Negative feedback loop; controlled condition; body temperature and glucose regulation. Using explained cycle? Positive feedback loop; blood clotting, during childbirth explained cycle?

Negative feedback loop: Body temperature and glucose regulation

1. The body's temperature and glucose levels are constantly monitored by the hypothalamus in the brain.

2. If the body temperature or glucose levels deviate from the set point, the hypothalamus sends signals to the appropriate organs to bring them back to the normal range.

3. For example, if the body temperature is too high, the hypothalamus signals the sweat glands to produce sweat, which cools the body down.

4. Once the body temperature or glucose levels return to the normal range, the hypothalamus stops sending signals, and the process stops.

Positive feedback loop: Blood clotting during childbirth

1. During childbirth, the body needs to form blood clots to prevent excessive bleeding.

2. When a blood vessel is damaged during childbirth, platelets in the blood are activated and start to stick to the site of the injury.

3. The platelets release chemicals that attract more platelets to the site, forming a plug that stops the bleeding.

4. As more platelets gather at the site, more chemicals are released, further attracting platelets and reinforcing the clot.

5. This process continues until the bleeding is stopped and the blood vessel is sealed off.

6. Once the clotting process is complete, the positive feedback loop is turned off, and the body returns to its normal state.

Negative Feedback Loop: Body Temperature and Glucose Regulation

- Controlled Condition: Body temperature/glucose level
- Sensor: Temperature sensors in the skin/glucose sensors in the pancreas
- Control Center: Hypothalamus/pancreas
- Mechanism:
- Body Temperature Regulation:
- When body temperature increases, the hypothalamus signals the skin to release sweat, which evaporates and cools the body.
- When body temperature decreases, the hypothalamus signals muscles to shiver, generating heat.
- Glucose Regulation:
- When glucose levels rise, the pancreas secretes insulin, which stimulates cells to take up glucose from the blood.
- When glucose levels decrease, the pancreas secretes glucagon, which stimulates the liver to release glucose into the blood.

Positive Feedback Loop: Blood Clotting

- Controlled Condition: Blood loss
- Sensor: Platelets and damaged blood vessels
- Control Center: None (self-sustaining cycle)
- Mechanism:
- When a blood vessel is damaged, platelets stick to the injured area and release substances that activate other platelets.
- This triggers a cascade of reactions that leads to the formation of a fibrin clot, which seals the wound and prevents further bleeding.

Positive Feedback Loop: Childbirth

- Controlled Condition: Uterine contractions
- Sensor: Stretch receptors in the uterus
- Control Center: None (self-sustaining cycle)
- Mechanism:
- When the fetus and placenta grow in the uterus, they stretch the uterine walls.
- This stretching triggers stretch receptors to send signals to the brain, which stimulates the release of oxytocin.
- Oxytocin causes further contractions, which increase the pressure on the cervix, leading to dilation and the eventual delivery of the baby.