Embryonic development and pregnancy

Question 1

Inner cell mass

Answer 1

Made up of undifferentiated stem cells, Develops into three primary germ layers: Endoderm- cells become lining of the digestive tract (digestive system), Mesoderm- cells become muscle and red blood cells (muscles and bones), Ectoderm- cells become skin cells

Question 2

Yolk sac

Answer 2

Endoderm side, provides nutrients for developing nutrients, not very big meaning that placenta then takes over in providing nutrients, site of red blood cell formation and becomes part of the umbilical cord

Question 3

Amnion

Answer 3

Ectoderm side, surrounds the embryo by the 8th day and secretes amniotic fluid its cavity, protect embryo against physical injury (absorbs shock), maintains temperature and allows foetus to move freely, ruptures before birth releasing fluid (breaking of the waters)

Question 4

Chlorion

Answer 4

Formed from the outer cells of the blastocyst, amnion fuses together with the chorion and develop into the foetal portion of the placenta

Question 5

Placenta

Answer 5

Supplies nutrients and oxygen to the foetus for cellular respiration and removes the wastes from the foetus produced in cellular respiration, endocrine organ as it secretes progesterone, taking over the role of corpus luteum, combination of foetal and maternal tissues, formed by end of first trimester

Question 6

Why doesn’t the foetal and maternal blood mix

Answer 6

Layer of tissue that means diffusion happens instead

Question 7

Umbilical cord

Answer 7

Contains tow umbilical arteries and one umbilical vein, outside layer- tough connective tissue

Question 8

What does the umbilical artery do

Answer 8

takes deoxygenated foetal blood away from the foetus to the placenta (takes blood away from the babies heart)

Question 9

What does the umbilical vein do

Answer 9

carries blood that has been clean and oxygenated back to the foetus (brings blood back to the foetus)

Question 10

Symptoms of pregnancy (11)

Answer 10

Lack of menstruation, Breast become fuller, firmer and tender, Nipples become darker as they get more blood supply, Nausea and vomiting due to the excess estrogen and other hormones, Increased frequency of urination as more waste products need to be removed, Enlarged abdomen (doesn’t usually occur until after 12 weeks), Foetal movement, Mood changes, Increased heart size as it is pumping more blood, Blood volume can double
Extra pressure on the heart and kidneys (more waste is removed)

Question 11

Factors that affect foetal development

Answer 11

Drugs, chemicals and pathogens can cross the placenta and affect the developing foetus, food, chemicals, infections, drug interactions

Question 12

How can food affect foetal development

Answer 12

Folate/folic acid which is essential for normal spinal cord development, Calcium which is needed for foetus bones, Listeria (bacteria that causes food poisoning) can severely affect the baby

Question 13

What infections affect foetal development

Answer 13

Measles and the flu

Question 14

What drug interaction can affect foetal development

Answer 14

Thalidomide which has 2 isomers- one good at preventing morning sickness but the other can form birth defects

Question 15

Problems with pregnancy

Answer 15

backache, constipation and heartburn

Question 16

Why can pregnancy cause backaches

Answer 16

hormones relax ligaments and change posture so the pelvis can then expand during delivery and the centre of gravity changes resulting in stress

Question 17

Why can pregnancy cause constipation

Answer 17

progesterone lowers the smooth muscle tone reducing the rate of peristalsis, some women also just don’t drink enough especially when breastfeeding

Question 18

Why can pregnancy cause heartburn

Answer 18

Stomach acids move to the oesophagus