1. Organs & Systems
3.2
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2. How do we look inside the body?
There are a variety of medical imaging techniques.
Can you name any?
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3. X ray
Electromagnetic radiation is transmitted through the body to produce an image on photographic film.
Best used for hard tissue like bone, but barium X rays can be used to look at some soft tissues.
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(severely broken arm; image from Mayo Clinic)

4. Electromagnetic Spectrum
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5. CT or CAT Scan CAT = computer axial tomography
X rays of very thin “slices”; computer puts together a 3-D image
Sometimes chemical tracers are used to follow blood flow, etc.
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6. CT Scan of Brain
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7. Ultrasound Also called medical sonography.
Uses high frequency sound waves.
Can observe movement of body parts, useful for watching organ (or fetal) function.
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8. MRI scan Magnetic resonance imaging
Produced using radio signals in a magnetic field.
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Image of a brain showing stroke.

9. Endoscopy
A flexible tube with a camera and light attached are inserted in to the body.
It is an alternative to barium X rays for detecting ulcers.
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10. Human Organ Systems
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Also: excretory, immune, endocrine, reproductive, integumentary

11. Digestive System
Physically & chemically breaks down food into smaller nutrient molecules which the body’s cells can absorb & use.
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12. Mouth to Stomach
Teeth aid in physical digestion & saliva begins chemical digestion.
Food is swallowed through the pharynx, moved by muscular contractions through the esophagus to the stomach.

13. Stomach
Gastric juices contain hydrochloric acid & pepsin (an enzyme) & mucus.
Stomach mixes contents, continuing physical & chemical digestion, and contents are now liquid.
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14. Small Intestine
In the duodenum, most of the chemical digestion takes place.
Digestive enzymes & substances are released from the pancreas & gall bladder.
Absorption occurs the rest of the length of the small intestine.
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15. Large Intestine Includes the colon, rectum, and anus.
Main functions are to absorb water, vitamins, various salts, and eliminate waste.
Bacteria are present, and help to digest food & produce nutrients such as vitamin K.
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16. Digestive System Recap
This is a nice simple video from kidshealth.org.
You can also watch this episode of The Magic School Bus on the Digestive System.
Here is a fun drag & drop quiz to review the structures in the digestive system.
Kids’ Health video link:
Magic School Bus (on YouTube):
Drag & drop link: