Endocrine System

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1.10   Fight-or-Flight Response – In response to stressful situations the adrenals release hormones into the bloodstream. The concentration of “adrenaline” increases when you are afraid and the concentration of “noradrenaline” increases when you feel aggressive. In these situations the heart steps up its activity, providing more blood for the brain and muscles, breathing gets faster and deeper, providing more oxygen, and perspiration is increased, resulting in the cooling of the body. Many muscles of the body tighten to prepare the body for rapid and vigorous action. Functions such as eating and digesting are postponed to conserve energy. In these ways all the forces of the body are prepared either to attack an enemy or flee to safety.

The Pancreas

1.11   The pancreas, a pinkish-yellow gland about 15 cm long lies crosswise behind the stomach. Its main function is to produce digestive juices to breakdown food. It also produces two hormones (insulin and glucagon) needed to regulate the blood glucose level and metabolism. The first part of the small intestines, the duodenum, loops round the pancreas. Digestive juices produced by the pancreas flow through an opening into the duodenum. These digestive juices have water and salt that aid digestion and decrease the effect of stomach acids. The substances in the digestive juices help in breaking down proteins, carbohydrates and fats. The clusters of cells scattered throughout the pancreas secrete hormones and send them directly into the bloodstream. Insulin hormone produced by these cells travels through the blood stream to cells throughout the body. Insulin helps cells to take in and use glucose from the blood for energy – thus stablising the blood glucose level. The other hormone, glucagon, has the opposite effect to insulin i.e. it increases glucose production. If there is an imbalance in the amount of these two hormones in the blood, either too high or too low sugar levels will result.