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Placentation, the Endocrinology of Gestation and Parturition - Coggle…
Placentation, the Endocrinology of Gestation and Parturition
Maintenance of pregnancy
The placenta secretes progesterone and estrogen
Progesterone is obligatory for early embryonic development by providing the stimulus for elevated secretion by the endometrial glands
High progesterone is responsible foe progesterone block, which inhibits myometrial contractions
Progesterone increases the blood in a pregnant female and peaks at different stages of gestation in different species
Corpus luteum always produces progesterone
Role of corpus luteum in maintenance of pregnancy varies among species
Stimulation of the maternal mammary gland
The placenta is a major endocrine organ during pregnancy
Serves as a transitory exchange organ
Hormone s from the placenta gain access to both the fetal and the maternal circulation
Produces hormones that can do a lot of things
Stimulate ovarian function
Maintain pregnancy
Influence fetal growth
Stimulate mammary function
Assist in parturition
Promotion of fetal growth
Placental exchange involves a number of mechanism found in other tissues
Simple diffusion
Gases and water pass from high to low concentrations
Facilitated diffusion
Glucose and other metabolically important materials like amino acids are transported by these
Active transport
Placenta has active transport pumps for sodium and potassium, as well as calcium
Placenta transfer toxic and potentially pathogenic materials
Many toxic substance easily cross the placental barrier
Ethyl alcohol
Lead
Phosphorous
Mercury
Parturition
Defined as giving birth to the young
The final step in the reproductive process
The fetus initiates stage 1 of parturition
Initiating a cascade of complex endocrine/biochemical events
The fetal pituitary-adrenal axis is obligator for the initiation of parturition
Expulsion of fetus (stage II) requires strong myometrial and abdominal muscle contractions
Relaxin is produced by either the corpus luteum or the placenta
It causes a softening of the connective tissue in the cervix and promotes elasticity of the pelvic ligaments