Term
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Definition
| The tendency of a living body to maintain relatively stable internal conditions in spite of greater changes in its external environment. The stability is kept by negative feedback. |
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Term
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Definition
| X-rays. Can penetrate soft tissues and darken photographic film. Dense tissues absorb the x-rays which leaves the film light in these areas. |
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Term
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Definition
| More sophisticated application of x-rays. X-rays are passed through the body and detected on the other side of the machine. A computer takes the detected x-rays and constructs a slice of the body. Useful for finding tumors, aneurysms, cerebral hemorrhages, kidney stones, and more. |
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Term
| Positron Emission Tomography (PET) |
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Definition
| Used to assess the metabolic state of a tissue and to distinguish which tissues are the most active at a given moment. Glucose that has been radioactively labeled is injected into the patient. Sensors pick up the gamma rays that are released and a computer analyzes them. The computer displays a color image that shows which tissues were using the most glucose at the moment. Can be used in cardiology to identify damaged heart tissue, as it will consume little or no glucose. |
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Term
| Magnetic Resonance Imaging (MRI) |
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Definition
| Superior to CT scanning for visualizing soft tissues. It uses a strong magnetic field and radio waves to produce an image of the body. It can produce clear images of nervous tissue; even allowing white and gray matter to be distinguished. Eliminates exposure to harmful x-rays. Functional MRI (fMRI) shows moment-to-moment changes in tissue function. |
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Term
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Definition
| Bounces high-frequency ultrasound waves off of internal organs to produce a computerized image. Not very useful for imaging bones, lungs, etc because it does not produce a sharp image. Favored in obstetrics to locate the placenta and evaluate fetal age, position, and development. Inexpensive and portable, no exposure to x-rays. |
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Term
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Definition
| Healthy 22 yr old male; 70kg (154lb); living in 20°C ambient temp.; engages in light physical activity; consumes 2800kcal. |
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Term
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Definition
| Healthy 22 yr old female; 58kg (128lb); living in 20°C ambient temp.; engages in light physical activity; consumes 2000kcal. |
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