RDA Flashcards
Label the following diagram of the male reproductive system
Where are sperm produced
Sertolli cells in the seminiferous tubules
What is produced by Leydig (interstitial cells) ?
Tetosterone
What is the path of sperm on ejaculation ?
Sperm are stored in the epididymis.
On ejaculation sperm pass through the two Vas Deferens (which are contractile), and are mixed with fluid from the seminal vesicles.
The fluid then leaves the ejaculatory duct, and passes into the urethra where it mixes with secretions from the prostate gland”
Label the following diagram of the female reproductive system
Summarise the main regulatory pathways within the adult human male reproductive system
FSH +ive on Sertolli cells
LH +ive on Leydig cells = Testosterone production = +ive on Sertolli cells
Testosterone -ive on Hypothalamus and Pituitary
Inhibin (from Seminifeous tubule)= -ive on Pituitary
What is ovarian follicle atresia ?
Ovarian follicle atresia is the periodic process in which immature ovarian follicles degenerate and are subsequently re-absorbed during the follicular phase of the menstrual cycle. Typically around 20 follicles mature each month but only a single follicle is ovulated. The rest undergo atresia. That single dominant follicle becomes a corpus luteum following ovulation
Explain what a corpus luteum is?
The corpus luteum (Latin for “yellow body”; ) is a temporary endocrine structure in female ovaries that is involved in the production of relatively high levels of progesterone, moderate levels of estradiol and inhibin A. It is the remains of the ovarian follicle that has released a mature ovum during a previous ovulation
What is the function of the corpus luteum if ovum is fertilized?
If the egg is fertilized and implantation occurs, the syncytiotrophoblast (derived from trophoblast) cells of the blastocyst secrete the hormone human chorionic gonadotropin (hCG, or a similar hormone in other species) by day 9 post-fertilization.
Human chorionic gonadotropin signals the corpus luteum to continue progesterone secretion, thereby maintaining the thick lining (endometrium) of the uterus and providing an area rich in blood vessels in which the zygote(s) can develop. From this point on, the corpus luteum is called the corpus luteum graviditatis.
At what point in oogenesis does the oocyte become haploid?
When it becomes a secondary oocyte.
What is folliculogenesis /
the maturation of the ovarian follicle, a densely packed shell of somatic cells that contains an immature oocyte.
What are the stages of folliculogenesis?
Primordial follicle - Dormant, small, only one layer of flat granulosa cells
Primary follicle Mitotic cells, cuboidal granulosa cells. Zona pellucida forms
Secondary follicle Presence of theca cells, multiple layers of granulosa cells
Antrum formation. The formation of a fluid-filled cavity adjacent to the oocyte called the antrum designates the follicle as an antral follicle, also called a Graafian follicle.
Tertiary follicle Fully formed antrum, no further cytodifferentiation, no novel progress
Ovulating follicle
Corpus Luteum
What are the two phases of the female mentrual cycle called
Follicular phase
Luteal phase
Why does LH remain low despite high GnRH levels rising During the follicular phase?
Follicles produce oestrogen which at low concentrations inhibit LH release
What is the relationship between FSH release and oestrogen levels?
FSH is released in response to low oestrogen levels. So as Oestrogen rises from the follicles, FSH starts to fall.
What is the relationship between oestrogen and LH
At low concentrations its inhibitory but at high concentrations oeastrogen stimulates LH release.
Wht are the three hormones secreted by the corpus luteum
Oestrogen
Inhibin
Progesterone
Which is the pathway in the brain is relevant to reward and pleasure?
mesolimbic dopaminergic system
What are the changes during male erection?
- Initiated by: increased parasympathetic activity releasing acetylcholine.
- The acetylcholine increases the activity of Nitric Oxide Synthase (NOS), and hence nitric oxide (NO) in vascular endothelial cells
- NO increases production of cyclic GMP which induces dilatation of pudendal artery smooth muscle.
- counteracts sympathetic-maintained myogenic tone
- increases blood flow in corpus cavernosum
- which compresses the dorsal vein, restricting the outflow of blood
- The urethra is protected from increased pressure by surrounding corpus spongiosum (less turgid)
Why is it important to state whether gestational age is from LMP or embryological view from moment of fertilization?
These dates can differ by +/- 2weeks
What is the overall average weight gain in pregnancy?
10-15kg
What is the main hormone of pregnancy in the first 10 weeks ?
HCG (human Chorionic Gonadotrophin)
What are the main three hormones seen in the second and third trimesters of pregnancy ?
Progesterone
Oestrogens (mainly oestriol)
Placental lactogen
These parallell the increased size of the placenta
Fetal adrenals are large and well developed even in the first trimester. True/False?
True
The human placenta does not express the enzyme CYP 17, that converts pregnenolone to androgens, so this part of biosynthesis takes place in the fetal adrenals
Outline the changes in blood pressure during human pregnancy
Maternal blood pressure is lowest during the second trimester (possibly to compensate for increased blood clotting tendency) rising slightly during the third but still remaining lower than normal. eg 70/120mmHg
What is the name given to the most severe form of ‘morning sickness’
Hyperemesis gravidarum
What are the changes seen in pregnancy (9)
- Increased weight
- Increased hormone levels / altered endocrine system
- Increased blood clotting tendency
- Decreased blood pressure
- Increased basal body temperature
- Increased breast size
- Increased vaginal mucus production
- Increased nausea and vomiting (‘morning sickness’)
- Altered brain function
- Altered appetite
- Altered fluid balance and urination frequency
- Altered emotional state
- Altered joints
- Altered immune system
Define embryo
“ the baby up to week 8 of development
Roughly how many days after fertilization does implantation occur?
