human placental lactogen

(noun)

Also called human chorionic somatomammotropin, this is a polypeptide placental hormone. Its structure and function is similar to that of human growth hormone. It modifies the metabolic state of the mother during pregnancy to facilitate the energy supply of the fetus.

Related Terms

Examples of human placental lactogen in the following topics:

  • Metabolic Changes

    • Changes are caused by steroid hormones, lactogen, and cortisol.
    • This is likely due to pregnancy related factors such as the presence of human placental lactogen that interferes with susceptible insulin receptors.

  • Placenta

    • In humans, the placenta averages 22 cm in length and 2–2.5 cm in thickness; it typically weights 500g and is a dark-reddish color due to the large quantities of blood contained within.
    • IgG antibodies can pass through the human placenta, thereby providing protection to the fetus in utero.
    • Human chorionic gonadotropin (hCG) is the first placental hormone produced, which can be found in maternal blood and urine as early as the first missed menstrual period (shortly after implantation has occurred) through about the hundredth day of pregnancy.
    • Women's blood serum will be completely negative for hCG by one to two weeks after birth. hCG testing is proof that all placental tissue is delivered. hCG is present only during pregnancy because it is secreted by the placenta, which is present only during pregnancy.
    • Human placental lactogen is lactogenic and promotes mammary gland growth in preparation for lactation in the mother.

  • Physiology of Lactation

    • In humans the process of feeding milk is called breastfeeding or nursing.
    • In most species, milk comes out of the mother's nipples ; however, the platypus (a non-placental mammal) releases milk through ducts in its abdomen.
    • At birth, prolactin levels remain high, while the delivery of the placenta results in a sudden drop in progesterone, estrogen, and human placental lactogen levels.

  • Other Hormone-Producing Structures

    • The placenta endocrine function in humans, aside from serving as the conduit for oxygen and nutrients for the fetus, secretes hormones that are important during pregnancy, such as human chorionic gonadotropin, human placental lactogen, estrogen, and progesterone.

  • Physiological Changes

    • Women also experience an increase in human chorionic gonadotropin (β-hCG), which is produced by the placenta and maintains progesterone production by the corpus luteum.
    • Human placental lactogen (HPL) is produced by the placenta, stimulating lipolysis and fatty acid metabolism by the woman and conserving blood glucose for use by the fetus.

  • Living Mammals

    • The eutherians, or placental mammals, and the metatherians, or marsupials, together comprise the clade of therian mammals.
    • Marsupials differ from eutherians in that there is a less complex placental connection.
    • There are 18 to 20 orders of placental mammals.
    • Some examples are Insectivora, the insect eaters; Edentata, the toothless anteaters; Rodentia, the rodents; Cetacea, the aquatic mammals including whales; Carnivora, carnivorous mammals including dogs, cats, and bears; and Primates, which includes humans.
    • Red foxes are eutherian (placental) mammals because the mothers nourish their young via a placenta during fetal development.

  • Uterus

    • The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans.
    • It is within the uterus that the fetus develops during gestation, usually developing completely in placental mammals such as humans.
    • Even during pregnancy, the mass of a human uterus amounts to only about a kilogram (2.2 pounds).
    • The human uterus is pear-shaped and about three inches (7.6 cm) long.
    • In all placental mammals, including humans, the endometrium builds a lining periodically which is shed or reabsorbed if no pregnancy occurs.

  • Fetal Circulation

    • Fetal circulation is the circulatory system of a human fetus, often encompassing the entire fetoplacental circulation that also includes the umbilical cord and the blood vessels within the placenta that carry fetal blood.
    • The fetal circulation works differently from that of born humans, mainly because the lungs are not in use.

  • Primates

    • Primates are one of the oldest of all surviving placental mammal groups.
    • Simians include monkeys, apes, and humans.
    • Humans are the exception since they inhabit every continent.
    • The functional portion of human DNA is approximately 98.4% identical to that of chimpanzees .
    • Both chimpanzees and humans diverged from gorillas about eight million years ago.

  • Listeriosis

    • Listeriosis has a low incidence in humans and occurs in pregnant women, newborn infants, elderly patients, and patients who are immunocompromised.
    • This involves a bacterial protein "internalin" which attaches to a protein on the intestinal cell membrane "cadherin. " These adhesion molecules are also to be found in two other unusually tough barriers in humans - the blood-brain barrier and the feto-placental barrier, and this may explain the apparent affinity that Listeria has for causing meningitis and affecting babies in-utero.