Theme C lecture 6 Flashcards
What is the function of the placenta?
It is the interface between the mother and the fetus responsible for exchange of gas and nutrients.
Placenta acts as a barrier
Immune function
Hormone production
How are nutrients and important gasses transmitted to the fetus?
Passive transport (diffusion)
Facilitated Diffusion
Active transport
Vesicular transport
What stuff passes through the placenta via passive transport?
O2
Steroid hormones
Fetal waste - Uric acid, Urea, creatinine
What stuff passes through the placenta via active transport?
Amino acids
Folate
Micronutrients
What stuff pass through the placenta via facilitated diffusion?
GLUT transporters transport glucose
What kind of molecules are transported by vesicular transport?
Large molecules (eg immunoglobulins)
How does the placenta act as a barrier?
Placenta metabolizes compounds as they pass through
How does the placenta prevent the higher concentration of glucocorticoids in the mother from reaching the fetus?
Placenta expresses 11beta-HSD2 to convert active glucocorticoids into inactive metabolites
What immune function does the placenta perform?
Placenta modulates maternal immune system to prevent rejection.
How does the placenta carry out its immune function?
Placenta secretes neurokinin B which binds to phosphocholines which parasites use to evade the immune system.
Placenta inhibits maternal T-cells via lymphocytic suppressors
Which antibodies cross the placenta and provide immunity for the fetus in early life?
IgG
Can diseases pass through the placenta?
Several conditions can pass from the mother to the fetus via the placenta but not all.
What is the placenta’s endocrine function?
Produces Growth factors such as , Lactogen, IGF2, Prolactin, Growth Hormone
Produces progesterone which maintains endometrial lining, and prevents preterm labour.
Produces hunger regulating hormones to regulate mother’s eating. (leptin/ghrelin)
Many other factors are produced by the placenta which include VEGF (family of growth factors) and Corticotropin releasing hormone
What is the function of placental lactogen?
Regulates maternal insulin levels (increases fatty acids and glucose in the blood)
What is the function of placental progesterone?
Maintains endometrial lining, prevents preterm labor.
What is the function of leptin/ghrelin?
Peptide hormones that regulate maternal hunger/appetite
Where does the placenta originally develop and how does this happen?
Placenta starts developing early in pregnancy and is important for implantation.
Where is the embryological origin of the placenta?
Trophoblast forms the placenta as it thickens at the point it connects to the uterus
How does the placenta anchor the fetus to the wall of the uterus?
Trophoblasts invade through the endometrial wall and arteries are produced which provide blood supply to the placenta.
What is placentation?
The development of specialised regions of fetal and maternal origin. When maternal cells and zygote-derived fetal cells come together within close proximity.
When does placentation complete itself during pregnancy in humans?
by the end of the 1st trimester of pregnancy.
*Placenta is the first organ to develop during pregnancy and the largest organ to be produced during gestation.
What is required for a normal pregnancy?
The placenta needs to develop at the correct position
What is placenta previa?
As the placenta grows it covers the cervix such that the fetus has no passage to pass out through which would cause the death of the mother.
How is placenta previa treated?
C-section is the best and safest method.