Embryonic development Flashcards by Steve Gabbs

-After Fertilization

-40 Week process

	-9 months

	- 3 trimesters of 3 months each

-Three stages of growth and development

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-First stage

-period from conception to the completion of implantation (12 to 14 days)

	-Called an ovum

	-Rapid cell division

	-Attachment or implantation occurs

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-Second stage

-Period from end of the ovum stage to the time the embryo measures roughly 3 cm from head to rump (54-56 days)

	-Called an embryo

	-Tissues, organs, and organ systems differentiate

		-This is the stage where all your major organs start to develop and are the most vulnerable to the effects drugs

	-Germ Layers

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-Germ Layers

-Ectoderm- outer

		-Endoderm -inner

		-Mesoderm - between

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-Third stage

-period of fetal development (210-214 days)

	-Called a fetus

	-Continued growth of organ systems

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-After delivery development stages are identified as

-Neonate- delivery through 1st month

	-Infant - 1 month to 1 year

	-Child - greater than 1 year

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-Development and Function of Intrauterine Structures

Placenta

-Organ of respiration for the fetus

		-Provides nutrient and oxygen

		-At term occupies ⅓ of the uterine surface and weighs about 1 pound

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-Development and Function of Intrauterine Structures

-Umbilical cord

-Lifeline between mother and fetus

		-Consists of three vessels

			- one floppy vein and two arteries

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-Development and Function of Intrauterine Structures

-Amnion

-Sac surrounding the embryo

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-Development and Function of Intrauterine Structures

-Anionic Fluid

-At term is about 1 liter

-Constantly absorbed and replenished

-Allows fetal movement and provides protection

-Aids in the thermoregulation

-Poluhydramnios- abnormally large amount of fluid present at birth

-Oligohydramnios - scant or decreased amount of amniotic fluid

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-Five stages of Fetal Lung Development

-Embryonal stage - first 8 weeks

-Pseudoglanddular week 7 through 16

-Canalicular- week 17 through 26

-Saccular and alveolar week 27 onto post term

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-Development milestone in Utero

-Embryonal stage

-Day 21: Pharynx develops

	-Day 24: Lung development begins (lung bud)

	-Day 31 : Lobar bronchi

	-Week 4: primitive heart beats

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-Development milestone in Utero

-Psudoglandular stage

-Week 7:diagram complete

	-Week 10: cilia

	-Week 12: palates complete

	-Week 12: major lobes of the lungs

	-Week 13: Gobet Cells

	-Week 16: 25 generations of airway branching (dichotomy)

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-Development milestone in Utero

-Canalicular stage

-Week 24: Immature surfactant

	-Week 24- 25: Vessels close enough to alveoli for gas exchange

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-Development milestone in Utero

-Saccular and Alveolar stage

-Week 32-34: true Alveoli

	-Week 35 onward: Mature Surfactant

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-Surfactant

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-Substance that allows the alveoli to stay open

	-Allows different sizes alveoli to open at same pressure

	-Produced by type 2 pneumocytes (alveolar cells)

	-Composed of

		-Phopholipids (PC)

		-Phosphattidyglycerol (PG)

		-Neutral lipids and proteins

-Immature Surfactant

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-Seen at 24 weeks

	-Lacks PG

-Mature Surfactant (With PG)

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-Fist seen at 35 weeks

	-Production inhibited by hypoxia, hypothermia acidosis

	-Babies born without mature surfactant RDS

-Measurement of surfactant and determination of lung maturity

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-Can be measured in amniotic fluid

L/S ratio- PV (lecithin)/ Sphingomylin-Spingomylin constant from week 18-34, then decreases-Lethin - rapidly increases between week 32 & 34-2:1 indicates mature surfactant- very low indication of RDS

-Foam stability index (FSI) or known as shake test

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-Mix amniotic fluid with ethanol

-Shake for 15 seconds

-Reading made after 15 minutes

-If ring bubbles exists- mature surfactant

	-Do not use silicone tubes= False foam forms

-Lamellar body count

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-Most common test

-Simple and rapid method with good specificity

->32000 lamellar bodies predicts a mature L/S ratio

-Artifically induced lung maturation administration of steroids

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-Between 24 and 38 weeks

-At least 48 hours before but thin 1 week of delivery to do good

-Betamethasone most commonly used

	-Im in 2 does of 12mg, 24 hours apart

-Fetal lung fluid

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-Lungs act as a gland and secrete own fluid

-At tem, amount = 20-30 ml/kg (volume of FRC)

-Function in patency of developing lung structures

-Removed at birth by squeezing through birth canal, absorption by lymphatics

-Development of the cardiovascular system

-Heart

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-first major organ to develop

		-Fully formed and functioning by the 8th gestational week

		-There is no exchange of maternal and fetal blood

-Fetal Heart Development and circulation -Fetal circulation

-Unique features -Pressures- opposite of adult -Lungs increase resistance to blood flow (Low PaO2)

-Fetal Heart Development and circulation -Fetal circulation -Placenta

organ of gas exchange

-Fetal Heart Development and circulation -Fetal circulation -Umbilical cord-

- Lifeline between mother and fetus -2 Smaller arteries, 1 large floppy vein -Umbilical vein returns oxygenated blood from placenta to fetus

-Fetal Heart Development and circulation -Fetal circulation -Ductus venosus

-Ductus venosus diverts some blood from inferior vena cava

-Fetal Heart Development and circulation -Fetal circulation -Foramen ovale

-Foramen ovale- opening in the interatrial septum, diverts blood to the left atrium, allows blood rich in O2 be supplied to the brain and heart

-Fetal Heart Development and circulation -Fetal circulation -Ductus arterious

-Ductus arterious, blood is diverted from the pulmonary arty, supplies the lower part of the body (low in O2)

-Fetal Heart Development and circulation process Step 1.)

Step 1.)-Oxygenated blood enters the umbilical vein from the placenta, SaO2 approximately 80%

-Fetal Heart Development and circulation process Step 2.)

Step 2.)-Enters ductus venous and presses through inferior vena cava, mixing with deoxygenated blood, SaO2 approximately 70%

-Fetal Heart Development and circulation process Step 3.)

Step 3)-Enters the right atrium, a large proportion of this blood is shunted into the left atrium through the foramen ovale to the left ventricle (Supplies nourishment to the upper extremities, brain), the rest of the fetal blood entering the right atrium passes into the right venticale and out the through the pulmonary trunk, DSaO2 is approximately 55%

-Fetal Heart Development and circulation process Step 4.)

Step 4.)-A minimal portion of the blood travels from the pulmonary trunk to the lungs, most of the blood in the pulmonary trunk bypasses the lungs through the ductus arteriosus through the descending aorta, SaO2 approximately 55-60%

-Fetal Heart Development and circulation process Step 5.)

Step 5.) -The blood is carried by the descending aorta to various parts of the lower regions of the body, to the placenta where blood is reoxygenated

-Transition to extrauterine life

-After birth systemic blood pressure rises -Causes closing of foramen ovale -Ductus arteriosus occurs over 96 hours,if not closed will require surgical intervention

-Barorreceptors

-Stretch receptors -Stimulate bradycardia and hypotension -Located in the bifurcation of the carotid arteries and in the aortic arch

-Chemoreceptors

-Sensitive to PAO2, PACO2, and PH -Regulation of ventilation -Located in the carotid arteries and aorta and are called carotid and aortic bodies -Aid in initiation of first breath

Embryonic development Flashcards

(39 cards)