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Placenta & Fetal Circulation

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Placenta & Fetal Circulation PLACENTA & FETAL CIRCULATION Reproductive block …………………………………………………………………………… Objectives​ : Unknown​ .. Resources​ : ✓ 435 embryology (males & females) lectures. ✓ BRS embryology Book. ✓ The Developing Human Clinically Oriented Embryology book. Color Index: ✓EXTRA ✓Important ✓Day, Week, Month Team members Afnan AlMalki & Helmi M AlSwerki. Sarah AlMutawa Razan AlSabti Reem Alageel Monirah Alsalouli \ اﻟﻤﺸﯿﻤﺔ Placenta​: ​video​ ​video ﯾﻌﻨﻲ ﺗﻜﻮﻧﺖ ﻣﻦ اﻷم واﻟﺠﻨﯿﻦ It is a Fetomaternal structure ﻗﺒﻞ ﻛﺬا ﻛﺎن ﯾﺆدي وﻇﯿﻔﺘﻬﺎ اﻟﻜﻮرﺑﺲ ﻟﯿﻮﺗﯿﻢ .Formed by the beginning of the 4th month ﺑﺲ ﻟﻮ ﻣﺎ ﺗﻜﻮﻧﺖ اﻟﺒﻼﺳﻨﺘﺎ ﺑﯿﺤﺼﻞ إﺟﻬﺎض ﻣﻮ ﻣﻌﻨﺎﺗﻪ ﻟﻮ ﻣﺎﺗﻜﻮﻧﺖ ﯾﺴﺘﻤﺮ اﻟﻜﻮرﺑﺲ ﻟﯿﻮﺗﯿﻢ ﻻ ﺑﺲ ﯾﻈﻬﺮ ﺑﺎﻟﺒﺪاﯾﺔ وﯾﻌﻄﻲ اﻟﺒﻼﺳﻨﺘﺎ وﻗﺖ ﻟﻠﺘﻜﻮن It is the primary site for exchange of gases and nutrients between the mother and the fetus. Formation of Placenta ​forms at the site of implantation Fetal Part Maternal Part - Villous Chorion: - Decidua Basalis:​ ​part of the decidua ​deep It is the ​bushy​ area at the embryonic pole to the conceptus. ​conceptus = Zygote - ​Decidua Gravid Endometrium:​ it is the Its villi are more in number, enlarged and functional layer​ of the endometrium during branch profusely pregnancy which is ​shed after parturition​. Full Term Placenta ​ ​just before birth Discoid in shape. Weighs (500 – 600)g. ﻋﺸﺎن ﻛﺬا اﻷم أول ﻣﺎ ﺗﻮﻟﺪ ﺗﻔﻘﺪ ﻧﺼﻒ ﻛﯿﻠﻮ ﺑﺴﺒﺒﻬﺎ ﻫﺬا ﻏﯿﺮ ﻓﻘﺪاﻧﻬﺎ ﻟﻮزن اﻟﺒﯿﺒﻲ وﻛﻤﯿﺔ اﻟﺴﻮاﺋﻞ :Has two surfaces Fetal Surface Maternal Surface 1. ​Smooth ​because it is covered with the Rough​. Formed of ​(15 –20​) irregular convex which are separated ارﺗﻔﺎع (amnion. areas (Cotyledons ﯾﻔﺼﻠﻮن اﻻرﺗﻔﺎﻋﺎت ﻋﻦ ﺑﻌﺾ .