What kind of image is this?
This is a CT scan, also known as a CAT scan.
What is it showing?
This is a CT image of a cross-section through the abdomen.
What do the A, L, P, and R around the outside of the image represent?
Anterior, posterior, left and right. The image is always shown as if you are standing at the patient’s feet.
What are the 4 densities that can be seen?
- black – air, seen outside the body and inside the stomach and intestines.
- dark gray – fat, seen around the kidneys and just beneath the skin.
- light gray – soft tissue, seen in the liver, spleen and muscles
- white – bone
What is #7?
7 is a vertebra. It surrounds the spinal cord.
What is #5?
It is the left kidney.
What is #6?
This is the aorta.
Why is the aorta and kidneys so white?
The patient was injected with IV contrast before the CT scan was performed to make the blood show up better.
What is the large organ on the patient’s right?
This is the liver. #1 is pointing to the left lobe of the liver.
What is the small organ in the lower right corner of the image?
That’s the spleen.
What is #8?
This is the top of the right kidney. It is difficult to tell except that it is bright white like the left kidney and it is symmetric with the left kidney. The right kidney is typically a little lower than the left so there is space for the liver.
What does “perirenal fat” mean?
This is fat around the kidney. “Peri-” means near. “Ren-” means kidney.
What is the black area between #1 and #3?
Air in the stomach
What kind of symmetry do people have?
Bilateral symmetry
What organs are symmetric and what are not?
Symmetric organs
- Brain*
- Eyes
- Ears
- Nose
- Teeth
- Tongue
- Lungs**
- Diaphragm
- Kidneys***
- Ureters
- Bladder
- Bones
- Muscles
*The brain is anatomically symmetric, but the two halves have somewhat different functions.
**The right lung has 3 lobes but the left lung only has 2 lobes due to the heart taking up more space in the left chest.
***The right kidney sits lower than the left kidney due to the liver.
Asymmetric organs
- Heart
- Liver
- Spleen
- Stomach
- Small Intestine
- Colon
- Appendix
What organ systems are represented here?
| System | Organs |
| Circulatory | Aorta, other blood vessels, spleen |
| Nervous | Spinal cord (within the spinal canal encircled by the vertebra) |
| Respiratory | A little bit of diaphragm is visible |
| Musculoskeletal | Ribs, vertebra, muscles in back and between ribs |
| Digestive | Stomach, small intestine, colon, liver |
| Excretory | Kidneys |
| Endocrine | Left adrenal gland (#4) |
| Immune | Spleen |
| Integumentary | Skin |
CoMo Science 
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