Embryo USMLE Flashcards
give the day/week in a pregnancy– fertilization by sperm, initiating embryogenesis
day 0
give the day/week in a pregnancy –implantation (as a blastocyst)
w/in week 1
give the day/week in a pregnancy– bilaminar disk
w/in week 2
give the day/week in a pregnancy– gastrulation, primitive streak, notochord, and neural plate begin to form
w/in week 3
give the day/week in a pregnancy–neural tube formed. Organogenesis. Extremely susceptible to teratogens
Week 4
give the day/week in a pregnancy-heart begins to beat. Upper and lower limb buds begin to form
week 4
give the day/week in a pregnancy–genitalia have male/female characteristics
week 10
rule of 2s for 2nd week
2 germ layers (bilaminar disk): epiblast, hypoblast.
2 cavities: amniotic cavity, yolk sac
2 components to placenta: cytotrophoblast, syncytiotrophoblast
rule of 3s for 3rd week
3 germ layers (gastrula) ectoderm, mesoderm, endodderm
the epiblast (precursor to ectoderm) invaginates to form this.
primitive streak
cells from the primitive streak give rise to what
both intraembryionic mesoderm and endoderm
give some adult sxs that arise from the surface ectoderm
adenohypophysis, lens of eye, epithelial linings, epidermis
give some adult sxs that arise from the neuroectoderm
neurohypohyisis, CNS neurons, oligodendrocytes, astrocytes, ependymal cells, pineal gland
give some adult sxs that arise from the neural crest cells
ANS, dorsal root ganglia,, cranial nerves, melanocytes, chromaffin cells of adrenal medulla, enterochromaffin cells, pia and arachnoid, celiac ganglion, schwann cells, odontoblasts, parafollicular (C) cells of thyroid, laryngeal cartilage, bones of the skull
give some adult sxs that arise from the mesoderm
dura mater, CT, mm, bone, CB sxs, lymphatics, blood, UG sxs, serous linings of body cavities (e.g., peritoneal), spleen, adrenal cortex, kidneys.
give some adult sxs that arise from the endoderm
gut tube epithelium and derivitives (e.g., lungs, liver, pancreas, thymus, parathyroid, thyroid follicular cells).
give some adult sxs that arise from the notochord
induces ectoderm to form neuroectoderm (neural plate). Its postnatal derivitive is the nucleus pulposus of the intervertebral disk
when are babies most susceptible to the effects of teratogens
3rd-8th weeks (organogenesis)
given the teratogen give some possible effects on the fetus:
etoh
birth defects and mental retardation (leading cause); FAS
given the teratogen give some possible effects on the fetus: ACE inhibitors
renal damage
given the teratogen give some possible effects on the fetus: Cocaine
abnormal fetal dvlpmt and fetal addiction
given the teratogen give some possible effects on the fetus: DES
vaginal clear cell adenocarcinoma
given the teratogen give some possible effects on the fetus: iodide
congenital goiter or hypothyroidism
given the teratogen give some possible effects on the fetus: 13-cis-retinoic acid
extremely high risk for birht defects
given the teratogen give some possible effects on the fetus: thalidomide
limb defects (“flipper” limbs)
given the teratogen give some possible effects on the fetus: tobacco
preterm labor, placental problems, ADHD
given the teratogen give some possible effects on the fetus: warfarin, X-rays
multiple anomalies
what else can cause congenital malformations
fetal infections (TORCH)
the umbilical cord contains 2 umbilical artieries which do this
and 1 umbilical vein which does this
return deoxygenated blood from fetal internal illiac arteries
supplies oxygenated blood from the placenta to the fetus
this sx in the umbilical cord removes nitrogenous waste from the fetal bladder (lika a urethra)
allantoic duct
what does the ascending aorta and pulmonary trunk arise from embryologically
truncus arteriosus
what do the smooth parts of left and right ventricle arise from embryologically
bulbus cordid
what do the trabeculated parts of left and right ventricle arise from embryologically
primitive ventricle
what do the trabeculated parts of left and right atrium arise from embryologically
primitive atria
what does the coronary sinus arise from embryologically
Left horn of sinus venosus (SV)
what does the smooth part of right atrium arise from embryologically
right horn of SV
what does the SVC arise from embryologically
right common cardinal vein and right anterior cardinal vein
fetal erythropoeis occurs in these 4 places (give them in correct order
1) Yolk sac (3-8 wk)
