Human Reproduction Flashcards
In the male reproductive system, what is the function of the:
a) testis?
b) epididymis?
c) vas deferens?
d) seminal vesicles and prostate gland?
a) Producing spermatozoa and secreting testosterone
b) Spermatozoa are stored and mature inside here
c) Transports spermatozoa from the testis to the urethra
d) Secrete a part of the seminal fluid each
In the female reproductive system, what is the function of the:
a) ovaries?
b) oviduct?
c) uterus?
d) cervix?
a) Producing ova and secreting oestrogen and progesterone
b) Ova pass along here from the ovary to the uterus
c) Has an outer muscle wall and an endometrium, which the embyro implants into
d) A ring of muscle at the entrance to the uterus
Where in the testis are the spermatozoa produced?
In the seminiferous tubules
How are spermatozoa produced in the seminiferous tubules?
› Each tubule is surrounded by a layer of germinal epithelium, then with a layer of spermatogonia on top
› Some spermatogonia grow larger to become primary spermatocytes
› These divide by meiosis, after the first division they become secondary spermatocytes, and after the second they become spermatids
› These then mature into spermatozoa
What is the function of the Sertoli cells in the seminiferous tubule?
To nourish and protect the spermatozoa from the immune system
What are some adaptations of spermatozoa?
› Acrosome at the tip of the head, contains hydrolytic enzymes
› Tail contains microtubules which are responsible for the swimming movements
› Many mitochondria in the middle piece to provide ATP for energy for said movement
What happens in oogenesis before birth?
› Some germinal epithelium cells in the ovaries divide by mitosis to produce oogonia
› These divide by mitosis and enlarge, producing primary oocytes
› These then begin meiosis but stop at prophase I
What happens in oogenesis after birth?
› Germinal epithelium cells divide to form follicle cells, which surround the primary oocytes, making primary follicles
› At puberty, hormones will stimulate a few follicles per month to develop further
› The primary follicle develops into a secondary follicle, and eventually a Graafian follicle
› The primary oocyte inside finishes dividing, producing a small polar body and a large secondary oocyte, which then stops developing at metaphase II
What happens to the spermatozoa after being ejaculated?
› Changes take place allowing them to swim more actively
› Changes to the membrane around the acrosome allow it to release its enzymes when it comes into contact with the secondary oocyte
› Capacitation increases the permeability of the membrane in front of the acrosome
What is the acrosome reaction?
› When the spermatozoon reach a secondary oocyte, the acrosome membrane ruptures
› Due to contact with the zona pellucida
› The enzymes digest the zona pellucida
› Enables the spermatozoon to reach the plasma membrane of the oocyte, where the genetic material of the spermatozoon enters
What is the cortical reaction?
› Reaction of the oocyte that produces the fertilisation membrane
› Preventing polyspermy (entry of more than one spermatozoon)
What happens to the zygote after fertilisation?
› Mitosis happens, first forming a mass of cells called the cleavage
› Division continues and a hollow ball of cells is formed called the blastocyst
› Cells around the outside of the blastocyst (trophoblasts) form an inner cell mass on one side
› Trophoblastic villi protrude and penetrate the endometrium, embedding the blastocyst there
What are some roles of the placenta?
› Producing hormones to support pregnancy
› Exchange of materials (nutrients, waste, gas) between mother’s and foetus’s blood
› A physical barrier against the mother’s higher blood pressure
› Providing passive immunity to the foetus
What are the significant hormones of the menstrual cycle?
› Gonadotrophic releasing hormone (GnRH) › Follicle stimulating hormone (FSH) › Luteinising hormone (LH) › Oestrogen › Progesterone
Explain the menstrual cycle
› GnRH secreted by hypothalamus, stimulates FSH secretion from anterior pituitary gland
› FSH stimulates development of primary follicles in ovary, and stimulates thecal cells to produce oestrogen
› Oestrogen inhibits FSH secretion, stimulates LH production from anterior pituitary gland, and stimulates build up of the endometrium
› LH stimulates ovulation, and conversion of vacant follicle to corpus luteum
› Corpus luteum secretes progesterone and oestrogen
› Continues endometrium build up, and progesterone inhibits LH and FSH secretion
› Causes corpus luteum to degenerate, and progesterone and oestrogen levels fall
› Endometrium breaks down and is lost through the vagina
› FSH is no longer inhibited, so a new cycle starts
