Female Reproduction System, Including Menstrural Cycle And Oogenesis Flashcards
Outline an overview of the female reproductive system
External genitalia is known collectively as the vulva
Internal reproductive organs: the vagina, the uterus, two uterine tubes and two ovaries
Describe the moms pubis/veneris
Rounded pad of fat lying anterior to the symphysis pubis
Describe the labia majora
Two folds of fat and areolar tissue, covered with skin and pubic hair on the outer surface and have a smooth inner surface
Describe the labia minora
Two small subcutaneous folds that lie between the labia majora. The upper layer passes above the clitoris to form the prepuce, which overhangs the clitoris. The lower layer passes below the clitoris to form the frenulum of the clitoris.
Describe the prepuse
Retractable piece of skin, formed by the labia minora, which surrounds and protects the clitoris
Describe the fourchette
Labia minora fuse posteriorly to produce the fourchette
Describe the vestibule
The area enclosed by the labia minora in which the openings of the urethra and the vagina are situated
Describe the urethral orifice
Immediately in front of the vaginal orifice. On either side lie the openings of the Skene’s ducts, two small blind-ended tubules 0.5 cm long running within the urethral wall
Describe the vaginal orifice
Aka the introitus of the vagina. The orifice is partially closed by the hymen, a thin membrane that tears before or during penetrative sexual intercourse
Describe the greater vestibular glands
Baratholin’s glands: two small glands that open on either side of the vaginal orifice. They secrete mucus, which lubricates the vaginal opening
Describe the clitoris
External part: clitoral glans. Densely filled with nerve ending.
Internal part: extremely vascular, erectile tissue
The erectile bodies: paired bulbs and paired corpora, which are continuous with the crura
Describe the blood supply and nerves in the vulva
Blood supply: internal and external pudendal arteries and corresponding veins
Lymphatic drainage: inguinal glands
Nerve supply: branches of the pudendal nerve
Define vagina
A canal from vestibule to the cervix, passing upwards and backwards into the pelvis along the line of the pelvic brim
Outline the function of a vagina
Passage and escape of menstrual flow
Receives the penis and ejaculate during inter course
Provides exit of fetus during birth
Name 4 other names for vagina, with reference to different anatomical locations
Anterior: bladder
Posterior: rectum
Superior: uterus
Inferior: external genitalia
Describe the structure of the vagina
Posterior wall-10 cm long
Anterior wall- 7.5cm because cervix projects at right angles into upper part
Upper end- vault
Cervix projects into the vault forming fornices
Posterior fornix- largest because vagina is attached to uterus at a higher level behind
Lateral fornices- lie either side
Anterior fornix- in front of the cervix
Describe the layers of the vagina
Lining: squamous epithelium, arranged in rugae. Kept moist by cervical secretions pH 4.9-3.5-acidic due to presence of Doderlein’s bacilli
Muscle layer: weaker inner circular fibres and stronger outer longitudinal fibres
Pelvic fascia: connective tissue surrounding the vagina
Describe the uterus
Hollow, pear-shaped muscular organ located in the true pelvis between the bladder and the rectum
Position of the uterus within the true pelvis is one of anteversion and anteflexion
Anteversion means that the uterus leans forward and anteflexion means that it bends forwards upon itself
The non-pregnant uterus is 7.5cm long, 5cm wide and 2.5cm in depth, each wall being 1.25cm thick, and weighs 60 grams
Describe the fungus
Doomed upper wall between the insertions of the uterine tube
Describe the cornuae
Upper outer angles of the uterus where the uterine tubes join
Describe the body/corpus
Makes up the upper two-thirds of the uterus
Describe the cavity
Within the body of the uterus, triangular in shape
Describe the isthmus
7mm long situated at the junction of the body and cervix
Describe the layers of the uterus
- Perimetrium: layer of peritoneum draped over the uterus and uterine tubes
- Myometrium: muscle layer
Inner layer- circular fibres around the cornua and cervix
Middle layer- interlacing spiral fibres- the upper part of the body
Outer longitudinal fibres- from the cervix anteriorly over the fundus to the cervix posteriorly - Endometrium
Functional layer- which thickens and is shed during menstrual cycle
Basal layer- from which functional layer regenerates every cycle
Describe the blood and nerve supply in the uterus
Blood supply:
Uterine and ovarian arteries- branches of internal iliac artery
Venous drainage- corresponding veins
Lymphatic drainage:
Lumbar and hypogastric nodes
Nerve supply:
11th, 12th thoracic and 1st lumbar nerve cervix by sacral nerves 2, 3 and 4
Describe the cervix
Part of the uterus
The lower part sits within the vagina, and upper part sits above the vagina
The cervical canal is made up of columnar epithelium that secretes mucus (known as compound racemose glands)
The muscle fibres are embedded in collagen enabling it to stretch in labour
The internal os is a narrow opening between he isthmus and cervix
The external os is a small round opening at the lower end of the cervix
Define the uterine tubes
Two tubes, each leading from an ovary into the uterus
What is the function of the uterine tube?
Propels the ovum towards the uterus, receives the spermatozoa as they travel upwards and provides a site for fertilisation
Where is the position of uterine tubes?
Extend laterally from the cornua of the uterus towards the side walls of the pelvis. They arch over the ovaries, the fringed ends hovering near the ovaries in order to receive the ovum. Hold in place by their attachment to the uterus and the peritoneum.
