A Simple Anatomy Lesson
indentThis is a short lesson on the anatomy of the human body. The body has nine major body systems working together to keep the body healthy. There are a lot of smaller and important systems in the body, but everyone should know the nine major ones well.
Bones make up the Skeletal System. There are 206 bones in the body.
Three things bones do:
This translates to:
All together they are called a skeleton. A skeleton has two parts.
The two parts are axial and appendicular.
The axial skeleton is the head and trunk of the skeleton.
The appendicular skeleton is made up the body's arms and legs (limbs), or extremities
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The body has more than 600 muscles. Muscles comprise the body's Muscular System.
The three types of muscles:
Muscles produce movement, maintain posture, and relieve the
tensions of structures in the body from activity. Muscles have cells that have the ability to contract. Some muscles you control, like when you move your arms or legs. Others you do not control, like when your heart
beats. Muscles convert energy from a body's chemical reactions into mechanical energy.
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The Circulatory System is made up of blood, blood vessels, and
the heart. Blood vessels are veins and arteries. Also, there are very important smaller blood vessels called arterioles and capillaries.
The circulatory system carries oxygen to all the parts of the body.
The circulatory system carries blood and nutrients to make a body strong.
The circulatory system's veins carry blood toward the heart.
The circulatory system's arteries carry blood away from the heart. The heart pumps the deoxygenated blood to the lungs. The new oxygenated blood returns to the heart and it contracts, pumping blood out to the body. The direction of blood flow is controlled the heart valves.
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The respiratory system is the body's system to breathe. The respiratory
system is made up of the lungs and the windpipe, or the pharynx,
larynx, and trachea. The nasal cavity, bronchi, and diaphragm are also part of the respiratory system. There are smaller organs called bronchioles and alveoli.
There are two lungs in the chest cavity, one on each side of the heart.
When you breathe in, you inhale oxygen.
When you exhale, you breathe out again and carbon dioxide is released into your lungs.
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The network of nerve cells in the body is called the nervous system.
The nervous system sends messages from one part of the body to another. Its main centers are the brain and the spinal cord. Together they are called the Central Nervous System.
The Autonomic Nervous System (ANS) which, together with the cranial
and spinal nerves, directs the body functions that you do not control,
like the heart beat. This system in the body is concerned with its regulation of activity of cardiac muscles, smooth muscles, and glands. It is divided into two parts called the sympathetic and parasympathetic systems.
The Peripheral Nervous System (PNS) is all parts of the nervous system outside of the central nervous system.
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The gland system in the body is called the Endocrine System.
Glands produce hormones. Hormones are chemicals that help other
body systems to work. Glands are made up of the thyroid gland, pituitary gland, adrenal gland, part of the pancreas, and the gonads. It also includes the parathyroid and reproduction glands.
The endocrine system has a thyroid gland.
The pituitary gland is the master endocrine gland. Its other name is the
hypophysis. It produces hormones that stimulate and regulate growth.
The endocrine system has an adrenal gland.
Part of the pancreas is within the endocrine system.
The endocrine system has gonads.
The endocrine system has a parathyroid.
The endocrine system has reproduction glands.
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The kidneys and bladder make up the urinary system.
Two kidneys filter waste products from the blood. In other words,
kidneys send waste and water to the bladder. When you have to urinate the
bladder tells you by urging you to relieve yourself.
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The digestive system breaks down food into nutrients.
The digestive system is made up of the mouth, esophagus, stomach, and
intestines.
The digestive system has a mouth.
The digestive system has an esophagus.
The digestive system has a stomach.
The digestive system has intestines.
Chewing is a part of digestion and takes place in the mouth by the teeth. Food travels through the esophagus to the stomach. Most of the digestion takes place in the stomach and small intestine. The intestines are both small and large.
Nutrients are used by the blood.
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When humans grow to adulthood, they have a developed reproduction system.
Bodies need this system to carry on the next generation, or to have babies.