Uterus, Uterine Tubes & Cervix Flashcards by aimen n

What is the uterus lining?

Lined by the endometrium (thin lining inside)
The muscular layer is the myometrium
The perimetrium is the outermost layer

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How are the ovaries attached?

Ovaries attached by a ligament close to the fimbrial end of the uterine tube

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Where us the most common place for fertilisation to occur?

Ampulla of the uterine tube is where fertilisation occurs

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When is the egg normally released for fertilisation?

Egg released from uterine tube around the first ⅚ days and fertilised in ampulla

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What is the role of the cervix?

Cervix acts as the mucosal plug but allows sperm to pass through

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What is the effect of maternal steroids on the uterus?

Maternal steroids increase size of new-born uterus.

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How does uterus grow in newborns?

Grows with height during infancy.
Myometrium dependent on estradiol.

Corpus of uterus undergoes greater increase in size than cervix.

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Why is a newborns uterus bigger than a 4 y/o

A newborns uterus is bigger in size compared to a 4y/o due to high estradiol exposure in utero causing larger myometrium

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What is the myometrium?

Outer muscular myometrium grows gradually throughout childhood.

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How does the myometrium change during puberty?

Increases rapidly in size and configuration during puberty.

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How is the myometrium altered during menstrual cycle?

Changes in size through the cycle. Capable of vast expansion during pregnancy.

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What are the 3 muscular layers of the myometrium?

3 muscular layers of myometrium:

Inner layer circular fibres
Middle layer figure of 8 or spiral fibres
Outer layer longitudinal fibres

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Explain how the endometrium differs in size due to age

Very thin in childhood. Begins to thicken at puberty.

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What causes changes in endometrial size?

Dependent on steroids. Responds cyclically to hormone changes.

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How can the endometrium be viewed clinically?

Can be seen and measured on an ultrasound scan. Good ‘bioassay’ of estradiol level…7-16mm

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What happens to the endometrium during the menstrual cycle?

Changes in glandular and epithelial cells through cycle. At menstruation most of the endometrium is lost

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Describe the fate of the endometrium after menstruation

After menstruation - stromal matrix with small columnar cells with glandular extensions 2-3mm thick
glands are simple and straight.

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What stimulates the proliferative phase (follicular phase)?

Proliferative phase in endometrium is stimulated by estradiol from the dominant follicle. (in ovary this is called follicular phase)

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Describe the endometrial cell structure during proliferation

Stromal cell division, ciliated surface. Glands expand and become tortuous, increased vascularity, neoangiogenesis
maximal cell division by days 12-14

Describe what occurs when the endometrium is >4mm

When endometrium >4mm induction of progesterone receptors and small muscular contractions of the myometrium

What is the luteal phase?

Secretory phase (luteal phase of ovary) 2-3 days after ovulation, the gradual rise in progesterone causes a reduction in cell division

What happens to the glands during luteal phase?

Glands increase in tortuosity and distend…secretion of glycoproteins and lipids commences

Describe the effects of the luteal phase on vascular systems

Oedema, increased vascular permeability arterioles contract and grow tightly wound.

What is the fate of myometrial cells during luteal phase?

Myometrial cells enlarge and movement is suppressed- blood supply increases

What causes the corpus luteum to remain?

Corpus luteum stimulated by LH from pituitary during luteal phase.

What hormone is responsible for corpus luteum saving?

The fertilised oocyte becomes a blastocyst and produces human chorionic gonadotrophin (hCG) which acts like LH ie on LH receptor, and ‘rescues’ the CL.

Why does the corpus luteum disintegrate?

In the absence of hCG, falling levels of steroid from the CL results in menstruation.

What causes menstruation?

Prostaglandin release causes constriction of spiral arterioles. Hypoxia causes necrosis. Vessels then dilate and bleeding ensues. Proteolytic enzymes released from the dying tissue.

How much tissue and blood is typically lost during menstruation?

Outer layer of endometrium shed, 50% lost in 24hrs, up to 80ml is considered normal. Bleeding normally lasts 4+ days.

What remains after menstruation?

Basal layer remains and is then covered by extension of glandular epithelium

What initiates the cycle to continue on again

Estrogen from follicle in next follicular phase starts cycle off again

What are the 3 cell types of the uterine tube mucosa?

1. Secretory 2. Columnar ciliated epithelial 3. Non-ciliated Peg

What does the muscularis of the uterine tube consist of?

Inner circular & outer longitudinal layers. | Blood vessels & lymphatics

What is the serosa of the uterine tube?

The outer layer

How does oestrogens affect the uterine tube?

Epithelial cells express high numbers of estrogen receptors & undergo differentiation in response to estradiol increase in height mid-cycle

Why can the oocyte only pass during mid-cycle ~Day 14?

Oocyte can only pass during mid-cycle. Cilia beat and secretory cells are active along with muscle layer contractions, all in response to oestrogen

What causes the onset of the luteal phase?

After a few days of exposure to progesterone the estrogen receptors are suppressed and estrogen effects are overcome causing decrease in height mid-luteal onwards

When is the egg released into the uterine tube?

Egg carried in follicular fluid exuded by follicle for uterine tube

How long does the egg remain in the uterine tube?

Egg remains in the tube for approximately 5 days

What may cause damage to the endometrium?

Damage to lining of the tube by infection, endometriosis, surgery or adhesions may cause blockage or damage to ciliated epithelia

What are the consequences of damaged endometrium?

pain infertility ectopic pregnancy

Describe how a laproscopy & dye procedure is carried out

1. Cannula placed into the uterus through the cervix 2. Blue dye injected which fills the uterus 3. Through abdomen (near naval) using a laparoscope can view uterine tube and dye 4. Would expect to see uterine tube and see dye travel to fimbriae 5. If dye not visible in both tubes we know there’s a block

Why is a laproscopy and dye such a common procedure despite being so invasive?

More accurate and produces informative results as can see if any other infection or pathology in uterus

Describe the Hystero Salpingo-contrast Sonography (HyCoSy) procedure

Cannula in uterus via cervix and inject ultrasound contrast dye to track progress of dye Less invasive

What is the cervix?

Muscular structure capable of great expansion.

Describe the structure of the endocervical mucosa

The endocervical mucosa is about 3mm thick Lined with a single layer of columnar mucous cells Contains numerous tubular mucous glands which empty viscous alkaline mucus into lumen - protective barrier to infection however has to allow passage of motile sperm

Describe the structure of the ectocervix

The ectocervix is covered with nonkeratinized stratified squamous epithelium, resembling the squamous epithelium lining the vagina