25 Questions
What triggers ovulation?
Peak in luteinising hormone (LH)
What are the two main hormones secreted by the corpus luteum?
Progesterone and a small amount of oestrogen
What happens to GnRH secretion during puberty in males?
It increases
What is the result of hypothalamus maturation in males?
Reduced sensitivity to testosterone and inhibin
What is the age range for the onset of puberty in females?
11-13 years old
What is the effect of oestrogen and progesterone on GnRH and LH/FSH secretion before puberty in females?
Inhibits GnRH and LH/FSH secretion
What happens to the reproductive organs during puberty in both males and females?
They increase in size
What is the outcome of maturation of the hypothalamus in females?
Increased GnRH secretion
What is the purpose of mitosis?
To proliferate somatic cells
What is the main difference between mitosis and meiosis?
All of the above
Where does fertilization normally occur?
In the uterine tube
What is the function of the epididymis?
To mature sperm
What is the primary function of the seminal vesicles?
To provide nutrients to sperm
What is the function of the prostate gland?
To provide energy to sperm
What is the function of the bulbourethral glands?
To lubricate the urethra
What is the approximate length of the vas deferens?
45cm
What is the composition of semen?
60% seminal vesicles, 30% prostate, 5% testes, 5% bulbourethral glands
What is the role of Sertoli cells in the seminiferous tubules?
To nourish developing germ cells
What is the final stage of spermatogenesis?
Differentiation of sperm cells
Where do oocytes pause during meiosis?
Prophase I
How many oocytes are present at birth?
400 000
What is the structure that surrounds the oocyte in a primary follicle?
Granulosa cells
What is the fate of the majority of oocytes in the ovaries?
They undergo atresia
What is the purpose of the epididymis in the male reproductive system?
To store and mature sperm cells
What is the term for the process by which sperm cells are formed?
Spermatogenesis
Study Notes
Cell Division
- Mitosis: 4 stages, occurs in somatic cells, produces 2 diploid daughter cells, chromosome number remains the same, purpose is cellular proliferation
- Meiosis: 8 stages, occurs in germ/sex cells, produces 4 haploid daughter cells, chromosome number is halved in each daughter cell, purpose is sexual proliferation
Female Reproductive System
- Ovaries open into the peritoneal cavity
- Fimbriae direct ovum into the uterine tube/fallopian tube/oviduct
- Successful fertilization normally occurs in the first third of the uterine tube
- Vagina: channel connecting to the cervix
Male Reproductive System
- Testis and scrotum: contains epididymis for maturation
- Vas deferens or ductus deferens: approximately 45cm long, has peristaltic movement, contains blood vessels and nerves
- Urethra: channel connecting to the penis
- Seminal vesicles: produce prostaglandin, stimulate motility of sperm, fructose, clotting agents
- Prostate gland: produces citric acid, proteolytic enzymes
- Bulbourethral (Cowper's) glands: produce mucous, alkaline fluid
Spermatogenesis
- Seminiferous tubules in testes: contain germ cells, develop into spermatocytes, nourished by Sertoli cells
- Spermatogonia: develop into primary spermatocytes (2n), then secondary spermatocytes (n), then spermatids (n)
- Spermatid differentiation: forms head, acrosome, midpiece, and flagellum
- Released into the lumen of seminiferous tubules to the epididymis for further maturation
Oogenesis
- Ovaries: suspended by ligaments, contain oogonia (5 million before birth, 400,000 at birth, 300,000 at puberty)
- Ovarian follicle: contains oocyte, blood vessels, lymphatic vessels, nerves
- Primordial follicle: primary oocyte pauses at Prophase I
- Primary follicle: layers of granulosa cells, zona pellucida
- Secondary follicle: at puberty, only 400 develop fully
- Ovulation: triggered by peak in luteinising hormone (LH), completes Meiosis I and pauses during early Meiosis II
Hormones in Males and Females
- Before puberty: low GnRH, low LH and FSH secretion
- Puberty: hypothalamus maturation, increased GnRH, LH, and FSH secretion, development of secondary characteristics
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