Pregnancy, Growth, Development And Genetics Flashcards
When does the prenatal period begin and end?
Begins at fertilisation, ends at birth
When does the Postnatal period begin and end?
Begins at birth, ends at death
Define: Ovum, Zygote, Embryo, Foetus
Ovum- from ovulation to fertilisation
Zygote- from fertilisation to implantation
Embryo- from implantation to 8th week of pregnancy
Foetus- 8+ weeks
Define fertilisation. Where does fertilisation usually take place?
Fertilisation is the meeting of the secondary oocyte and the sperm cell. It typically within the uterine tubes.
How is the body prepared for the transportation of sex cells?
Sperm cells contain large amount of mitochondria and prostaglandins which stimulate the tail to swim and give the cell energy. Prostaglandins also cause muscular contractions of the uterus and uterine tubes to help push the sperm cells forward
What does fertilisation result in?
A diploid zygote containing 23 pairs of chromosomes
What is the name of the protein which the sperm uses to erode away the corona radiata of the egg cell?
Acrosome
When does the 1st, 2nd and 3rd trimester occur during pregnancy?
1st trimester- weeks 1-12
2nd trimester- weeks 13-27
3rd trimester- weeks 28+
Following fertilisation, the cells undergo a period of mitosis where they divide to become increasingly smaller. What is this period called?
The period of cleavage
How long does it take for the dividing mass of cells to move down the uterine tube and into the uterus?
On average, 3 days
At the end of the first week following fertilisation, the mass of cells implants into the lining of the endometrium. At this point, what is the mass of cells called? What is the uterus lining called?
Mass of cells is called the blastocyst
Uterus endometrium is called the decidua
What does the blastocyst become?
The embryo (embryoblast) and the placenta
What is the outer layer of the blastocyst called?
The trophoblast
Which hormone does the trophoblast secrete to maintain pregnancy? This hormone is also the basis of pregnancy testing.
HCG- human chorionic gonadotrophin
Which four primary hormones does the placenta secrete? What are the roles of these hormones?
Placental lactogen- stimulates breast development
Estrogen and progesterone- maintain uterine lining, inhibit secretion of LH and FSH, stimulate development of mammary glands
Relaxin- relaxes the pelvis
When does the neural tube form and what does it become? Which process forms the neural tube?
The tube forms during the 4th week of pregnancy and develops into the spinal cord and brain. Neurulation forms the neural tube.
What occurs during gastrulation?
The inner cell mass becomes the 3 layer (ectoderm, endoderm and mesoderm) building blocks for the embryo
What does the ectoderm become?
The nervous system and sensory organs
What does the mesoderm become?
Muscle and bone tissue, blood, vessels, reproductive organs and kidneys.
What does the endoderm become?
The epithelial linings of the digestive tract, respiratory tract, urinary bladder and urethra.
Name the 5 roles of the placenta.
To obtain nutrients and oxygen for the foetus
To dispose of fetal waste products (e.g. CO2, urea, bilirubin)
To produce hormones (HCG)
Immunological role
Protects and nurtures the foetus
What are the names of the two membranes surrounding the foetus?
The chorion (closest to mum) and the amnion (closest to baby)
Give six functions of amniotic fluid
- barrier to infection
- prevents amnion from sticking to the foetus
- provides a constant environmental temperature
- allows the foetus to move freely
- cushions against knocks and bumps
- allows for symmetrical growth of the foetus
What is the medical term given for too much amniotic fluid?
What about too little?
Polyhydramnios- too much
Oligohydramnios- too little
