Answer:
B. False
Explanation:
Child-birth in mammals is not an example of endocrine-controlled negative feedback, because the production of oxytocin during childbirth doesn't result in additional oxytocin being synthesized by the posterior pituitary gland.
Oxytocin is the enzyme which is necessary at the time of birth in order to contract the walls of the uterus and expel the baby out of the body. Oxytocin levels rise at the onset of labour,causing regular contractions of womb and abdominal muscles. Oxytocin induced contractions become stronger and more frequent without the influence of progesterone and estrogen, which at high levels prevent labour.
Answer:
False
Explanation:
Negative feedback mechanisms act like a thermostat in the
home. As the temperature rises (deviation from the ideal normal
value), the thermostat detects the change and triggers the air-
conditioning to turn on and cool the house. Once the
temperature reaches its thermostat setting (ideal normal value),
the air conditioning turns off. <_o3a_p>
In negative feedback, the response will reverse or cause the
opposite effect of the original stimulus. Negative feedback can
be explained with the process of insulin production and
release. After a meal the blood sugar level will be elevated due
to the absorption of sugars from the digestive tract. This
triggers the release of insulin from pancreas. Insulin converts
sugar into cells and hence the blood sugar level drops. This
low blood sugar level will result in the cessation of insulin
release. This insulin response is a negative feedback. Most
endocrine glands are under the control of negative feedback
mechanisms <_o3a_p>
Positive feedback mechanisms are rare. It amplifies changes
rather than reversing them. The release of oxytocin from the
posterior pituitary gland during labor is an example of positive
feedback mechanism. Oxytocin stimulates the muscle
contractions that push the baby through the birth canal. The
release of oxytocin result in stronger or augmented contractions
during labor. The contractions intensify and increase until the
baby is outside the birth canal. When the stimulus to the
pressure receptors ends, oxytocin production stops and labor
contractions cease.
Positive feedback mechanisms control self-perpetuating events
that can be out of control and do not require continuous
adjustment. In positive feedback mechanisms, the original
stimulus is promoted rather than negated. Positive feedback
increases the deviation from an ideal normal value.
