs, where all the lymphocytes and all the body cells are produced and T-lymphocytes are developed.

Thymus :

It is a lobed organ, located near the herat and beneath the breast bone. It is large at the time of birth but with age, the size keep on reducing and becomes very small by attaining puberty.

Growth and maturation of T- lymphocytes takes place in thymus only.

Secondary Lymphoid Organs :

These organs provide the sites for the interaction of lymphocytes with the antigen, which then proliferate to become effector cells.

These are of following types :

  1. Spleen 
  2. Lymph nodes,
  3. Mucosal associated lymphoid tissue (MALT)

Peyer’s patches of small intestine and appendix are also some of the secondary lymphoid organs.

Spleen :

   It is a large bean-shaped organ containing lymphocytes and phagocytes. It filters the blood by trapping the pathogens in it.

Lymph nodes:

These are small solid structures located at different points along the lymphatic system. Their function is to trap the Microorganisms or other antigens, that enter the lymph and tissue fluid.

Mucosal  Associated Lymphoid Tissue {MALT}:

This is located within the lining of main tracts in the body like respiratory, urogenital tracts.MALT constitutes about 50% of the lymphoid tissue in human body.


    The term AIDS stands for acquired immune deficiency syndrome.

    The disease is acquired during life time.

     AIDS is caused by human immune deficiency virus (HIV).

     HIV is retrovirus having RNA as the genetic material .

Mode of transmission –

  • Sexual contact with infected persons.
  • By transfusion of contaminated blood and blood products.
  • By sharing infected needles as in the case of intravenous drug abusers.
  • From infected mother to her child through placenta.

Life cycle of HIV

  • After getting into the body the virus enters into macrophages or T- helper cells.
  • The viral RNA genome replicated to form viral DNA with the enzyme called reverse transcriptase.
  • The viral DNA gets incorporated into the host cell‚Äôs DNA and directs the infected cells to produce virus particles and the macrophages continue to produce virus.
  • Viruses released from macrophages attack T-helper cells and cause a progressive ceduction in the number of T-helper cells and due to which the person starts suffering from infections with several other microorganisms.
  • Diagnosed by ELISA ( enzyme linked immune-sorbent assay).
  • Treated with anti-retroviral drugs but that is only  partially effective.

Prevention of AIDS -:

  • To follow safe blood transfusion.
  • To use disposable needles.
  • To distribute free condoms.


  • Cancer is the uncontrolled cell division leading to the formation of a mass of cell called as a tumor.
  • Contact inhibition is the property of normal cells by virtue of which contact with other cells  inhibits their uncontrolled growth.
  • Cancer cells lost the property of contact inhibition and as a result of this, cancerous cells continue to divide giving rise to masses of cells called tumors.
  • Tumors are of two types : being and malignant.
  • Benign tumors normally remain confined to their original location and do not spread to other parts of the body.
  • The malignant tumors are a mass of proliferating cells called neoplastic or tumor cells.
  • Malignant tumors grow very rapidly and ultimately damage surrounding tissues.
  • The propently by which cancer cells moves to distant places from their origin by blood and invade the normal cells and make them cancerous is called as metastasis.

Causes of Cancer :-

  • Transformation of normal cells into cancerous cells may be induced by physical, chemical or biological agents called as carcinogens.
  • Physical carcinogens-ionizing radiation like X-rays, gamma rays and non-ionizing radiations like UV radiation of sun.
  • Chemical carcinogens – tobacco smoke and some other chemicals.

Biological Carcinogens-

  1. Cancer causing viruses are called oncogenic viruses have genes called viral oncogenes.
  2. Cellular oncogenes or proto-oncogenes in normal cells, when get activated lead to oncogenic transformation of normal cells.

Detection of cancer

  • Biopsy and histo-pathoigical study of the tissues.
  • Radiography by using X-rays , CT (computed tomography).
  • MRI (magnetic resonance imaging).
  • Use of antibodies against cancer-specific antigens.

Treatment of cancer-

  • Surgery 
  • Radiation therapy 
  • Chemotherapy
  • Biological response modifiers-alpha-interferon which activate the immune system and help in destroying the tumor.

Drugs and Alcohol Abuse:-

The drugs which are commonly abused are opioids, cannabinoids and coca alkaloids.

