Human Anatomy by

by Barbara Foster

Have you ever been curious about what the body is made of, how it works, and what each part does? Then you've probably had an interest in anatomy. Your body has several important systems, all working in tandem with each other. Here, we'll examine these systems and how they work.

Skeletal System

When many people imagine anatomy, they think of a skeleton. Your skeletal system is made up of your bones. Bones give your body the structure and shape it needs to move. They also help to protect your soft internal organs. Your bones have a hard, powerful outer surface made of compact material that can withstand forces, and they have a jelly-like interior called bone marrow. There are 206 bones within an adult's body. In order to grow, bones need calcium, which can be found in milk.

Muscular System

Muscles are made up of bundles of long, thin cells. Your body's motions come from muscles either contracting or relaxing. The muscles that move bones, such as in your arm, work in pairs together to produce movement. For example, as you raise your forearm, the muscle at the front of your upper arm, your bicep, contracts and forms a bulge. As you let your forearm back down, your tricep on the back of your upper arm will contract and your bicep will relax. In order to become stronger, people exercise. That exercise leads to tiny micro-tears in the fibers, which heal and become stronger.

Cardiovascular System

Your heart is a muscle, but it's also part of its own system: the cardiovascular system. Your heart's job is to pump blood, which will circulate throughout the body. Blood is pumped through arteries and capillaries and comes back to the heart through veins. Your heart is always working, so it's important to take proper care of it by exercising and eating well.

Digestive System

Your digestive system is very important and includes many different organs. Food travels from your mouth through your esophagus to your stomach, then into your intestines and your rectum. As it moves throughout the body, the food is digested. In other words, useable nutrients are absorbed into the bloodstream, and waste is disposed of as feces.

Respiratory System

Your body needs oxygen to function. The organs that are responsible for taking in and processing the air are part of the respiratory system. Those organs include the pharynx, larynx, trachea, bronchial tubes, and lungs. The lungs have a hard job to do: They absorb oxygen so that it can be sent to the heart and circulated throughout the body. The lungs can be harmed when breathing in bad chemicals, such as from cigarettes.

Nervous System

In addition to containing a vast network of arteries, veins, muscles, and bones, your body also contains a network of nerves, which touch almost every part of the body. The system can be broken up into two major systems: the central nervous system and the peripheral nervous system. The central nervous system contains the brain and spinal cord, which is the epicenter of nerve cells. Outside of that region is the peripheral nervous system where nerves often connect with other muscles and tissues. As human beings, we have fairly big brains, which allow us to read, think, and react to things.

Excretory System

The excretory system is similar to the digestive system in that it's responsible for discharging wastes. The difference is that the excretory system gets rid of liquid waste. This system is responsible for keeping the chemical balance in the bloodstream. Related organs include the kidneys, skin, and bladder. Through urine and sweat, waste is excreted.

Endocrine System

Growing up, you may hear a lot about hormones. Hormones are related to the endocrine system, which consists of a group of organs that communicate with chemical messages. There are quite a few organs in this system, all with their own unique chemical signature: the pineal gland, pituitary gland, hypothalamus, thymus, thyroid, adrenal glands, pancreas, and sex glands. This is one of the least-understood systems of the body, but we do know that these organs release chemicals into the bloodstream to let the rest of the body know what to do.