1
Q
what gene on the Y chromosome determines the male sex?
A
SRY gene - means testes develop
2
Q
what are the 3 stages of gametogenesis?
A
- mitosis
- meiosis 1
- meiosis 2
3
Q
what happens in the mitosis stage of gametogenesis?
A
proliferation of the primordial germ cells
each mitotic division produces 2 genetically identical daughter cells
4
Q
what happens just before meioses 1?
A
interphase
- homologous chromosome pairs are duplicated
5
Q
what happens in the meiosis 1 stage of gametogenesis?
A
- separates the homologous chromosome pairs in the diploid
- producing 2 haploids
6
Q
what happens in the meiosis 2 stage of gametogenesis?
A
- Sister chromatids separated
- produces 4 haploids
7
Q
how in genetic variation introduced into gametes?
A
- cross over in prophase 1
- independent assortment
8
Q
where does spermatogenesis happen?
A
testes (seminiferous tubules)
9
Q
what is the name of the germ cell that undergoes spermatogenesis?
and oogenesis?
A
spermatogonium (a spermatogonia)
oogonia ( an oogonium)
10
Q
what does mitosis of a spermatogonia/oogonia produce?
A
a primary spermatocyte
a primary oocyte
11
Q
what does meiosis 1 of a primary spermatocyte/oocyte produce?
A
secondary spermatocytes/oocytes
2 haploids
12
Q
what does meiosis 2 of a secondary spermatocyte produce?
A
4 spermatids, these then differentiate into sperm
fertilised oocyte
13
Q
what is the blood testses barrier?
A
Sertoli cells forming a ring around circumference of tubule stopping movement into lumen
14
Q
what is the purpose of the blood testes barrier?
A
- retains luminal fluid
- proper conditions for germ cell development
15
Q
what are the 2 compartments of the blood testes barrier?
A
basal (BM to tight junctions of Sertoli cells)
central (tight junctions to lumen)
16
Q
what stage of spermatogenesis happens in the basal compartment?
A
differentiate into primary spermatocytes
17
Q
what stage of spermatogenesis happens in the central compartment?
A
meiosis 1 and 2
18
Q
what gonadotrophin stimulates Sertoli cells?
A
FSH
19
Q
what gonadotrophin stimulates Leydig cells?
A
LH
20
Q
what do sertoli cells do in the HPG axis?
A
FSH stimulates Sertoli cells to release inhibit and initiate spermatogenesis
21
Q
what do Leydig cells do in the HPG axis?
A
LH stimulates Leydig cells to secrete testosterone.
22
Q
what are the local and general affects of testosterone (HPG axis)
A
local : diffuses into Sertoli cells and stimulates spermatogenesis
general: reproductive tract
23
Q
what hormones of the HPG axis increase during puberty?
A
GnRH,GHRH, FSH, LH,GH
24
Q
physical changes for males in puberty
A
- 9-14
- testicular enlargement
- facial hair growth
- spermatogenesis begins
- growth spurt
- body odour
- mood changes
- acne
25
physical changes for females in puberty
- 8-14
- menarche (2.5 yrs into puberty)
- growth spurt
- hair growth (pubic an axillary)
- breast enlargement
- body odour and mood changes
- acne
26
what is menopause? when does it happen?
The cessation of menstruation, when the ovaries STOP releasing eggs because of a reduction in circulating oestrogen
27
when does menopause happen?
usually occurring between 48-52 years,
28
give 3 short term signs of menopause?
hot flushes
shorter menstruation cycle
skin dryness
29
give 3 long term symptoms of menopause?
vagina dryness
hair loss
general aches and pains
30
what can menopause put women more at risk of developing ?
Osteoporosis
oestrogen is essential for bone density
drops
31
menstrual cycle can be split into 2 phases of equal length, seperated by ovulation:
follicular - development of mature follicle and secondary oocyte
luteal - post ovulation and death of corpus callosum
32
what does FSH do in the female HPG axis? (4)
- binds ot granulosa cells
-stimulates follicle growth
-permit the conversion of androgens (from theca cells) to oestrogens
stimulate inhibin secretion
33
what does LH do in the female HPG axis?
acts on theca cells
stimulates production and secretion of androgens
34
how does moderate oestrogen levels affect HPG axis?
negative feedback
35
how does high oestrogen levels affect HPG axis?
positive effect
36
how does progesterone + oestrogen present affect HPG axis?
negative feedback
37
what does inhibin do?
secreted by granulosa cells
selectively inhibits ant.pituitiary release of FSH
38
how many follicles mature during the follicular phase of menstrual cycle (day 1-13)?
only 1 dominant follicle reaches maturity
39
what is the impact of the LH surge on granulosa cells?
