Reproductive Health

As you all know that health is connected with working of physical organs so reproductive health will mean well being in respect of reproductive organs like testes , ovary and their ducts . If these organs are functioning well then we can say that person is reproductively healthy or not depending upon the mental and social aspect of that person . Mentally ill person for example will not fit in this category . 

In order to understand status of reproductive health in our country we need to have data about population like sex ratio in states , population of people in various age groups in addition to other aspects like health facilities available to them .

HUMAN REPRODUCTIVE SYSTEM..

In this post we will discuss following points :

1. Male reproductive system

2. Female reproductive system

3. Structure of human gametes and role of hormones in male reproductive physiology 

4. Menstrual cycle in females 

5. Events in fertilisation in humans 

6. Gestation and endocrinology off  female reproductive system

7. Parturition and lactation 

Introduction 

Humans are sexually dimorphic means male and females individuals are separate . Male individuals possess testes as gonads whereas females have ovaries as gonads . Male and female also look different morphologically owing to secondary sexual characteristics . Male individuals produce sperms in testes whereas females produce ova in ovaries . Sperms are passed into female reproductive tract which may lead to fertilisation and formation of zygote a single cell which later undergoes mitotic divisions to produce multicellular structure called embryo. An embryo is an immature baby which get nutrition and protection inside mother womb and finally delivered out on maturity .Then mother feed the Baby with milk and takes care of him / her till it becomes self dependent for basic activities .

Male reproductive system

Male reproductive system has gonads , their glands and external genitalia .

Gonads are named testes in human male and they are enclosed in pouch like scrotal sac or scrotum . This scrotal sac has two chamber for testes . Scrotal sac provide lower-than body temperature for formation of sperms inside testes . Testes descend into scrotum from abdominal cavity via inguinal canal with the help of spermatic cords which is having blood vessels, nerves , muscles ( cremaster to raise or lower testes in response to low and high temperature ) . Connective tissue attaching base of testes to scrotal sac wall is called gubernaculum . Sometimes testes fail to descend this is called cryptorchidism . This results in sterility in male .

Testis themselves are enclosed in covering of outermost  tunica vaginalis , middle tunica albuginea and innermost tunica vasculosa .So tunica vasculosa is more near to seminiferous tubules which form sperms . Testes has about 250 lobules formed due to septa or partition of testicular space . Each lobule has 1-3 seminiferous tubules which are coiled tube like structure lined by germinal epithelial cells . These cells are also called sperm mother cells and become interrupted at places by Sertoli cells.Sertoli cells provide nutrition to developing sperms .These cells help to concentrate androgen by producing ABP ( androgen binding proteins ) in seminiferous tubules . Sperm mother cells undergo meiotic division and produce spermatids which get differentiated to form sperm cells .Between seminiferous tubules lies interstitial tissue which contain blood vessel , nerves and Leydig cells which produce androgen or testosterone hormone .These endocrine cells play important role in spermatogenesis .If we cut T.S. of seminiferous tubules we get empty space in centre which is generally named lumen . From lumen to border of these tubules we get layer of different cells . At the base lies spermatogonia which form layer of primary spermatocyte towards lumen . Primary spermatocytes undergo meiotic division and form secondary spermatocyte which in turn produce spermatids cells . Spermatids stop division process and just get modified into sperm. Sperms become attached to tip of Sertoli cells for nutrition . Blood is naturally prevented from coming in contact with sperms ( blood testis barrier ) .

CH 3 - HUMAN  REPRODUCTION

1.Each   testis       has  about  250   compartments  called----------------------

Ans-testicular lobules

2.The seminiferous  tubule is lined  by   two  types  of  cells  called---------------and  -----------------

Ans-male germ cells and Sertoli cells

3.-------------------cells  in  the  seminiferous  tubule   synthesise and   secrete  testicular hormone

Ans-interstitial cells  or leydig cells

4.The  cells  that  nourish  the sperm  in  the  seminiferous  tubule  is  called---------------

Ans-sertoli cells

5.----------------------cells  undergo  meiotic  divisions  and    produce sperms in testes

Ans-male germ  cells

6.The  secretions  of male  accessory  glands  collectively  called------------------------

