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Human Reproduction Notes & Short tricks – 7tricks

human reproduction

Human Reproduction:-

Significance of fertilization

(a) It provides a stimulus for the egg to complete its maturation.
(b) It activates the ovum to develop into a new individual by repeated mitotic division.
(c) Fertilization restores the diploid number of chromosomes (46 in man) in the zygote by adding a male’s haploid set of chromosomes.
(d) It makes the egg more active metabolically.
(e) It combines the character of two parents and introduces variations. So help in evolution.
(f) Sex chromosomes of sperm are either X or Y and help in sex determination.
(g) Fertilization membrane formed after sperm entry, checks the entry of additional sperms.
(h) Copulation path sets the axis of division.

Menstrual Cycle:-

(1) Menstruation occurs in humans, apes and old world monkeys.
(2) Menstruation is bleeding from the uterus of adult females at intervals of one lunar month.
(3) Beginning of menstruation or first menstruation is called menarche.
(4) The beginning of menstruation varies. It usually occurs between 12 and 15 years.
(5) The cycle of events starting from one menstruation till the next one is called Menstrual Cycle.
(6) In human females, menstruation is repeated at an average interval of about 28/29 days.
(7) One ovum is released (ovulation) during the middle of each menstrual cycle.
(8) It is regulated by certain hormones, some of which are secreted by the pituitary gland.
(9) The pituitary gland is stimulated by releasing factors produced in the hypothalamus.
(10) The hormones produced by the pituitary gland influence the ovaries. The hormones secreted by the ovaries affect the walls of the uterus.

Phases of Menstrual Cycle

The menstrual cycle consists of the following four phases:

(1) Menstrual Phase:

(i) In a 28 days menstrual cycle, the menses takes place on cycle days 3-5.
(ii) The production of LH from the anterior lobe of the pituitary gland is reduced.
(iii) The withdrawal of this hormone causes degeneration of the corpus luteum and, therefore progesterone production is reduced.
(iv) Production of oestrogen is also reduced in this phase.
(v) The endometrium of the uterus breaks down & menstruation begins.
(vi) The cells of endometrium secretions, blood & unfertilised ovum constitute the menstrual flow.

(2) Follicular Phase:

(i) This phase usually includes cycle days 6-13 or 14 in a 28 days cycle.
(ii) The follicle-stimulating hormone (FSH) secreted by the anterior lobe of the pituitary gland stimulates the ovarian follicle to secrete oestrogens.
(iii) Oestrogen stimulates the proliferation of the endometrium of the uterine wall.
(iv) The endometrium becomes thicker by rapid cell multiplication and this is accompanied by an increase in uterine glands & blood vessels.

(3) Ovulatory Phase:

(i) Both LH & FSH attain a peak level in the middle of the cycle (about the 14th day).
(ii) Oestrogen concentration in blood increases.
(iii) Rapid secretion of LH induces rupturing of gryphon follicle and thereby the release of the ovum.
(iv) In fact LH causes ovulation.

(4) Luteal Phase:

(i) Includes cycle days 15 to 28.
(ii) Corpus luteum secretes progestrone.
(iii) Endometrium thickens.
(iv) Uterine glands become secretory.

Hormonal Control of MC

(i) FSH stimulates the ovarian follicles to produce oestrogens.
(ii) LH stimulates the corpus luteum to secrete progesterone.
(iii) Menstrual phase is caused by the increased production of oestrogens.
(iv) LH causes ovulation
(v) Proliferative phase is caused by the increased production of oestrogens.
(vi) Secretory phase is caused by increased production of progesterone.

 Biology Cramming Point:-

1- Cutin is a lipid. It is not a protein.
2- Sucrose is a non-reducing sugar.
3- Isoprenoids are monomers of carotenoids, steroids and terpenes.
4- ATP, RuBP, NADP all have ribose sugar in them
5- Most enzymes work at a slightly alkaline pH.
6- With each cardiac output Kidney receives 10%. {both Kidneys receives 20 %}
7- In a molecule of DNA nucleotides are linked both vertically and horizontally.
8- Tetroses are the least abundant carbohydrates in nature.
9- Charged pores in a cell membrane are formed by Channel proteins.
10- Cytokinesis is the division of CELL after the division of cytoplasm. It is not the division of cytoplasm.
11- Bacterial chromosome has DNA only, nothing else.
12-NOSTOC lacks mitochondria and hence it is not present.
13- Chromosome condensation is at PEAK in the METAPHASE phase.
14- All those sugars ending in ”ulose” are KETO SUGARS { exceptions are Fructose and Dihydroxyacetone}, these are also keto.
15- Agar, Pectin, Starch do not contain NITROGEN in them.
16- CHITIN has NITROGEN in it.
17- Alkaloids { Nicotine, Daturine, Atropine } are frequently present in the solanacea family.
18-Acoelomates, Psuedocoelomates, Coelomates ALL have MESODERM in them.
19-CAPSID of Polio Virus is SPHERICAL in shape.
20- ENDOSPORES are formed during the DECLINE phase.
21-Spores are formed during ASEXUAL reproduction in Rhizopus.
22-Most superficial infections are caused by Duetromycetes fungi.
23-RED ALGAE also help in Coral formation.
24-Secondary host of Liverfluke is SNAIL.
25-TRANSDUCED bacteria has three types of DNA.{of itself, of other bacteria and of Virus }
26-RHIZOPUS is Aseptate and Multinucleate.
27-Bacteriophage is always DNA, it cannot have RNA.
28-First organ system ever developed in evolution after the formation of Mesoderm is neither Digestive nor Nervous but it is an EXCRETORY system by PLATYHELMENTHES.
29-HYDRA has no specialized muscle cells because it lacks MESODERM.

Mind -Map Human Reproduction –

Mind Maps for human reproduction

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