Describe the positive feedback loop that is in play during human labor
What will be an ideal response?
As the fetus nears full term, it typically shifts position so that its head touches the mother's cervix. Receptors in the cervix respond to pressure by sending signals along nerves to the hypothalamus, which in turn tells the posterior lobe of the pituitary to secrete the hormone oxytocin. In a positive feedback loop, oxytocin binds to receptor on smooth muscle cells of the uterus, causing stronger uterine contractions that put additional pressure on the cervix. The added pressure triggers more oxytocin secretion, causing more cervical stretching, and so on, until the fetus is expelled.
You might also like to view...
Mollusks breathe using ________.
Fill in the blank(s) with the appropriate word(s).
When a human oocyte ovulates, it arrests in metaphase II until it is fertilized by a sperm. How many chromosomes are present in the oocyte at metaphase II?
a)46 b)2 with sister chromatids still attached c)4 d)23 with sister chromatids still attached d)1
The maternal effect in Lymnaea is such that the genotype of the egg determines the direction of shell coiling regardless of the genotype of the offspring. Apparently, the cause of this spectacular maternal effect results from ________
A) orientation of the spindle apparatus in early cleavage B) allelic substitution as demonstrated from RNA injection experiments C) colicins "poisoning" one of the cleavage centers D) the F factor exerting its influence on the centrosome E) genophores present in the egg cytoplasm
Which cell is classified as an agranulocyte?
a. monocytes b. platelets c. basophils d. neutrophils e. eosinophils