Ans-seminal plasma

7.The   part  closer to the  ovary  is  funnel  shaped named---------------------------------------

Ans- infundibulam

8.The   wall  of  uterus  is  three  layerd  called--------------------,------------------,and------------------

Ans-perimetrium,myometrium,endometrium

9.-------------------------is  the   tiny  finger like  structure  that  lies at the  upper  junction  of  the

 Two   labia  minora  above   the  urethral  opening

Ans-clitoris

10.Fertilisation  in  huaman  occurs  at ----------------------of the   oviduct

Ans-ampulla  isthmus junction

11. A  primary spermatocyte   completes  the  first  meiotic  division  leading to  the formation of    two  equal    haploid  cells called------------------------------------------

Ans-secondary spermatocytes

12.-----------------------pitutary  hormone    acts  on  the  Leydig cells   and  stimulate  synthesisis

And  secretion  of  androgens

Ans-LH

13.The  sperm    head  contain  an  elongated   haploid nucleus ,the   anterior portion  of  which

Is  covered  by  a  cap like  structure  called-------------------------

ANS-acrosome

14.The   seminal  plasma    along  with the  sperms  constitute-----------------------

Ans-semen

15.The    primary  follicle    get  surrounded  by  more  layers of  granulose cells   and  new  theca

       And   are  called----------------------------------

Ans-secondary follicles

16.The  tertiary  follicle  is  characterized  by  a  fluid  filled cavity called------------------------

Ans-antrum

17.The  secondary  oocyte    forms  a  new  membrane  at  the  time  of  ovulation  ------------------

Ans-------zona pellucida

18.The  first  menstruation  begins  at puberty  is called--------------------------------

Ans-menarch

19.After  the  ovulation  the   ruptured     graffian  follicle  changed into  yellow mass  of

Cells  that produce  progesterone  called-----------------------------------------

Ans-corpusluteum-

20.On  the  14 th   day  of  menstrual cycle   the  pituitary  hormones----------------and-----------are

Peak  in  the  blood

Ans-LH  and FSH

21.The  hormone(pituitary)  that  help in  the  ovulation  is------------------------------

Ans  LH

22.The  embryo  with  8  to  16 blastomers  called-------------------------------------

Ans-morula

23.The blastomeres  in  the  blastocyst    are  arranged  into  an  outer layer  called  -----------------

And  an    inner  group  of  cells  attached   to  it  is called-----------------------

Ans-trophoblast  and inner  cell  mass

24.The  chorionic villai   and uterine tissue   become   interdigitated  with   each other   and  jointly   form    a  structural  and  functional  unit between foetus and  maternal  body called

---------------------------------

Ans-placenta

25.The  placenta   produces  two  hormones---------------------and -----------------------------

Ans-human chorionic  gonadotrophin,placental lactogen

26.The  inner cell  mass  contains    certain  cells  called-----------------cells   which  have the

Potency  to    give  rise  to all  the  tissues  and  organs

Ans-stem  cells

27.The  signal  for  parturition  arise from  -------------------and ------------------------

Ans-fully  matured foetus  and  placenta

28.The  milk  produced    during the  initial  days of  lactation is  ---------------------which  contains

Several  antibodies  essential  for  the  child

Ans-colostrum

29.Why   it  is   seen  that  the  testis  located  out  side  the  body  wall?

Ans-The  testes  are  located  out side  the  abdominal  cavity  within  a  pouch called  scrotum

Which  helphs in  maintaining  the  low  temperature  of  testes 2 to 2.5^oc  lower than that

        Of the   body  that   is  very  essential for  spermatogenisis

30.Name  the  human  male  accessory  glands

Ans-seminal vesicles,prostrate  gland, bulbourethral  glands

31.Mention  the  role  of  fimbriae  in  fertilization.

Ans-The  edges  of   infundibulum  possess  finger like  projections   called  fimbriae which helph in  collection  of  ova  during  ovulation

32.Mention  the  role  of  endometrium  in  fertilization

Ans-The  endometrium   undergoes  cyclical  changes   during  menstrual  cycle ,this  is  highly

Glandular  in  nature  and    implantation  of  embryo occur  on  it.

