Negative feedback loops play an important role in regulating health in the human body. A negative feedback circuit, also known as a brake circuit, is a type of self-tuning system. In a negative feedback loop, increased system production hinders future system production. The body reduces its own production of certain proteins or hormones when the levels are too high.
Negative feedback systems work to maintain a relatively constant level of production. For example, the body maintains temperature, calorie intake, blood pressure, pulse, and respiratory rate based on negative feedback loops.
Negative feedback loops Production control
Imagine that your body is a factory that produces Product X. Also, imagine that producing too much Product X is expensive, wasteful, and harmful. This means that the body needs a way to slow down the factory when enough Product X is produced. This happens through a negative feedback loop. This means that the rate of production depends on the amount of Product X. When it starts to accumulate, production slows down.
You can think of a factory as a large assembly line that supplies the shelves last. When the shelves are full, the queue should slow down. The product has nowhere to put and can be used to make other products that can harm the body. However, if the shelves are empty, there is plenty of room. The assembly line can be extended until the shelves are full again so that the shelves are always filled to the desired level.
Otherwise it will be a positive feedback. In this case, the more Product X there was, the faster the plant produced.
Several well-studied negative feedback loops govern many different functions in the body.
- The hypothalamus is a gland in the brain that produces gonadotropin-releasing hormone (GnRH).
- GnRH signals the pituitary gland in the brain to produce follicle-stimulating hormone (FSH).
- FSH causes the ovaries to make estrogen.
- High levels of estrogen (as well as progesterone and testosterone, which are regulated by similar loops) suppress gonadoliberin production. This causes the pituitary gland to produce less FSH, which causes the ovaries to produce less estrogen.
The male reproductive axis is structured similarly to the female axis, with luteinizing hormone (LH), FSH, and testosterone in a negative feedback loop associated with fertility.
Another negative feedback loop regulates the acidity of the vagina. Vaginal PH varies depending on the specific bacteria present.
- Normal vaginal pH is about 4, slightly acidic. This helps prevent the growth of problem bacteria , including those that cause sexually transmitted diseases (STDs) .
- Lactic acid, which maintains this pH, is produced by lactobacilli, part of the normal flora of the vagina . These bacteria grow faster and produce more acid at a higher pH.
- One of the characteristics of bacterial vaginosis is a pH greater than 5, which causes the normal flora to produce acid that inhibits the growth of infectious bacteria.
- When the pH approaches 4, lactobacilli can slow down the production of lactic acid.
In search of homeostasis
One of the keywords that is important in understanding negative feedback loops is homeostasis . Homeostasis is defined as the desire for stability of the system. Homeostasis is very important in the human body. Many systems must self-regulate to keep the body at optimal levels of health .
Some systems that regulate through negative feedback to achieve homeostasis include:
- Blood pressure
- Body temperature
- Blood glucose
When people have trouble maintaining these systems, this can include deregulation of negative feedback.
For example, in diabetes, the pancreas does not respond adequately to high blood sugar levels by producing more insulin. In type 1 diabetes, this is because there are fewer cells available for insulin production. The human immune system has damaged the cells that produce insulin.
In addition, respiration regulates the levels of oxygen and carbon dioxide in the body, which are tightly controlled by the brain mechanisms that mediate respiration.