MFAC1521 Lecture Notes - Lecture 11: Morning Sickness, Starvation Response, Orexigenic
29 Jun 2018
School
Department
Course
Professor
Maternal physiology
By Karen Gibson
Placental hormones
Features
Functions
Human chorionic gonadotropin
Glycoprotein molecular weight
(mw) 39,000
2 subunits = a and b
Maintains corpus luteum so
pregnancy is maintained
Promotes steroidogenesis in the
fetoplacental unit
*This hormone is tested in a
pregnancy test
May have a role in stimulating
testicular secretion of
testosterone and gonadal
differentiation
Human placental lactogen
-
Decreases peripheral insulin
sensitivity which increases insulin
resistance of cells à maternal
hyperglycaemia
Thus mobilises free fatty acids
from fat stores à fatty acids
converted to glucose à glucose
transported to fetus
Home pregnancy test
Animation: http://www.sumanasinc.com/webcontent/animations/content/pregtest.html
Urine of a pregnant women contains human chorionic gonadotropin (hCG) produced by the placenta.
A pregnancy test contains:
• Monoclonal antibodies (extracted from mouse antibodies)
• A capillary membrane (draws urine by capillary action)
• Three zones of function = reaction zone (R), test zone (T), control zone (C)
o Reaction zone contains freely migrating anti-hCG antibodies (Ab) = monoclonal antibodies
§ Anti-hCG Ab are artificially linked to enzymes
o Test zone contains permanently immobilised polyclonal mixture of antibodies (that bind to
epitopes on hCG) and dye molecules (acts as substrates for the enzymes in the R zone to
catalyse a colour reaction)
o Control zone contains anti-mouse antibodies (that bind to epitopes of monoclonal
antibodies in R zone) and dye molecules
*Epitopes = binding sites of a molecule
Mechanisms behind a positive pregnancy test:
• Urine sample travels to R zone first
• Urine with hCG will bind to the enzyme-linked anti-hCG Ab and catalyse a colour reaction in the R
zone
• These hCG-anti-HCG Ab complexes + other unbound monoclonal antibodies dissolve in the fluid and
are carried along the test strip by capillary flow
• They reach the T zone
• Immobilised polyclonal antibodies bind to hCG molecules
• The unbound monoclonal antibodies continue to flow along the strip to the C zone
• The unbound antibodies bind to the anti-mouse antibodies and catalyse a colour reaction in the C
zone
