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Pregnan cy. Placenta Organ which provides nutrients & removes waste Complete by end of 3rd month Chorionic Villi (vascular projections from Chorion) are.

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Presentation on theme: "Pregnan cy. Placenta Organ which provides nutrients & removes waste Complete by end of 3rd month Chorionic Villi (vascular projections from Chorion) are."— Presentation transcript:

1 Pregnan cy

2 Placenta Organ which provides nutrients & removes waste Complete by end of 3rd month Chorionic Villi (vascular projections from Chorion) are embedded in endometrium & allow nutrient / waste exchange, via active transport & diffusion. (16m 2 SA) Attached to foetus via umbilical cord Umbilical veins, umbilical arteries (foetus) Uterine veins, uterine arteries (mother)

3 Early Embryonic Period Immediately after fertilisation zygote divides (cleavage) Journey between uterine tube  uterus (approx. 3-4 days) Cells divide but no new cytoplasm 36 hrs. 1st cleavage is complete 48 hrs. 2nd cleavage complete 72 hrs. 4th cleavage complete Cleavage continues forming a ‘blastocyst’ (approx. 5 days after fertilisation) Thin layer of cells surrounding a fluid filled cavity with one specific area of greater cell density (inner cell mass)

4 Early Embryonic Period cont. Acquires nutrients from uterine fluid Approx. 7-8 days after fertilisation blastocyst (0.25mm diameter) sinks into endometrium (due to an enzyme) and becomes firmly attached (implantation) Inner cell mass faces towards endometrium, blastocyst is completely covered. Nutrients from endometrium Increased oestrogen / progesterone from Corpus Luteum maintain endometrium & inhibit pituitary hormones

5 Early Embryonic Period cont. Chorion secretes HCG, maintains Corpus Luteum Secretion starts at 2nd week preg  3rd month. Then placenta secretes oestrogen / progesterone & doesn’t need Corpus Luteum.

6 first two months of pregnancy: embryo Primary Germ layers: after implantation, inner cell mass breaks up into 3 layers (Primary Germ Layers) 1. Ectoderm: (closer to body stalk) epidermis (top layer) of the skin, hair, nails, glands of skin, lens in the eye, receptor cells, epithelium in mouth, nose and anal canal, teeth enamel, nervous system, A. lobe of Pituitary gland, Adrenal medulla. Early Embryonic Period cont.

7 Primary Germ layers: 2. Mesoderm: (middle) Skeletal, smooth & cardiac muscles, connective tissues, lymphoid tissues, epithelium (top layers) of body / joint cavities, kidney, ureter, gonads, reproductive tracts, adrenal cortex & dermis of skin 3. Endoderm (furthest from body stalk) Epithelium of A.C., bladder, urethra, gallbladder, pharynx, larynx, trachea, lungs, tonsils, thyroid, thymus glands, vagina. Early Embryonic Period cont.

8 EARLY Embryonic Period cont. Embryonic Membranes Lie outside the embryo: protect and nourish Amnion: Encases embryo, filled with amniotic fluid By 8th day surrounds embryo Protection (shock absorber) Constant body temp Freedom of growth / movement Yolk Sac: First site of red blood cell formation placenta.

9 EARLY Embryonic Period cont. Embryonic Membranes Allantois: joins with yolk sac to become umbilical cord Chorion: outer cells of blastocyst with layer of mesodermal cells As amnion enlarges it fuses with Chorion. Chorion eventually becomes foetal placenta.

10 Embryonic Period 4 weeks: 4mm Development of muscle segments on either side of the ‘spine’ tube Tail evident, brain & liver begins to form, heart forms and begins to beat. 5 weeks Arm / leg buds appear 8 weeks 3cm, 1g Enlarged head with eye slits & jaw, nose & ear lobes Hands with fingers, feet with toes External sexual organs evident

11 FOETAL Period 12 weeks 6cm Body straightens, upright posture Finger toe nails appear & hair appears Bone marrow with red blood cells formed 16 weeks 18 cm, 100g Fingerprints Movement of foetus 120 – 160 / min (mum: 60 – 80 / min) Skeleton complete 20 week 25 cm, 300g Body covered with fine hair Gripping reflexes

12 FOETAL Period 24 weeks cm, 565 – 680 g Respiratory movements Digestive glands functioning Eyebrows / eye lashes 28 weeks 38 cm, 1kg+ Brain much larger with convolutions In males testes descend into scrotum All systems functioning minus respiratory 32 weeks 41 – 45cm, 2.2 kg Fat beneath skin 36 – 40 weeks 50 cm, 3.3 kg Boys approx 100g heavier Eyes open Well formed nose Fine body hair is shed

13 Pregnant Mother Signs of Pregnancy Failure to menstruate Fuller, firmer, more tender breasts Larger, darker nipples Morning sickness (nausea / vomiting) Increased urination frequency (pressure form uterus) Enlargement of abdomen. Changes to Mother during pregnancy no great change to a woman during embryonic period during lat foetal period, foetus has high demands mother functions slow down  nutrients stay in blood longer Constipation mothers blood vol increases (40%) & faster circulation (increased heart rate and vol) Increased urine production

14 Treatment of infertility May be fixed by microsurgery, surrogacy, AID or ART Artificial Insemination by Donor (AID) 70% - 80% effective Male is sterile therefore semen is donated by an unknown man (generally physically similar). All donors are screened for STI’s and genetic diseases, mental problems and general health. Semen is injected into woman’s upper vagina around expected time of ovulation for 3-4 consecutive days. (generally for 3 months) Surrogacy Woman agrees to bear a child for a couple. (fertilised either naturally or artificially with male semen and surrogate egg OR using ART)

15 Treatment of infertility Assisted Reproductive Technologies (ART) In vitro Fertilisation (IVF) takes ovum from mother, fertilise outside body, then transplant embryo to uterus Gamete Intrafallopian transfer (GIFT) variation of IVF Eggs and sperm immediately mixed together, then mixture immediately injected in to fallopian (uterine) tube. Most require women to take fertility drugs which increase number of eggs released by ovaries. Often more embryos are created than are needed so the excess are frozen. (may be used if initial is unsuccessful, donated to another couple, discarded or used for research)

16 Treatment of infertility Assisted Reproductive Technologies (ART) cont. Intracytoplasmic Sperm Injection (ICSI) 20-30% effective Single sperm injected into a single egg and embryo transplanted into females uterus. May increase likeliness of birth defects. Donor Egg or Embryo Donated egg is mixed with parents sperm and resulting embryo implanted into females Uterus. Could also be donated embryo.


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