Reproductive system Flashcards

1
Q

Explain the Hypothalamic-Pituitary-Gonadal Axis

A

-Hypothalamus releases gonadotropin-releasing hormone (GnRH)
-GnRH stimulates anterior pituitary to produce LH and FSH
-LH and FSH stimulate development of follicles in the ovaries
-Theca granulosa cells around the follicles secrete oestrogen
-Oestrogen has a negative feedback effect on the hypothalamus and anterior pituitary to suppress the release of GnRH, LH and FSH

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2
Q

Where is oestrogen produced

A

-Theca granulosa cells around the follicles of the ovaries

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3
Q

What is oestrogen and what 4 things does it stimulate ?

A

-Sex steroid hormone : 17-beta oestradiol is the most prevalent and active version
-Stimulates :

-Breast tissue development
-Growth and development of the female sex organs (vulva, vagina and uterus) at puberty
-Blood vessel development in the uterus
-Development of the endometrium

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4
Q

What is progesterone, when and where is it produced ?

A

-Sex steroid hormone
-Produced by the corpus luteum after ovulation
-When pregnancy occurs it is produced mainly by the placenta from 10 wks gestation onwards

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5
Q

Give 3 actions of progesterone

A

-Thicken and maintain endometrium
-Thicken cervical mucus
-Increase the body temperature

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6
Q

When does puberty start in girls and how long does it last ?

A

Starts at 8 to14
Around 4 yrs

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7
Q

Why do overweight children tend to start puberty earlier ?

A

-Aromatase is an enzyme found in adipose tissue and is important for oestrogen production
-The more fat tissue, the more aromatase responsible for oestrogen production

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8
Q

Explain the tanner staging of puberty

A

-Stage I : under 10 - no pubic hair or breast development
-Stage II : 10-11 - light and thin hair, breast buds for behind areola
-Stage III : 11-13 - course and curly hair, breasts elevate beyond areola
-Stage IV : 13-14 - adult like hair but not reaching thigh, areola mound forms and projects from surrounding tissue
-Stage V : above 14 - hair extending to the medial thigh, areolar mounds reduce and adult breasts from

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9
Q

What are the 2 stages that make up the menstrual cycle ?

A

-Follicular phase (day 1-14) : from start on menstruation to moment of ovulation
-Luteal phase (final 14 days of cycle (from moment of ovulation to the start of menstruation)

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10
Q

What 4 stages do follicles in the ovaries go through?

A

-Primordial follicles
-Primary follicles
-Secondary follicles
These 3 stages occur independent of the menstrual cycle.
-Antral follicles (Graafian follicles) : requires stimulation from FSH to develop

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11
Q

What make up the follicles in the ovaries ?

A

-Oocytes, surrounded by granulosa cells

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12
Q

What occurs during the follicular phase of the menstrual cycle ?

A

-FSH stimulates development of the secondary follicles
-The granulosa cells secrete increasing amounts of oestradiol.
-The oestradiol has a negative feedback effect on the pituitary gland, reducing FSH and LH
-Increased oestrogen, causes cervical mucus to become more permeable allowing sperm to penetrate the cervix around ovulation
-One follicle becomes the dominant follicle
-LH spokes before ovulation, causing the dominant follicle to release the ovum
-Ovulation happens 14 days before the end of the menstrual cycle.

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13
Q

What occurs during the luteal phase of the menstrual cycle if no fertilisation has occurred.

A

-The follicle that released the ovum collapses forming the corpus luteum.
-The corpus luteum degenerates and stops producing oestrogen and progesterone, this causes the endometrium to break down and menstruation to occur.
-Stromal cells of the endometrium release prostaglandins, this encourages the endometrium to breakdown and the uterus to contract.
-Menstruation starts on day 1.
-The negative feedback from oestrogen and progesterone on the hypothalamus and pituitary gland ceases, allowing LH and FSH to begin to rise and the cycle to restart.

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14
Q

What is the role of progesterone produced by the corpus luteum ?

A

-Maintains the endometrial lining
-Causes the cervical mucus to become thick and no longer penetrable
It is sereted by the the luteal cells

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15
Q

What maintains the corpus luteum if fertilisation occurs?

A

-The syncytiotrophoblast of the embryo secretes HCG.
-HCG maintains the corpus luteum
-Without HCG it degenerates

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16
Q

What is shed during menstruation ?

