Homeostasis
The ability of an organism to maintain constant internal conditions in the face of fluctuating external conditions.
In mammals, such as the fetal pig, homeostasis keeps many important factors at the right rate or level. For example, our bodies keeps a constant body temperature.
Homeostasis keeps the same;
For example; if you become dehydrated, the amount of water in your blood falls below the normal level. Your body responds by making you thirsty and encouraging you to drink. IF you drink a lot of fluid, your body responds with more frequent urination, again returning the fluid in your blood to normal levels (Bozzone, Green 315-316).
Negative Feedback: Negative Feedback mechanisms change the variable back to its original state or "ideal value".
A good example of negative feedback would be the control of blood sugar (glucose) by insulin. When blood sugar rises, receptors in the body sense a change . In turn, the control center (pancreas) secretes insulin into the blood effectively lowering blood sugar levels. Once blood sugar levels reach homeostasis, the pancreas stops releasing insulin.
Positive Feedback: A positive feedback mechanism is the exact opposite of a negative feedback. With negative feedback, the output reduces the original effect of the stimulus. In a positive feedback system, the output enhances the original stimulus.
A good example of positive feedback would be blood clotting. Once a 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 Lutz).
Homeostasis keeps the same;
- Amount of water in the blood
- The concentration of salts and waste products in the blood
- The concentration of oxygen in the blood
- The concentration of glucose in the blood
- The (resting) heart and breathing rates
- Blood pressure
For example; if you become dehydrated, the amount of water in your blood falls below the normal level. Your body responds by making you thirsty and encouraging you to drink. IF you drink a lot of fluid, your body responds with more frequent urination, again returning the fluid in your blood to normal levels (Bozzone, Green 315-316).
Negative Feedback: Negative Feedback mechanisms change the variable back to its original state or "ideal value".
A good example of negative feedback would be the control of blood sugar (glucose) by insulin. When blood sugar rises, receptors in the body sense a change . In turn, the control center (pancreas) secretes insulin into the blood effectively lowering blood sugar levels. Once blood sugar levels reach homeostasis, the pancreas stops releasing insulin.
Positive Feedback: A positive feedback mechanism is the exact opposite of a negative feedback. With negative feedback, the output reduces the original effect of the stimulus. In a positive feedback system, the output enhances the original stimulus.
A good example of positive feedback would be blood clotting. Once a 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 Lutz).
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To compare the homeostasis of a mammal to a non-mammalian organism we will use an American Robin.
One of the most unique things about robins is simply how closely their homeostasis system is to ours of humans. Their body and brain are able to control body heat just as humans can. Also, the way birds in general have developed different beaks to pick their food from the ground, or trees, etc. Robins for example have developed their beaks to pick worms out of the ground because worms are their main source of food.
- Mammals and birds share the ability to maintain a constant body temperature. As for most organisms body temperature varies along with the outside temperature.
- Animals that maintain a fairly constant body temperature (birds and mammals) are called endotherms, while those that have a variable body temperature (all others) are called ectotherms . Endotherms normally maintain their body temperatures at around 35 - 40°C, so are sometimes called warm-blooded animals, but in fact ectothermic animals can also have very warm blood during the day by basking in the sun, or by extended muscle activity (Biology Mad).
- This is why most birds fly South during the winter, to find warmer weather and go back during spring and summer seasons.
- An example of a birds homeostasis would be that of a constant body temperature. Once the bird body temperature starts to overheat, it's body and mind work together to lower that body temperature down to normal.
One of the most unique things about robins is simply how closely their homeostasis system is to ours of humans. Their body and brain are able to control body heat just as humans can. Also, the way birds in general have developed different beaks to pick their food from the ground, or trees, etc. Robins for example have developed their beaks to pick worms out of the ground because worms are their main source of food.
References:
Lutz , Jennifer . "Homeostasis: positive/ negative feedback mechanisms." Anatomy & Physiology. Anatomy and Physiology , n.d. Web. 25 May 2014.
"Homeostasis ." . Biology Mad , n.d. Web. 25 May 2014.
Lutz , Jennifer . "Homeostasis: positive/ negative feedback mechanisms." Anatomy & Physiology. Anatomy and Physiology , n.d. Web. 25 May 2014.
"Homeostasis ." . Biology Mad , n.d. Web. 25 May 2014.