{"id":451,"date":"2015-08-12T17:29:32","date_gmt":"2015-08-12T17:29:32","guid":{"rendered":"http:\/\/sites.msudenver.edu\/haysc\/?page_id=451"},"modified":"2025-09-29T17:25:34","modified_gmt":"2025-09-29T17:25:34","slug":"outline-4-bio-2320-pregnancy-and-development","status":"publish","type":"page","link":"https:\/\/sites.msudenver.edu\/haysc\/biology-courses\/human-anatomy-and-physiology-ii-homepage-bio-2320\/outline-4-bio-2320-pregnancy-and-development\/","title":{"rendered":"Outline-4, BIO 2320, Pregnancy and Development"},"content":{"rendered":"

IV. PREGNANCY & DEVELOPMENT<\/strong><\/p>\n

A. Fertilization<\/strong><\/p>\n

1. Oviduct is site<\/p>\n

2. Capacitation<\/p>\n

Enables sperm to fertilize ovum<\/em><\/p>\n

3. Diploid;\u00a0Zygote<\/strong><\/p>\n

4. Sex determination<\/p>\n

5. Twins<\/p>\n

a. Dizygotic (fraternal)<\/p>\n

b. Monozygotic (identical)<\/p>\n

B. Cleavage\u00a0<\/strong>(30hrs.-4days); Morula<\/p>\n

Mitosis divisions as embryo travels along oviduct towards uterus<\/em><\/p>\n

C. Blastocyst\u00a0<\/strong>Stage (day 5)<\/p>\n

Rearrangement of cells, embryo is in the uterus<\/em><\/p>\n

1. Trophoblast cells<\/p>\n

Outermost cells destined to become placenta<\/em><\/p>\n

2. Inner cell mass<\/p>\n

Group of cells destined to become fetus<\/em><\/p>\n

3. Implantation (Day 7-8)<\/p>\n

Embryo burrows into endometrium<\/em><\/p>\n

D. Gastrulation & Germ Layers\u00a0<\/strong>(2nd week)<\/p>\n

1. Ectoderm<\/strong><\/p>\n

Outer germ layer destined to become nervous tissue and skin<\/em><\/p>\n

2. Mesoderm<\/strong><\/p>\n

Middle layer destined to become skeleton, muscles, heart, vessels….<\/em><\/p>\n

3. Endoderm<\/strong><\/p>\n

Inner layer destined to become lungs and GI organs<\/em><\/p>\n

E. Neurulation\u00a0<\/strong>(3rd week; embryo is 2 mm long)<\/p>\n

1. Neural grove<\/p>\n

2. Neural tube<\/p>\n

Results in brain and spinal cord<\/em><\/p>\n

F. Organogenesis\u00a0<\/strong>(4th week; 5mm long)<\/p>\n

1. All major organs, arm\/leg buds, have begun their formation<\/p>\n

2. Thalidomide ; German measles can adversely affect organogenesis<\/p>\n

G. Embryo vs Fetus<\/strong>– by end of 3rd mo., all major organs<\/p>\n

established [25 mm, 1 gram], all left is growth for 2nd & 3rd trimester<\/p>\n

H. Maintenance of endometrium<\/p>\n

1. Estrogen & Progesterone<\/strong><\/p>\n

Quite important in maintaining endometrium, from corpus luteum in early pregnancy, from placenta later in pregnancy<\/em><\/p>\n

2. Birth control pills<\/p>\n

Most are a combination of estrogen and progesterone, what does this do to ovulation?<\/em><\/p>\n

3. HCG\u00a0<\/strong>(2-12 wks)<\/p>\n

Human Chorionic Gondotropin, made by embryo, maintains corpus luteum<\/em><\/p>\n

I. Placental development (begins at 4 wks, mostly functional by 12 wks)<\/p>\n

1. Overall function<\/p>\n

Nutrients, Waste, Estrogen & Progesterone production<\/p>\n

2. Maternal tissue<\/p>\n

– Decidua basalis<\/p>\n

Of endometrium<\/em><\/p>\n

3. Fetal tissue<\/p>\n

a. Trophoblast cells become the…<\/p>\n

b. Chorion<\/strong><\/p>\n

c. Villi<\/p>\n

d. Umbilical Artery & Vein form capillary beds in villi, which become surrounded by maternal blood<\/p>\n

e. Umbilicus<\/p>\n

Arteries and vein<\/em><\/p>\n

f. Amnion, Amniotic fluid<\/strong><\/p>\n

Sac surrounding fetus, filled with fluid for protection, movement, and temperature constancy<\/em><\/p>\n

J. Gestation\u00a0<\/strong>(280 days)<\/p>\n

K. Parturition<\/strong><\/p>\n

1. Labor (contractions every 30 min)<\/p>\n

2. Amniotic fluid released<\/p>\n

3. Positive feedback<\/p>\n

As labor increases,\u00a0Oxytocin<\/strong>\u00a0increases<\/em><\/p>\n

a. Increased estrogen which increases<\/p>\n

uterine contractility towards end of pregnancy, then levels drop<\/p>\n

b. Decreased progesterone<\/p>\n

c. Prostaglandin<\/p>\n

Made by placenta, causes uterine smooth muscle contraction<\/em><\/p>\n

d. Oxytocin\u00a0<\/strong>(Increased # receptors)<\/p>\n

Causes strong uterine contractions<\/em><\/p>\n

e. Head as a wedge<\/p>\n

f. Relaxin, made by placenta<\/p>\n

helps to dilate cervix, relax symphysis pubis<\/em><\/p>\n

\"Hormones<\/a><\/p>\n

4. Afterbirth [10-45 min later]\n

Placenta<\/em><\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

IV. PREGNANCY & DEVELOPMENT A. Fertilization 1. Oviduct is site 2. Capacitation Enables sperm to fertilize ovum 3. Diploid;\u00a0Zygote 4. Sex determination 5. Twins a. Dizygotic (fraternal) b. Monozygotic (identical) B. Cleavage\u00a0(30hrs.-4days); Morula Mitosis divisions as embryo travels along oviduct … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":270,"featured_media":0,"parent":209,"menu_order":0,"comment_status":"closed","ping_status":"open","template":"","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"class_list":["post-451","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/sites.msudenver.edu\/haysc\/wp-json\/wp\/v2\/pages\/451","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sites.msudenver.edu\/haysc\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/sites.msudenver.edu\/haysc\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/sites.msudenver.edu\/haysc\/wp-json\/wp\/v2\/users\/270"}],"replies":[{"embeddable":true,"href":"https:\/\/sites.msudenver.edu\/haysc\/wp-json\/wp\/v2\/comments?post=451"}],"version-history":[{"count":0,"href":"https:\/\/sites.msudenver.edu\/haysc\/wp-json\/wp\/v2\/pages\/451\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/sites.msudenver.edu\/haysc\/wp-json\/wp\/v2\/pages\/209"}],"wp:attachment":[{"href":"https:\/\/sites.msudenver.edu\/haysc\/wp-json\/wp\/v2\/media?parent=451"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}