Homeostasis is maintenance and regulation a constant internal environment in a living organism in response to changes in the external environment condition. The endocrine system works along with the nervous system to maintain homeostasis.
When any change occurs in the body, the receptors sense the change to make adjustments. Signals are sent to the brain which thereby generate responses that are signalled to effector. The effector is usually a gland. Body uses two feedback loops in order to maintain homeostasis.
1. Negative feedback- When any change occurs in the body, message is sent to the brain which then instructs the effector (gland and muscles) to reverse the change. Thus, any homeostatic process that changes the direction of stimulus is negative feedback. For example- when a person intakes food, the food is digested which causes the blood glucose levels to rise. Higher blood glucose levels thereby cause the pancreas to secrete insulin in the blood. Upon high insulin levels glucose is transported into cells and glucose is stored in liver cells as glycogen, thereby dropping the glucose levels and hence the pancreas stops secreting insulin
2. Positive feedback- When any change occurs in the body and the body intensifies the change until the stimulus causing the change is ridden off it is known as positive feedback. For example- positive feedback results in the birth of a human infant. The head of the foetus pushes against the cervix causing it to stretch. Cervix sends nerve impulses to the brain. The brain thereby stimulates secretion of oxytocin by the pituitary gland which travels in the bloodstream to uterus and causes the uterus to contract thus pushing the foetus towards cervix.
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