Lets know complete about Placenta

Placenta is the intimate connection between the foetus and uterine wall of the mother to exchange the materials. The outer surface of the chorion in human develops a number of finger like projection, known as chorionic villi, which grows into the tissue of the uterus.

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Pla­cen­ta

These vil­li , pen­e­trate the tis­sue of the uter­ine wall in which they are embed­ded, make up the organ known as the pla­cen­ta by means of which the devel­op­ing embryo obtains nutri­ents and oxy­gen and gets rid of car­bon diox­ide and meta­bol­ic wastes. Because of the chori­on­ic takes part in the for­ma­tion of pla­cen­ta, the human pla­cen­ta is called the chori­on­ic placenta.

It con­sist of foetal part, the chori­on and a mater­nal part the decid­ua basalis. The foetal part of pla­cen­ta grows to invade the uter­ine mucosa with its chori­on­ic villi. 

The degree of inti­ma­cy is so strong that the blood ves­sels of the chori­on­ic vil­li are bathed in moth­er’s blood.This is due to ero­sion of the uter­ine mucosa, includ­ing its epithe­li­um, con­nec­tive tis­sue and the endothe­lial lin­ing. This type of pla­cen­ta which is based on the inti­ma­cy between foetal and mater­nal parts of the pla­cen­ta, is referred to as haemo­cho­r­i­al placenta.

The pla­cen­ta is con­nect­ed to embryo through an umbil­i­cal cord which helps in the trans­port of sub­stance to and from the embryo. On the basis of the dis­tri­b­u­tion of vil­li on chori­on ‚human pla­cen­ta is called Metadis­coidal Placenta.

The placenta performs the following functions:-

(i) Nutri­tion : All the nutri­tive ele­ments from the mater­nal blood pass into the foe­tus through the placenta.

(ii) Res­pi­ra­tion, Oxy­gen pass­es from the mater­nal blood to the foetal blood through the pla­cen­ta, and car­bon diox­ide pass­es in the reverse direction.

(iii) Excre­tion, the foetal excre­to­ry prod­ucts dif­fuse into the mater­nal blood through pla­cen­ta and are excret­ed by the mother.

(iv) Stor­age, pla­cen­ta stores glyco­gen, fat etc.

(v) As a bar­ri­er. Pla­cen­ta soaps and effi­cient bar­ri­ers and allow those mate­r­i­al to pass into the fetal blood that are nec­es­sary. Ter­ato­gens are cer­tain agent (virus or Chem­i­cals )or drugs that cause abnor­mal devel­op­ment in devel­op­ing embryo /foetus.

The most well-known syn­thet­ic Ter­ato­gen drug is thalido­mide. this drug caus­es mul­ti­ple dif­fer­ent in the grow­ing embryo.

(vi) Endocrine func­tion. Pla­cen­ta secretes hor­mones such as oestro­gen, prog­es­terone, human chron­ic gonadotropin(hCG), human chori­on­ic somatomam­motropin — (hCS). (It was for­mer­ly known as human pla­cen­tal lac­to­gen HPL), chori­on­ic thy­rotropin, chori­on­ic cor­ti­cotropin and relaxing. 

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Pla­cen­ta Foetus

The hCG stim­u­lates and main­tains the cor­pus luteum to secrete prog­es­terone until the end of preg­nan­cy. The hCG stim­u­lates the growth of the mam­ma­ry glands dur­ing preg­nan­cy. Relax­in facil­i­tates par­tu­ri­tion (act of birth) by soft­en­ing the con­nec­tive tis­sue of the pubic symphysis.

In addi­tion, the lev­els of hor­mones like oestro­gens, prog­es­terone, cor­ti­sol, pro­lactin, thy­rox­ine, etc. Are increased in the mater­nal blood dur­ing preg­nan­cy. Increased pro­duc­tion of these hor­mone is nec­es­sary for sup­port­ing the fetal growth ‚meta­bol­ic changes in the moth­er and main­te­nance of pregnancy.

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