8-9days
What is the average weight of the foetus at 40 weeks ?
3400g
Summarise the average weight gain of the foetus in each trimester
- t1 - 50g
- t2 - 1050g
- t3 - 2100g
What is the average length of a foetus at 40 weeks?
36cm
What is the only viable chromosomal abnormality with too few chromosomes ?
Turner’s syndrome (45 XO)
Which 4 organs develop relatively late in pregrnancy ?
Lungs
Immune system
Digestive system
Brain
List the 5 functions of the plancenta
- Exchange of nutrients and waste products
- Connection (or anchorage).
- Separation of the fetal and maternal vscular systems
- Biosynthesis.
- Immunoregulation to ensure that there is no rejection of the conceptus during pregnancy.
What is the primary subunit of the placenta
Placental villus
Label the following diagram of the placenta
Within the umbilical cord which vessel carries oxygenated and which carries deoxygenated blood?
Umbilical vein - oxygenated
Umpilcal artery - deoxygenated
ie parallel function to the lungs
What is a subdivision of placenta called?
Cotyledon
Roughly how many cotyledons are found in a placenta ?
30-60
What are the two outer layers of the conceptus called (at implantation)
syncytiotrophoblast - outer layer. multinucleated. contain fluid-filled lacunae.
cytotrophoblast - where the placenta will proliferate
Label cytotrophoblasts and synctyotrophoblasts on the following diagram
Until when does the cytotrophoblast shell remain in place?
8weeks (PF) 10weeks (GA)
When does the cytotrophoblast plug break down from the spiral arteries?
10-12 weeks (GA)
What is the purpose of remodelling maternal spiral arteries ?
Remodelling converts the narrow, vasoactive spiral arteries to wide-bore vessels that can transport very large volumes of maternal blood to the placenta, and hence provide the quantities of nutrients needed. The lack of smooth muscle cells in these remodelled vessels is important, as this means that the blood flow remains high as these arteries cannot respond to vasoconstrictors.
what is the cytotrophic shell and how is it formed?
The cytotrophoblastic shell is the external layer of cytotrophoblasts from the fetus that is found on the maternal surface of the placenta.
A cytotrophoblast cap penetrates through the fetus’ syncytiotrophoblasts and reaches the maternal decidua, forming the anchoring villus. The cytotrophoblast layer spreads and contacts the cytotrophoblast layers of neighboring anchoring villi, creating a continuous layer called the cytotrophoblastic shell
Gaps in the cytotrophoblastic shell allow endometrial arteries and veins to reach the intervillous space
What percentage of conceptuses are estimated to be lost in the first trimester?
30%
What age foetus is termed “Very pre-term”?
Before 32 weeks (GA)
What age foetus is termed “Moderately pre-term”?
32-37 weeks (GA)
What are the primary causes or IUGR (intruterine growth restriction)
most often involve poor maternal nutritionor lack of adequate oxygen supply to the fetus.
What are 2 major categories of IUGR and which is more common?
: symmetrical and asymmetrical (70%)
Describe the aetiology of assymetric IUGR
- Restriction of weight followed by length.
- The head continues to grow at normal or near-normal rates (head sparing).
- Lack of subcutaneous fat = t thin and small body out of proportion with the liver.
- embryo/fetus grows normally for the first two trimesters but encounters difficulties in the third, sometimes secondary to complications such as pre-eclampsia.
This type of IUGR is most commonly caused by extrinsic factors that affect the fetus at later gestational ages. Specific causes include:
Chronic high blood pressure
Severe malnutrition
Genetic mutations, Ehlers–Danlos syndrome
Outline the causes of symmetical IUGR
- Commonly known as global growth restriction, indicates the fetus has developed slowly throughout the duration of the pregnancy.
- Head circumference is in proportion to the rest of the body.
- Fetus is more likely to have permanent neurological sequelae.
Common causes include:
- Early intrauterine infections, such as cytomegalovirus, rubella or toxoplasmosis
- Chromosomal abnormalities
- Anemia
- Maternal substance abuse (prenatal alcohol use can result in Fetal alcohol syndrome)
What is the difference between stillbirth and miscarriage?
Stillbirth refers to death on an infant in uterus. Definitions vary. One option is to use the viability limit (23 weeks), so deliveries before this gestational age are defined as miscarriages (non-viable infants), and those after it (potentially viable infants) as stillbirths.
What is the difference between late and early miscarriage?
Early miscarriage: first trimester
Late miscarriage: second trimester less than 22 weeks.
What are the main events of human labour?
- Cervical ripening and effacement
- Co-ordinated myometrial contractions
- Preceded by
“Braxton Hicks contractions” or ‘contractures’
- Rupture of fetal membranes
- Delivery of infant
- Delivery of placenta
- Contraction (involution) of uterus
What is the name given to the powerful contractions of the uterus, leading to a rapid decrease in overall size
Involution
define the key phases of the menstrual cycle
Part 1= Endometrial cycle:
menstrual phase (5 days),
repair and proliferative phase (9 days),
secretory phase (13 days).
Part 2= Ovarian cycle:
follicular phase (14 days),
luteal phase (14 days)
What are the 4 development fileds of child development?
1) gross motor and posture
2) fine motor and vision
3) language and hearing
4) social, emotional and behaviours.