Opioids :- 

Opioids are the drugs which bind to specific opioid receptors present in our central nervous system and gastrointestinal tract.

Heroin :-

Commonly called smack is chemically diacetylmorphine which is a white, odourless, bitter crystalline compound and is obtained by acetylation of morphine extracted from the latex poppy plant papaver somniferum Heroin is a depressant and slows down body functions.

Cannabinoids :-

Cannabinoids interact with cannabinoid receptors present principally in the brain.

Natural cannabinoids are obtained from the inflorescences of the plant cannabis sativa.

The flower tops, leaves and the resin of cannabis plant are used in various combinations to produce marijuana, hashish,  charas and ganja.

Effects on cardiovascular system of the body.

Coca alkaloid :- 

  • Coca alkaloid or cocaine is obtained from coca plant Erythroxylum coca.
  • Coca alkaloid interferes with the transport of the neuro-trasmitter dopamine.
  • Cocaine, commonly called as coke or crack.
  • It has a potent stimulating action on central nervous system, producing a sense of euphoria and increased energy.
  • Excessive dosage of cocaine cause hallucinations. 
  • Morphine is a very effective sedative and pain killer is often abused.
  • Some plants with hallucinogenic properties are Atropabelladona.

Tobacco :-

  • Tobacco contains nicotine, an alkaloid.
  • Nicotine stimulates adrenal gland to release adrenaline and nor-adrenline into blood circulation, both of which raise blood pressure and increase heart rate.
  • Smoking of tobacco is associated with increased incidence of cancers of lung, urinary bladder, throat, oral cavity, bronchitis,emphysema, coronary heart disease, gastric ulcer etc.

Adolescence and drug / alcohol abuse

 Alcohol use often turns to abuse and addiction.

  • Adolescence means both ‚Äėa period‚Äô and ‚Äėa process‚Äô during which a child becomes mature in terms of his/her attitudes and beliefs for effective participation in society.
  • 12-18 years of age may be thought of as adolescence period.
  • Adolescence is accompanied by several biological and behavioural changes.
  • Curiosity, need for adventure and excitement, and experimentation, constitute common causes, which motivate youngsters towards drug and alcohol use.

Addiction and dependence :-

  • Addiction is a psychological attachment to certain effects- such as euphoria and a temporary feeling of well- being- associated with drugs and alcohol.
  • With repeated use of drugs, the tolerance level of the receptors present in our body increases and consequently the receptors respond only to higher doses of drugs or alcohol leading to greater intake and addiction.
  • Dependence  is the tendency of the body to manifest a characteristic and unpleasant withdrawal syndrome if regular dose of drugs/ alcohol is abruptly discontinued.
  • Withdrawal syndrome is characterised by anxiety, shakiness, nausea and sweating.
  • Acute, or short-term, tolerance is caused by repeated exposure to a drug over a relatively short period of time. Cocaine abuse often results in acute tolerance.
  • Chronic, or long-team, tolerance develops when an individual‚Äôs body adapts to constant exposure to a drug over weeks or months.

Effects, prevention and control of drug / alcohol abuse :-

  • Immediate effects are reckless behavior, vandalism and violence.
  • Excessive doses of drugs may lead to coma and death due to respiratory failure, heart failure or cerebral haemorrhage.
  • Those who take drugs intravenously can get infected with AIDS, hepatitis B.
  • The chronic use of drugs and alcohol damages nervous system and cause liver cirrhosis.
  • The use of drugs and alcohol during pregnancy is also known to adversely affect the foetus.
  • Use of anabolic steroids in females can cause masculinisation, increased aggressiveness, mood swings, depression, abnormal menstrual cycles excessive hair, growth on the face and body, enlargement of clitoris, deepening of voice.
  • In males anabolic steroids can cause acne, increased aggressiveness, mood swings, depression, reduction of size of the testicles, decreased sperm production, potential for kidney any liver dysfunction, breast enlargement, premature baldness enlargement of the prostate gland.

Prevention and control :-

  • The measures useful for prevention and control of alcohol and drugs abuse among adolescents.
  • Avoid undue peer pressure on children.
  • Children should be educated and counseled to bear problems and stress in life.
  • The child should seek help from parents and elders.
  • Affected individuals should seek medical help of qualified psychologists, psychiatrists, and addiction and rehabilitation programmes.