12. Reproductive System Flashcards
What 2 things does sexual reproduction involve?
Meiosis
Fertilisation
What does fertilisation produce?
A zygote containing 46 chromosomes
What are the 5 functions of the female reproductive system?
- Formation of ova
- Reception of spermatozoa
- Provide suitable environment for fertilisation
- Parturition (childbirth)
- Lactation
What are the 2 functions of the male reproductive system?
- Production of spermatozoa
- Transmission of spermatozoa to the female
What is the gland called within the breasts?
Mammary glands
What supports the breast between the skin and underlying fascia?
Suspensory ligaments
Briefly describe how the two main hormones are involved in lactation.
Prolactin stimulates milk synthesis whilst suckling stimulates oxytocin causing milk ejection.
What are the 3 functions of the uterus?
- Pathway for sperm
- Site for zygote implantation,
- Location for foetal development
Briefly describe the 3 layers of tissue found in the uterus.
- Perimetrium - outer layer
- Myometrium - inner layer of 3 smooth muscle layers
- Endometrium - highly vascular inner layer
Briefly describe the 2 layers of the endometrium
- Stratum functionalis - the changing layer which sheds during mentruation
- Stratum basalis - permanent deeper layer that regenerates the stratum functionalis
Name the 3 regions of the uterus
Fundus , body, and cervix
Describe the 3 roles of the placenta
- Site of exchange of nutrients and waste between mother and foetus
- Produces hormones
- Protective barrier to most micro-organisms
How are the mother and foetus connected through the placenta?
Umbilical cord which is 50-60cm long
Briefly describe the 6 main hormones produced by the placenta
Progesterone - maintains the endometrium lining
Oestrogen - promotes growth of the breast tissue and myometrium.
Human Chorionic Gonadotropin (hCH) - maintains corpus luteum for 8 weeks and increases transfer of nutrients
Human placental lactogen (hPL) - increases glucose and lipids in maternal blood
Relaxin - relaxes ligaments
Coricotropin releasing hormone (CRH) - triggers release of cortisol and prevents rejection of foetus
What is Placenta Praevia?
Occurs when the placenta attaches to the lower part of the uterine wall, potentially blocking the opening of the cervix
What are the risks of Placenta Praevia?
After 20 weeks is prone to haemorrhage.
Wall of cervix stretches and can detach from the placenta. Uterine vessels rupture often presenting as painless, ante-partum vaginal bleeding.
What is Placenta Accreta?
Abnormally deep attachment of the placenta through the endometrium into the myometrium. Due to inadequate endometrium so placenta has to dig deeper when implanting.
What are the two types of Placenta Accreta?
Increta = invades myometrium
Percreta = Through uterine wall to viscera (such as bladder)
Name 2 potential causes of Placenta Accreta?
- C-section
- Fibroid removal
- Placenta Praevia
What is Placenta Abruption and how does it present?
Rupture of blood vessels adhering the placenta to the uterine wall leading to separation of the placenta from the uterus.
Presents as abdominal pain and ante-partum bleeding.
What are the terms used for the two types of twins and how many placentas do they have?
Monozygotic / identical - 1 placenta
Dizygotic / non-identical - 2 placentas
Describe how the ova leaves the ovary and travels to the uterus.
Finger-like projections called fimbriae sweep the ova into the fallopian tubes.
Cilia line the tubes and help move the ova towards the uterus along with smooth muscle layers performing peristalsis.
What sex hormones do the ovaries produce?
Oestrogen and progesterone
What is the term used for the formation of female gametes (ova) in the ovaries?
Oogenesis
What is the term for an immature egg cell?
Oocyte
When does oogenesis begin and end?
Begins in the foetus and the formation of primary oocytes stops at birth leaving approximately 2 million oocytes.
What is a primordial follicle?
Primordial follicles are the entire structure of a primary oocyte surrounded by a layer of follicular cells.
Briefly describe the process of maturation of oocytes that occurs each month after puberty.
Anterior pituitary releases FHS and LH.
FHS stimulates the maturation of the primordial follicles to secondary follicles, and then mature follicles.
A surge of LH triggers ovulation - the release of a secondary oocyte from a mature follicle.
The remains of the ovarian follicle that has ovulated becomes the corpus luteum which produces progesterone and oestrogen.
What is the average length of the menstrual cycle?
28 days
What are the 4 phases of the menstrual cycle and when do they occur?
Menstrual phase (1-5 days)
Pre-ovulatory phase (6-13 days)
Ovulation phase (day 14)
Post-ovulatory phase (days 15 - 28)
Briefly describe what occurs in the uterus during the phases of the menstrual cycle.
Menstrual phase - the endometrium is being shredded in response to the sudden drop in progesterone.
Pre-ovulation - The endometrium thickens in response to the rising oestrogen levels
Briefly describe what occurs in the ovaries during the phases of the menstrual cycle.
Menstrual phase - follicles are developing under the influence of FSH
Pre-ovulation - Follicles start to mature, secreting oestrogen. Follicles secrete inhibin which decreases FSH and prevents other follicles developing.
Ovulation - High oestrogen stimulates LH secretion. LH causes rupture of the mature follicle and expulsion of the egg.
Post-ovulation - the corpus luteum forms from the follicle wall and produces progesterone and some oestrogen. These maintain endometrium in preparation for pregnancy.
Describe the early stage of a fertilised egg.
Zygote embeds in the uterine wall.
Human chorionic gonadotropin (hCG) maintains and stimulates the corpus luteum to produce progesterone and oestrogen.
After a few weeks, the placenta takes over.
Describe what occurs during puberty (female)
Occurs typically between 10-14yrs of age.
Burst of GnRH triggers pulses of LH and FSH increasing over 3-4 years.
Internal reproductive organs mature and menarche occurs.
Breasts develop, hair growth, hips widen and voice deepens.
What is the menopause
The menopause is the permanent cessation of menstruation for 12 consecutive months.
What occurs in the body during the menopause?
Naturally occurs at 45-55 years of age as a result of ovarian aging whereby the number of follicles becomes exhausted.
Oestrogen and progesterone production decreases creating a negative feedback leading to high FSH and LH.