(The umbilical cord is attached to its center. by grooves (placental septa .2 3. The ​chorionic vessels​ are ​radiating​ from Each cotyledon is covered by a thin layer of ﯾﻐﻄﻮن اﻻرﺗﻔﺎﻋﺎت.theumbilical cord decidua basalis ﺑﻬﺬه اﻟﺠﺰﺋﯿﺔ ﻏﯿﺮﻧﺎ اﺳﺘﺪﻻﻻت اﻻﻟﻮان اﻻﺣﻤﺮ دم ﻣﺆﻛﺴﺞ و اﻻزرق دم ﻏﯿﺮ ﻣﺆﻛﺴﺞ واﻟﻠﻲ ﺗﺤﺘﻪ ﺧﻂ اﻟﻤﻬﻢ - Structure of a ​Cotyledon​: consists of ​two or more stem villi​ ​with their many branch villi. It receives (80-100) ​maternal spiral arteries​ that enter the intervillous spaces at regular intervals - Intervillous Space: ​large​ blood filled spaces​ ​which are freely communicating They​ receive spiral arteries​ from the lacunae in the ​syncytiotrophoblast​. The spaces are drained through ​endometrial veins. ​Both arteries and veins pass through pores in the ​cytotrophoblastic shell. اﻟﻜﻮﺗﯿﻠﯿﺪون ﻣﺜﻞ ﻣﺎ ﻗﻠﻨﺎ ﻗﺒﻞ إﻧﻬﺎ ارﺗﻔﺎع، ﯾﻌﻨﻲ زي اﻟﺠﺒﻞ داﺧﻠﻪ 2 أو أﻛﺜﺮ ﻣﻦ ﻣﻌﺒﺮ ﻟﻠﺒﻠﻮد ﻓﺰﻟﺰ ﻧﺴﻤﯿﻬﻢ ﺳﺘﯿﻢ ﻓﯿﻼي ، ﻛﻞ ﺳﺘﯿﻢ ﻓﯿﻼي ﺑﯿﺪﺧﻞ وﯾﺘﻔﺮع ﯾﺼﯿﺮ اﺳﻢ اﻟﺘﻔﺮﻋﺎت ﻓﯿﻼي و ﺑﯿﺪﺧﻞ ﻓﻲ ﺗﺠﻮﯾﻔﻬﻢ اﻻﻣﺒﻼﯾﻜﻞ ﺑﻠﻮد ﻓﺰﻟﺰ ﻣﻦ اﻟﺠﻨﯿﻦ، ﻓﻨﻘﺪر ﻧﻘﺴﻢ اﻟﻔﯿﻼي ﻟـ3 ﻣﺮاﺣﻞ أول ﻣﺎ ﺻﺎر ﻟﻬﺎ ﺗﻔﺮع ﺗﻜﻮن ﺑﺮاﯾﻤﺮي ﺑﻌﺪﯾﻦ ﯾﺰﯾﺪ اﻟﺘﻔﺮع ﺗﺼﯿﺮ ﺳﻜﻨﺪري ﺑﻌﺪﯾﻦ ﯾﺪﺧﻞ ﻓﯿﻬﺎ اﻻﻣﺒﻼﯾﻜﺎل ﻓﺰﻟﺰ ﺗﺼﯿﺮ ﺗﯿﺮﺷﺮي، ﻃﯿﺐ اﻟﺤﯿﻦ ﻫﺬه اﻟﻔﯿﻼي، راح ﯾﻜﻮن ﻓﯿﻪ ﺑﯿﻨﻬﻢ ﻣﺴﺎﻓﺎت ﻧﺴﻤﯿﻬﺎ اﻧﺘﺮﻓﻠﺲ ﺳﺒﯿﺲ ﺑﺘﺴﺘﻘﺒﻞ 100 ﺳﺒﺎﯾﺮل ارﺗﺮي ﺟﺎي ﻣﻦ اﻧﺪوﻣﺘﺮﯾﻢ اﻷم، ﻣﺴﻤﯿﻨﻪ ﺑﺎﻟﺼﻮرة اﻧﺪوﻣﺘﺮﯾﺎل ارﺗﺮي، ﯾﻌﻄﻲ اﻟﺠﻨﯿﻦ اﻟﻐﺎزات واﻟﻤﻮاد اﻟﻤﻐﺬﯾﺔ اﻟﻼزﻣﺔ وﯾﺮﺟﻊ ﻋﻠﻰ ﻫﯿﺌﺔ اﻧﺪوﻣﺘﺮﯾﺎل ﻓﯿﻦ ُﯾﻔ ّﻀﻞ ﺗﺒﺪون ﺑﺪورة اﻷم Placental Circulation 2-​Fetal Placental Circulation 1-​ Maternal Placental Circulation Two Umbilical Arteries: 80 –100 ​spiral endometrial arteries​ discharge Carry ​poorly oxygenated​ blood from the fetus into the intervillous space. The blood is to the placenta. propelled in ​jet like fountains by the maternal within the branch chorionic