CA Science Center: Body Worlds (Part Five)

The information found in the captions is derived from the exhibit except those found in parentheses. Those are my own words.

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As the above picture comments, these were once living people who gave permission to use them for scientific and educational purposes. I hope you enjoy the pictures as much as I enjoyed viewing the exhibit, keeping in mind to respect the bodies and parts involved.

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Shall We Continue with Organs and Remaining Body Parts?

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Lungs

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Our life requires a continuous supply of oxygen, which we extract from the air.  The lungs form a large surface where oxygen is absorbed into the blood.  Every minute, about 10 to 12 pints of air pass into the lungs.  To reach the lungs, the air first passes the nose and mouth, and then the larynx and windpipe {trachea}.  The windpipe splits into the two major bronchi one leading to each lung.  Like the branches of a tree, the bronchi subdivide into ever smaller parts.

Spleen

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The spleen consists of lymphatic tissues.  It breaks down old blood cells and plays a key role in the body’s immune system.  It is located on the left of the upper abdomen, right underneath the diaphragm.  While the spleen performs a number of important functions it is not essential to life.  Other organs such as the liver and bone marrow are able to take over many of its jobs. (So why do we have a spleen?  Just kidding.)

Cecum

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The cecum, the first part of the large intestine, is located on the right-hand side of the lower abdomen.  Attached to the cecum is the appendix, which varies tremendously in size and position.  The appendix stores healthy bacteria that serve an immune function in the intestinal area.  Removal of the appendix due to appendicitis is one of the most common surgical procedures.

Kidney

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This cross-section of the kidney shows the outer cortex, where the blood is filtered, the inner medulla, {including the white, cone-shaped blocks of tissue}, where urine is concentrated.  Urine empties from the tip of the cones into the collecting area, the renal pelvis.  From there, the urine passes down the ureters into the bladder.

 Thyroid Gland

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The key organ for sound is the larynx, located between the oral cavity and the windpipe.  The upper part of the larynx is the epiglottis.  When we swallow, this cartilage flap covers the windpipe entrance, directing food and liquid into the esophagus.
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The thyroid is located below the larynx, in front of and to the sides of the trachea.  The gland produces hormones that control metabolic function and that regulate the body’s level of activity.  It can enlarge and cause the neck to swell, a condition known as a goitre.

Stomach

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The stomach is a hollow, muscular organ, capable of holding 2 to 3 quarts of food and liquids.  It stores food, bathes it in acid to kill any microorganisms, and initiates chemical and mechanical digestion.  It then slowly releases its contents into the intestines.  The stomach’s size, shape, and position depend on the amount of food in it, the position of the body, and the person’s age and eating habits.

Opened Stomach

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The stomach’s inner wall is lined with a furrowed mucous membrane.  It has roughly 5 millions glands, secreting around 2 quarts of gastric juices each day. The juice mainly contains hydrochloric acid and enzymes that begin to break food down.  The glans also secrete a type of mucus to stop the stomach from digesting itself.

Heart

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Blood flow between the atria and the ventricles is controlled by one-way valves.  These are flaps of fibrous tissue, called cusps.  As the ventricles begin to contract, the pressure inside the ventricles rises and slams the cusps tightly shut. There are also valves at the openings to the aorta and pulmonary arteries preventing backflow.  This heart shows all the four valves from above.

Large Intestine

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Indigestible material from the small intestine is passed on to the large intestine.  There, water is absorbed to thicken the waste products.  The large intestine also absorbs vitamins that are produced by billions of bacteria in the colon.

Diaphragm

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When we breathe in, muscles work to expand the chest.  The primary respiratory muscle is the diaphragm.  This dome-shaped muscular partition separates the chest from the abdomen.  When its muscle fibers contract, the diaphragm is pulled down and the thoracic cavity enlarges.  The intercostal muscles between the ribs also enlarge the thoracic cavity by pulling the chest up and out.  As the lungs expand, air flows in.  When we breathe out, the diaphragm and intercostal muscles simply relax and return to their resting position.

Pancreas

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The pancreas produces a powerful juice that breaks down fat, proteins, and carbohydrates.  The juice is released into the duodenum as food arrives from the stomach.  The pancreas also secretes two hormones, insulin and glucagon, directly into the bloodstream.  These regulate the sugar levels in the blood.  If the pancreas does not produce enough insulin, sugar levels in the body rise.  This condition is known as diabetes mellitus.  High levels of blood sugar may damage small blood vessels in organs such as the eye, kidney and heart.

