physiology notes:

1. Pregnancy: period of time from fertilization until birth

Conceptus: developing offspring

Gestation: time of development

2. Embryo: age of conceptus from 1 week to 8 weeks.

Fetus: conceptus from week 9 to birth

3. Capcitation is the breakdown of the membrane surround the acrosome or cap of the

sperm to allow the release of hyaluronidase.

4. Acrosomal reaction: release of enzymes in the area of the oocyte; intercellular

matrix (hyaluronic acid) is penetrated allowing passage of sperm of the oocyte

surface

5. Polyspermy: when many sperm enter the egg. Monospermy is mechanism in

humans. Fusion of one sperm with oocyte membrane→ depolarization preventing

additional sperm from entering. Also cortical reaction produces enzymes that

destroy sperm receptors.

6. Male and female pronuclei: sperm and ovum nuclei before they fuse.
7. Cleavage: cell divisions without growth following fertilization; results in smaller

cells produced called blastomeres.

8. Blastocyst: a single layere sphere filed with fluid; has trophoblast outer layer and

Inner cell mass→ embryo.

9.Morula: berry-shaped ball of cells of 16 cells formed about 3 days after conception.

10. Implantation: blastocyst arrives in uterus (endometrium) ; trophoblast cells attach to lining and release digestive enzymes and becomes enclosed with. HCG from trophoblast cells→ corpus luteum→ progesterone; eventually, placenta takes over estrogen and progesterone function. Pregnancy tests use HCG levels for determination.

11. Human Chorionic Gonadotropin: see #10

12. Placenta: contains embryonic part (trophoblast layer= chorion) and maternal (endometrium); serves as a an organ for nutrition, respiration, excretion.

13. Gastrula: 3 cell layered embryo.

14. Functions of:

a. amnion: membranous sac surrounding the embryo

b. yolk sac: not a great source of nutrients; it does produce the first blood cells primordial germ cells

c. allantois: becomes part of the umbilical cord; develops into urinary bladder

d. chorion: encloses the other membranes; part of placenta

15. Three primary germ layers: p. 1126 chart

Ectoderm: forms skin, nervous system

Mesoderm: forms blood, muscles, bone, urogenital system

Endoderm: digestive, respiratory

16. Primitive streak: formed during process of gastrulation; determines axis of embryo

17. Neurulation:

a. neural plate: thickening of overlying ectoderm above notochord

b. neural folds: sides of neural groove rise up

c. Neural tube: formed from closing of neural folds.

d. Neural crest: migratory cells that form cranial and spinal nerves and adrenal medulla.

18. Endoderm structures: see #15

19. Mesoderm specialization: notochord→backbone; somites form sclerotome→

vertebra, dermatome→ dermis and myotome→ skeletal muscles

20. Teratogens: chemicals that can cause degeneration of developing fetal structures (alcohol, drugs, nicotine; German measles, thalidomide)

21. Relaxin: placental hormone causing relaxation of pelvis ligaments and pubic symphysis

22.Distinguish between:

a. Human placental lactogen: stimulates breasts for milk production (also called human chorionic somatomammotropin)

b. human chorionic thyrotropin: increases maternal metabolism

23. Oxytocin: from fetus: causes placenta→ prostaglandins which cause muscular contractions; posterior pituitary also releases oxytocin= more contractions

24. 3 stages of labor:

a. dilation stage: beginning of labor to dilation of cervix (10 cm); may last 6-12 hours

b. expulsion stage: full dilation to delivery; average time is 2 hours; crowning; episiotomy possible

c. placental stage: removal of placenta (30 minutes after delivery)

25. Prolactin effect: causes milk production in mammary glands

26. Colostrum: secretion in mother’s milk containing proteins, minerals and antibodies

27. Ectopic pregnancy: embryo implants outside the uterine lining; often happens