villi, they form: blood pressure. Arterio-capillary venous network: The pressure of this entering blood is higher It brings the fetal blood extremely close to the than that in the intervillous space. maternal blood. It forms a roof of the space. As the pressure The well oxygenated fetal blood in the dissipates, the blood flows slowly around the capillaries passes into veins accompanying the branch villi. chorionic arteries. Exchange of metabolites and gases with the At the umbilical cord, they form the fetal blood. As the pressure decreases, the One Umbilical Vein. blood flows back from the​ chorionic plate​ and enter the​ endometrial veins​ to the maternal circulation. ﻛﯿﻒ ﺗﻨﺘﻘﻞ اﻟﻐﺎزات ﻣﻦ اﻷم إﻟﻰ اﻟﺠﻨﯿﻦ؟ ﺑﺘﺘﺤﺮك ﻣﻦ اﻟﻀﻐﻂ اﻟﻌﺎﻟﻲ(دم اﻷم) ﻗﻠﻨﺎ ﻓﻮق إن اﻟﻔﯿﻼي ﯾﺤﺘﻮي ﻋﻠﻰ اﻻﻣﺒﻼﯾﻜﺎل ﻓﺰﻟﺰ، وﺑﻤﺎ إﻧﻬﺎ ﻓﺰﻟﺰ ﯾﻌﻨﻲ ارﺗﺮي إﻟﻰ اﻟﻀﻐﻂ اﻟﻤﻨﺨﻔﺾ(دم اﻟﺠﻨﯿﻦ) ﻃﯿﺐ وﻣﯿﻦ اﻟﻲ ﺑﯿﻌـﻠﻲ ﺿﻐﻂ اﻷم؟ وﺟﻮد وﻛﺎﺑﻠﺮي وﻓﯿﻦ، ﻃﯿﺐ ﺧﻠﻮﻧﺎ ﻧﻌﺮف اﻷﺣﺪاث ﺑﺎﻟﺘﺮﺗﯿﺐ: ﺑﺎﻟﺒﺪاﯾﺔ اﻟﻔﯿﻼي ﺑﯿﺪﺧﻠﻬﺎ ﺟﺰﺋﺎت اﻻوﻛﺴﺠﯿﻦ، ﺑﺎﻟﺘﺎﻟﻲ ﻟﻮ اﻷم ﻛﺎن ﻋﻨﺪﻫﺎ اﻧﯿﻤﯿﺎ وﻗﻞ اﻻوﻛﺴﺠﯿﻦ 2 اﻣﺒﻼﯾﻜﺎل ارﺗﺮﯾﺰ ﻣﻦ اﻟﺠﻨﯿﻦ ﯾﺤﺘﻮي ﻋﻠﻰ دم ﻏﯿﺮ ﻣﺆﻛﺴﺞ ، ﺑﯿﺘﺤﻮل اﻻرﺗﺮي .واﻧﺨﻔﺾ ﺿﻐﻄﻬﺎ ﻣﺎ راح ﯾﺤﺼﻞ ﻓﯿﻪ ﺗﺒﺎدل ﻏﺎزات اﻟﻰ ﻛﺎﺑﻠﺮي ﻋﺸﺎن ﺗﺤﺪث ﻋﻤﻠﯿﺔ ﺗﺒﺎدل اﻟﻐﺎزات، ﺑﯿﺎﺧﺬﻫﺎ ﻣﻦ دم اﻻم اﻟﻲ ﺟﺎي ﻃﺮﯾﻘﺔ ﺿﺦ اﻻرﺗﺮي ﻓﻲ اﻟﺴﺒﯿﺲ ﺑﺘﻜﻮن زي اﻟﻨﺎﻓﻮرة ﻛﻞ ﻣﺎ زاد ﺿﻐﻂ اﻷم ﻣﻦ اﻟﺴﺒﺎﯾﺮل ارﺗﺮي وﺻﺐ ﻓﻲ اﻻﻧﺘﺮ ﻓﻠﺲ ﺳﺒﯿﺲ، وﺑﻌﺪ ﻣﺎ ﺗﻨﺘﻬﻲ ﻋﻤﻠﯿﺔ ﺗﺒﺎدل ﺑﯿﻀﺦ وإذا ﻗﻞ اﻟﻀﻐﻂ ﺑﯿﻘﻞ ﺑﻤﻌﻨﻲ إن اﻟﻀﺦ ﻣﻮ ﻣﺴﺘﻤﺮ ﺑﯿﻌﺘﻤﺪ ﻋﻠﻰ اﻟﻀﻐﻂ اﻟﻐﺎزات اﻟﻜﺎﺑﻠﺮي ﺑﯿﺠﺘﻤﻊ ﻣﻊ اﻟﻜﻮرﯾﻮﻧﻚ ارﺗﺮي وﯾﺼﯿﺮون 1 ﻓﯿﻦ ﻧﺴﻤﯿﻪ اﻣﺒﻼﯾﻜﺎل ﻓﯿﻦ وﻫﻨﺎ ﺑﯿﺤﺘﻮي ﻋﻠﻰ دم ﻣﺆﻛﺴﺞ . ﺣﺎﺟﺰ ﺑﯿﻦ اﻟﻤﺘﺮﻧﻞ واﻟﻔﯿﺘﺎل ﺑﻠﻮد :Placental Membrane It is a composite thin membrane of extra fetal tissues which separates the fetal and maternal bloods. Up to ​20 weeks​, it is composed of ​4​ layers: ​(pic B) 1. Syncytiotrophoblast.​ ​most outer 2. Cytotrophoblast. 