2) Liver (6-30 wk)
3) Spleen (9-28 wk)
4) Bone Marrow (28 wk onward)
mneu : Young Liver Synthesizes Blood
adult hemoglobin sx
α2β2
fetal hgb sx
α2γ2
bloood in umbilical vv is _____ saturated w/ O2
80%
fetal circulation involves 3 important shunts because this organ is not yet in use
lungs
Shunt 1: Most oxygenated blood reaching the heart via the IVC is diverted through this sx and pumped out of the aorta to the head
foramen ovale
Shunt 2: Deoxygenated blood from the SVC is expelled into the pulmonary artery and _________ to the lower body of the fetus
ductus arteriosus
Shunt 3: Blood entering the fetus through the umbilical vv is conducted via this into the IVC
ductus venosis
describe what happens at birth when the infant takes a breath
decreased resistance in pulmonary vasculature causes increased L atrial presure v. right atrial pressure; foramen ovale closes. Increased O2 leads to decrease in prostaglandins, causing closure of ductus arteriosis
what drug closes the PDA
indomethacin
what “drug” can keep a patent PDA open
Prostaglandins
the ligamentum teres hepatis arises from the _____
umbilical vein
the mediaL umbilical ligaments arises from the
UmbiLical artieries
the ligamentum arteriosum arises from the
ductus arteriosus
the ligamentum venosum arises from the
ductus venosus
the fossa ovalis develops from the
foramen ovale
the mediaN umbilical ligament arises from the urachus which arises from the
AllaNtois
what is the urachus
part of the allantoic duct between the bladder and the umbilicus
the nucleus pulposus of the intervertebral disk arises from teh
notochord
what aortic arch doese the MAXillary aa arise from
1st
mneu: 1st arch is MAXimal
what aortic arch doese the Stapedial aa and hyoid aa arise from
2nd
mneu: second=stepedial
what aortic arch doese the Common Corotid aa & the proximal part of the internal Carotic arise from
3rd
mneu: C is 3rd letter of alphabet
what aortic arch doese the aortic arch on L and proximal part of the subclavian aa on R arise from
4th
mneu:4th arch (4 limbs)=systemic
what aortic arch doese the proximal part of pulmonary and (on L only) ductus arteriosus arise from
6th
mneu :6 upside down looks kind of like a P
6=pulmonary and pulmonary to systemic shunt ductus arteriosis
branchial clefts are derived from this tissue
ectoderm
mneu: CAP covers outside from inside (Clefts=ectoderm, Arches=mesoderm, Pouches=endoderm)
branchial arches are derived from this tissue
mesoderm and neural crests
branchial pouches are derived from this tissue
endoderm
branchial is sometimes called this
pharyngeal
clefts are sometimes called this
grooves
Give 2 bones/cartilage, muscles, and 1 nerve that arrises from branchial arch 1 derivitives
Meckel’s cartilage: Mandible, Malleus, incus, sphenoMandibular ligament
Muscles: Muscles of Mastication (temporalis, Masseter, lateral and Medial pterygoids), Mylohyoid, anterior belly of digastric, tensor tympany, tensor veli palatini, anterior 2/3 of tongue
nerve: CN V2, V3
Give 2 bones/cartilage, muscles, and 1 nerve that arrises from branchial arch 2 derivitives
Reichert’s cartilage: Stapes, Syloid process, lesser horn of hyoid, Stylohyoid ligament
Muscles: mm of facial expression, stapedius, stylohyoid, posterior belly of digastric
Nerve: CN VII
Give 1 bones/cartilage, muscles, and 1 nerve that arrises from branchial arch 3 derivitives
Cartilage: greater horn of hyoid
mm: stylopharyngeus
nn: CN IX
hint: think of pharynx: stylopharyngeus is innervated by glossopharyngeal nerve
Give 2 cartilage, muscles, and 1 nerve that arrises from branchial arch 4-6 derivitives
cartilages: thyroid, cricoid, arytenoids, corniculate, cuneform
mm (4th arch): most pharyngeal constrictors, cricothyroid, levator veli palatini
mm (6th arch): all intrinsic mm of larynx EXCEPT CRICOTHYROID
nerve: 4th arch – CN X (superior laryngeal branch)
6th arch - CN X (recurrent laryngael branch)
give the brancial arch innervation of arch 1
CN V2 & V3
give the brancial arch innervation of arch 2
CN VII
give the brancial arch innervation of arch 3
CN IX
give the brancial arch innervation of arch 4 & 6
CN X
1st branchial arch forms this portion of the tongue
what is its innervation
anterior 2/3
CN V3 (sensation) CN VII (taste)
3rd & 4th branchial arches forms this portion of the tongue
what is its innervation
post 1/3
CN IX-taste
CN X-extreme posterior
give the cranial nn and nucleus responsible for taste
CN VII, IX, X (solitary nucleus
