Organ and Organ System – Definition, Parts & Functions

Organ and Organ System: Have you ever wondered how the human body functions vigorously every day? What are the main organs responsible for breathing, circulation, digestion, excretion, etc.? Is there any system that groups many organs together to perform a specific function? Yes, organ systems combine many organs to perform many different functions and activities in our body.

There are two broad levels of organisation in the living world, and they are lower level and higher levels of organisation. The lower level of organisation is further divided into the molecular level and cellular level. All living organisms exhibit a unique organisation. Let us read more about the organ and organ system, their specific parts and function in the given below article.

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Levels of Organisation

Living organisms exhibit a unique organisation. There are two broad levels of an organisation- lower levels and higher levels of an organisation.

1. Lower levels of the organisation start from the basic unit of all living organisms called the cell. The cell is the lowest level of organisation. It is the smallest living unit and is capable of performing all the functions of life. In order of increasing complexity, the different levels of organisation are:

Cells → Tissues → Organs → Organ systems → Organism

2. Higher levels of the organisation start from the organism (individual). The organ systems collectively form an organism. In order of increasing complexity, the different levels of the higher level of organisation are:

Organisms → Population → Community → Ecosystem → Biosphere

A cell is the lowest level of cellular organisation. It is the smallest living unit and is capable of performing all the functions of life. In unicellular organisms like Amoeba, Paramecium (also written as Paramoecium), and bacteria, all the functions are carried out by a single cell. But it is not so in a multicellular organism.

The organisms that consist of one or more cells, in contrast to unicellular organisms, are called multicellular organisms. Cells that are alike in size and shape team up and work together to do special jobs. These cell “teams” are called tissues.

A group of similar kinds of cells that work together to do the same job is called a tissue.

What are Organs?

The word organ is obtained from the Latin word “organum.” An organ is a collection of tissues that structurally form a functional unit specialized to perform a particular function. Organs may be external or internal. The organs such as the stomach, heart, kidneys, intestine are internal organs. External organs, for example, include the ear, eye, arms, legs, hands, and feet. The skin is the largest organ in the human body. It covers and protects our bodies. It helps to get rid of waste like salts, water, and heat.

Different Kinds of Organs	Functions	Diagram
Brain	It controls and coordinates memory, thoughts, and other organs.
Heart	It pumps all the oxygenated blood throughout the body.
Lungs	It separates oxygen from the air and removes carbon dioxide from the blood.
Stomach	It is a J-shaped organ that helps in digesting food.
Intestines	It is a group of tubes that helps to filter out wastes and absorbs important nutrients from the food.
Kidneys	These are two bean-shaped organs that help in filtering blood and produce urine.
Skin	It helps to remove waste in the form of sweat, regulates temperature, etc.
Liver	It helps in the production of bile and helps in excretion.

What is Organ Systems?

A group of organs working together to perform one or more functions in the living organism is called an organ system. The skeletal system, circulatory system, etc., are some examples of organ systems.

There are some organs that are parts of more than one system, such as the liver, large intestine, etc. For example:

1. The liver is a part of the digestive system. The liver is also a part of the excretory system too.
2. The large intestine is a part of the digestive system. But it is also a part of the excretory system.

Different Types of Organ Systems in Human Body

1. Skeletal System: Bones, cartilages, tendons, and ligaments in our body form our skeletal system. There are 206 bones and 22 joints in an adult human body. The structure formed by these bones is called a skeleton.

Parts of Skeletal System: The parts involved in the skeletal system are the bones of the skull, ribs (chest), vertebral column (backbone or spine), axial and appendicular skeleton.

Functions of Skeletal System

1. It protects delicate internal organs from injury.
2. It provides form and shape to the body.
3. Bones provide a surface to which muscle contraction and relaxation of muscles produce movement.

Fig: Skeletal System

2. Muscular System: Muscles of our body form our muscular system. There are more than 600 muscles in our body. There are three types of muscles, and they are cardiac, smooth, and skeletal.

Functions of Muscular System

1. It gives shape to our bodies.
2. It also helps in the locomotion of the body.
3. It provides protection to internal organs from injury.

Fig: Muscular System

3. Digestive System: Organs that help in the digestion of food from the digestive system. Digestion is the process of breaking down food into simpler substances that can be used by our body.

