Homeostasis
...And how it works with other systems.
Fun fact about homeostasis
Nervous system
The Autonomic Nervous System includes the Sympathetic Nervous System (SNS) and the Parasympathetic Nervous System (PNS). The SNS is responsible for the Flight or Fight response of the body. When we get scared, the SNS increases our heart rate and provides energy to our muscles in preparation for action. In order to provide more energy to the heart, lungs and muscle, it inhibits digestion by making blood flow away from the digestive tract. The PNS is responsible for stimulating digestion by increasing blood flow to the digestive tract. The PNS stimulates salivary gland secretion and increases peristalsis. This increases the digestion of food and absorption of nutrients.
The ANS controls digestive functions such as: secretion of saliva from the salivary glands, peristalsis to move food along the digestive tract, gastric acid production in the stomach, sphincter open and closing, hormone release from glands in the digestive system, and the storing energy in the form of fat.
Two types of nerves help control the action of the digestive system. Extrinsic nerves controlled by the brain cause muscle contractions that push food along the digestive tract. They also cause the stomach and pancreas to produce more digestive juice. Intrinsic nerves within the walls of the esophagus, stomach, small intestine, and large intestine react when their walls are stretched by food. They cause the release of substances that speed up or slow down the movement of food, and the production of juices, by the digestive organs .http://www.kidport.com/reflib/science/HumanBody/DigestiveSystem/NervesDigestSystem.htm#Nerves
Skeletal system
Circulatory system
Why junk food is bad for you
Junk food is food that is calorie-dense and nutrient poor. In recent decades, junk food, fast food and convenience food consumption in the United States have increased dramatically, with 25 percent of people now consuming predominantly junk food diets. This trend has occurred concurrently with rising epidemics of numerous chronic diseases and accounts for a long list of reasons why eating junk food is bad. http://healthyeating.sfgate.com/reasons-eating-junk-food-not-good-3364.html