Embryology Flashcards
What is fertilization?
when sperm and oocyte come (egg) together to form a zyogote
Key hormones in ovulation
Luteinizing hormone Follicle Stimulating Hormone Estrogen Progesterone HCG (human chorionic gonadatropin)
Luteinizing hormone
- produced in pituitary gland
- triggers ovulation and development of corpus luteum
Follicle Stimulating Hormone
- produced in pituitary
- stimulates the growth of eggs and release of the mature egg
Estrogen
- made in ovaries
- helps uterus grow and prepares body for delivery
Progesterone
- released by ovaries
- prepares the endometrium for pregnancy; causes lining to thicken
HCG
- produced by cells in the placenta
- stimulates the corpus luteum to produce progesterone to maintain the pregnancy.
Early division is known as
cleavage
What is a morula?
Forms when a zyogte continues to divide until it becomes 16 cell
What is the morula become
a blastocyst/blastocyte
Key components of blastocyst
- trophoblast is single layer of large flattened cells which become the placenta
- embryoblast is the inner cell mass that gives rise to the embryo
What do trophoblast become in week 2?
-divides into Cytotrophobolast and synctiotrophoblast
What does the embryoblast become in week 2?
-divides into Epiblast and hypoblast
What does the extraembryonic mesoderm become?
-divides into Somatic and splanchnic layers
the embryoblast cell
become hypoblast which becomes yolk sac and epiblast which gives rise to germ layers and forms amniotic cavity
What is the lacunar stage and why is it important
arteries and veins from mother start growing to decidua basalis bringing blood
What is gastrulation?
process in which an embryo transforms from a one-dimensional layer of epithelial cells (blastula) and reorganizes into a multilayered and multidimensional structure called the gastrula
Two functions of the primitive streak
established bilaterally symmetry and determines the site of gastrulation
How are germ layers formed
Through gastrulation
Two factors that contribute to the cell differentiation and positioning
-primitive streak and primitive groove
Ectoderm
- Neural tissues: spinal cord, peripheral nerves, and brain
- epithelial tissues: skin, linings of the mouth, nostrils, sweat glands, hair and nails, and tooth enamel
Endoderm
- pharynx
- GI tract
- respiratory system
Mesoderm
- paraxial mesoderm: skeleton (except skull), dermis, and connective tissue
- intermediate mesoderm: genitourinary system, ducts, and accessory glands
- lateral plate mesoderm: connective tissue of viscera and limns, serous membranes of pleural, pericardium and peritoneum, blood and lymph cells, cardiovascular lymph systems
When does cardiac development begin?
starts day 18-19
What are the germ layers of the heart?
mesoderm that becomes the mesothelium, endothelium, and myocardium
What are the 5 regions of the embryonic heart?
- truncus arteriosus
- bulbus cordis
- primitive ventricle
- primitive atrium
- sinus venosus.
What does the truncus arteriosus become?
ascending aorta (aka aortic arch) and pulmonary trunk
What does the bulbus cordis become?
Right ventricle and outflow tract
What does the primitive ventricle become?
Left ventricle
What does the primitive atrium become?
anterior portions of right and left atrium
What does the sinus venosus become?
posterior portion of right and left atrium, the SA node, and the coronary sinus
Heart valves and the septum develop from
septum intermedium
What are the unique anatomical features of fetal circulation?
- foramen ovale shunt
- ductus arteriosis shunt
- ductus venous shunt
Describe fetal circulation
blood goes from right atrium to left atrium to LV to AA to outside body back to RA to ascending aorta and through umbilical cord which carries CO2 and waste
Describe newborn circulation
RA»_space; tricuspid valve»_space; RV»_space; pulmonic valve»_space; pulmonic artery»_space; lungs to pick up O2»_space; pulmonary vein»_space; LA»_space; mitral valve»_space; LV »_space; aortic valve»_space; aorta»_space; blood to body»_space; blood returns through superior vena cava»_space; inferior vena cava»_space; RA
When does the respiratory system develop?
approx day 25
what does the ductus arteriosis do?
moves blood from pulmonary artery to aorta
What does the ductus venous do?
lets highly oxygenated blood bypass the liver to the inferior vena cava and then to the right atrium of the heart
What does the ductus venous do?
lets highly oxygenated blood bypass the liver to the inferior vena cava and then to the right atrium of the heart
What happens at birth with the heart?
After the first breath, there is a drop in pulmonary pressure allowing pulmonary blood flow which closes the foramen ovale and constricts the ductus arteriosus and ductus venosus
What are the stages of lung development?
- Embryonic Period
- Pseudoglandular Period
- Canalicular Period
- Terminal sac period
- Alveolar period
What happens in pseudoglandular period?
5-16 weeks
- all elements of the lungs are developed except those involved in gas exchange
- terminal bronchus present but not respiratory bronchioles, alveoli, and alveoli ducts
- fetuses born up to 17 weeks will not survive
What happens in canalicular period?
16-26 weeks
- lumen of bronchi and bronchioles become larger
- tissue becomes mores vascular
- respiratory bronchioles and alveolar ducts develop
- some terminal sacs develop
- respiration is possible at then end of this stage
What happens in canalicular period?
16-26 weeks
- lumen of bronchi and bronchioles become larger
- tissue becomes mores vascular
- respiratory bronchioles and alveolar ducts develop
- some terminal sacs develop
- pulmonary capillaries
- respiration is possible at then end of this stage
What happens in the terminal sac period?
26 weeks-birth
- many more terminal sacs develop
- epithelium becomes very thin
- type I alveolar cells develop
- capillary network develops rapidly
- capillaries bulge into the alveoli
- increase # in alveoli, bronchioles, and pulmonary capillaries
- surfactant is produced
What happens in the alveolar period?
Late fetal -childhood
- squamous epithelium form
- terminal sacs become alveolar ducts
- septa develops to increase surface are for better gas exchange
- alveoli form after birth (continue to develop for 3-8 years)
What happens during the embryonic period?
- lung bud formation
- trachea and bronchi differentiation
What are the germ layers of the respiratory tract?
endoderm and mesoderm
What makes up the GI tract?
- Foregut
- Midgut
- Hindgut
What makes up the GI tract?
- Foregut
- Midgut
- Hindgut
What does the foregut make?
esophagus, stomach, proximal duodenum, pancreas, liver, and gallbladder
-near cranial end*
What does the midgut make?
distal duodenum, jejunum, ileum, cecum, appendix, ascending colon, and proximal 2/3 of transverse colon
What does the hindgut make?
distal 1/3 of transverse colon, descending colon, sigmoid colon and the upper anal canal
-near caudal end*
What happens during the embryonic folding and the GI tract?
development of gut tube and peritoneum
What germ layers make up the GI tract?
endoderm, mesoderm, and ectoderm
Key event durng 4 months to birth during GI developement?
peristalsis and absorption
Errors in midgut development
omphaloceles, umbilical hernias, gastroschisis
Errors in hindgut development
hirschprung’s disease which can result in congenital megacolon
Diaphragm abnormalities result when
when there is a hole in the diaphragm that leads to herniation of abdominal contents in the chest cavity
-this is called congenital diaphragm herniation
