Embryology Flashcards
What happens if there is a mutation in the homeobox?
Significant anatomical defects
What do regulatory genes do?
Turn genes on/off
Define morphogenesis
Shaping of an organism by embryonic processes, including differentiation of cells, tissues and organs
What happens in the first 6 days following fertilisation?
1- zygote
2- early cleavage cell
3- morula
4- early blastocyst
What happens to the blastocyst?
Cell division is asymmetrical and lose their totipotencu and begin to differentiate
What do blastocysts differentiate into?
Inner cell mass= fetus
Outer cell mass= placenta
What is formed in week 2?
Embryonic disc
What is the ectoderm?
Skin
Nervous system
What is the mesoderm?
Muscle
Skeleton
Kidneys
Reproductive organs
What is the endoderm?
Endocrine glands
Lungs
Digestive tract
What happens in week 3?
Heart and nervous system begin to form
Neural plate begins to form
What happens in week 4?
Folding of the embryo into a C shape
Beating heart present
What forms 25 days post fertilisation?
Placenta and umbilical cord
Function of the placenta as a storage compound:
Stores glycogen to metabolise into glucose for fetus
Stores iron and fat soluble vitamins
Placenta function as an endocrine:
Produces oestrogen and progesterone (steroid)
Produces HCG, HPL, PAPP-A/B
How does the placenta get oestrogen?
The fetus causes that
What does oestrogen do?
Growth of uterine muscle
Increases size of nipple and duct development
Where is progesterone made?
Placenta
From cholesterol
Purpose of progesterone?
Relaxes uterine muscle
Regulates storage of body fat
Why do levels of progesterone fall after birth?
So prolactin can be formed and lactation can occurr
What produces HCG?
trophoblasts from 7-10 weeks
Forms the basis of pregnancy tests
What hormone does HCG stimulate the corpus luteum to make?
Progesterone
What does HPL do?
Mobilises fatty acid from maternal body stores
Increases insulin levels
Function of PAPP-A/B
A= prevents rejection of fetus from mothers cell mediated response
B= used to check progress of placenta in diabetes/pre-eclampsia
Function of placenta with respiration:
O2 and CO2 transferred to and from maternal circulation from fetus by diffusion
Mother will experience alkalosis
How does the placenta act as a protection:
Acts as a filter to most bacteria
Immunoglobulins from mother is passed to fetus during late pregnancy
Function of the placenta in excretion:
CO2 is the main product excreted
Bilirubin is also excreted
Function of the placenta in nutrition
Fetus receives the raw materials for growth
( glucose, amino acids, FA)
The function of the placenta with the transfer of substances:
Simple diffusion of lipid soluble
water pores transfer water soluble
F.D glucose using carriers
A.T when transferring ions
Maternal surface of the placenta:
Dark red
Divided into cotyledons
Cotyledons contain villi
What’s in the cord?
AVA
2 arteries and 1 vein
What are the names of the two placental membranes?
Chorion and amnion
Features of the chorion (outer) membrane
Rough, thick and fibrous
Produces oxytocin to stimulate uterine activity
Continuous with the edge of placenta
Features of Amnion (inner) membrane:
Smooth and translucent
Joins onto cord
Contains amniotic fluid
What happens in week 8?
Fetal circulation is functioning
External genetalia is present with anus
Ossification of bones
All organs are here
What happens in week 11?
Fetus heart rate can be heard with a Doppler
Has all organs for survival
What happens in week 13?
Has fully formed limbs
Uterus may pop outside of pelvic cavity
Week 20
Halfway through
Movements are easy to feel
What is the surfactant?
Slippery substance that allows the alveoli to inflate and prevents collapse
Week 24:
Baby should have a regular wake and sleep cycle
Week 32:
Baby is head down
Week 37:
Pregnancy is considered term
Week 40:
Baby is fully term
