Female Reproductive System Flashcards
1
Q
What is the vagina?
A
- it is a hollow, distensible fibromuscular tube that extends from the vestibule (opening) to the cervix
- during sexual intercourse and when a woman gives birth the vagina temporarily widens and lengthens
- the vaginal canal passes upwards and backwards into the pelvis with the anterior and posterior walls in close contact along a line approximately parallel to the plane of the pelvic brim
2
Q
Describe the structure of the vagina
A
- the posterior wall is 10 cm long whereas the anterior wall is only 7.5cm in length
- > this is because the cervix projects into its upper part at a right angle
- the upper end of the vagina is known as the vault
- > where the cervix projects into it the vault forms a circular recess that is described as four arches or fornices
- the posterior fornix is the largest of these because the vagina is attached to the uterus at a higher level behind than in front
- the anterior fornix lies in front of the cervix
- the latter fornices lie on either side
3
Q
Describe the vaginal layers
A
- vagina is lined by a layer of moist squamous epithelial cells folded into folds (rugae)
- -> distend during intercourse and childbirth to allow the vaginal walls to stretch
- -> kept moist by cervical secretions pH 4.5 (acidic) due to presence of lactic acid formed by the acion of Doderlein’s bacilli on glycogen
- lining of smooth muscle
- -> made up of weak inner coats of circular fibres and stronger outer coat of longitudinal fibres
- -> maintains the tone of the vagina
- pelvic fascia
- -> surrounds the vagina and allows for the independent expansion and contraction
4
Q
Describe the function of the vagina
A
- the vagina allows the escape of the menstrual fluids
- receives the penis and the ejected sperm during sexual intercourse
- provides an exit for the fetus during birth
5
Q
Describe the nerve supply to the vagina
A
- the nerve supply is derived from the pelvis plexus
- the vaginal nerves follow the vaginal arteries to supply the vaginal walls and the erectile tissue of the vulva
6
Q
Describe the function of the uterus
A
- the main function of the uterus is to nourish the developing fetus prior to birth
- it prepares for pregnancy each month and following pregnancy expels the products of conception
7
Q
Describe the changes that occur in the vagina during pregnancy
A
- an increase in blood flow to the vagina results in a bluish-purple coloration - chadwicks sign (8 weeks)
- in preparation for the distension that occurs in labour the vaginal walls undergo changes
- > mucosa thickens
- > connective tissue loosens
- > smooth muscle cells hypertrophy - increased volume of vaginal secretions due to high levels of oestrogen results in a thick white discharge (leucorrhoea)
- higher levels of oestrogen cause an increase in the activity and proliferation of the lactobilli
- > leads to increased vaginal acidity (pH from 3.5-6)
- > protects women from genital tract infection
- >
8
Q
Describe the structures that support the uterus
A
- the uterus is supported by the pelvic floor and maintained in position by several ligaments
- the transverse cervical ligaments fan out from the sides of the cervix to the side walls of the pelvis, sometimes known as Cardinal ligaments
- the uterosacral ligaments pass backwards from the cervix to the sacrum
- the pubocervical ligaments pass forwards from the cervix under the bladder to the pubic bones
- the broad ligaments are formed from the folds of peritoneum which are draped over the uterine tubes
- -> they hang down like a curtain and spread from the sides of the uterus to the side walls of the pelvis - the round ligaments have little value as a support but tend to maintain the anteverted position of the uterus
- -> they arise from the cornua of the uterus, in front of and below the insertion of each uterine tube and pass along the folds of the broad ligament, through the inguinal canal to be inserted into each labium manus - the ovarian ligaments also begin at the cornua of the uterus but behind the uterine tubes and pass down between the folds of the broad ligament to the ovaries
9
Q
Describe the structure of the uterus
A
- the non pregnant uterus is 7.5cm long, 5cm wide and 2.5cm in depth, each wall being 1.25cm thick
- the cervix forms the lower 1/3 of the uterus and measures 2.5cm in each direction
- the cornua - are the upper outer angles of the uterus where the uterine tubes join
- fundus -> domed upper wall between insertions of Fallopian tubes
- body -> makes up the upper 2/3 (corpus)
- cavity -> potential space between anterior and posterior walls, triangular in shape, bas being uppermost
- isthmus -> narrow area between cavity and cervix 7mm long enlarges in pregnancy to be the lower segment, it enlarges during pregnancy to form the lower uterine segment
- cervix -> protrudes into vagina, upper half is supravaginal and lower half infravaginal
- internal os -> mouth narrow opening between isthmus and cervix
- external os -> small opening at lower end of the cervix, after childbirth it becomes a transverse slit
- cervical canal -> continuation of uterine cavity narrow at each end and wider in the middle
10
Q
Describe the 3 layers of the uterus
A
- endometrium
- -> it forms a lining of ciliated epithelium (mucous membrane) on a base of connective tissue or storms
- -> the endometrium is constantly changing in thickness throughout the menstrual cycle
- -> the basal layer does not alter but provides the foundation from which the upper layers regenerate
- -> the epithelial cells are cubical in shape and secrete an alkaline mucus
- myometrium
- -> is thick in the upper part of the uterus and is sparser in the isthmus and cervix
- -> its fibres run in all directions and interlace to surround the blood vessels and lymphatics that pass to and from the endometrium
- -> the outer layer is formed of longitudinal fibres that are continuous with those of the uterine tube, uterine ligaments and the vagina
- perimetrium
- -> is a double serous membrane, an extension of the peritoneum, which is draped over the fundus and the anterior surface of the uterus to the level of the internal os
- -> it is then reflected onto the bladder forming a small pouch between the uterus and the bladder called the uterovesical pouch
- -> the posterior surface is covered to where the cervix protrudes into the vagina and is then reflected onto the rectum forming the recto-uterine pouch
- -> laterally the perimetrium extends over the uterine tubes forming a double fold, the broad ligament, leaving the lateral borders of the body uncovered
11
Q
Describe the blood supply to the uterus
A
- the uterine artery arrives at the level of the cervix and is a branch of the internal iliac artery
- -> it sends a small branch to the upper vagina and then runs upwards in a twisted fashion to meet the ovarian artery and form an anastomosis with it near the cornu - the ovarian artery is a branch of the abdominal aorta, leaving near the renal artery
- -> it supplies the ovary and uterine tube before joining the uterine artery - the blood drains through the corresponding veins
12
Q
What is the uterus?