Describe the interstitial portion
It is 1.25cm long and lies within the wall of the uterus. It’s lumen is 1mm wide
Describe the isthmus
Another narrow part that extends for 2.5 cm from the uterus
Describe the ampulla
The wider portion, where fertilisation usually occurs. 5cm long.
Describe the infundibulum
The funnel-shaped fringed end that is composed of many processes known as fimbriae. One fimbria is elongated to form the ovarian fimbria, which is attached to the ovary.
Describe the structure of the uterine tube
Longitudinal and circular muscle
Lining of ciliated columnar epithelium:
-wafts ovum from infundibulum towards the uterus
-contains foods or plicae
-contains goblet-shaped cells which produce secretions to nourish the ova
Describe the blood and nerve supply in the uterine tubes
Blood supply:
Ovarian and uterine arteries- branches of the internal iliac artery and corresponding veins
Lymphatic drainage: lumbar glands
Nerve supply: ovarian plexus and the parasympathetic system
Describe the function of the ovaries
The ovaries produce oocytes and the hormones, oestrogen and progesterone
What is the position of the ovaries?
They are attached to the uterus by the ovarian ligaments. 3cm x 2cm x 1cm, almond shaped
The ovary is comprised of the medulla and the cortex
Describe the medulla
It is the supporting framework, which is made of fibrous tissue; the ovarian blood vessels, lymphatics and nerves travel through it. The hilum is where these vessels enter the ovary (known as the mesovarium)
Describe the cortex
It is the functioning part of the ovary. It contains the ovarian follicles in different stages of development, surrounded by stoma (unique type of connective tissue)
What is puberty?
The age at which the internal reproductive organs reach maturity, usually between the ages of 12 and 14 (though it is correlated with body mass)
What is the hormonal trigger for puberty?
Hypothalamus releases luteinising hormone releasing hormone (LHRH)
LHRH acts on the anterior pituitary gland, causing it to release follicle stimulating hormone (FSH) and luteinising hormone (LH)
FSH and LH cause the ovaries to secrete oestrogens
Oestrogens are responsible for secondary sex characteristics
Name 6 secondary sex characteristics in females
Maturation of the uterus, uterine tubes and ovaries
Development and enlargement of the breasts
Growth of pubic and axillary hair
Increase in height
Widening of the pelvis
Increased fat deposition in the subcutaneous tissue, especially at the hips and breasts
Define menarche
Onset of menstruation
Define menopause
Ceasing of menstruation
Define menstruation
A ‘period’ of vaginal bleeding as the lining of the uterus sheds and is passed through the vagina
Define reproductive cycle
Aka the menstrual cycle
A series of events, occurring regularly in females every 26-30 days throughout the childbearing period between menarche and menopause
The cycle consists of a series of changes taking place concurrently in the ovaries and uterine lining, stimulated by changes in hormones
Describe what happens in the ovary during the reproductive (menstrual) cycle
Oogenesis: maturation of ova
In utero:
By 20 weeks gestational age: primary ova are formed in the developing ovaries of the fetus. Over 1 million are present at the time of birth
These follicles are immature; their development is halted until menarche
During each cycle, one or so follicles mature. Maturation is controlled by the hypothalamus secretes luteinising hormone releasing hormone (LHRH) and the anterior pituitary gland, which releases gonadotropins (follicle stimulation hormone FSH) and luteinising hormone (LH), both of which act on the ovary
Hormones:
The developing follicle is a source of hormones
During first half of cycle, while ovum is developing within the follicles, the follicle secretes increasing amounts of oestrogen
However, after ovulation, the corpus luteum secretes primarily progesterone, with some oestrogen and inhibin
Describe the stages of development of one ovarian follicle
Before ovulation:
The follicle develops from an immature (primordial) follicle to a mature (Graafian) follicle. The follicle is filled with follicular fluid, which increases. The Graafian follicle migrates from the cortex to the surface of the ovary.
Ovulation:
On day 14 of the cycle, the follicle ruptures, releasing the ovum into the peritoneal cavity. It is ‘caught’ by the fimbriae at the end of the uterine tube. It is propelled by cilia, along the uterine tube towards the uterus. Body temp rises by 1 degree Celsius
After ovulation:
Corpus luteum develops, which secretes progesterone (and oestrogen and inhibin). Progesterone causes LH and FSH to fall. If the ovum is not fertilised, falling LH levels lead to degeneration and death of the corpus luteum. If the ovum is fertilised, the corpus luteum continues to secrete hormones for 3-4 months.
Describe what happens in the uterus during the reproductive (menstrual) cycle
Menstrual: days 1-4
Progesterone and oestrogen levels therefore fall, and the functional layer of the endometrium is shed in menstruation as the myometrium contracts.
Proliferative: days 5-14
The maturing ovarian follicle stimulates the thickening (regrowth) of the functional layer of the endometrium in preparation for the reception for the fertilised ovum. The endometrium thickens, becoming very vascular and rich in mucus-secreting glands. This stand ends at ovulation.
Secretory: days 15-28
Progesterone from the corpus luteum stimulates the endometrium to become oedematous and the secretary glands produce increased amounts of watery mucus. This assist the motile spermatozoa through the uterus to the uterine tubes, whee the ovum is usually fertilised. This stage begins at ovulation.
