Chapter 3 Physiology in pregnancy

1. Chapter 3 Physiology in pregnancy • pregnancy:the condition of being with child or gravid.from the fertilization to the expelling of the fetus with placenta and membranes. • Sec.1 fertilization, development,transport and implantation of fertilized ovum. • Sec.2 the formation and function of fetal attachment. • Sec.3 the maternal changes during pregnancy.

2. Sec.1 fertilization, development,transport and implantation of fertilized ovum • 1.fertilization:semen enters vagina→spermatozoons contact with endometrium,the α-/β-amylase remove the decapacitation factor on spermatozoons’ acrosomal enzyme,then the spermatozoons with the ability of fertilization(capacitation) in uterrus and fallopian tubes,the spermatozoons meet the ovum at the ampulla→external mem. Of acrosome rupture→acrosomal enzyme released(acrosome reaction) →the spermatozoons penetrate the radiate corona and zone pellucida→Fusion

3. 2.implantation:fertilized ovum→vitelline sphere (early blastosphere) →into uterine cavity→late blastosphere→implantation including apposition,adhesion,penetration. • The necessary factors: • (1)the zone pellucida disappear. • (2)the syncytiotrophoblastic cells appear. • (3)synchronic development of blastosphere and endometrium. • (4)enough progesterone. • 3.decidua formation:thicker,more vascular and edematous than premenstrual endometrium.

4. Sec.3 changes during pregnancy • (一)changes of reproductive tract. • 1.uterus • (1)corpus:a increase in size (7*5*3→35*22*25cm),the capacity (5→5000ml),the weight(50→1000g),the thickness(1→0.5-1cm);the rate of the hypertrophy of different parts varies(fundus→inferior portion→cervix) so that the contractility decreases from fundus to cervix , the fetus is delivered.

5. with the pregnant weeks,more vascular(500-700ml/min) • (2)isthmus:softer and longer(1→7-10cm) • (3)cervix:increased vascularity,edema of the entire cervix,hyperplasia of cervical glands. • 2.ovary. • 3.fallopian tubes. • 4.vagina: violet coloration;desquamation of epithelium with more glycogen↑→acidity↑. • 5.vulva:pigmentation. • (二)breasts

6. An increase in size and a nodular sensation due to the hypertrophy of the mammary alveoli,the nipples soon become larger ,more deeply pigmented and more erectile.scattered around the areola are some roundish nodules called Montgomery tubercles which result from the hypertrophy of the sebaceous glands. • 三.circulatery system • 1.heart:the growing uterus pushes the diaphragm upward,with the result that the heart is displaced to the left,upward and somewhat in the direction of the anterior chest wall.a certain degree of rotation is believed to take place.the capacity increases by 10%, the heart rate increases by 10-15bpm. • 2.output:increases from 10weeks,the peak at 32-34w. • 3.Bp.:few changes if any.

7. 4.venous pressure:increased vp, in the legs is demonstrable in later months of pregnancy,which contributes to the ankle edema,varicose veins in the legs and vulva during gestation. • Supine hypotension syntrom:supine position for a long time →inferior vene cava compressed→back-volume↓→output↓→Bp↓→cm. of hypotension. • (四)blood system • 1.volume:increasing from 6-8w,peak at 32-34w, about 1500ml(1000ml of plasma,500ml of erythrocytes→hemodilution) • 2.composition:RBC→3.6*1012/L,Hemoglobin→110g/L, WBC→10*109-12*109/L,coagulating factors→most inceasing→hyper-coagulation,plasmal protein decreases mildly due to hemodilution.

8. (五)urinary system • both RPF. and GFR.increase by about 35% and 50% respectively ,the metabolites of the gravida /fetus can be excreted.under the influence of progesterone,a condition of atonia in relaxation or loss of irritability not only of uterus,but also of the ureters,large bowel and bile ducts→dilatation of ureters and renal pelvis associated with stasis of urine → acute nephropyelitis especially in the right side. • (六)respiratory system:in a word,the ventilation volume increases;the immunologic competence↓. • (七)digestive sys:estrogen→gingiva-hyperplasia progesterone→atonia of stomach and bowel→ heart burn,vomit,constipation

9. (八)skin • 1.the pigmentation of the areola,linea alba, vulva,occasionally irregularly shaped,brownish patches of varying size appear on the face and neck,the cloasma or the mask of pregnancy,which fortunately usually disappears after delivery. • 2.during late months of pregnancy,reddish,slightly depressed streaks often develop in the skin of abdomen,and sometimes also in the skin covering the breasts and the thighs.these striae gravidarum occur in about 1/2 of all pregnancies. • (九)endocrine changes • 1.pituitary gland:the anterior lobe hyperplasia • (1)high level of E and P→inhibites Gn releasing • (2)PRL:increases from 7w,peak ante-delivery • 2.adrenalin cortex:the level cortisol and aldosterone increases by 3 and 4 times respectively

10. 3.thyroid gland:the enlargement usually concomitant with normal pregnancy due to hypertrophy of adenomatous tissue,to an increase blood supply and to the formation of new follicles.but most thyroxin is connected with thyroxin binding globulin,so no hyperthyroidism occurs. • (十)metabolic changes • 1.BMR:mildly rising . • 2.weight: from 13w increases by 350g per week,about 12.5Kg during the entire pregnancy. • 3.metabolism of carbohydrate • (1)fasting-sugar higher due to higher insulin-secretion • (2)insulin-resistant factors • 4.fat metabolism

11. Deposit of fat increasing charaterized by a hyperlipemia and a tendency to ketosis. • 5.protein metabolism:positive nitrogen balance • 6.water metabolism:water-retention of about 7L • 7.mineral metabolism:in the late months of gestation→ • calcium and iron supplying→to avoid deficiency of calcium and iron. • (十一)bone,joint and ligament • 1.bone:no changes normally. • 2.joint and ligament:relaxin→loosening of joints and ligaments→the birth canal widened. thanks

12. implantation

14. Hegar

16. True basal capsular Decidua change

17. Striea gravidarum