12. REPRODUCTIVE SYSTEM Flashcards
Provide alternative names for:
a. Female gametes
b. Male gametes
c. Childbirth
a. ova
b. spermatozoa
c. parturition
Name the ‘sinuses’ which store milk in the breasts
Lactiferous sinuses
With regards to breast milk, describe the functions of:
a. Prolactin
b. Oxytocin
a. Prolactin stimulates milk synthesis
b. Oxytocin causes milk ejection
Name four functions of the uterus
The uterus serves as a pathway for sperm, the site of zygote implantation and location for foetal development. The uterus contracts to initiate labour.
Name the three layers of the uterine wall
Perimetrium [visceral peritoneum]
Myometrium [three smooth muscle layers]
Endometrium [highly vascular]
Name four functions of the uterus
- Pathway for sperm
- Site of zygote implantation
- Location for foetal development
- The uterus contracts to initiate labour (parturition)
Describe specifically the structure and function of the endometrium
The endometrium is the highly vascular inner layer of the uterus that is divided into the ‘stratum functionalis’ which sloughs off during menstruation and the ‘stratum basalis’, which is the permanent deeper layer that regenerates the stratum functionalis. The endometrium is vitally important as the site of zygote and placental implantation.
Name one uterine tissue layer that contains smooth muscle
Myometrium
Name one ligament that holds the uterus in place
The broad ligament
Which layer of the uterus sheds during menstruation?
The stratum functionalis of the endometrium
Describe the difference between an embryo and a foetus
During the first eight weeks of pregnancy, the zygote (fertilised egg) is called an embryo. After eight weeks, the embryo becomes a foetus.
Describe the function and role of the placenta
The placenta is the site of exchange of nutrients and wastes between the mother and foetus and is attached to the endometrium. The placenta produces progesterone and oestrogen, which are needed to maintain the pregnancy.
What characteristic makes the placenta unique?
The placenta is unique because it develops from two individuals (maternal part from the endometrium)
Discuss the following statement: “The placenta is an effective barrier to all medicine and drugs”
Although the placenta is a protective barrier to most micro-organisms, unfortunately many drugs and substances such as alcohol can freely pass through the placenta and cause birth defects (especially during the first three months - teratogenic).
Which cell type cannot cross the placenta?
Blood cells
Describe the functions of the following placental hormones:
a. Progesterone
b. Relaxin
c. Oestrogen
d. Human Chorionic Gonadotropin (hCG)
e. Corticotropin releasing hormone (CRH)
f. Human placental lactogen (hPL)
a. Progesterone: maintains endometrial lining to sustain and nourish the foetus
b. Relaxin: targets ligaments and relaxes them
c. Oestrogen: promotes growth of breast tissue and myometrium
d. hCG: Maintains the corpus luteum for 8 weeks; increases transfer of nutrients to foetus.
e. CRH: triggers release of cortisol from adrenals to prevent the rejection of the foetus.
f. hPL: Increases the amount of glucose and lipids in maternal blood.
Using definitions, compare the following placental complications:
- Placenta praevia
- Placenta accreta
- Placental abruption
- Placenta praevia: occurs when the placenta attaches to the lower part of the uterine wall, potentially occluding the cervical opening.
- Placenta accreta: is the abnormally deep attachment of the placenta through the endometrium and into the myometrium.
- Placental abruption: is the rupture of the blood vessels adhering the placenta to the uterine wall, leading to separation of the placenta from the uterus.
Describe two differences between ‘monozygotic’ and ‘dizygotic’ twins.
Monozygotic twins are identical and originate from a single fertilised ovum that splits into two embryos that share one placenta. Dizygotic twins are non-identical and originate from two ova, fertilised by two sperm, and each have their own placenta.
Describe the two functions of the fallopian tubes.
The fallopian tubes provide a route for the sperm to meet the ova and for the ova/fertilised ova to reach the uterus.
Explain how the ovum travels from the ovary into the fallopian tubes.
Finger-like projections called fimbriae surround the ovary and ‘sweep’ the ova into the fallopian tube. The tubes, lined with ciliated columnar epithelium, help move the ova towards the uterus. The smooth muscle layer of the fallopian tube also performs peristalsis to assist in the ova movement.
Describe two functions of the ovary
The ovaries are the female gonads and produce female gametes. They also secrete the sex hormones oestrogen and progesterone.