- increases inhibin so stops FSH production
| - Granulosa cells become luteinised and express receptors for LH.
40
when does ovulation happen in menstrual cycle?
day 14
41
what triggers ovulation?
LH surge causes dominant follicle to rupture and release mature oocyte
42
what does it mean if cells have been luteinised?
proliferation ceases, terminal differentiation, produces high levels of progesterone
eg. follicle post rupture
43
how is the cycle stalled after ovulation?
- the follicle remains luteinised after the LH surge
- therefore it is now secreting oestrogen + progesterone
- this causes negative feedback on the HPG axis.
- cycle is stalled in anticipation of fertilisation
44
what is the corpus luteum?
tissue of the collapsed mature follicle after ovulation
becomes glandular and secretes oestrogen, progesterone and inhibin
45
what happens in the luteal phase of menstrual cycle?
day 14-28
- corpus luteum secretes steroids to create conditions for fertilisation
- if no fertilisation by day 28, it regresses
- hormones fall and HPG resets
- menstruation occurs
46
what happens to the corpus leteum if fertilisation occurs?
- it doesn't regress, its maintained
- due to placental HcG
- it produces progesterone and oestrogen for first 2 months of pregnancy
47
what are the 2 layers of the uterus?
myometrium - smooth muscle, external
endometrium - internal
48
3 layers of the endometrium:
1. stratum compactum
2. stratum spongiosum
3. stratum basalis
49
what are the 3 phases of the uterine cycle?
1. menses
2. proliferative
3. secretory
50
what happens in menses?
- the endometrium degenerates
- corpus luteum brakes down
- there's menstrual flow when the spinal arteries rupture
51
what happens in proliferative phase of uterine cycle?
alongside follicular phase
OESTROGEN:
- endometrium thickens
- increased growth and mobility of myometrium
- thin alkaline cervical mucous
- renews glandular structures
- initiates fallopian tibe formation
52
what happens in secretory phase of uterine cycle?
alongside the luteal phase
PROGESTRONE
- endometrium thickens to glandular form
- reduction of mobility of myometrium
- thick acidic cervical mucous
- increases spiral arteries
53
how is the egg transported to site of fertilisation?
1. after ovulation, emerges on surface of ovary
2. fimbriae move towards it
3. fimbrae cilia sweep egg into fallopian tube
4. fallopian cilia beat it close to uterus
54
in what window must fertilisation happen?
5 days before to 1 day after ovulation’
55
what factors help the transport of sperm from vagina (during intercourse) to Fallopian tube
- flagella + ejaculate pressure propels sperm through external OS of Cervix
- mitochondria supply energy needed for long trip
- cervical muscus is watery
56
what final adaptions do the sperm undertake when in the Fallopian tubes? what is this process called?
capacitation
- stronger tail
- develops acrosomal enzymes in membrane which allows it to fuse with egg
57
where does fusion of the egg and sperm commonly take place?
in the ampulla of the Fallopian tube
58
how does sperm fertilise the egg?
1. binds to glycoprotein receptors on the zona pellucida surface
2. acrosomal enzymes digest a path through to egg plasma membrane
3. sperm head bases into cytosol of egg
59
what is a fertilised egg called? with 23 pairs of chromosomes?>
a zygotę
60
how does the egg prevent polyspermy?
- egg membrane potential changes after one sperm has fused with it
- releases enzymes that inactivate sperm receptors on zona pellucida (cortical reaction)
61
what process occurs 4-7 hours post fusion?
meiosis 2 resumes
- forms a polar body which. degernates
- and a fertilised zygote with 23 chromosomes from egg, 23 from sperm
62
day 2-3 post fertilisation : what happens during CLEAVAGE?
- zygote remains in Fallopian tubes
- due to smooth muscle contractions stimulated by oestrogen at the junctions between tube and uterus
- cell divisions occur (not cell growth) to increase numbers
- these cells are totipotent
63
what does totipotent mean?
stem cells that could develop into an entire individual
64
day 4 post fertilisation : what happens during COMPACTION?
cells flatten and tight junctions form
65
day 5 post fertilisation : what happens during COMPACTION?
fertilised egg is now a rapidly dividing ball of cells known as a BLASTOCYST
- cells begin to differentiate
66
what are the layers of the blastocysts?
- central fluid filled cavity
- inner cell mass
- the trophoblasts ( outer cell layer)
67
day 6 post fertilisation : what happens during EXPANSION?
