Important Notes for NEET Biology - Human Reproduction
Human Reproduction is an avital chapter for the NEET exam preparation as per the NEET biology syllabus. This article is going to fulfill all your understanding, and it would be helpful for the NEET aspirants as well as for the other exams. These important notes of biology for human productions for NEET will cover all the significant concepts and topics for the exam. Check and refer to this article for gaining the utmost knowledge and do not let your preparation go futile and quickly start preparation with important notes of biology for human production to crack NEET within the first attempt.
Human Reproduction - Introduction
Reproduction is a process of producing progenies, and the reproductive system is a system of organs that partakes in this reproduction process.
Humans are viviparous, and they are sexually reproducing their offspring. The rate of reproduction is always logier in sexual reproduction.
The human’s reproductive system consists of three distinguishable sex organs; these are:
Primary Sex Organs: Primary sex organs are also considered as gonads that form gametes like ovary in females and testis in males.
Secondary Sex Organs: Glands and ducts are essential for sexual reproduction and do not produce gametes that are considered secondary sex organs.
Accessory/External Sex Characters: These are the criteria that do not possess a direct role in reproduction but significantly provide definite structures to both males and females.
The Male Reproductive System
The male reproductive system is situated in the pelvis region and includes a paired duct system such as vasa efferentia, urethra, epididymis, vas deferens, ejaculatory duct, and a pair of testis.
Testes
Testes are located within a pouch of the outside of an abdominal cavity called the scrotum.
In the scrotum, sperms are generated at the 2-2.5०C lower temperature than the body temperature. They are being produced in the seminiferous lobules, which are the coiled section of testicular lobules.
The testes are connected to the scrotum by gubernaculum testis, and the inguinal canal is the medium by which the scrotum communicates with the abdominal cavity.
There are also two types of cells present: Male-germ cells and Sertoli cells.
Germ cells produce spermatozoa by undergoing spermatogenesis, and Sertoli cells are identified as nurse cells for distinguishing spermatozoa.
Secondary Sex Organs
Through rete testis, the seminiferous tubules open into the vasa efferentia, and thereafter it leaves the testes and opens into the epididymis.
The epididymis is differentiated into three parts: Anterior caput epididymis, middle corpus epididymis, and posterior cauda epididymis.
Ejaculation takes place due to the robust contraction of the urethra, and the duct system operates the semen to the exterior.
Ejaculatory ducts assist in the emission of seminal fluid.
The urethra is present from the bladder through the prostate glands and finally into the penis. It consists of four parts: Prostatic, urinary, membranous, and penile.
The penis is the concourse organ, and the glans penis is highly sensitive to stimulation.
Hormonal Control of Male Reproductive System
Leydig’s cells of the testis secrete the testosterone hormone, which helps to maintain the growth and functions of the secondary sex organs. Well, the Follicular Stimulating Hormone (FSH) and Interstitial Cells Stimulating Hormone (ICSH) control the Leydig’s cells of the testis and seminiferous tubules.
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The Female Reproductive System
The Female Reproductive System includes a pair of oviducts, ovaries, a uterus, a vagina, a pair of mammary glands, and external genitalia.
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What is the Menstrual Cycle?
This is the cyclic change in the reproductive propagation of females.
The first menstruation begins at puberty, and it happens every month when the lining of the womb sheds and red blood-like material comes out from the vagina.
Menstruation signals indicate that women are releasing eggs that can be fertilized.
The duration of the menstrual cycle differs from one woman to another, and the average time period is 28 days. This remains to stop in the time of pregnancy and maybe inhibited during lactation and totally stops at menopause.
Fertilization and Implantation:
The process of fertilization is known as the fusion of sperm with an ovum which forms a diploid.
This process activates the secondary oocyte cell to overpast the division.
This usually happens when sperm and egg interact with the ampulla.
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During the process of fertilization, a sperm gets in touch with an ovum, and the changes in the membrane restrict the entry of additional sperms.
The secretions of the acrosome aid the sperm to enter into the cytoplasm of the ovum, and thus the meiotic division of the secondary oocyte induces the completion process. Soon the ovum and the haploid nucleus are combined together to make a diploid zygote.
Cleavage happens expeditiously in the active cytoplasm, and it is the mitotic division of the zygote, which forms blastomeres.
After 5th cleavage and 31 cell division, Morula forms, and it significantly changes to blastula due to the blastomeres rearrangements.
