Question

regardless of the condition outside the body the homeostasis in human maintain the blood glucose concentration at which percent​

Answer 1

Insulin is secreted by the Islets of Langerhan which are special groups of cells in the pancreas.

After a carbohydrate meal, the level of glucose in the blood will start to rise as the digestive system breaks up and absorbs carbohydrates as glucose.

After several hours without a meal, the blood sugar level will fall as cells use up the glucose in aerobic respiration.

As the blood sugar concentration rises, the Islets of Langerhan are stimulated to secrete insulin.

Although most cells in the body respond to insulin the main target organ for insulin is the liver. It is there that glucose is converted into glycogen. Excessive intake of carbohydrates saturates glycogen stores in the body and causes excess glucose to be stored as fat.

When blood sugar levels fall, not only does the pancreas make less insulin, but it is stimulated to produce another hormone called glucagon. Glucagon acts on the liver to cause the breakdown of glycogen into glucose before releasing it into the blood. Glucagon has the opposite effect of insulin.

Negative feedback causes the release of insulin and glucagon to slow down when blood sugar levels drop to normal levels.

An example of a positive feedback mechanism is that of child birth. Receptors in the uterus detect the pressure of the unborn child's head. The signal is transmitted to the pituitary gland where it responds by releasing oxytocin. Oxytocin causes the uterus to contract causing the head to put more pressure on the uterus and causing receptors to continue firing thus causing further secretion of oxytocin. This causes the uterus to continue to contract until the baby is born.

Another part of homeostasis is thermoregulation where the body maintains its core temperature within a narrow range. Receptors in the skin detect temperature changes. Signals are sent to the hypothalamus which in turn signal the muscles in the skin, effectors, to contract causing shivering and goose-bumps. This is a very simple homeostatic mechanism.