Controlling Fertility Flashcards
Fertility
Ability to produce offspring
Continuous Fertility
Male
Levels of FSH and ICSE are kept relatively constant through negative feedback. As a result, sperm are produced continually.
Cyclical Fertility
In women, fertility is cyclical. Levels of oestrogen and progesterone, FSH and LH fluctuate. As a result women are only fertile for small number of days before and after ovulation during each menstrual cycle.
Ovulation
Release of an ovum from one of ovaries
Identifying women’s fertile period
body temperature - increases after ovulation
cervical mucus - clearer, wetter and more slippery
timing of menstrual cycle - ovulation occurs 10 to 16 dayys before start of period
stimulating ovulation
Prevent negative feedback effect of oestrogen on FSH
Mimic normal action FSH and LH, stimulating ovulation
Artificial stimulation ovulation can lead to….
multiple births - super ovulation
can be used un IVF too to help collect ova as several need to be collected
AI may be useful when?
man has a low sperm count
couple are unable to have vaginal intercourse
condition means couple need help to conceive
when donor sperm is being used by same-sex couple or when a man in mixed-sex couple is sterile
Sperm sample AI
A sample of sperm is treated to remove dead sperm, slow sperm and impurities. A concentrated sample of healthy sperm is then passed through a catheter into the uterus. A sperm donor may also be used in artificial insemination in cases of a male being sterile.
Intra cytoplasmic sperm injection used when
sperm count low
mature sperm are abnormally shaped or don’t move normally
sperm needs to be surgically removed
frozen sperm has reduced quality being used
ICSI sperm sample
Sperm collected and head of sperm drawn into needle and injected directly into egg in order to increase chances of fertilisation.
IVF can be used when
issues with sperm quality
womens blocked oviduct
where one or both partners may pass genetic condition
donor or sperm egg being used
IVF
Involves one or more eggs being removed from woman’s ovaries. These are then fertilised with sperm in laboratory
IVF steps
- the mother is given FSH and LH to stimulate maturation of several eggs in ovary
- egg are collected from mother and fertilised with sperm from father in culture dish in lab
- fertilised eggare incubated until they develop into embryos
- at stage when tiny balls of at least 8 cells, one or 2 embryos inserted into other’s uterus
develop of what has allowed IVF treatments to develop further
microscopy techniques
Pre-inplantation genetic diagnosis (PGD)
IVF is used in conjunction with PGD where one or more parents at risk of serious inherited disease to their children. PGD can be used to check single gene disorders and chromosome abnormalities in developing embryos before they are implanted.
Physical contraception
Condom/diaphrahms
IUD
Spermicidal agent
abstaining
surgical methods - vasectomy
Oral pill
contains mixture of oestrogen and progesterone that mimics negative feedback effect which prevents release of FSH and lH
Mini-pill
contains progestrone only which causes thickening of cervical mucus
Morning after pill
Contains stronger doses of oestrogen and progesterone than the contraception pill. Prevents or delays ovulation
What type of ART is used to stimulate ovulation
Clomifene
Antenatal screening
Used to identify any possible rusk to mother or foetus during pregnancy or identify health issues that will affect the baby
If risk identified further tests can be carried out and prenatal diagnosis given
Ultrasound imaging
Dating scan
Anomaly scan
Dating scan
carried out weeks 8-14
used to determine stage of pregnancy and due date
used with tests for marker chemicals which vary during pregnancy
Anomaly scans
Carried out weeks 18-20
may detect serious physical abnormalities
Blood and urine tests
Routine blood and urine tests are carried out throughout pregnancy to monitor the
concentrations of marker chemicals.
This is why they are used in conjunction with scans, as measuring chemicals at wrong time can lead to false pos
can indicate pre-eclampsia and down’s syndrome
Diagnostic testing
Amniocentesis
Chorionic Villus Samping CVS
Amniocentisis
Uses small number of amniotic fluid from amniotic sac surrounding foetus to check genetic disorders
@ 14-16 weeks
sample of amniotic fluid is removed and cultured
Approx 2 weeks for results
CVS
Tests a sample of cells from mothers placenta for genetic disorder
8 weeks
sample of placenta cells removed and cultured
immediate karyotyping results
what diagnosis has higher miscarriage results
CVS
PKU
autosomal recessive inherited metabolic condition
sufferers require 2 recessive alleles to be affected
heel prick test in newborn babies
pedigree analysis chart
how genetic disorders are inherited in a family
probability
4 types of patterns in inheritance of single gene disorders
autosomal recessive
autosomal dominant
incomplete dominance
sex-linked recessive
X and Y
sex chromosomes
all others autosomal
Autosomal recessive inheritance
Expressed rarely - require 2 recessive alleles (homozygous recessive)
may skip generations, affect both genders equally
e.g. cystic fibrosis
autosomal dominant inheritance
sufferers require one dominant allele so can be homozygous dominant or heterozygous
affects both genders equally
e.g. Huntington’s disease
Incomplete dominance
Dominant allele not fully expressed
Both incomplete dominance allele are shown with upper case letters in genetic diagrams
e.g BW WW BB
genotype and phenotype
Phenotype - description
Genotype - WW, BB, WB
sex-linked recessive inheritance
sex chromosomes mainly responsible for determining gender, carry some genes that code for body functions.
men more susceptible
Haemophilia
sufferers unable to clot their blood resulting in excessive bleeding, even from small cuts or bruises.
Sex-linked - recessive allele on X chromosome
