Written by Kara Collier
Outline
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Our body is composed of different organ systems, working together to maintain homeostasis and keep us alive.
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Hormones facilitate communication between the various organs.
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Lifestyle factors such as lack of movement, poor food choices, stress, and insufficient sleep, act as stressors that disrupt efficient hormone signaling.
Like a bustling city, our bodies are composed of interdependent systems responsible for essential parts of the body's operation. These systems must communicate with one another to work correctly. They also need to communicate effectively to send resources where they are needed most. There are a couple of ways our bodies can achieve this level of cooperation.
Like the phone networks in real cities, our nervous system allows for fast point-to-point communication between our brain and the various organs. The brain has direct, almost instantaneous, control over functions that are essential to life through the nervous system, such as our breath and heartbeat. The nervous system utilizes electrical impulses to quickly (on the order of milliseconds) respond to the environment. While this type of centralized control is essential, it is also helpful to allow the various organ systems to communicate without involving the brain. The body uses the endocrine and circulatory systems for this type of decentralized communication.
The endocrine system has glands spread throughout the body. These glands secrete chemical messengers called hormones into the circulatory system (bloodstream) to send messages to other parts of the body. Using the circulatory system for communication is analogous to sending bike or car messengers out on the roads of the city. The circulatory system is not point-to-point like the nervous system. Instead, it's a shared resource, accessible to almost every cell in our body. As long as the cell has a door (receptor) for a specific signaling molecule (hormone), it can detect the concentration of that molecule in the bloodstream.
While this method of communication between organs may not seem as fast or efficient as that of the nervous system, it allows for prolonged physiological responses on the target cells. Another significant difference between the nervous and endocrine systems is chemical feedback loops regulate hormone messengers. For example, when high blood glucose triggers the release of insulin in the beta cells of the pancreas, the insulin will act to lower the glucose levels in the bloodstream. In response, the beta cells will gradually stop the production of insulin. It's just one of many types of feedback loops that help control our hormone levels.
There are many hormones in the human body. For example, melatonin is a hormone produced by the pineal gland in the brain. It promotes sleep and helps control our circadian rhythm. Then there's epinephrine and norepinephrine, which are produced by the adrenal glands and control our blood pressure, heart rate, glycogenolysis (turning the storage form of glucose into usable glucose), and lipolysis (turning stored fat into free fatty acids). They also play a crucial role in the fight-or-flight response, exercise, and fasting. Triiodothyronine (T3) and Thyroxine (T4) are produced by the pituitary gland and affect our metabolic rate, body temperature, and heart rate.
Because long-acting feedback loops control hormone levels, they are powerfully affected by certain environmental factors and behaviors. For example, altering the sleep or wake-up time can lead to circadian rhythm disruption. Because our circadian rhythm influences the timing and release of other hormones, this can lead to downstream effects such as fatigue, weight gain, and mental health issues. The overabundance of processed, carbohydrate-rich foods in the Standard American Diet is another example of our environment affecting our hormones.
By constantly elevating our blood sugar, we force our pancreas to release a higher than normal amount of insulin to absorb the excess sugar. After a while, the constant overproduction of insulin causes our cells to become less responsive to the insulin signal; a condition called insulin resistance. If this cycle continues, it can lead to Type 2 diabetes and other chronic diseases. Finally, everyday stress can stimulate our fight-or-flight response and flood our bodies with adrenaline and cortisol. It can be healthy in moderation, but it can lead to anxiety, depression, weight gain, and other chronic issues if the stress is not addressed.
While hormones play an essential function in the body, environmental factors and certain behaviors can cause these well-tuned systems to malfunction. In the next section, we will focus on hormones that affect our metabolism and energy levels—leptin and insulin—and discuss situations that may cause them to misbehave.
Hungry to learn more?
If you're interested in gaining deeper insights into how hormones interact with blood glucose, check out our Blog article: How Does Blood Sugar Affect Your Hormones?