Question

What are examples of homeostatic imbalances that require the 3 organ systems: nervous, endocrine and immune to work together in order to reach homeostasis? How does each system contribute?

Answer 1

Homeostasis

All of the organs and organ systems of the human body work together like a well-oiled machine. This is because they are closely regulated by the nervous and endocrine systems. The nervous system controls virtually all body activities, and the endocrine system secretes hormones that regulate these activities. Functioning together, the organ systems supply body cells with all the substances they need and eliminate their wastes. They also keep temperature, pH, and other conditions at just the right levels to support life processes.

Maintaining Homeostasis

The process in which organ systems work to maintain a stable internal environment is called homeostasis. Keeping a stable internal environment requires constant adjustments. Here are just three of the many ways that human organ systems help the body maintain homeostasis:

• Respiratory system: A high concentration of carbon dioxide in the blood triggers faster breathing. The lungs exhale more frequently, which removes carbon dioxide from the body more quickly.
• Endocrine system: A high concentration of sugar in the blood triggers secretion of insulin by an endocrine gland called the pancreas. Insulin is a hormone that helps cells absorb sugar from the blood.

So how does your body maintain homeostasis? The regulation of your internal environment is done primarily through negative feedback. Negative feedback is a response to a stimulus that keeps a variable close to a set value (Figure below). Essentially, it "shuts off" or "turns on" a system when it varies from a set value.

For example, your body has an internal thermostat. During a winter day, in your house a thermostat senses the temperature in a room and responds by turning on or off the heater. Your body acts in much the same way. When body temperature rises, receptors in the skin and the brain sense the temperature change. The temperature change triggers a command from the brain. This command can cause several responses. If you are too hot, the skin makes sweat and blood vessels near the skin surface dilate. This response helps decrease body temperature.

Another example of negative feedback has to do with blood glucose levels. When glucose (sugar) levels in the blood are too high pancreas secretes insulin to stimulate the absorption of glucose and the conversion of glucose into glycogen, which is stored in the liver. As blood glucose levels decrease, less insulin is produced. When glucose levels are too low, another hormone called glucagon is produced, which causes the liver to convert glycogen back to glucose.

Immune system response : Homeostasis

Immune is derived from the latin word immunis, which means free or untouched and essential for survival. Our immune system is amazingly complex. It is what helps our body maintain homeostasis, particularly in the intestine, as the largest organ of immunity in the body. A healthy immune system has the remarkable ability to distinguish between the body’s own cells and foreign cells, thereby allowing it to identify and fight infections and anything that is foreign to the body. This is all the more remarkable when you remember that more than 99% of the human microbiome is “good bacteria” that regulates our digestion, metabolism, and immunity.

The most important and powerful system in the body’s defense mechanism is the lymphatic system. This is responsible for cleansing the cellular environment, returning proteins and tissue fluids to the blood, providing a pathway for the absorption of fats and fat-soluble vitamins into the bloodstream and, most importantly, defending the body against disease.

The lymphatic system works together with many different organs and systems to keep us alive and healthy. The world around us contains countless viruses, bacteria, fungi and parasites capable of surviving and thriving inside our body. Collectively, we call these pathogens, and they are responsible for many diseases. The lymphatic system helps our bodies deal with pathogens.

The lymphatic system — with its tissues and organs that produce, store, and carry white blood cells that fight infections and other diseases — includes the bone marrow, spleen, thymus, lymph nodes, and lymphatic vessels.

Our body has many different types of T cells (Thymus-dependent cells), and all of them are important to the immune system. T helper cells regulate the immune system and activate other white blood cells. Cytotoxic T cells destroy virally infected and cancerous cells. Memory T cells keep a record of every infection you have been exposed to, so if you are exposed to the same infection again your immune system can recognize that you are under attack very quickly and respond.