Parts of Digestive System

1. Mouth: Tongue, teeth, and salivary glands
2. Oesophagus (Food Pipe)
3. Stomach
4. Liver and gallbladder
5. Small intestine
6. Pancreas
7. Large intestine
8. Anus

Functions of Digestive System

1. To convert complex food into a simple, soluble form so that it can be easily absorbed by the blood.

Fig: Digestive System

4. Respiratory System: Respiratory system helps us to breathe. The air we breathe in is called inhaled air. The air we breathe out is called exhaled air.

Parts of Respiratory System

1. Nose
2. Trachea (windpipe)
3. Bronchi (singular bronchus)
4. Lungs

Functions of Respiratory System

1. The respiratory system is involved in taking in oxygen from the air and provides oxygen for the breakdown of food to produce energy.
2. It removes carbon dioxide as the waste product of metabolism.
3. It helps to facilitate the sense of smell.
4. It also helps to balance the heat content in the body.

Fig: Respiratory System

5. Circulatory System: It is also called the cardiovascular system. It is a system that circulates blood and lymph through the body.

Parts of Circulatory System

1. Heart
2. Blood vessels (arteries, veins, and capillaries)
3. blood ( plasma, red and white blood cells, platelets)

Functions of Circulatory System

1. To transport gases and materials like nutrients, hormones, etc., throughout the body.
2. It removes waste products such as carbon dioxide from the cells.
3. White blood cells fight against diseases throughout the body.

Fig: Circulatory System

6. Nervous System: It is one of the most complex systems in the human body that controls and coordinates activities and actions.

Parts of Nervous System

1. Brain
2. Spinal cord
3. Nerves (cranial nerves, spinal nerves)
4. Sense organs (eye, ear, nose, tongue, skin).

Functions of Nervous System

1. Controls the working of the body and coordinates body parts.
2. It activates or provokes muscles and glands for their respective functions for a particular time.
3. The nervous system responds to the stimuli.
4. The sensory neurons provide information from the outside world to the brain.

Fig: Nervous System

7. Excretory System: The organs that remove waste from our body make up an excretory system. The process of removing the metabolic wastes from the body is called excretion. The organs of excretion are the lungs, kidneys, and skin.

Parts of Excretory System

1. Kidneys
2. Ureters
3. Urinary Bladder
4. Urethra

Skin, liver, large intestine also are involved in removing waste from the body.

Functions of Excretory System

1. It removes waste from the blood and forms urine.

Fig: Excretory System

8. Reproductive System: All living beings produce young ones of their own kind. This process of producing young ones of its own kind is called reproduction. It is an important characteristic of all living organisms, and it is essential to ensure the continuity of life.

Parts of Male Reproductive System

1. Penis
2. Scrotum
3. Testes
4. Epididymis
5. Vas deferens
6. Prostate
7. Seminal vesicles

Parts of Female Reproductive System

1. Ovaries
2. Fallopian tubes
3. Uterus
4. Cervix
5. Vagina

Functions of Reproductive System

1. The main function of the reproductive system is to produce sperm cells and eggs.
2. The sperm and ovum are transported to a common site for fertilization.
3. Penis places the sperm inside the body of a female.
4. Females produce young ones.

Fig: Reproductive System

Summary

Living things exist along with non-living objects on this earth. However, living things or living organisms show certain characteristics that distinguish them from other non-living things. The characteristics of living things include cellular organisation, nutrition, respiration, excretion, reproduction, movement, response to stimuli, etc. These actions and reactions are caused due to many organs and organ systems present in the human body – a group of cells combined to form tissue. A group of tissues combines together to form organs. A group of organs combines to perform specific functions of an organ system. There are many organ systems such as the digestive, respiratory, circulatory, nervous, etc.

Frequently Asked Questions (FAQs) on Organ and Organ System

Q.1. What is the largest organ?
Ans: The skin is the largest organ of the human body.

Q.2. What are the 5 types of organ systems?
Ans: The 5 types of organ systems are the digestive system, respiratory system, circulatory system, nervous system, excretory system, etc.

Q.3. What’s the heaviest organ in the human body?
Ans: The liver is the heaviest organ in the human body. It weighs approximately about 1.36-1.59 kilograms.

Q.4. What is the weakest bone in your body?
Ans: The clavicle or collarbone is the weakest bone in our body; since it is a thin bone, it is easy to break.

Q.5. What are the 3 most important organs?
Ans: Every organ that is present in our body is equally important. The 3 most important and vital organs of the human body are the brain, heart, and lungs.

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