Placenta act as endocrine tissues. Justify? Solution
Placenta acts as an endocrine tissue and secretes hormones like:
human chorionic gonadotropin (hcG)
human placental lactogen (hpL),
These hormones are needed for supporting the foetal growth and to maintain pregnancy.
Mention the fate of Corpus luteum and its effect on the uterus in the absence of fertilization of the ovum in a human female? Solution
In the absence of fertilization, the Corpus luteum degenerates. It causes disintegration of the endometrium of uterus, leading to menstruation.
Why is it considered that the presence or absence of hymen is not an indication of virginity? Solution
Hymen is the membrane that partially covers the vaginal opening. The hymen get torn during the first coitus. But it can also be torn by active participation in sports like horse-riding, cycling or by a sudden fall or jolt and insertion of a vaginal tampon; so its presence or absence cannot indicate virginity.
Short Answer Type Questions (3 Marks)
Why is breast-feeding recommended during the initial period of an infant's growth? Give reason? Solution
The Yellowish fluid that comes out of the mammary glands of the mother, during the initial few days of lactation, following parturition, is called colostrum; it contains several antibodies which provide resistance to the newborn.
Mother's milk is the balanced diet for the Infant; it is digested easily and provide all the required nutrients.
Explain the events in a normal woman during her menstrual cycle, on the following days:
(a) the level of pituitary gonadotropins, follicle-stimulating hormone and luteinising hormone increase steadily.
(b) The endometrium is regenerated and it has thickened further.
(c) Following ovulation, the remaining parts of the ruptured follicle forms the Corpus luteum.
The Corpus luteum secretes a large quantity of progesterone.
Not all copulations lead to pregnancy. Give reason. Solution
The sperm and ovum must reach the ampullary- isthmic junction at the same time, if fertilization occurs, though copulation has occurred.
Explain the functions of myometrium and endometrium in human females. Solution
Myometrium is the muscular layer, whose vigorous contractions at the end of gestation lead to parturition.
Endometrium is the glandular layer, where implantation occurs; it also forms a part of the placenta.
Question 24 Why is it considered that the presence or absence of hymen is not an indication of virginity? Solution
Hymen is the membrane that partially covers the vaginal opening.
The hymen gets torn during the first coitus.
But it can also be torn by active participation in sports like horse-riding, cycling, or by a sudden fall or jolt and insertion of vaginal tampon; so its presence or absence cannot indicate virginity.
Differentiate between morula and blastocyst. Solution
It is a solid sphere of cells formed by cleavage of zygote.
Zona pellucida is intact.
It is a hollow sphere of cells, formed by the rearrangement of blastomers of morula.
Zona pellucida disintegrates with the enlargement of blastocoel.
Long Answer Type Questions (5 Marks)
Mention the source and the function of following hormones: hcG, LH FSH, Relaxin. Solution
(i) Stimulates growth and maturation of ovarian follicles.
(ii) Secretion of estrogens by follicular cells
(i) Stimulate ovulation
(ii) Formation of Corpus luteum
(iii) Secretion of progesterone by Corpus luteum
(i) Supporting fetal growth (ii) Metabolic changes in the mother (iii) Maintenance of pregnancy
Softening of pubic symphysis for parturition
(a) Name the hormone secreted and write their functions:
(i) by Corpus luteum and Placenta
(ii) during follicular phase and parturition
(b)Name the stages in human female where;
(i) Corpus luteum and Placenta coexist
(ii) Corpus luteum temporarily ceases to exist. Solution
(i) Corpus luteum secretes progesterone. Progesterone is necessary to maintain the endometrium, that is necessary for implantation of the embryo.
Placenta secretes human chorionic gonadotropin (hCG), human placental lactogen (hPL), estrogens and progesterone.
These hormones are essential for fetal growth, supporting the metabolic changes in the Mother's body and maintaining pregnancy.
(ii) During follicular phase, follicle stimulating hormone is secreted by the anterior pituitary.
it stimulates the growth and maturation of ovarian follicles.
The follicular cell secrete estrogens, that are essential for maintenance of the secondary sex organ during this phase.
The level of luteinizing hormone, secreted by anterior pituitary slowly increases and reaches a peak level towards the end of follicular phase.
During parturition, the foetal- ejection reflex stimulates the secretion of Oxytocin. Oxytocin induces the vigorous contraction of uterine smooth muscles that result in childbirth or parturition.
(i) During pregnancy.
(ii) When the ovum is not fertilized, that is during menstrual phase, follicular phase and ovulating phase.
Describe the structure of mammary glands of a human female?
A human female has a pair of functional mammary glands that consists of glandular tissue and variable quantity of the fat.
The glandular tissue is divided into 15 to 20 mammary lobes; each lobe contains clusters of cells, called alveoli, which opens into mammary tubules.
The mammary tubules of each lobe join to form a mammary duct.
Several mammary ducts join to form a wider mammary ampulla that is connected to lactiferous duct, through which milk comes out.
The milk is actually secreted by the cells of alveoli and is stored in the lumen of alveoli.
(i) Vas deferens and Vasa efferentia
(ii) Spermatogenesis and spermiogenesis. Solution
Vas deferens arises from epididymis and opens into urethra.
This conducts the sperm to the urethra and then to outside.
It receives ducts of the associated glands.
It ascends into the abdominal cavity.
Vasa efferentia arise from rete testis and open into epididymis.
They conduct the sperms out of the testes.
They do not receive ducts of any associated glands.
They remain inside the scrotum (extra abdominal).
It is the process of formation of spermatozoa in the testes.
It involves cell divisions.
Spermatogonia of the seminiferous tubules are involved.
It is the process of transformation of spermatids into spermatozoa.
It does not involve any cell division.
Sertoli cells of the seminiferous tubules are involved.