- diameter of blastocyst increases because cavity expands
| - the zona pellucida layer thins
68
day 6+ post fertilisation : what happens during HATCHING?
embryo hatches from the zona pellucida
69
when does implantation of the blastocyst happen>
21st day of cycle
70
what happens during APPOSITION implantation stage?
hatched blastocyst orientates and synchs with endometrium
71
what happens during ATTACHEMENT implantation stage?
- endometrial epithelial cells & trophoblastic cells attach
| - via links called Integrins
72
what happens during DIFFERENTIATION implantation stage?
trophoblast (outer part of blastocyst) develops 2 layers
- cytotrophoblast (inner)
- syncytiotrophoblast (outer)
73
what is the significance of the syncytiotrophoblast layer of the trophoblast?
will be involved with placenta, has proteolytic enzymes
74
what happens during INVASION implantation stage?
enzymatic degradation of the basal lamina
75
what happens during DECIDUAL implantation stage?
stroma cells adjacent to blatstocyst differentiate
76
what happens during MATERNAL RECOGNITION implantation stage?
- secretion of interleukin-2
| - prevents antigenic rejection of embryo
77
how does the early embryo (just after implantation) get metabolic fuel and raw materials?
provided by endometrial epithelial cells
78
what structure supplies metabolic fuel and raw materials to the embryo AFTER a few weeks?
placenta
79
from what does the placenta develop?
from the outer cell layer of the primary trophoblastic cell mass (TCM)
= the chorion
TCM invades endometrium
via chorion villi projecting
80
what are the placental sinuses?
pools of maternal blood that surround the villus of the chorion
81
what does the umbilical vein transport?
oxygenated blood from mother
| into placenta and liver of foetus
82
what do the 2 umbilical arteries transport?
deoxygenated blood from foetus to placenta and back to mother via umbilical cord
83
how is blood transported from the liver to the heart of the foetus?
the ductus venous shunts blood from umbilical vein at level of liver, into the IVC, which carries the oxygenated blood to heart
84
what blood does the fetal IVC pass into the heart?
oxygenated/deoxygenated?
mixed
```
partially oxygenated (from mother)
partially deoxygenated (from fetal circulation)
```
85
what are the 3 routes blood can take in the fetal heart, from the RA?
1. normal,
RA → RV→ pulmonary artery→ lungs → ...
2. bypass lungs,
RA → RV → pulmonary artery → through the ductus arteriosus → aorta
3. bypass lungs
RA → through patent foramen Ovale → LA → LV → aorta
86
do fetal and maternal blood ever mix?
never
87
what is the maternal part of the placenta called?
the decidua
- uterine lining that forms maternal part of placenta,
- it underlies the chorion
88
give 2 examples of how the placenta has a metabolic role ?
- it provides nutrients and energy
| - it synthesises glycogen, cholesterol, fatty acids
89
give 7 examples of what the placenta transports?
- O2 and CO2
- water
- amino acids
- maternal antibodies
- waster products eg. urea
- drugs
- steroid hormones
90
at what stage after implantation is the placenta fully established?
- 5 weeks after
- fetal heart is pumping blood
- nutrient and waste mechanism is functioning
91
what is the amniotic cavity?
- space between inner cell mass (embryo) and outer layer of trophoblast cells (chorion)
- forms as placenta develops
- foetus floats in it
92
what is the amnion?
ie. amniotic sac
= epithelial layer lining the amntioic cavity
- fuses with chorion to form 1 combined membrane surrounds the foetus
contains amniotic fluid
93
what is the role of amniotic fluid?
buffers mechanical disturbances and temperature variances
94
what structure produces almost all of the oestrogen and progesterone for the first 2 months of pregnancy?
the corpus luteum
95
which hormones gradually increase throughout pregnancy?
oestrogen and progesterone plasma concentrations
96
what is the effect of oestrogen during pregnancy? (4)
- stimulates uterine muscles to grow
- regulates progesterone
- prepares breasts for feeding
- synthesis oxycontin receptors
97
what is the effect of progesterone during pregnancy? (2)
- inhibits uterine contractility - so foetus isn't expelled prematurely
- increases thickness of uterine lining - to prevent miscarriage
98
what is hCG and what cells produce it?
human chorionic gonadotropin
produced by implanted trophoblast cells
99
what are the roles of hCG?
- pregnancy test
- prevents degeneration of corpus luteum
- stimulates it to produce o+p
100
when is hCG secretion at its peak ?