Nervous System

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From scalp to toes, an extraordinarily sophisticated network of nerve fibers controls and monitors the body.  These fibers originate directly in either the brain or spinal cord and become increasingly fine as they branch out into the peripheral regions of the body.  Here, only the main branches are shown.  Nerve cells are the basic units of the nervous system.  They transmit tiny electrical signals whose number and timing convey information from one part of the body to another.  These signals can travel at up to 250 mph.
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The nervous system regulates hundreds of activities simultaneously.  It monitors and controls almost all bodily processes, ranging from automatic functions of which we are largely unconscious, such as breathing and digestion, to complex activities that involve thought and learning.  It is also the source of our consciousness, intelligence, and creativity, and allows us to communicate and experience emotions.

Central Nervous System

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The brain and the spinal cord form the central nervous system.  This system controls and integrates all body functions.  The spinal cord is enclosed in the backbone.  From between the vertebrae, 31 pairs of spinal nerves emanate from the central nervous system and branch throughout the body.  They transmit the signals between the central nervous system and the rest of the body.

Brain

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The brain processes sensory information, coordinates thinking and most movement, and allows us to feel, remember, and communicate.  The cerebrum is the largest part of the brain.  The skull bones protect the brain, rather like a shell around a walnut.  As humans evolved, the cerebrum, formed by the two cerebral hemispheres, gradually grew and expanded.  This is where voluntary action is coordinated.  To grow within the restricted skull space, the surface became convoluted and furrowed.  The furrows hide roughly two-thirds of the brain’s surface.  Spread out flat, the cerebral cortex would be approximately 16 sq. feet.

Dissected Brain

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A deep longitudinal groove separates the cerebrum into the left and right hemispheres.  At its bottom, a white band called the corpus callosum joins the cerebral hemispheres and allows them to communicate.  Beneath it are the brain stem and cerebellum.  The cerebellum is responsible for coordinating movement, while the brain stem regulates many basic functions such as breathing and the cardiovascular system.  The spinal cord emanates from the base of the brainstem.This dissection shows the corpus callosum from above.  It joins both cerebral hemispheres and allows for much of the inter-hemispheric communication.
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This dissection shows the corpus callosum from above.  it joins both cerebral hemispheres and allows for much of the inter-hemispheric communication.
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On the right side of the brain, the lateral ventricle and the basal ganglia are exposed.  These clusters of gray nerve cells pre-process millions of nerve signals entering or leaving the cortex.  They also send signals on to the relevant brain “centers” for further analysis.

Frontal Brain Slices

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Grey matter is mostly found in the outermost layer of the cerebrum {cortex} and in a group of nuclei deep in the hemispheres called basal ganglia.  The cerebral cortex plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness.  The basal ganglia control unconscious brain functions.  They also send signals on to the relevant brain regions for further analysis.

Frontal Brain Slices

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The brain has four interlinked cavities called ventricles.  Fluid circulates within these ventricles.  Among other functions, the fluid serves as an internal shock absorber.
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Both the brain and the spinal cord contain areas of grey and white matter; as can best be seen in a cross sections.  Grey matter is mostly composed of densely packed nerve cells {neurons}.  They process nerve impulses.  On the contrary, white matter consists of long, fine fibers.  They interconnect the different regions of the central nervous system and transmit the nerve impulses.

Brain Slice with Tumor

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When the flow within the ventricles is blocked due to conditions such as a tumor, inflammation, or congenital malformation, the amount of fluid will increase.  This causes the ventricles to expand, thereby compressing and damaging brain tissue.  This condition is called water on the brain or hydrocephalus.  The malignant tumor growth shown here has taken over a large portion of the brain stem, putting pressure on and blocking the ventricles.

Brain Slice with Hemorrhage

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In a stroke, an artery to the brain is blocked or blood leaks from a ruptured blood vessel.  both can seriously damage brain tissue.  Depending on the location and severity of brain tissue damage, dysfunctions may occur such as loss of speech.  Paralysis occurs on the side of the body opposite the affected brain hemisphere.  The stroke victim cannot survive if the stroke damages brain areas responsible for life-sustaining functions such as in the brainstem.  Approx. 15% of all deaths are due to strokes.

This concludes the organs and remaining body parts.  The last post will include information that may or may not be interesting and helpful to you.

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