Embryo USMLE Flashcards by Mani Yavi

give the day/week in a pregnancy– fertilization by sperm, initiating embryogenesis

day 0

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give the day/week in a pregnancy –implantation (as a blastocyst)

w/in week 1

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give the day/week in a pregnancy– bilaminar disk

w/in week 2

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give the day/week in a pregnancy– gastrulation, primitive streak, notochord, and neural plate begin to form

w/in week 3

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give the day/week in a pregnancy–neural tube formed. Organogenesis. Extremely susceptible to teratogens

Week 4

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give the day/week in a pregnancy-heart begins to beat. Upper and lower limb buds begin to form

week 4

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give the day/week in a pregnancy–genitalia have male/female characteristics

week 10

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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

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rule of 3s for 3rd week

3 germ layers (gastrula) ectoderm, mesoderm, endodderm

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the epiblast (precursor to ectoderm) invaginates to form this.

primitive streak

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cells from the primitive streak give rise to what

both intraembryionic mesoderm and endoderm

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give some adult sxs that arise from the surface ectoderm

adenohypophysis, lens of eye, epithelial linings, epidermis

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give some adult sxs that arise from the neuroectoderm

neurohypohyisis, CNS neurons, oligodendrocytes, astrocytes, ependymal cells, pineal gland

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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

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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.

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give some adult sxs that arise from the endoderm

gut tube epithelium and derivitives (e.g., lungs, liver, pancreas, thymus, parathyroid, thyroid follicular cells).

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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

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when are babies most susceptible to the effects of teratogens

3rd-8th weeks (organogenesis)

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given the teratogen give some possible effects on the fetus:

etoh

birth defects and mental retardation (leading cause); FAS

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given the teratogen give some possible effects on the fetus: ACE inhibitors

renal damage

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given the teratogen give some possible effects on the fetus: Cocaine

abnormal fetal dvlpmt and fetal addiction

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given the teratogen give some possible effects on the fetus: DES

vaginal clear cell adenocarcinoma

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given the teratogen give some possible effects on the fetus: iodide

congenital goiter or hypothyroidism

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given the teratogen give some possible effects on the fetus: 13-cis-retinoic acid

extremely high risk for birht defects

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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

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