Blastulation is a process of blastula formation, and a mammalian blastula with a huge blastocoel is known as a blastocyst.
The blastomeres are arrayed significantly into an outer layer known as the trophoblast, and the attachment of inner cells to the trophoblast is known as inner cell mass.
The formation of the endometrium happens when the trophoblast layer gets associated with it, and the inner cell mass formed as the embryo.
After this procedure, the uterine cells divide expeditiously and cover up the blastocyst. Thus, the blastocyst gets inlaid to the endometrium. This leads to pregnancy.
The implantation occurs between the 6th to 9th day after fertilization
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FAQs on Human Reproduction NEET Notes for Biology
1. What is the Size of the Ovum?
The size varies in animals and generally, it varies from 10 microns to a few centimeters. Ovum is a single cell released by any of the ovaries which are a part of the female reproductive system. When it is infused with the sperm produced by the male reproductive system, it has the capability to reproduce a new organism. The word “ovum” is derived from a Latin word and it means “egg” in English. The meaning of it was first defined in 1672. Ovum is generally spherical and enveloped in one or more layers. The size of an ovum changes from animal to animal and organism to organism depending on the size of the yolk. The very important function of an ovum is to carry the female chromosomes from the female reproductive system and it also creates the right environment to fertilize with the sperm released by the male reproductive system. It also plays a key role in providing all the required nutrients to the embryo formed until it sinks in the uterus and when the embryo sinks in the uterus, the placenta takes the duty to supply the required nutrients. It is also the central and important part as it carries the female genetic material. The ovum degenerates if it does not get fertilized with the sperm, within 24 hours of its release.
2. What is Spermatogenesis?
This is a biological process where the haploid spermatozoa produce the germ cells. Spermatogenesis is the process in which germ cells release the sperm which starts at puberty and continues till the death of the organism though the quantity of sperm decreases with the age, it does not stop. The spermatogonia multiply through the mitosis process and then undergoes division to form haploid cells. Spermiogenesis is the process through which the sperms are formed once the spermatids are nourished. It can be simply explained as the beginning of the generation of sperm cells in the male reproductive system. The testes have many tube-like structures called the seminiferous tubules in which the sperm cells are produced, later they divide and undergo mitosis reaction. They are continually produced but all the areas of the tubules do not produce sperms. One immature sperm cell takes 74 days to reach the final stage of maturation once it is produced.
3. What is the Timing of the Gestation Period Animals?
The gestation period varies from one animal to another. For cats and dogs, it takes 60-65 days and for elephants, it takes 22 months. Gestation happens in mammals and it could be simply explained as the time period between the organism getting conceived and its delivery of the offspring. During the process of gestation, the embryo develops into a fully-formed baby. In some cases, the beginning of the gestation is counted from the previous menstrual date. So, the gestation period is different from animal to animal and the shortest gestation period can be observed in the Virginia Opossum which has 12 days of the gestation period and the longest gestation period is seen in the elephants which have a gestation cycle of 22 months. To be simply put, smaller animals have less length of the gestation period and larger animals have more length of gestation period. However, the Guinea pig is an exception to this case.
4. What is the Reason Behind Menopause?
It generally occurs between the age of 45 to 55 and the reason is the cessation of the female reproductive system. Another reason is: ovaries gradually curtail the secretion of estrogen. Menopause transition generally begins between the ages of 45 to 55 years in women. It is a point where a woman does not get periods for 12 months. It affects differently from person to person. It can last for 14 years or could also last for 7 years. Menopause is dependent on many factors like the person’s lifestyle, habits etc, during this time the levels of estrogen and progesterone changes significantly. The energy produced in their body is used by it differently, the fat cells easily gain weight leading to obesity, one can also see a change in body shape, health, bone structure, growth and also mental health due to changes in hormonal activity. The levels of estrogen decrease and brings out many symptoms in women going through menopause. Some of the symptoms include hot flashes, changes in period cycle, disturbed sleeping pattern, bladder control etc, after menopause, we can observe changes in the vagina like it becomes drier and women stay moody and get easily irritated during menopause. Women gain so much weight and become obese during menopause hence, it is very important for them to bring changes in their lifestyle like avoiding caffeine, start exercising etc,
5. How Does the Foetal Ejection Reflex in Human Females Induce?
The Foetal ejection reflex in human females is induced by the completely developed placenta and fetus.
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