biology grade 12 homeostasis

Question

Explain in detail an example of a positive OR negative feedback loop system and its importance.

Answer 1

Another classic example of positive feedback is childbirth.

1. The baby drops lower in the uterus to initiate labor, causing the head of the baby to push against the the cervix, creating cervical stretch.
2. Nerve impulses from the cervix are transmitted to the brain.
3. The brain stimulates the pituitary gland to secrete oxytocin.
4. Oxytocin is carried to the uterus via the bloodstream and stimulates uterine contractions, pushing the baby against the cervix.

Process repeats with each contraction occurring closer together until the baby is delivered, stopping the feedback loop.

This is important because the cervix needs to dilate in order safely deliver the baby and lessen the damage to the mothers tissues. Also, this is important because if the mother's body did not initiate this process, the delivery of the baby would be dangerous for both the mother and the child. It is more likely they would both suffer from severe complications.

Answer 2

Since someone else has already tackled negative feedback, I'll take on an example of a positive feedback loop: lactation.

In mammals, the production of milk is stimulated by the hormone prolactin. Prolactin is released when an infant suckles at the breast. So when a baby breastfeeds, it stimulates prolactin production, which increases milk production, which gives the baby a reason to breastfeed, which produces even more prolactin, and so on. The looping nature of this interaction important in humans (and other mammals) because it means mothers stop wasting energy on producing milk once the baby stops actually using it, which is evolutionarily advantageous when food is scarce--imagine how inefficient it would be to produce milk constantly!

It is also important in agriculture because it explains why dairy cows can continue producing milk well after their babies have grown up if they are regularly milked by humans. The physical action of milking is what stimulates prolactin production, so it doesn't really matter who is doing the milking so long as it's done consistently to maintain the positive feedback loop.

Answer 3

A classic example of a negative feedback loop is blood sugar regulation. When blood sugar levels are too high, the body releases insulin to stimulate uptake of sugar into adipose cells in order to lower blood sugar levels until it is at a stable level while when blood sugar levels are too low the body will release glucagon to stimulate the release of glucose into the blood stream to raise blood sugar levels. This is important because too high of blood sugar levels for extended periods of time (hyperglycemia) can cause organ damage while too low blood sugar (hypoglycemia) can cause headaches, nausea and other neurological damage