A

-The superficial and middle layers of the endometrium separate from the basal layer
-The tissue breaks down in the uterus and is released via the cervix and vagina

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17
Q

explain the differentiation that occurs a week after fertilisation

A

-Implanted blastocyst differentiates
-The embroblast splints into yolk sac and amniotic vacity with the embryonic disc in between
-The cells of the disc develope into the fetal pole and then the fetus

18
Q

What is the chorion

A

-Surrounds the complex of yolk sac, amniotic cavity and embryonic disc
-Ineer later of cytotrophoblast
-Outer layer of synctiotrophoblast embedded in the endometrium

19
Q

what happens to the embryonic disc at around 5 weeks gestation

A

-Develops into fetal pole containing 3 layers
-Outer ectoderm
-Middle mesoderm
-Inner endoderm

20
Q

what does the ectoderm form

A

skin
hair
nails
teeth
CNS

21
Q

what does the mesoderm form

A

heart
muscle
bone
connective tissue
blood
kidneys

22
Q

what does the endoderm form

A

Gi tract
lungs
liver
pancreas
thyroid
reproductive system

23
Q

when does the fetal heart form and begin to beat

A

6 weeks
along with spinal cord and muscle development

24
Q

why arteries grow out from the myometrium into the endometrium of the uterus

A

spiral arteries

25
Q

what grows out from the syncytiotrophoblast into the endometrium and contains fetal blood vessels

A

chorionic villi

26
Q

what forms the placenta and the umbilical cord

A

-Placenta : cells of the chorion frondosum. Placenta development is usually completed by 10 wks gestation
-Umbilical cord : connecting stalk

27
Q

explain the development of the lacunae

A

-Trophoblast invasion of endometrium sends signals to spiral arteries reducing their resistance
-These arteries eventually break down leaving pools of blood (lacunae)
-Maternal blood flows from uterine arteries into lacunae and back out through uterine veins
-The lacunae surround chorionic villi, separated by placental membrane

28
Q

what can occur if formation of the lacunae is inadequate

A

Pre-eclampsia

29
Q

what is the role of the placenta

A

-Oxygen delivery
-CO2, hydrogen ions, bicarbonate and lactic acid removal
-Nutrition (glucose, vitamins and minerals)
-Excretion : urea and creatinine
-Immunity through antibody transfer

30
Q

what are the endocrine productions of the placenta ?

A

-Oestrogen
-Progesterone

31
Q

explain the hormonal changes in pregnancy

A

-Anterior pituitary : increases ACTH, prolactin and melanocyte stimulating hormone
-Adrenals : higher cortisol and aldosterone
-Suppressed FSH and LH due to increased prolactin
-Skin : increased pigmentation resulting in linea nigra and melasma
-Thyroid : Raised T3 and T4 but normal TSH
-HCG rises, plateaus at 8-12 wks and gradually falls
-Placenta : rise in oestrogen and progesterone

32
Q

when does the placenta take over production of progesterone from the corpus luteum ?

A

10 wks gestation

33
Q

what are the changes to the uterus, cervix and vagina in preganncy

A

-Uterus : increases in size due to hypertrophy of myometrium
-Cervics : possible cervical ectropion and increased cervical discharge
-vagina : hypertrophy of vaginal muscles and increased vaginal discharge

34
Q

what are the cardiovascular changes in pregnancy

A

-> Increased : blood volume, plasma volume, cardiac output (with increased stroke volume and HR)
-> Decreased : peripheral vascular resistance, BLP
-> Varicose veins
-> Peripheral vasodilation causing flushes and hot sweats.

35
Q

what are the respiratory changes in pregnancy

A

Increased tidal volume and resp rate later in pregnancy

36
Q

what are the renal changes in pregnancy

A

-> Increased : blood flow to kindneys, GFR, aldosterone (leading to increased salt and water reabsorption and retention), protein excretion.
-> dilation of ureters and collecting system, leading to physiological hydronephrosis (more right-sided)

37
Q

what are the haematological changes in pregnancy

A

-> Increased : RBC production, plasma volume, clotting factors
-> Reduced : Hb concentration and haematocrit = anaemia,

38
Q

what does increased clotting factors in pregnant women increase the risk of

A

VTE - they are hyper-coagulable

39
Q

what does increased RBC production increase the need for in pregnancy

A

-Iron
-Folate
-B12

40
Q

Name 6 other biochemical changes in pregnancy

A

-> Increased WBC, ESR and D-dimer, ALP
-> Decreased : plt count, albumin

41
Q

Give 5 skin changes in pregnancy

A

-> Increased pigmentation = linea nigra and melasma
-> Striae gravidarum
-> Pruritus
-> Spider naevi
-> Palmar erythema