Homeostasis: positive vs. negative feedback mechanisms.

1. A student defined homeostasis as “the condition in which the body approaches room temperature and stays there.” Do you agree with this definition?

          No. Homeostasis is a process in which the body's internal environment is kept stable despite           changes in external conditions.  

2. The difference between negative and positive feedback systems is that in negative feedback systems, the response ____________ the original stimulus, but in positive feedback systems, the response ___________ the original stimulus.

a)      Reverses; enhances

b)     Enhances; reverses

3. Most often, the nervous and endocrine systems acting together or separately regulate homeostasis. The _________ system detects body changes and sends nerve impulses to counteract changes in controlled conditions. The ____________system regulates homeostasis by secreting ____________.

a)      Endocrine; nervous; hormones

b)     Reproductive; endocrine; saliva

c)      Nervous; endocrine; hormones

d)     Skin; endocrine; hormones;

e)      Nervous; respiratory; mucus

4. After labor begins the baby's head puts pressure on the cervix, causing the cervix to stretch. This stimulates stretch receptors the trigger the mother's hypothalamus to release oxytocin, which increases the uterine contractions and pushes the baby against the cervix. This causes the cervix to stretch farther and the cycle continues.

a)      This is an example of positive feedback

b)     This is an example of negative feedback

5. Body temperature regulation is an example of positive feedback

a)      True

b)     False

6. Most hormones are regulated by negative feedback

a)      True

b)     False