1. Homeostasis is the maintenance of a constantinternal balance, e.g.
a system. 2. Negative feedback in a living organism is when a variable triggers acounteractive response. Some examples of negative feedback are temperatureregulation and blood sugar/pressure regulation. Negative feedback happens in aloop, the loop starts at the stimulus which is noticed by the sensors, then thecontrol creates the response and the effect of the control becomes the effector. 3. Negative feedback involves a counteractiveresponse, to keep a variable or component maintained while positive feedbackdoes not involve a counteractive response, just an intensified variable. Anexample of negative feedback would be temperature regulation while an exampleof positive feedback would be child birth.
– 4. Positive feedbackloops are rare in living organisms because the systems do not need to bemaintained, rather completed, an example of this would be childbirth as at theend of the cycle, the baby is no longer in the womb. The body does not containmany of these system as most of the components of the body need to be kept at aconstant, e.g. body temperature, this is why they are negative systems. Thebody has a set temperature of around 37oC, if the body’s temperatureis too high, homeostasis will work to bring it back down to the normal range.This done through actions such as an increased breath rate, sweating andincreased blood flow to the skin, all these help to cool down the body, forexample sweating triggers evaporation.
If the body is too cold, negativefeedback triggers reactions such as shivering, which causes heat to be createdfrom the muscles. Another reaction would be the inactivity of sweat glands;this helps the body retain any heat it has. Positive feedbackcauses four main steps in the birth of a baby, they are:1. The head causes pressure on thecervix.
2. When stretch receptors are hit,oxytocin is released from effector pituitary gland. 3.
Oxytocin binds to receptors on theuterus and causes muscular contractions.4. The contractions push baby down,which causes pressure on the cervix.5.
The cycle repeats from steps 1 to 4