Mitosis and Meisosis Flashcards
1
Q
diploid cell
A
Cell that contains 2 sets of chromosomes - one from each parent
2
Q
Germ cell
A
cells that lead to production of gametes - produced by meiosis
3
Q
Haploid cell
A
Cell that contains one complete set of chromosomes
4
Q
Meiosis
A
Cellular reproduction that forms 4 haploid cells from one diploid cell. Contains 2 cellular divisions that follow only one round of DNA replication - produces germ cells
5
Q
Mitosis
A
5 step process by which a cell separates replicated chromosomes before cytokinesis and forms 2 daughter cells from one original cell .
6
Q
What are the stages of miotosis
A
Prophase Prometaphase Metaphase Anaphase Telophase
7
Q
Somatic cell
A
Any plant or animal cell that isn’t a germ cell, formed by mitosis
8
Q
Stem cells
A
Biological cells that can differentiate into other types of cells and divide to produce more of the same type of stem cells. They are always and only found in multicellular organisms
9
Q
Zygote
A
Fertilised egg cell
10
Q
Cytoskeleton
A
???
11
Q
Early prophase
A
cell rounds up into a ball
chromatin begins to condense
nucleolus disappears
centrioles begin to move to opposite poles of cell
microtubules dissolve and reassemble around centrosomes from which they extend
12
Q
Prometaphase
A
chromosomes condense and arrange into sister pairs - chromatids
chromosomes begin to move
centrioles begin to move to opposite poles of cell
microtubules have formed the mitotic spindle
proteins attach to the centromeres to form kinetochores
spindle microtubules attach to kinetochores and pull on chromosomes
nuclear envelope disperses
13
Q
Metaphase
A
Paired chromatids align along the cell equator by the mitotic spindle
14
Q
Midline of cell
A
mitotic plate
15
Q
Anaphase
A
Paired chromosomes separate at their kinetochores and move to opposite poles along the microtubules
16
Q
Telophase
A
Chromosomes arrive at opposite poles
new nuclear envelopes form around each daughter nucleus
mitotic spindle disperses
chromosomes disperse as their chromatin becomes diffuse
17
Q
Cytokinesis
A
Actin ring
cleavage furrow
18
Q
What holds pairs of homologous chromosomes together?
A
Synapsis
19
Q
Synapsis
A
Early in prophase 1 homologous chromosomes come together to form a synapse, bound by synaptonemal complex and cohesion proteins
20
Q
crossing over/ crossover
A
Occurs between homologous chromosomes but not sister chromatids. There is an exchange of genetic material
21
Q
Primordial germ cells
A
Earliest recogniseable precursors of gametes 24 days after fertilisation in the endodermal layer of yolk sac
22
Q
Germ cells
A
exit from the yolk sac and migrate through dorsal mesentery to primordia of gonads
23
Q
what is oogenesis
A
development of an ovum
24
Q
What is spermatogenesis
A
development of a mature spermatozoa
25
Oogenesis
primordial germ cells develop in yolk sac > oogonium (in gonads) > mitosis > oogonium > start meiosis 1 > primary oocytes arrested in prophase 1 (at birth) > 1st meiotic division producing polar body > secondary oocyte arrested in metaphase 2 during ovulation > 2nd meiotic division producing polar body > mature ovum > fertilised egg
26
Spermatogenesis
Primordial germ cells in yolk sac > spermogonium > mitosis > primary spermatocytes > 1st meiotic divisions > secondary spermatocytes > 2nd meiotic divisions > spermatids > spermatogenesis packaging > spermatozoa
27
Symptoms of pregnancy
```
Varicose veins
Anaemia
Flushed and hot
Breast enlargement
Pelvic pain
swollen ankles
morning sickness
constipation
heartburn
breathless
urinary infection
urinary frequency
glucose in urine
```
28
What causes pregnancy symptoms
```
Adaptations in the...
respiratory system
renal system
cardiovascular system
metabolism
```
29
Positive feedback systems in pregnancy
prolactin secretion in breast feeding
oxytocin secretion in labour
oestrogen secretion by follicles to trigger ovulation
30
Ovulation
hypothalamus releases Gonadotropin-releasing hormone which acts on anterior pituitary gland to release FSH which stimulates growth and development of follicle. Oestradiol from maturing follicle stimulates release of LH which stimulates ovulation and corpus luteum formation
31
Luteal phase
corpus luteum releases progesterone which prepares the uterus
corpus luteum not sustained in the absence of fertilisation
32
Fertilisation
spermatozoa and oocyte fuse and undergo mitosis which forms a blastocyst.
