intro Flashcards
(23 cards)
Describe the process of sex determination at the genetic level. How does the presence of the SRY gene on the Y chromosome influence male development?
The human body has two major types of cells, somatic (body cells) and highly
specialised germ cells. The somatic cells have two copies of each chromosome arranged
in pairs, one from each parent (diploid number of chromosome), containing 46
chromosomes. Forty-four (44) chromosomes are called; autosomes and are arranged in
homologous pairs numbered (1-22). The remaining pair is the sex chromosome. In the
female, it is called XX, while in the male, it is called the XY chromosome.
The germ cells are in the testis and ovaries only. They contain one copy of each
chromosome (haploid number). The male germ cell has either a 23X or a 23Y number of
chromosomes, while the female germ cells always contain a 23X chromosome so that at
fertilisation, diploidy is reestablished. The XY chromosomes determine maleness.
Situated on the short arm of the Y chromosome is a region called the sex-determining
region of Y chromosomes (SRY gene). This gene encodes the testis determining factor
and is closely related to a glycoprotein H-Y antigen. The H-Y antigen is responsible for
the differentiation of indifferent gonads to the testis
Discuss the role of the androgen receptor gene located on the X chromosome in sexual differentiation. How do mutations in this gene lead to androgen insensitivity syndrome?
The hormonal effect of the H-Y antigen on both the external and internal genitalia is determined by the X chromosome
component, which contains the gene for the androgen receptor. Mutations in this gene results to partial or incomplete ability of cells to respond to androgens. This unresponsiveness can impair or prevent the development of male genitals, as well as impairing or preventing the development of male secondary sexual characteristics at puberty.
Explain the significance of Barr bodies in female somatic cells and their role in X chromosome inactivation.
In the female somatic cells, only one x chromosome is active. The other condenses and forms a bar body near the nuclear membrane. It can also form a nuclear drumstick in 1-15% of PMNL. A Barr body is an inactive X chromosome found in the nucleus of female mammal cells. Since females have two X chromosomes but only need one to be active, the other one becomes inactive. This process, called lyonization, ensures that females don’t make twice the amount of X-linked genes as males, who have only one X chromosome. The inactive X chromosome forms a dense structure known as a Barr body, which can be seen under a microscope near the edge of the cell’s nucleus. This process helps keep the genetic activity balanced between males
and females.
Outline the stages of gonadal development from the genital ridge in both male and female embryos. How do the Wolffian and Müllerian ducts contribute to the formation of internal genitalia
In males (46,XY), the Wolffian ducts develop into the vas deferens, epididymis, and seminal vesicles, stimulated by testosterone. In females (46,XX), the Müllerian ducts develop into the fallopian tubes, uterus, and upper vagina due to the absence of anti-Müllerian hormone (AMH).
Describe the hormonal regulation of sexual differentiation, particularly the roles of anti-Müllerian hormone (AMH) and testosterone.
Discuss the embryological basis of congenital reproductive disorders such as cryptorchidism, Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, and persistent Müllerian duct syndrome.
Differentiate between sex and gender
Classification of sex and gender
Explain the genetic and hormonal mechanisms underlying Klinefelter’s syndrome (47,XXY). How does this condition affect spermatogenesis and secondary sexual characteristics?
Discuss Turner’s syndrome (45,XO) and its impact on ovarian development and fertility. How does hormone replacement therapy (HRT) improve quality of life in these patients?-
abnormal sexual development: types, explain
chromosomal abnormalities ; list and explain
what’s puberty. onset and factors influencing onset. Explain the concept of critical body weight and fat percentage in triggering puberty. Why do conditions such as malnutrition or obesity influence the onset of puberty?
Characteristics of puberty for males
Characteristics of puberty in females
Thelarcke
Adrenarche
Pubarche
Menarche
What hormonal changes occur during menopause?
Ovarian follicles degenerate, leading to a decline in estrogen and progesterone. This results in elevated FSH and LH levels due to loss of negative feedback. Symptoms include hot flashes, osteoporosis, and mood changes.
Describe the role of gonadotropin-releasing hormone (GnRH) in initiating puberty. How do kisspeptins influence GnRH secretion?
menstruation, perimenstruation, postmenstruation, symptoms, characteristics
What are the causes and consequences of precocious puberty?
How does hypogonadotropic hypogonadism lead to delayed puberty?
Discuss the impact of sickle cell disease and malnutrition on pubertal development.