80 days after last mentsruation
101
when is hCG secretion at its lowest?
after peak (day 80) it decreases and is at lowest by end of 3rd month of pregnancy
102
what happens once hCG is at A very low concentration (end of 3 months)
- corpus luteum degenerates
| - trophoblast cells of the placenta take over role of secreting oestrogen and progesterone
103
how does the placenta (trophoblast cells) synthesise progesterone?
- contains specific enzymes that do so
104
how does the placenta (trophoblast cells) synthesise oestrogen?
- maternal ovaries + adrenal medulla + fetal adnreal medulla
- supply cells with androgens (precursors)
105
why are their no menstrual cycles during pregnancy?
- high concentrations of progesterone + oestrogen secreted by corpus luteum, and then placenta
- mean constantly low levels of gonadotropins (LH and FSH)
106
where is prolactin produced?
anterior pituitary gland
107
what is the role of prolactin?
- prevents ovulation
| - helps milk production
108
when are prolactin levels high?
end of pregnancy
109
where is Relaxin produced?
ovary + placenta
highest in early pregnancy
110
what is the role of Relaxin?
limits uterine activity
softens cervix - cervial ripening
111
where is oxycontin produced?
posterior pituitary
112
what is the role of oxycontin?
- stimulates uterine contractions during labour
- triggers caring reproductive behaviours
- its used as a dug to induce labour
113
what are prostaglandins?
hormones produced by uterine tissues to initiate labour
eg. PGF2a
enhances actions of oxytocin
114
physiological changes during pregnancy: adrenal cortex
increase secretion of aldosterone and cortisol
115
physiological changes during pregnancy: kidneys
```
increased secretion of:
- renin
erythropoietin
- 1,25-dihydroxyvitamin D
-retention of water and salt
```
116
physiological changes during pregnancy: posterior pituitary gland
increased section of Vasopressin/antidiuretic hormone (ADH)
117
physiological changes during pregnancy: blood volume
increased
118
physiological changes during pregnancy: bone turnover
increased because more PTH and vitamin D
119
physiological changes during pregnancy: respiration
hyperventilation occurs due to increased progesterone
increased alveolar ventilation
120
physiological changes during pregnancy: GI
increased acid reflux and gastroparesis (delayed emptying)
121
physiological changes during pregnancy: skin
- linea nigra (dark central abdominal line)
- striae gravidarum (stretch marks in lumbar/lower abdomen regions)
- darkened areolar on breasts
122
what is parturition
‘birth process’ = last few weeks of pregnancy + delivery (intra-uterine to extra-uterine life)
123
changes to smooth muscle during parturition :
rising oestrogen stimulates smooth muscle cells to synthesise CONNEXINS
these proteins form gap junctions
helps to coordinate contractions
124
what is the term for the growth and remodelling of cervix prior to labour?
making the cervix soft and flexible
cervical ripening
125
when does cervical ripening happen? what hormone stimulates it?
last 3 months of pregnancy, due to rising oestrogen and decreasing progesterone
126
what hormones mediate the actions of the enzymes that break down the collagen fibres of the cervix to make it softer/flexible during cervial ripening?
enzymes actions mediated by oestrogen, placental prostaglandins and relaxin
127
what initiates labour?
increased PGFa → increased oxytocin
+ pressure on cervix
128
what are the 3 main steps of labour?
1. amniotic sac raptures
2. uterine contractions
3. cervix dilation (widest = 10sm)
129
what are the 3 actual phases of labour?
1. latent pahse
2. actions phase
3. post partum phase
130
what happens in the latent phase of labour?
8 hours of minor cervical dilation
131
what happens in the action phase of labour?
- organised uterine contractions and cervical dilations
- full dilation results in foetal expulsion
- then placental expulsion
132
what happens in the post partum phase of labour?
extra-uterine life
133
how do contraceptives work?/
contain oestrogen and progesterone
these hormones inhibit anterior pituitary gland from releasing LH and FSH (gonadotrpoins)
therefore ovulation cannot happen
1 SUGER
flashcards
Decks in class (9)
# Cards
-
SUGER anatomy: inguinal canal29
-
SUGER anatomy: female genitalia93
-
SUGER anatomy: male genitalia101
-
SUGAR anatomy: male/female urethras, ureter narrowing sites and pathway of ureters26
-
SUGER: anatomy and histology of the kidney and adrenal glands77
-
SUGER: anatomy of the posterior abdominal wall, urogenital triangle and pelvic floor muscles63
-
skin physiology and histology42
-
histology of the pituitary gland, pineal gland, parathyroid gland and endocrine pancreas33
-
reproduction133