33.What is  the  composition of  seminal plasma

Ans-fructose,calcium  and certain  enzymes

How plants reproduce asexually and naturally?

 Vegetative Propagation

Stem , leaves , roots are vegetative parts of plants.

Flowers are reproductive parts of the plants which perform sexual reproduction. Vegetative parts are produced much before the reproductive parts in a plant.

Sometimes vegetative propagation happens in plants in addition to the sexual reproduction.

For example in banana flowers utilised for sexual reproduction where as modified stem rhizomes are used in vegetative propagation .

Some plants are vegetatively propagated with the help of roots for example sweet potato.

Some plants are propagated with the help of modified stem. For example Ginger turmeric are propagated by modified stem having buds and stored food. 

Onion and garlic are grown by modified shoot called bulb which have leaves filled with food.

Potatoes which we eat are having nodes for eyes having buds which can grow into new potato if planted in soil. These modified stems of potato are called stem tuber. They also store food . 

Suckers our modified stems in mint and chrysanthemum which are produced from base of another shoot and they grow parallel to the ground coming out of the soil to sprout new shoots . They remain themselves underground most of the part except where they produce aerial shoots .

Offsets are modified stem in aquatic plants producing bunch of leaves at their top and help water hyacinth to cover the surface of water .

Terror of Bengal is the name given to this plant ( Eichornia crassipes )  

Expertise in small tool in bio lab can make you to handle surgical tool easily

Simple to complex

 

 Asexual Reproduction

In this type of reproduction new individuals are produced by a single individual parent . Gametes generally are not required except in special cases ( parthenogenesis ) . 

For example a mother bacterial cell will produce two daughter cells  without involving any gametic cells and second partner . So this is uniparental.

No meiosis will be required in such cases as no gamete is required. 

Daughter cells produced from such type of reproduction are difficult to distinguish from each other as they are morphologically and genetically similar. They may have few variation on account of DNA copying errors . 

Asexual reproduction is seen in both plants and animals in addition to microbes . As we move up the ladder in animal world its occurence decreases and sexual reproduction dominates vehemently .

Different modes of asexual reproduction:

Binary fission : It takes place in bacterial and protozoal cells . Eg. Curd Bacteria , amoeba , paramecium . In this one big cell divides into two nearly equally small daughter cells which will grow like their mother cells in near future . In this nuclear material is divided equally into daughter cells .

Multiple fission : It occurs in plasmodium ( which is a protozoan  parasite causing malaria in humans ) . Single mother cells divide it's nucleus into many nuclei which become surrounded by some cytoplasmic material to form multiple daughter cells instead of only two . 

Budding : In case of yeast and hydra which exhibit budding mechanism to reproduce we find that cell division is required without reducing chromosome number . Mitotic division in parent body leads to bud like growth which continue to grow in size . Ultimately a small body similar to parent is seen attached to its outer surface in hydra .

In yeast divisions just lead to increase in number of daughter cells which remain attached with parent yeast . In yeast actually it is variant of binary fission in which unequal cell division after nuclear division leads to two daughter cells out of which smaller one remain attached to larger daughter cell . 

Sporulation 

During unfavorable conditions amoeba with generally divides by binary fission tend to tide over these conditions by remaining inactive and protected under a resistant coat called cyst wall.  When favourable conditions are back amoeba multiply by multiple fission and the products are released from the cyst which provided shelter from harsh conditions. 

Spore formation in fungi , algae .

Zoospores : these are reproductive structures units which are motile on account of flagella . Flagella vary in number . Zoospores can be dispersed with the help of these flagella .

Immovable spores are also seen in fungi and algae called aplanospores .

Conidia are immovable spores produced on the tip of conidiophores in aspergillus and penicillium .They are generally attached to each other in tandem .

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Regeneration  or reproduction 

In some animals like planaria if we cut the animal into two or more parts they can regenerate whole body from the cut parts . This ability is termed as regeneration .

Other animals  star fish , lizard have limited capacity for regeneration.

 

Basic terms in reproduction 

1. Reproduction : 

A Biological process in which new individuals are produced from existing individuals. It may or may not  involve fusion of gametes . Sometimes gametes are also not formed e.g. binary fission and budding . 

