What does the word “feedback” mean? With what do you associate this term?”

Receiving Progress Reports Purpose of progress reports; For students to gauge their performance in there classes.

What would you consider normal or acceptable range for your grades?

What happens when you fall outside of (below) that range? Have to do work! Change your behavior in order to get back into that acceptable range.

Human body works in the same fashion through homeostasis

What things/processes in the human body need to be kept within a particular range? Urine pH; 4.6–8.0 Sugar levels; 70 and100 mg/dL Body temperature; 98.6 Blood pressure; 120/80

NEGATIVE FEEDBACK MECHANISMS Push a system back to its original equilibrium position Negative feedback is usually helpful Tries to keep the body constant. Example; Fever

It works like driving car down the road. Constant adjustment to the right or left is required to keep the car on the road.

POSITIVE FEEDBACK MECHANISMS Push a system to a new state of equilibrium In a positive feedback system the change will continue to increase in one direction until something happens in the body to stop it. Example; Heart attack

Positive feedback is usually undesirable. In some situations positive feedback is advantageous Example: Labor, womans body is producing a lot of oxytocin

Positive feedback

When you are not able to control the steering wheel and the car veers off the road. Unless you fix the problem your car will be trashed in the junk yard

Negative Feedback Imagine you are out walking in the country. As you walk, the sun rises higher in the sky and the air temperature increases. Your body senses that your internal temperature is rising and you start to sweat, which reduces your body temperature by evaporating water from your skin, returning your temperature to normal.

POSITIVE FEEDBACK Imagine you are lost on a high snowy mountain. When your body senses that it is cooling, various mechanisms such as shivering help to raise your internal temperature again, but if these are insufficient to restore normal body temperature, your metabolic processes start to slow down, as, like most chemical reactions, they happen more slowly at lower temperatures. As a result you become lethargic and sleepy and move around less and less, allowing your body to cool even further. Unless you are rescued at this point, your body will reach a new equilibrium – you will die of hypothermia.

Negative feedback Human body temperature - The hypothalamus of a human responds to temperature fluctuations and responds accordingly. If the temperature drops, the body shivers to bring up the temperature and if it is too warm, the body will sweat to cool down due to evaporation.

Negative feedback Human blood pressure - When blood pressure increases, signals are sent to the brain from the blood vessels. Signals are sent to the heart from the brain and heart rate slows down, thus helping blood pressure to return to normal.

Positive Feedback When a human is hungry, metabolism slows down to conserve energy and allow the human to continue living with less food.

Negative feedback Regulation of blood sugar in humans - When blood sugar rises, insulin sends a signal to the liver, muscles and other cells to store the excess glucose. Some is stored as body fat and other is stored as glycogen in the liver and muscles.

Positive feedback Production of human red blood cells - A decrease in oxygen is detected by the kidneys and they secrete a hormone. This hormone stimulates the production of more red blood cells.

Positive feedback If you get a bad cut, the blood vessel is damaged, platelets start to cling to the injured site and release chemicals that attract more platelets. The platelets continue to pile up and release chemicals until a clot is formed.

Positive feedback During labor, a hormone called oxytocin is released that intensifies and speeds up contractions. The increase in contractions causes more oxytocin to be released and the cycle goes on until the baby is born. The birth ends the release of oxytocin and ends the positive feedback mechanism.

Just remember that positive feedback mechanisms enhance the original stimulus and negative feedback mechanisms inhibit it.