33
Post-fertilisation
Blastocyst secretes hCG which supports the corpus luteum corpus luteum continues to release progesterone and oestrogen which sustains the uterus.
34
When is the hCG peak?
between week 2 and week 14
35
What is hCG?
Human Chorionic Gonadotropin
36
hCG
glycoprotein hormone, which is rapidly secreted from trophoblast. Used for pregnancy testing and causes morning sickness
37
What can hCG be a sign of
Pregnancy
ectopic pregnancy
trophoblastic tumours
pineal tumours
38
Miscarriage
If progesterone fails for any reason the endometrium and developing embryo are shed producing a miscarriage and the corpus luteum dies
39
What hormones are produced by the placenta?
Progesterone - takes over from corpus luteum by weeks 10-12
Oestrogen
hCG
Human placental lactogen
40
Where is progesterone synthesised?
Placenta
41
What affect does progesterone have on uterus?
smooth muscle relaxation preventing fetal expulsion and cervical plug formation which acts as a microbial barrier.
42
What does progesterone target?
uterus
homeostasis
breast
relaxes other smooth muscle in the body - blood vessels, GI tract, ureters and bronchi
43
What does progesterone do to homeostasis?
Hyperventilation
| weakly stimulates sodium reabsorption and increases water recovery - causing water retention
44
What does progesterone do to breasts?
stimulates development of lobular tissue but inhibits milk production
45
what is lobular tissue?
milk producing glands and ducts of the breast
46
when do progesterone levels fall?
last few days of pregnancy
47
What does oestrogen affect?
uterus
| breasts
48
what does oestrogen do to the uterus?
myometrial cell growth - for growing fetus, connexin insertion - electrochemical links (gap junctions) between myometrial cells
oxytocin receptor insertion in prep for labour
PGE2 production stimulated which softens the cervix
49
what does oestrogen do to the breast?
breast duct development
| but inhibits milk production
50
oestrogen production
complex production as placenta is unable to produce the enzyme needed to convert progestogens to androgens so fetal contribution is needed
51
normal hypothalamic pituitary axis
hypothalamus produces corticotropin releasing hormone which causes the anterior pituitary to produce corticotropin > adrenal cortex produces cortisol
52
How is oestrogen produced in pregnancy?
Placenta secretes corticotropin releasing hormone > causes anterior pituitary in mother and fetus to secrete corticotropin which acts on the adrenal cortex in fetus and mother to secrete cortisol and DHEA in fetus and just cortisol in mother. DHEA > oestrogen > supports pregnancy
53
what does cortisol do to fetus?
lung maturation
54
what does a sudden surge of CRH do?
triggers labour
55
oestrogen levels over pregnancy
increase over 40 weeks and sharply decline after birth
56
what does human placental lactogen affect?
mother and fetus
57
what does human placental lactogen do in the mother?
insuline resistance - decreases glucose utilisation and increases blood glucose
Lipid breakdown - generates free fatty acids
breast development
has similarities with growth hormone
58
what does human placental lactogen do in fetus?
promotes growth due to more glucose available from mother by insulin resistance
59
what happens to blood volume in pregnancy?
vascular capacity increased by utero placenta circulation
| blood loss expected at delivery
60
what happens to blood oxygen carrying in pregnancy?
O2 requirements increase - greater maternal and fetal needs
61
What happens to blood clotting in pregnancy?
haemostasis required when placenta shears off after delivery. In pregnancy there is a drop in anti-thrombin levels and so blood is in a pro-thrombotic state
62
Anaemia in pregnancy
due to increase in blood plasma there are fewer RBCs for the volume of blood - functional anaemia despite the increase in red blood cell mass
63
what chemicals are needed more in pregnancy?
Folate
| Iron
64
what happens to the heart in pregnancy?
more oxygen needed and circulation distance increased
| increased abdominal mass moves heart upward and out
65
how is BP calculated
cardiac output x systemic vascular resistance
66
how is cardiac output calculated
stroke volume x heart rate
67
what happens to cardiac output in pregnancy
increase in venous return causes increase in stroke volume - starling's law and due to oestrogen which increases contractility. This increases cardiac output, as does oestrogen by increasing heart rate
68
what happens to BP in pregnancy?
as cardiac output has increased by 45% systemic vascular resistance has to fall to maintain BP.
