About the size of a small cauliflower, the brain is a mass of jelly-like fats and tissues weighing approximately 1.4 kilograms. It contains about 100 billion neurons that coordinate our physical and mental processes, and its divided into four areas – the cerebrum (the largest part of the brain; it sits at the top of the organ), the cerebellum (sits underneath the back of the cerebrum and is the second largest area of the brain), the diencephalon (situated in the middle of the cerebrum at the top of the brain stem) and the brain stem (posterior part of the brain, responsible for many life support processes such as regulating heart rate).
This is an image that focuses on the sensory motor cortex portion of the cerebrum. Despite the fact that all mammalian brains have generally the same structure, the human brain is the largest according to general size equivalence. Most notably, the human brain has highly developed frontal lobes, the section of the brain responsible for reason, self-control and creative thought.
Pictured here is a human heart, opened to expose the ventricles and AV valve. This particular patient suffered from extreme heart failure due to the over-stretching and enlargement of the left ventricle.
The heart is a muscle and is divided into four major sections: the right and left atrium (receiving chambers) at the top and the right and left ventricle (discharging chambers) in the lower portion. The organ is responsible for pumping the blood through the circulatory system and keeping the body stocked up with oxygen.
These sponge-like organs nearly fill the chest cavity and function to deliver oxygen to the blood and remove carbon dioxide from it. On the left is a picture of a healthy lung capable of normal respiration, and on the right, a lung with emphysema, a condition which greatly impacts the ability to breathe. The lungs possess clusters of alveoli that are wrapped in blood vessels and it's here that gaseous exchange takes place.
For fans of fascinating facts, here's one about adult human lungs: although they have a combined weight of only a couple of kilograms, they contain 2,400 kilometers of airways making a total surface area of approximately 750 square feet (about 70 square meters).
Internal image of a 65-year old woman's healthy stomach. The image was gathered with an endoscope, a lighted optical instrument used to look inside the body. Envisioned here is the lower portion of the inside of the stomach — the section in which food passes.
The stomach is a J-shaped elastic sac and is located between the esophagus and the small intestine. It is the widest part of the digestive system and is principally responsible for storing and breaking down food.
Although humans are capable of living without the spleen, it has a number of important functions in the body. Located in the upper left section of the abdomen, it destroys old red blood cells, cleans the blood and helps to fight infection. It acts as a filter and when blood flows through it white blood cells attack foreign invaders.
The image here is a spleen immediately after removal. The total size of this organ is roughly four inches. The red color is due to the presence of oxidized red blood cells.
The appendix is a narrow worm-like pouch that can be seen at the bottom of this image. It is an inflamed appendix that you can see, and may need removal. Located near where the small and large intestine meet, the appendix has no known function although there is evidence to suggest that in our evolutionary ancestors the organ was used to digest tough substances such as tree bark. It is not used for digestion now, and some scientists speculate that over time the appendix may disappear from humans altogether.
Seen here is a magnified image of an ovary removed from a woman during a hysterectomy. The patient suffered from uterine disease impacting the reproductive system. Near the top of the image is the yellowish corpus luteum, a portion of the ovary that develops during the menstrual cycle. Women have two ovaries, oval or almond-shaped glands which lie on either side of the uterus, and their primary functions are to produce eggs and hormones (the sex hormones estrogen and progesterone).
The prostate is a gland of the male reproductive system and it lies just beneath the bladder. It is only found in men and is about the size of a chestnut. The main function of the prostate gland is to release a fluid that works to prevent acid in the vaginal tract from destroying sperm. This helps to ensure the longevity of DNA during reproduction. In addition, the prostate's muscles help to propel ejaculate.
In this picture, we see a prostate that has been removed from a human male. This particular specimen had expanded to nearly three inches, which is not uncommon as the gland becomes larger in older men. An enlarged prostate does not always cause symptoms or problems.