2. Gametes :

Gametes are specialised cells which are produced by male and female individuals in special organs called gonads and finally used in fertilization which is actual fusion of these  specialised cells. Female gamete is commonly known as egg and male gamete is called sperm.Generally gametes have haploid number of chromosomes for e.g. human gametes have 23 chromosomes where as other cells have 46 chromosomes. In some conditions they might show diploidy or aneuploidy ( different from normal chromosomes number).

3. Zygote 

A zygote is a diploid cell which is  produced when syngamy or fusion of male and female gametes occur . Zygote will develop into advanced stage " embryo " if provided with suitable conditions of growth . 

4. Fertilisation 

Fertilisation involves all events which lead to actual fusion of gametes or syngamy.It may occur inside or outside the female body . In frog it is external and in humans it is internal fertilisation which leads to development of zygote or new life .

5. Hermaphrodite 

A hermaphrodite is an animal which has both male and female gonads or gamete producing cells . Eg. Earthworm and leech .

6. Monoecious vs Dioecious 

Monoecious is the term used for plant  /trees and animals if they have both male and female gonads in same individual. China rose , mustard plant and earthworm 

Dioecious is term used in case female and male gonads occur in different individual in same species . For e.g. papaya plant and cockroach have different sexes . Testes is found in Male cockroach and ovaries are found in female cockroach. Similarly pollen grain are produced by male papaya plant and fruits are produced by ovaries of female papaya plant. Morphologically male and female individuals may be similar or dissimilar. For e.g. humans have sexual dimorphism. But it is difficult to identify male mulberry plant from female one until sexual maturity . 

 

Topic 1 :Reproduction : mechanism of perpetuation of species

 

Reproduction is a mechanism in living organisms to perpetuate their species . 

Reproduction is production of new beings from existing beings of a species . 

Reproduction may or may not be characteristic of all living organisms . For eg. in mules reproduction does not occur as they don't produce gametes . They are hybrid offspring of donkey and horse . 

Reproduction may or may not require presence of opposite sexes ( male and female ) . This sounds bizarre as we are ourselves product of both parents . In some animals like honey bee , rotifers , whip-tailed lizard  production of male or female does not require fertilisation of sperms and ova . Only one gamete develop further into offspring without undergoing doubling of chromosomes . 

This phenomenon of parthenogenesis does not induce variations like sexual reproduction does .

Question arises why nature has not selected only one mode of reproduction . Why it has maintained both asexual and sexual modes of reproduction. 

If we analyse these modes we find that sexual mode of reproduction has been successfully implemented by higher forms of life with some degree of asexual reproduction in same or different species . For instance honey bee queen can perform both sexual and asexual mode by allowing  fertilisation of its gamete to produce female offspring and allowing development of its haploid eggs into haploid drones without fusion with sperms. However ploidy will be different in different castes of bees . Drones will be haploid with 16 chromosomes and females will be diploid with 32 chromosomes. 

In whiptailed lizard story is entirely different. They have no male being only females are produced from haploid eggs which can themselves produce eggs on sexual maturity . These haploid eggs then develop parthenogenetically into female lizards.

Variation in case of asexual reproduction will be far lesser than that in sexual reproduction . Parthenogenesis is also no exception . 

Many organisms are entirely sexually reproducing and lack any of such asexual forms that is seen in rotifers , drones and whiptailed lizards.

Variation in species is beneficial in case current environment changes which may become unfavourable to most of the individual but some of the variants will be successful in tiding over these harsh conditions and propagate the species further .

Same is true with plants which have evolved along with animals on same planet . I don't need to mention ice ages and great extinction on earth . 

Life is chemistry of biomolecules

 Life is all about specific interactions between various biomolecules . Biomolecules are of varied types carbohydrates, lipids , amino acids , nucleic acids depending on the structure they have and function they perform they are categorised. Biomolecules are found in all life forms even in viruses . There are prions which are solely made of proteins and viriods which are made of only RNA.

These biomolecules have congregated into the cells which further assembled into tissues , organs and organs system . 

Species as of today have cells , tissue and organ system based level of organisation . 

In order to maintain themselves they have evolved a mechanism called reproduction . We learn more about reproduction in next post.