69
How does systemic vascular resistance fall
renal blood blow doubled
large utero-placental bed takes blood
skin blood flow increase by 5 times - helps lose heat - causing flushed and hot feeling
Vasodilation caused by progesterone
70
pregnancy impact on veins
venous compression due to expanding uterus, impairs venous return causing pooling and distension - varicose veins
71
how can pregnant women not position themselves?
lying on left side
72
What happens to the lungs in pregnancy?
oxygen consumption and CO2 production increase and the diaphragm is displaced by abdomen
73
respiratory changes in pregnancy
tidal volume increase
resp. rate unchanged
airway resistance and functional residual capacity drops. partial pressure of CO2 is lower
74
what causes respiratory changes in pregnancy?
progesterone
75
carbon dioxide control in pregnancy
progesterone increases sensitivity of chemoreceptors to CO2 which increases ventilation and drops the pressure of CO2 - breathlessness
76
What happens in the kidneys in pregnancy?
increased perfusion due to increased plasma volume, decreased reno-vascular resistance and increased cardiac output and decreased plasma oncotic pressure due to dilution
77
why is there an increase in urine production in pregnancy?
increase in glomerular filtrate rate
greater reabsorption but still more urine produced
glucose in urine as filtered glucose may exceed reabsorption limit
78
Later in pregnancy what is the main cause of urinary frequency?
Pressure on bladder by enlarging uterus
79
fluid changes in pregnancy
aldesterone activated to ensure too much sodium isnt lost
osmoregulation changes and so plasma osmolarity dropping doesn't cause more water loss
results in retention of water and sodium - swollen ankles
all caused by progesterone
80
metabolism in pregnancy
metabolic rate increases
81
Changes in GI tract in pregnancy
slower transit - constipation
increased nutrient absorption
oesophageal reflux - heart burn
82
breast changes
oestrogen - mammary duct development
progesterone - lobular tissue development
these both inhibit prolactin which stimulates milk production
83
what happens in breasts after delivery
drop in oestrogen and progesterone stops inhibition of prolactin so milk production occurs and oxytocin causes milk ejection
84
what causes prolactin release
nipple stimulation causes hypothalamus to release prolactin releasing hormone which causes anterior pituitary to secrete prolactin
85
what does prolactin do
suppresses ovulation and causes breast tissue development in pregnancy and causes milk production after pregnancy
86
what causes oxytocin release
nipple stimulation and cervix/ vaginal distension cause oxytocin production in hypothalamus and release from posterior pituitary
87
what does oxytocin do?
uterine contraction and milk ejection - myoepithelial cell contraction
88
Glands
epithelial tissue derivatives specialised for secretion
89
secretion
biochemical release from a particular type of cell upon stimulation
90
endocrine glands
secretions enter bloodstream - ductless glands
91
exocrine glands
gland with ducts that channels its secretion
92
hormone
chemical messengers secreted into the blood by endocrine glands in response to an appropriate signal and exerting their effects on target cells that have receptors that bind with the hormone
93
types of hormones
hydrophilic and lipophilic
94
what hormones are hydrophilic
peptides and catecholamines
95
what hormones are lipophilic
steroids and thyroid hormone
96
peptide hormones
produced by protein synthesis, travel in blood, cannot enter cells, bind to cell surface receptor, trigger event on inside surface of membrane
fast acting
97
Steroid hormones
```
produced by modification of cholesterol molecule by enzymes
travel in blood bound to plasma proteins
enter cells easily
intracellular receptor
act on DNA to alter cell function
slow acting - time for transcription
```
98
why is the type of hormone important?
affects administration, peptide hormones cannot be given orally as they will be digested in the stomach
99
how do peptide hormones work
bind to receptor on outside of cell and cause ATP conversion to cAMP
100
how do steroid hormones work?
pass through phospholipid bilayer and bind to receptor on gene, causing protein synthesis leading to cell response
101
role of endocrine system
```
metabolism, water and electrolyte balance
stress response
growth and development
reproduction
RBC production
coordination of circulation
coordination of digestion
```
102
endocrine glands
```
hypothalamus
pituitary
thyroid
parathyroid
adrenal cortex
adrenal medulla
kidney
stomach
pancreatic islets
duodenum and jejunum
ovary
testis
```
103
pituitary
anterior and posterior lobe
| connects to hypothalamus via pituitary stalk
104
hypothalamus
controls pituitary hormone release
| interface between events inside and outside the body and their endocrine response
105
what hormones are released by hypothalamus?