3. Connective tissue of the villus​. 4. Endothelium of fetal capillaries. At full term​ it becomes thinner and composed of ​3​ layers only: ​(pic ​C​) اﻟﺠﻨﯿﻦ ﻛﺒﺮ ﻓﯿﺤﺘﺎج راﺑﺪ ﺗﺮاﻧﺴﻔﯿﻮﺷﻦ ﻓﺒﯿﺘﺨﻠﺺ ﻣﻦ واﺣﺪ ﻣﻦ اﻟﻠﯿﺮز اﻷرﺑﻌﺔ وﻫﻮ ال ﺳﺎﯾﺘﻮﺗﺮوﻓﻮﺑﻼﺳﺖ 1. Syncytiotrophoblast. 2. Connective tissue. 3. Endothelium of the capillaries. At some sites, the syncytio comes in direct contact with the endothelium of the capillaries and forms ​Vasculo-Syncytial​ placental membrane. FUNCTIONS OF THE PLACENT 1-Metabolic اﻟﻤﺸﯿﻤﺔ ﻫﻲ ﺑﻨﻔﺴﻬﺎ ﺗﺼﻨﻌﻬﻢ ﻣﺎ ﺗﻌﺘﻤﺪ ﻋﻠﻰ اﻻم .Synthesis of: Glycogen, Cholesterol and Fatty Acids- -They supply the fetus with nutrients and energy. 2-Transportation -Exchange of O2, CO2 and CO is through simple diffusion. ﻓﺎذا .Gases -The fetus extracts (20 –30) ml of O2/minute from the maternal blood ﺻﺎر ﻟﻼم ﻫﯿﺒﻮﻛﺴﯿﺎ راح ﯾﺼﯿﺮ ﻟﻠﺠﻨﯿﻦ Nutrients & -Water, Amino acids, Carbohydrates, Vitamins and Free Fatty Acids are Electrolytes: rapidly transferred to the fetus. Maternal -Maternal​ immunoglobulin G​ gives the fetus passive immunity to some Antibodies infectious diseases (measles, small box) and not to others (chicken box). ﻟﻬﺬا ﺑﻌﺪ اﻟﻮﻻدة ﻣﺎ ﯾﻌﻄﻰ اﻟﻄﻔﻞ ﺗﻄﯿﻤﺎت اﻟﺤﺼﺒﻪ اﻻ ﺑﻌﺪ 4-3 ﺷﻬﻮر, ﻻن اﻻﻧﺘﻲ ﺑﺎدﯾﯿﺰ اﻟﻲ اﺧﺬﻫﺎ ﻣﻦ اﻻم ﺑﺪت ﺗﺮوح Drugs & Drug -They cross the placenta by simple diffusion. metabolites -They can affect the fetus directly or indirectly by interfering with placental metabolism. Hormones -Protein hormones do not reach the embryo in sufficient amounts. some of these hormones (​Thyroxine & Testosterone ​which may cause masculinization of a female fetus) ​can cross ​the placental membrane. Waste products -Urea and uric acid pass through the placental membrane by simple diffusion. 