Lecture 23: Embryology, Pregnancy and Child Birth Flashcards
Spermatozoa viable for how many hours in female tract?
48 hours
Oocytes viable for how long?
12-24 hours
Sperm must be undergo what? takes 6-8 hours after ejaculation.
Capacitation
Once a single sperm binds to oocyte plasma membrane a reaction occurs to exclude what?
All other sperm
Blastocyst implants into endometrium by secreting what, onto the endometrial surface?
digestive enzymes, cytokines and growth factors
Trophoblast cells secrete what substance which is measured in urine to test for pregnancy.
human chorionic gonadotrophin
hCG prompts corpus luteum to keep secreting what, until
placenta takes over?
progesterone
Placenta makes and secrete what two hormones for the remainder of pregnancy until birth?
oestrogen and progesterone
Chorionic villi project from fetal tissue into maternal
blood vessels to form what two structures?
umbilical arteries and vein
Placenta =
chorionic villi + decidua basalis
The umbilical vein during pregnancy does what?
oxygenated blood => mother=>placenta =>Fetus
The umbilical artery does what during pregnancy?
deoxygenated blood + waste => fetus =>placenta =>mother
What are the four Embryonic membranes:
- AMNION
- YOLK SAC
- ALLANTOIS
- CHORION
Name the 3 primary germ layers:
- ECTODERM
- MESODERM
- ENDODERM
What do the three germ layers contain?
Ectoderm => epidermis, nervous system
Mesoderm => smooth muscle, connective tissue, blood vessels, blood cells, skeleton, skeletal muscle, reproductive and excretory
organs.
Endoderm => epithelial linings of respiratory passages and digestive tract.
Neuroectoderm forms what two structures?
Brain and spinal cord
Neural crest cells form what?
dorsal root (sensory) ganglia of spinal and cranial nerves.
What do Somites form?
axial skeleton + adjacent muscles + dermis.
As the embryo folds it encloses part of the yolk sac
that goes on to develop into what structure?
digestive tube
Endodermal tube forms the EPITHELIAL LININGS of what 3 structures?
Digestive system, respiratory systems and associated glands
Intermediate mesoderm forms what?
gonads, kidneys, adrenal cortex
Lateral somatic mesoderm form what?
dermis, peritoneum, limb buds
Lateral splanchnic mesoderm forms what?
cardiovascular system organs, connective tissues, all but
epithelial lining of digestive and respiratory organs.
Blood supply to the foregut ( epigastric )?
Coeliac artery (except pharynx, respiratory tract, most of oesophagus)
Midgut ( umbilical) derivatives
- Small intestines (inc. most of duodenum)
* Caecum, vermiform appendix, ascending colon, right 1⁄2 - 2/3 of transverse colon.
Blood supply to the midgut (umbilcal) derivatives
Superior mesenteric artery
Hindgut (hypogastric) derivatives
- Distal part of transverse colon, descending colon, sigmoid colon, rectum, anal canal.
- Epithelium of urinary bladder and most of urethra.
Blood supply to the hindgut derivatives?
Inferior mesenteric artery
4thweek of development – ventral and dorsal buds from?
Foregut
By the end of the 6th week, the rotation of the duodenum has brought ventral and dorsal buds together to?
Fuse
Ventral bud forms what?
head and uncinate process.
Dorsal bud forms what?
Neck, body and tail
Endoderm of primitive gut gives rise to most of the what?? of the digestive tract.
epithelium and glands
Epithelium from cranial and caudal extremities is
derived from the ?
ectoderm of the stomodeum
Muscular and connective tissue components of
digestive tract are derived from the?
splanchnic mesenchyme surrounding primitive gut.
4 weeks gestation:
Signals from heart trigger underlying endoderm to generate primary liver bud as an outgrowth of the ventral wall of the? .
FOREGUT
Five Months
A protective coating begins to form on baby’s skin, what is it called?
vernix caseosa
By 4th month the uterus fills the?
pelvis
By 9th month the fundus of the uterus is at the level of the?
xiphoid process
Abdominal organs are pushed superiorly under the?
diaphragm.
Coccyx permitted to move more posteriorly to increase?
pelvic outlet
Conjugate distance between sacral promontory and
posterosuperior aspect of pubic symphysis is?
Fixed
Transverse diameter & amount of pelvic rotation permitted around sacrum is increased due to?
effect of relaxin hormones on pelvic ligaments
Back pain in pregnancy
- Increased maternal weight spine.
- Referred pain from visceral compression.
- Direct compression on exiting nerve roots in pelvis.
- Venous congestion in pelvis and lumbar spine from uterus compression inferior vena cava.
- Relaxin hormone causing ligamentous laxity.
- Pelvic instability.
What is the let down reflex?
oxytocin binds to myoepithelial cells surrounding alveoli –>
milk ejected form alveoli into ducts from both breasts