```
corticotropin releasing hormone
thyrotropin releasing hormone
somatostatin
gonadotropin releasing hormone
growth hormone releasing hormone
prolactin releasing hormone
prolactin inhibiting factor
```
106
anterior pituitary
controls activity of other endocrine glands
involved in ovulation and pregnancy
sperm production
growth
107
what hormones are released by anterior pituitary gland?
```
thyroid stimulating hormone
adrenocorticotrophic hormones
luteinising hormone
follicle stimulating hormone
growth hormone
prolactin
```
108
how is the hypothalamus and pituitary linked?
anterior pituitary - blood vessels
| posterior pituitary - neurones
109
posterior pituitary
involved in regulating water balance
uterine contraction
ejection of milk
110
what hormones are released by posterior pituitary?
ADH
| oxytocin
111
what is the process of hormones of thyroid?
HPT axis
112
what is the process of hormones of reproduction?
HPG axis
113
what is the process of hormones of adrenal gland
HPA axis
114
Testis
releases testosterone
which:
masculinises the reproductive tract and external genitalia
promotes growth and maturation of reproductive system at puberty
spermatogenesis
develops sex drive
secondary sexual characteristics
115
ovaries
```
release oestrogen and progesterone
which:
mature and maintain reproductive system
female secondary sexual characteristics
ova maturation and release
transport of sperm to site of fertilisation
preparing uterus for development of embryo and foetus
contribute to ability to produce milk
```
116
thyroid
controls metabolic rate
increases heart rate
needed for normal growth and development
117
what hormones does thyroid release?
triiodothyronine (T3)
| thyroxine (T4)
118
parathyroid
calcium metabolism
| raises free plasma calcium by mobilising bone stores, reducing urine loss and increasing gut absorption
119
what hormones does the parathyroid release
PTH
120
kidney
releases renin if circulating volume or BP is low - sodium is retained and volume restored. releases erythropoietin when hypoxic to increase RBC formation in bone marrow
121
hormones released by kideny
renin - stimulates aldosterone release from adrenal cortex
| erythropoietin
122
adrenal cortex
metabolic response to stress
| body sodium levels
123
what hormones are released by adrenal cortex?
cortisol
aldosterone
DHEA
124
adrenal medulla
fight/ flight response
125
what hormones does the adrenal medulla release
catecholamines
126
what hormones are involved in digestion and food absorption?
```
gherlin
gastrin
secretin and CCK
GIP
Peptide YY3-36
insulin
glucagon
somatostatin
```
127
what does gherlin do?
stimulates appetite
128
what does gastrin do?
stimulates HCL production for protein digestion
129
what does secretin and CCK do?
coordination of digestive functions
130
what does Peptide YY do?
signals satiety
131
what does somatostatin do?
inhibits absorption of nutrients
132
adipose tissue
endocrine gland
133
what does adipose tissue secrete?
```
visfatin
apelin
leptin
TNF-alpha
adiponectin
RBP-4
resistin
many causing insulin resistance
```
134
Which axis is involved in the formation of mature sperm?
HPG axis
135
HPG axis
Hypothalamus produces CnRH > pituitary releases FSH and LH > FSH acts on Sertoli cells and LH on Leydig cells
136
Where are Sertoli cells found?
Seminiferous tubule of testes
137
Where are Leydig cells found?
Interstitium of testes
138
What do Sertoli cells do?
in response to FSH they produce Androgen binding protein which causes spermatogenesis
139
what do Leydig cells do?
Produce testosterone in response to LH.