3-Endocrine Synthesis اذا ﻣﺎ ﻓﯿﻪ.Progesterone Maintains pregnancy if the corpus luteum is not functioning well ﺑﺮوﺟﺴﺘﺮون ﻣﺎ ﺑﯿﻜﻤﻞ اﻟﺤﻤﻞ وﺑﺘﺠﻬﺾ اﻷم Estrogen Stimulates uterine growth and development of the mammary glands.​for lactation ​hCS or Hpl -A growth hormone that gives the fetus the priority on maternal blood hCS=Human Chorionic glucose. Hpl : playing a role in gestational diabetes. Somatomammotropic. ​ Hpl=Human Placental -It promotes breast development for milk production. lactogen. ﯾﻈﻬﺮ ﺑﺪري .hCG Maintains the corpus luteum and used as indicator of pregnancy ﺑﺎﻟﺤﻤﻞ Drugs that can cross the placental membrane: ● Fetal drug addiction can be due to some drugs as Heroin, ​Nicotine and Alcohol​. ​(the baby after birth will have withdrawal symptoms) ● All sedatives and analgesics can affect the fetus to some degree. ﻋﺸﺎن ﻛﺬا .Drugs used for management of labor can cause respiratory distress to the newborn ● ﺑﻮﻗﺖ اﻟﻮﻻدة ﻧﻌﻄﻲ اﻷم ﺟﺮﻋﺔ ﻗﻠﯿﻠﺔ ﻣﻦ اﻟﻤﺨﺪر وﺑﻌﺪ ﻣﺎ ﯾﻄﻠﻊ اﻟﻄﻔﻞ ﻧﺰﯾﺪ اﻟﺠﺮﻋﺔ ﻋﺸﺎن اﻟﺨﯿﺎﻃﺔ وﻏﯿﺮه Mechanism of transportation ​in boys slides only the transportation through the placental membrane is by one of the following mechanism: ● Simple (passive)​ ​diffusion ﻣﻦ اﻻﻋﻠﻰ اﻟﻰ اﻻﻗﻞ .Depends on difference in pressure ● Active transport Requires energy. ● Facilitated transport Through electrical discharge. ● Pinocytosis The material engulfer is a small sample of extracellular fluid. Anomalies of Placenta: depends on structure (Placenta Accreta) or position (Placenta Percreta & Previa) Placenta ​A​ccreta Placenta Percreta Placenta Previa ﺑﺪال ﻣﺎ ﺗﻜﻮﻧﺖ ﺑﺎﻻﻧﺪوﻣﯿﺘﺮﯾﻮم ﺗﻜﻮﻧﺖ Abnormal ​A​bsence of The blastocyst is implanted close to ﺑﺎﻟﻤﺎﯾﻮﻣﺘﺮﯾﻮم (اﻟﻌﻀﻠﻪ) chorionic villi with partial or overlying the ​internal uterine os. or complete absence of Chorionic villi penetrate the It is associated with late pregnancy myometrium to the ​ .bleeding ﻣﺎ ﯾﻜﻤﻞ .the decidua basalis .perimetrium اﻟﺤﻤﻞ Delivery is through ​Cesarean ﻟﯿﻪ ﺗﻮﻟﺪ ﻗﯿﺼﺮي ؟ ﻻن ﻫﻨﺎ اﻟﻤﺸﯿﻤﺔ ﺑﺘﻄﻠﻊ ﻗﺒﻞ اﻟﻄﻔﻞ .The most common presenting section وﻗﺖ اﻟﻮﻻدة ﻓﺎذا ﻃﻠﻌﺖ ﻗﺒﻠﻪ ﻛﯿﻒ ﺑﯿﺘﻨﻔﺲ ﺑﺘﺴﺒﺐ ﻟﻪ اﺧﺘﻨﺎق ﻓﺎﻟﺤﻞ sign of these two anomalies is اﻻﻣﺜﻞ اﻟﻘﺼﯿﺮي ﻣﺎ ﯾﻜﻤﻞ اﻟﺤﻤﻞ .trimester bleeding ﺑﻌﺪ رﺑﻊ اﻟﻰ ﺛﻠﺚ ﺳﺎﻋﺔ ﻣﻦ اﻟﻮﻻدة ﺗﺒﺪأ اﻻﻧﻘﺒﺎﺿﺎت ﻣﺮه ﺛﺎﻧﯿﻪ :Fate of Placenta The strong uterine contractions that continue after birth compress uterine blood vessels to limit bleeding and cause the placenta to detach from the uterine wall (within 15 minutes after birth of دور اﻟﻄﺒﯿﺐ ﯾﺘﺄﻛﺪ أن اﻟﻤﺸﯿﻤﺔ ﻧﺰﻟﺖ ﻛﺎﻣﻠﻪ, ﻻن اذا ﺑﻘﻲ ﻗﻄﻌﻪ ﻣﺎ ﻧﺰﻟﺖ ﺑﯿﺼﯿﺮ ﻧﺰﯾﻒ ﻟﻸم .(the infant ​Fetal Circulation ​ ​video Fetal Cardiovascular system is designed: 1-To serve prenatal needs. 2-To permit modifications at birth, which establish the neonatal circulation. Important structures in transitional circulation Ductus venosus Ductus arteriosus Foramen ovale 1 1. After ligation of the 2. After Aeration of the ​lungs at birth​: umbilical cord: 1. Sudden fall of blood pressure in 1. Marked ​increase​ in the pulmonary ​blood flow​. the IVC and the right Atrium. 2. Dramatic ​fall ​in pulmonary vascular ​resistance​. 2. The valve ​(between IVC and umbilical vein) 3. Thinning​ in the wall of the pulmonary arteries​. of the ductus venosus constricts. 3. Changes ​after birth​: ﺗﻘﻔﻞ ﻣﺮه وﺣﺪه ﻣﺎ ﺗﺤﺘﺎج ﻓﺘﺮات ﻋﻜﺲ اﻟﺪﻛﺖ ارﺗﯿﺮﯾﻮﺳﯿﺲ :Closure of foramen ovale .1 A. Physiological closure(​“concomitant of ligation​”​ ​different in pressure, pressure drop in right atrium) B. Anatomical closure​.”requires 3 months” 2. Constriction of ductus arteriosus​ : A.
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