Structure of Main Body Systems
How The Human Body Works
The Su Yi Win
Health & Social Care (Foundation)
Victoria University College
Main Body Systems
• A human body system consists of specific cells, tissues and organs that work together to perform specific functions. These systems work together to maintain your overall health. Some
of the body systems are as below :
• Consists of the Heart, Blood Vessels (Veins, Arteries, Capillaries) and Blood. Its main function is to allow blood to circulate and transport nutreints and oxygen to and from body cells.
• The Heart is a muscular pumping organ located medial to the lungs along the body’s midline in the thoracic region.
• Blood vessels are lined with a thin layer of simple squamous epithelium that keeps the blood cells inside the vessels and prevents clots from forming.
• Arteries carry blood away from the heart to the lungs to be oxygenated.
• Veins return de-oxygenated blood from the tissues back to the heart for re-oxygenation.
• Capillaries are the smallest and thinnest blood vessels. They run through almost every tissue of the body to transport oxygenated blood from the arteries and carry back waste products from the veins.
• Arteries have the thickest and
most elastic walls so that they
can withstand oxygenated blood
with high pressure from the
• Veins have thinner walls and
many have one-way valves to
prevent blood flowing away from
• Blood is made up of red blood
cells, white blood cells, platelets
• Red blood cells contain the red
pigment haemoglobin, that is
composed of irons and proteins.
• The respiratory system is composed of the lungs, heart and blood vessels. Its main function is to deliver oxygen to the body’s blood and take away carbon dioxide.
• The lungs are a pair of spongy, air-filled organs located on either side of the throax. The trachea transports inhaled air into the lungs through bronchi. These bronchi branch into smaller bronchioles (microscopic) that leads to small, spongy sacs
called alveoli, where gaseous exchange occurs.
• Alveolar walls are extremely thin and is composed of a single layer of tissues and tiny blood vessels called pulmonary
• Capillaries carry oxygenated blood from the heart to the alveoli. • Human cells & tissue require oxygen to function properly and release carbon dioxide as waste products.
• Inhaled air is rich in oxygen which the alveoli is full of. Oxygen moves by diffusion across the alveolar walls to the blood in the capillaries.
• The capillaries also contains carbon dioxide and other waste products carried back from the body cells (de-oxygenated
• The red blood cells in the blood carry the fresh oxygen and nutrients from inhaled air, and release the carbon dioxide and waste products back into the lungs for exhalation
• Group of organs working together to convert food into energy and nutrients for the entire body.
• The gastrointestinal tract is made up of the oral cavity, esophagus, stomach, liver, pancreas, small intestine and large intestine.
• Food is first ingested by the mouth, where teeth chop food into small pieces and is moistened by saliva. Saliva contains the enzyme amylase which acts on the food and digests starch
(carbohydrates) into simple sugars of maltose.
• The esophagus is a muscular tube, extending from the throat to the stomach. By a series of muscle contractions, peristalsis, the esophagus delivers food into the stomach. At the end of the
esophagus is a muscular ring called the esophageal sphincter that closes the end of the esophagus and trap food in the stomach.
• The stomach is a muscular sac at the left side of the thorax. It produces gastric acid, which contains mainly hydrochloric acid and digestive enzymes...
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