140
What does testosterone do?
allows sertoli cells to produce androgen binding protein, which than binds to testosterone and causes spermatogenesis and
peripheral effects
141
what are the peripheral effects of testosterone?
maintain libido
muscle bone growth
secondary sex characteristics
accessory gland maintenance
142
Negative feedback of the HGT axis in males
Inhibin is produced by Sertoli cells which reduces FSH production by pituitary which reduces androgen binding protein levels
143
Testosterone affect on negative feedback of HPG axis
rise in testosterone levels causes reduced production of GnRH by hypothalamus and decreased production of LH and FSH by pituitary
144
which cells are affected by testosterone
sustentacular cells of seminiferous tubules
145
Phases of spermatogenesis
spermatocytogenesis
| Spermiogenesis
146
what happens in spermatocytogenesis
germ cell undergoes cell division to form spermatids
147
What happens in spermiogenesis
maturation and differentiation of spermatids
148
what are spermatids
immature sperm
149
what are leydig cells
interstitial cells
150
where are sertoli cells?
around outside of lumen of testes, surrounded by basement membrane
151
what is spermiogenesis
remodelling and differentiation into mature spermatozoa
152
what are the phases of spermiogenesis
golgi
acrosomal
tail
maturation
153
what happens in the golgi phase
golgi body enzymes form the acrosome
154
what happens in the acrosomal phase
acrosome condenses around the nuclues which allows it to penetrate the egg and protects the nucleus
155
what happens in tail phase
centriole elongates to form the tail
156
what happens in maturation phase
loss of excess cytoplasm to make it aerodynamic
157
What is spermiation?
process by which mature spermatozoa are released from the protective sertoli cells into the lumen of the seminiferous tubule and the remaining unnecessary cytoplasm and organelles are removed.
The spermatozoa are mature but lack motility - so are sterile . They are transported to the epididymus in testicular fluid secreted by sertoli cells and peristaltic contraction . Sperm travel and stored in vas deferens, this is aided by secretions of the seminal gland, they gain motility
158
Making spermatozoa fertile
once motile sperm are still not fertile they have to undergo capacitation
159
Capacitation
A glycoprotein coat covers the acrosome and prevents the sperm fertilising the egg. Capacitation happens due to enzymes fertilisation promoting peptide (produced by prostate gland) and heparin in female reproductive tract which remove the coat and allow sperm to bind to the egg .
160
FPP
produced in prostate gland as a component of seminal fluid. High levels in MRT prevent capacitation but they drop in the FRT and promotes capacitation
161
sperm transport into FRT
ejaculate is deposited in the anterior vagina near the cervix . The vagina is open to infection so has high acidity and immunological defence so to reduce the risk of damage to sperm they must travel quickly through the cervical canal. The cervix is only penetrable at certain points of the month - when there is a watery mucus and oestrogen levels are high - 2-3 days per cycle. The cervix has crypts - infoldings of epithelial cells in the endocervical canal which create a reservoir for sperm so they can be released over several hours and chance of fertilisation is increased .
162
what is in ejaculate?
spermatozoa
seminal fluid
enzymes - protease, seminalplasmin, prostatic enzyme and fibrinolysin
163
normal semen
more than 1.5ml
| pH higher than 7.2
164
normal sperm
```
conc. = >15 million/ ml
total no. = >39 million per ejaculate
total motility = >40% or >32% with progressive motility
vitality = >58% live spermatozoa
sperm morphology = >4%
```
165
Blood testing for fertility
hormone profile - FSH, LH, Testosterone and prolactin
166
History taking for fertility
libido status, erectile dysfunction, diabetes, retrograde ejaculation, taking drugs that may affect erection
167
Examine penis and scrotum
```
size
STD symptoms
hypospadias
urethral meatus - hole may be in wrong place
texture
scar tissue
inflammation
ductus deferens
blockages
```
168
hypogonadism
diminished functional activity of the gonads - testes or ovaries, may result in diminished production of sex hormones
due to testicular disorder or disease involving hypothalamus and pituitary gland
169
Hypergonadotrophic hypogonadism
issues with testes or ovaries - primary/ peripheral hypogonadism
When there is a problem with testosterone production it causes low levels which sends signals to hypothalamus causing more GnRH to be released and more FSH and LH but testes are damaged so testosterone remains low. Presentation = high FSH, LH and GnRH but low Testosterone
170
Hypogonadotrophic hypogonadism
low testosterone because there is low gonadotrophin because there is a problem with the hypothalamus
171
What causes hypogonadotrophic hypogonadism
kallmann syndrome
drugs
alcohol
infectious lesions
172
What causes high prolactin, and low testosterone, LH and FSH
Hypersecretion of prolactin
caused by pituitary tumours and is drug induced
leads to inhibition of GnRH - reduces LH, FSH and testosterone
causes low libido and erectile dysfunction
173
what does prolactin do?
inhibits release/ reduces release of GnRH
174
Follicular phase of menstrual cycle
pre-ovulation
Hypothalamus releases GnRH which causes anterior pituitary to release FSH and LH
FSH causes 15-20 follicles to start developing and this causes the granulosa cells around follicles to secrete oestrogen
175
Phases of menstrual cycle
follicular phase
luteal phase
14 days each
176
which phase is always 14 days in the menstrual cycle
luteal phase
177
What does FSH do?
stimulates development of follicles
178
What does LH do?