Oogenesis refers to the fromation of female _________ in the ovaries. Oogenesis begins in the ___________. Primary ___________ are formed from germ cells during foetal development. The formation of primary oocytes stops at _____ and they are surrounded by a layer of follicular cells. This entire structure is called a ____________ follicle. During a woman’s reproductive lifetime, about ______ follicles will mature and ovulate whilst the remainder ___________.
gametes foetus oocytes birth primordial 400 degenerate
Describe how FSH and LH play a role in post pubertal oogenesis.
FSH stimulates the maturation of the primordial follicles, which give rise to primary follicles, then secondary follicles and finally mature follicles.
A surge of LH triggers ovulation (the release of the ovum).
Briefly explain the formation of the corpus luteum
The remains of the ovarian follicle that has ovulated, becomes the corpus luteum (“yellow body”) which produces progesterone and some oestrogen to maintain the endometrium for the first 8 weeks of gestation. hCG prevents the degradation of the corpus luteum in the case of fertilisation.
List four stages of the menstrual cycle
- Menstrual phase (days 1-5)
- Pre-ovulatory phase (day 6-13)
- Ovulation (day 14)
- Post-ovulatory phase (day 15-28)
Describe in detail the first half of a typical menstrual cycle (Day 1-13)
During days 1-5 (menstrual phase), the endometrium is being shed and in the ovaries the follicles are developing under the influence of FSH. During days 6-13 (pre-ovulatory phase), the endometrium thickens in response to rising oestrogen levels and follicles start to mature and secrete oestrogen. Follicles also secrete inhibin which decreases the secretion of FSH, stopping further follicles from maturing.
Describe in detail the second half of a typical menstrual cycle (Day 14-28)
The ovulation phase occurs on day 14, when the high oestrogen levels creates a positive feedback loop that stimulates LH secretion. LH causes the rupture of a mature follicle and expulsion of the egg.
Days 15-28 is known as the post-ovulatory phase. The corpus luteum forms from the follicle wall and produces progesterone and some oestrogen. This is essential for establishing and maintaining the endometrium in pregnancy if the egg has been fertilised.
How is the corpus luteum formed?
The remains of the ovarian follicle that has ruptured to release an egg (ovulated), becomes the corpus luteum.
Describe what happens to a:
a. Fertilised egg
b. Non-fertilised egg
a. When the egg is fertilised, the zygote embeds in the uterine wall. The embryo (embedded zygote) produces hCG to maintain and stimulate the corpus luteum to produce progesterone and oestrogen, a role which is taken over by the placenta after a few weeks.
b. 14 days after ovulation, the corpus luteum degenerates into the corpus albicans. The levels of progesterone and oestrogen drop and a new cycle starts with menstruation.
Name three hormones involved in the onset of puberty.
Follicle stimulating hormone (FSH) Luteinising hormone (LH) Gonadotropin releasing hormone (GnRH)
List three body changes that typically occur during puberty
Breast development
Hair growth (pubic, axillary, legs)
Hips widen
Voice deepens
Define ‘menopause’
The menopause is the permanent cessation of menstruation for 12 consecutive months that naturally occurs at age 45-55.
Describe how the normal menopause develops.
Menopause occurs due to the number of follicles in the ovaries being exhausted, causing a drop in oestrogen and progesterone production and ovulation. This decline affects negative feedback, leading to high FSH and LH.
List three signs/symptoms of menopause
- Hot flushes and increased sweating
- Mood changes, irritability, anxiety
- Atrophy of mucosal linings: Vaginal dryness and painful intercourse; xerostomia
- Decreased libido
- Breast shrinkage
Explain why women experiencing menopause is at increased risk of osteoporosis
The decrease in oestrogen leads to a decline in osteoblasts and bone formation and maintenance. Oestrogen would normally suppress osteoclasts, thus a drop in oestrogen results in increased osteoclastic activity.
Explain why it is important to maintain balance blood glucose during menopause
Hypoglycaemia can contribute to increased hot flushes. Hyperglycaemia can result in an acidic environment detrimental to bone formation and a host of other things.
Name four components of the male reproductive system.
Two testes One penis One prostate gland Two epididymis Two vas deferens Two spermatic cords Two seminal vesicles Two ejaculatory ducts
Which nervous system stimulates erectile tissue and involuntary muscle
The parasympathetic nervous system produces nitric oxide that causes vasodilation.