The human body contains 11 major organ systems that work together to keep us alive. The document describes the main functions of each organ system, including the skeletal, muscular, integumentary, nervous, endocrine, circulatory, lymphatic, respiratory, digestive, urinary, and reproductive systems. It then provides more detail on how the circulatory and respiratory systems work together to transport oxygen and remove carbon dioxide throughout the body. Next, it explains the roles of the digestive and excretory systems in breaking down food, absorbing nutrients, and eliminating waste. Finally, it outlines how the nervous system acts as the master control system, while the endocrine system relies on hormones to send long-distance messages through the body.

1. THE HUMAN SYSTEM

2. What is Organ System?
• Different can work together to perform a common function, like how the parts of your digestive system break
down food. We refer to an integrated
• unit as an organ system. Groups of organ systems work together to make complete, functional organisms, like
us! There are 11 major organ systems
• in the human which include the circulatory, respiratory, digestive, excretory, nervous and endocrine systems.
The immune, integumentary, skeletal,
• muscle and reproductive systems are also part of the human body.

3. THE MAJOR ORGAN SYSTEM OF THE HUMAN BODY AND THEIR
FUNCTIONS
• 1. Skeletal- provide support and protection, store calcium and other minerals bone and cartilage
• 2. Muscular- provides movement generates heat that maintains body temp. Skeletal Muscles.
• 3. Integumentray- protects against environmental hazards, provides sensory information, regulates body temperature skin,
nails,
• Hair, sweat glands.
• 4. Nervous- directs immediate responses, coordinates or moderates activities of other organ systems, provides and interprets
• sensory information about external conditions. Brain, spinal chord, nerves.
• 5. Endocrine- adjusts metabolic activity, controls structural and functional changes during development. Testes, ovaries,
adrenal glands, pituitary gland, pancreas, thyroid gland.
• 6. Circulatory/Cardiovascular- distributes blood, water, dissolved materials including nutrients, waste products, oxygen, and
• COz heart, blood, blood vessels.

4. • 7. Lymphatic- defends against infection and disease. Spleen, thymus, tonsils, lymph nodes.
• 8. Respiratory- provides O2 to bloodstream, removes CO2 from bloodstream, sinuses,, bronchi, lungs, alveoli, nasal,
• Cavities, trachea, larynx.
• 9. Digestive- processes and digests food. Breaks down food and absorbs nutrients teeth, tongue, pharynx, esophagus,
• stomach, small and large intestine, liver, gall bladder, pancreas.
• 10. Urinary- rid body of wastes kidneys, ureters, bladder, urethra.
• 11. Male Reproductive- produce male sex cells (sperm) and hormones testes, epididimys, prostate glands, penis, and
• scrotum.
• 12. Female Reproductive- produces female sex cells (oocytes) and hormones, supports developing embryo from
• conception to delivery, provides milk to nourish newborn. Clitorus, ovaries, vagina, uterus, labia, uterine tube, and
• mammary glands.

5. THE CIRCULATORYAND RESPIRATORY SYSTEMS
• The circulatory system is responsible for transporting blood throughout the body. It consists of the heart and
• blood vessels known as veins, arteries, and capillaries. Think of blood vessels as the highways of the body,
• bringing important cargo to and from the cells. In the circulatory system, blood is pumped from the heart to the
• lungs, so they’ll get oxygen, and then pumped to the body’s cells. In order for blood to provide oxygen to the
• body, the body must have a way of obtaining that oxygen. The respiratory system allows air to enter the lungs
• and for oxygen to diffuse into the blood and route the body’s tissues. The entrance to the respiratory system
• can be found in the nose and the mouth, where air enters the body and then travels through the larynx and
• pharynx in the throat to the trachea or windpipe. From the trachea, right and left branches, known as bronchi,
• carry oxygen to the alveoli, where oxygen moves into the blood, while carbon dioxide moves into the lungs to
• be exhaled. The alveoli are the smallest parts of the respiratory system and deal specifically with exchange of
• gases, like traders at a market.

6. DIGESTIVE AND EXCRETORY SYSTEMS
The digestive system is responsible for bringing food into the body and breaking it down to useable components.
It starts at the mouth, where we ingest our food and use our saliva, teeth and tongue to bite and mash it. The food
then travels through the esophagus into the stomach, where strong acids break it down even further. During the
last two stages of digestion, nutrients and water are absorbed through the small intestine and the large intestine,
respectively. Any remaining waste products are stored in the rectum and eliminated through the anus. The urinary
or excretory system is where liquid waste is eliminated as urine. The excretory system starts with the kidneys,
important organs for cleaning the blood and balancing water in the body. In the excretory system, the liquid part of
the blood, or plasma, enters through the kidneys, where important nutrients, like sugar and some salt, are
reabsorbed into the body. Compounds we don’t need, like urea or excess water, are sent to the bladder in the form
of urine. Urine leaves the body through the urinary tract and exits the body at the urethra.

7. NERVOUS, ENDOCRINE AND IMMUNE SYSTEMS
• Without a master control system that tells our bodies what to do, none of the organ systems we’ve talked about
• so far would work. The organs in the human nervous system are made up of cells, called neurons, that use
• chemicals and electricity to send messages. This system has two main parts, the Central Nervous System (CNS)
• and the Peripheral Nervous System (PNS), which you can see in the diagram below. The Central Nervous
• System consist of the brain and the spinal chord, which serve as the main control centers for the body and
• process all incoming and outgoing messages. The Peripheral Nervous System includes all the nerves in your
• body that bring messages to the Central Nervous System and from the CNS to the muscles.

8. • Whereas the nervous system mainly uses electrical signals to communicate between cells, the endocrine system
• Relies upon chemicals, called hormones, to send long distance messages through the body. For distance
• messages through the body. For example, instead of communicating directly by talking to your neighbor, you
• decide to send him or her a letter. The main organs found in the human endocrine system are located in the
• brain and include the hypothalamus, thalamus and pituitary gland. They talk to other endocrine organs, like the
• adrenal glands, testes and ovaries to assist with other organ systems.