Causes ovulation
179
What does oestrogen do?
promotes female secondary characteristics
develops breast tissue, vulva, vagina and uterus and endometrium
stimulates blood vessels in uterus
causes mucus in cervix to become thinner to allow penetration of sperm
Causes negative feedback
180
Oestrogen...
causes negative feedback on hypothalamus and anterior pituitary. Rise in oestrogen suppresses release of FSH and LH
181
What happens just before ovulation?
dip in oestrogen as follicles get ready to release egg
| rise in LH which causes 1 follicle to reach surface of ovary and release the ovum at day 14
182
luteal phase
follicle that released ovum collapses and becomes corpus luteum and releases progesterone
183
when does ovulation happen?
day 14
184
what does progesterone do?
steroid sex hormone
thickens and maintains endometrium
thickens cervical mucus
increase body temperature
185
corpus luteum
secretes progesterone and oestrogen
186
what happens if egg is fertilised
embryo secretes hCG
| maintains corpus luteum
187
what happens if egg is not fertilised
corpus luteum degenerates and no long produces progesterone and oestrogen. this reduces negative feedback causing FSH and LH to be secreted
drop in oestrogen and progesterone causes endometrium to break down causing menstruation
188
when does menstruation start?
day 1
189
menstruation
where superficial and middle layers of endometrium separate from basal layer and are broken down in uterus and released through cervix and vagina
lasting 1-8 days
190
development of ovarian follicles
primordial follicle > primary follicle > secondary follicle > graafian/ mature follicle > ovulation
191
what does oestrogen do in negative feedback
as oestrogen is produced it causes reduction of FSH production
basal level of LH
192
mature follicle
produces large amounts of oestrogen which causes positive feedback and increases LH production via GnRH - causes LH surge. FSH is produced but inhibin prevents surge of FSH
193
What does the LH surge do?
restarts meiosis
oocyte undergoes another meiotic division
activates enzymes that break down wall to rupture follicle
oestrogen production stops as follicle dies
194
luteal phase
progesterone inhibits FSH and LH to stop further follicle development and ovulation
prepares uterus for pregnancy
oestrogen should cause positive feedback but is overridden by progesterone negative feedback
195
if fertilisation does not occur
```
corpus luteum degenerates spontaneously
progesterone fails
uterus loses its endocrine support
menstruation
FSH and LH gets to work again on follicles
```
196
what are the 2 layers of the uterine wall
myometrium
| endometrium
197
what does oestrogen do to the uterus
promotes growth of endometrium and myometrium
| promotes formation of progesterone receptors
198
what does progesterone do to the uterus?
acts on oestrogen-primed endometrium
loosens and softens connective tissue - making implantation easier
promotes secretion of nutrients
quietens uterine activity
199
uterine loss
no occupants so no hCG, so corpus luteum degenerates
progesterone and oestrogen support lost
uterine prostaglandins cause vasoconstriction and tissue death
blood and endometrial debris loss through vagina
200
menstrual disorders
dysmeorrhea
mennorrhagia
amenorrhea
oligomenorrhea
201
what is dysmenorrhea?
painful periods
202
what is Menorrhagia?
heavy or prolonged periods
203
What is amenorrhea?
absence of periods
204
what is oligomenorrhea
light periods
205
how does the combined pill work?
low dose of oestrogen = reduces FSH from ant. pituitary, reduces development of follicle and no ovulation
Progestrogen = makes cervical mucus sperm-unfriendly
decreases LH from ant. pituitary and GnRH from hypothalamus
reduces motility of fallopian tube
206
what makes up the combined pill
progestogen
| low dose of oestrogen
207
Progestogen only pill
low dose of progestogen taken continuously
makes cervical mucus inhospitable to sperm
hinders implantation - effect on endometrium and motility and secretions of fallopian tubes
menstruation - often ceases initially but returns long-term
causes breakthrough bleeding and irregular menses