give the cranial nn responsible for pain
CN V3, IX, X
give the cranial nn responsilbe for motor
CN XII
1st branchial cleft develops into this
external auditory meatus
2nd-4th branchial cleft develops into this
temporary cervical sinuses, which are obliterated by proliferation of 2nd arch mesenchyme
persistant cervical sinuses can lead to this
branchial cyst in the neck
what parts of the ear develop from the 1st branchial arch
bones: Malleus/incus
mm: Tensor tyMpani (V3)
what parts of the ear develop from the 1st branchial cleft
external auditory meatus
what parts of the ear develop from the 2st branchial arch
bones: stapes
mm: stapedius (VII)
what is a branchial membrane
located at the jx of clefts and pouches
what part of the ear develops from the 1st branchial membrane
eardrum and eustachian tube
what does the 1st branchial pouch develop into
middle ear cavity, eustachian tube, mastoid air cell
note: 1st pouch contributes to endoderm-lined sxs of ear
what does the 2nd branchial pouch develop into
epithenial lining of the palatine tonsil
what does the 3rd branchial pouch (dorsal wings) develop into
INFERIOR PARATHYROIDS
what does the 3rd branchial pouch (ventral wings) develop into
thymus
what does the 4th branchial pouch develop into
superior parathyroids
aberant development of 3rd and 4th pouches can result in this syndrome which leads to T-cell deficiency (thymic aplasia) and hypocalcemia (failure of parathyroid development
DiGeorge syndrome
The development of the thyroid: The thyroid diverticulum arises from the floor of primitive pharyx, which descends into the neck. It is connected to the tongue by the thyroglossal duct, which normally disappears but may persist as a pyramidal lobe of thyroid. Foramen cecum is normal remnant of thyroglossal duct. The most common ectopic thyroid tissue is found at this site
tongue
A cleft lip is the result of failure of fusion of these two processes
maxillary and medial nasal processes (formation of primary plate)
A cleft palate is failure of fusion of these things
lateral palatine processes, the nasal septum, and/or the median palatine processes (formation of secondary paalate)
diaphram is derived from 4 sxs what are they
1) septum transversum
2) pleuroperitoneal folds
3) body wall
4) dorsal mesentery of esophagus
mneu: Several Parts Build Diaphram
Diaphram descends during dvlpmt but maintains innervation from above. what is the innervation.
C3-5
mneu: C3,4,5 keeps the diaphram alive
incomplete develop of the diaphram may cause abdominal contents to herniate into the thorax. What is this called
hiatal hernia
what part of the gut is the pancreas derived
foregut
which pancreatic bud develops into the pancreatic head, uncinate proces (lower half of head), and main pancreatic duct.
ventral pancratic bud
which pancreatic bud develops into the body, tail, isthmus, and accessory pancreatic duct
dorsal pancreatic duct
this describes when ventral and dorsal pancreatic buds abnormally encircle the duodenum forming a ring of pancreatic tissue that may cause duodenal narrowing
annular pancreus
T or F: Spleen arises from dorsal mesentary but is supplied by artery of foregut
T
name the genital ducts of the embryo
mesonephric (wolffian) duct
paramesonephric (mullerian) duct
what does the mesonephric (wolffian) duct develop into
Seminal vesicles, Epididymis, Ejaculatory duct, and Ductus deferens
what does the paramesonephric (wolffian) duct develop into
fallopian tube, uterus, and part of vagina
this substance secreted by the testes, suppresses development of paramesonephric ducts in males
mullerian inhibiting substance
increase in these hormones cause the development of the mesonephric ducts
increase androgens
genetial tubercle exposed to dihydrotestosterone will develop into
glans penis
genetial tubercle exposed to estrogen will develop into
glans clitoris
UG sinus exposed to dihydrotestosterone will develop into
corpus spongiosum, bulbourethral glands (cowpers), prostate gland
UG sinus exposed to estrogen will develop into
vestibular bulbs, greater vestibular glands (of Bartholin), urethral and paraurethral glands (of Skene
UG folds exposed to dihydrotestosterone will develop into
ventral shaft of penis (penile urethra)
UG folds exposed to estrogen will develop into
labia minora
labioscrotal swelling exposed to dihydrotestosterone will develop into
scrotum
labioscrotal swelling exposed to estrogenwill develop into
labia majora
