Explanation of the terms: Fertilization, implantation, placenta, gestation and parturition
Identical and fraternal twins: meaning and differences only.
REPRODUCTION IN HUMAN BEINGS:-
-Humans use sexual mode of reproduction.
-Sexual maturation: The period of life when production of germ cells i.e. Ova (female) and sperm (male) start in the body. This period of sexual maturation is called puberty.
Changes at puberty:-
Male and females:-
-Thick hair growth in armpits and genital areas.
-Skin becomes oily, may result in pimples.
-Breast size increases
-Girls begin to menstruate.
-Thick hair growth on face
-voice begins to crack
These changes signal that sexual maturity is taking place
MALE REPRODUCTIVE SYSTEM:-
-A pair of testes are located inside the scrotum which is present outside the abdominal cavity.
-scrotum has a relatively lower temperature needed for the production of sperms.
-male germ cell i.e. sperms are formed here.
-testes release male sex hormone (testosterone)
-regulate production of sperms.
-bring changes at puberty.
(ii) Vas deferns:
- It passes the sperm from the testes to the urethera.
- it is a common passage for both sperm and urine.
(iv) Associated gland:-
- Seminal vesicles and prostate gland add their secretion to the sperms. This fluid provides nourishment to sperms and make their transport easy.
- sperm along with secretion of glands form semen.
FEMALE REPRODUCTIVE SYSTEM:
- A pair of ovary is located at both sides of the abdomen.
- Female germ cell i.e. eggs are produced here.
- At the time of birth of a girl, thousand of immature eggs are present in the ovary
- At the onset of puberty, some of these eggs start maturing.
- One egg is produced every month by one of the ovaries.
(ii) Oviduct or Fallopian tube:-
- Receives the egg produced by the ovary and transfer it to the uterus.
- Fertilization i.e. fusion of gametes takes place here.
- It is a bag like structure where development of the baby takes place
- uterus opens into vagina through cervix.
FERTILISATION OF EGG:-
- The fertilized egg called zygote is planted in uterus and develops into an embryo.
- The embryo gets nutrition from the mothers blood with the help of special tissue called placenta. It provides a large surface area for the exchange of glucose, oxygen and waste material.
- The time period from fertilization upto the birth of the baby is called gestation period.
WHEN EGG IS NOT FERTILISED:-
- The uterus prepares itself every month to receive fertilized egg
-The lining of the uterus becomes thick and spongy, required to support the embryo.
-When fertilisation had not taken place this lining is not needed any longer.
-This lining breaks and comes out through the vagina as blood and mucus.
-this cycle takes around 28 days every month and is called menstruation.
IMPLANTATION: In humans, implantation is the stage of pregnancy at which the embryo adheres to the wall of the uterus. At this stage of parental development, the conceptus is called a blastocyst. It is by this adhesion that the embryo receives oxygen and nutrients from the mother to be able to grow.
PLACENTA: The placenta is an organ that develops in the uterus during pregnancy. This structure provides oxygen and nutrients to the growing baby and removes waste products from the baby's blood. The placenta attaches to the wall of the uterus, and the baby's umbilical cord arises from it. The organ is usually attached to the top, side, front or back of the uterus. In rare cases, the placenta might attach in the lower uterine region (placenta previa).
GESTATION: Gestation, in mammals, the time between conception and birth, during which the embryo or fetus is developing in the uterus.
PARTURTION: The act or process of giving birth is known as parturtion.
Shaalaa.com | Reproduction part 16 (Sexual reproduction in humans: Puberty)
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