A
- the uterus is a hollow, pear-shaped muscular organ
- it is located in the true pelvis between the bladder and the rectum
- the position of the uterus within the true pelvis is one of anteversion (leans forward) and anteflexion (bends forward on itself)
13
Q
Describe how the uterus changes during pregnancy
A
- during pregnancy, it is transformed into a thin-walled organ sufficient enough to accommodate the fetus, placenta and amniotic fluid
- the uterus increases in all dimensions and also changes shape
- uterine hyperplasia begins after implantation and is driven by oestrogen and growth factors
- early growth results in thickening of the uterine wall
- -> the endometrium thickens into the decidua
- -> the three layers of the myometrium become clearly defined as - - the uterine muscle undergoes initial hyperplasia (development of new fibres) and subsequent hypertrophy (increase in length and thickness of existing muscle fibres)
- later uterine growth is mostly hypertrophy and hyperplasia of the myocytes and remodelling of connective tissue which is driven by distension as the fetus enlarges
- the muscle fibres increase in length and width as the timing and speed of the myometrial action potentials change and the muscle cells increase their content of actin, myosin, gap junctions, sarcoplasmic reticulum and mitochondria
- in early pregnancy the uterine isthmus increases from about 7 to 25 mm, from 32-34 weeks the isthmus forms the lower uterine segment
- a effacement commences, the internal so is incorporated into the LUS
- the blastocyst usually implants in the fundus, by 12 weeks the fetus fills the uterine cavity and the fundus can just be palpated at the pelvic brim
- -> by 20 weeks the fundus reaches the maternal umbilicus
- -> and by 36 weeks it reaches the sternum - as the uterus expands during pregnancy it loses its anteverted and anteflexed configuration and becomes erect, tilting and then rotating to the right under the pressure of the descending colon
- the uterus changes from its non-pregnant pear-shape and becomes spherical and then cylindrical
- uterine quiescence is mediated by progesterone, relaxin, nitric oxide and prostacyclin
- -> the uterus is never completely quiescent and exhibits low-frequency activity throughout the pregnancy
- -> Braxton hicks contractions are painless contractions that are measurable from the first trimester of pregnancy
- -> these contractions do not dilate the cervix but assist in the circulation of blood to the placenta - the uterine ligaments soften and thicken under the influence of oestrogen, resulting in increased mobility and capacity of the pelvis
14
Q
Describe the structure of the uterine tubes
A
Interstitial portion - 1.25 cm long and lies within the wall of the uterus, its lumen is 1mm wide
Isthmus - another narrow part that extends 2.5cm from the uterus
Ampulla - the wider portion where fertilization usually occurs, it is 5cm long
Infundibulum - the funnel-shaped fringed end that is composed of many processes known as fimbriae
- one fimbriae is elongated to form the ovarian fimbria which is attached to the ovary
- blood supply, lymphatic drainage and nerve supply is shared with the ovaries
15
Q
Describe the 3 layers of the uterine tubes
A
- The lining of the tubes
- > mucous membrane of ciliated cubical epithelium that is folded into plicae
- > the folds slow the ovum down on its way to the uterus
- > in this lining are goblet cells that produce a secretion containing glycogen to nourish the oocyte
- > beneath the lining is a layer of vascular connective tissue - the muscle coat -> consist of 2 layers
- > an inner circular layer and an outer longitudinal layer, both of smooth muscle
- > the peristaltic movement of the uterine tube is due to the action of these muscles - The tube
- > covered with peritoneum but the infundibulum passes through it to open the peritoneal cavity
