Human Body

Human Body

If we were to “disassemble” the human body at the microscopic level, the cell would be the most basic unit.

The average adult has between 30 and 40 trillion cells, with an estimated 242 billion new cells produced daily. A tissue is formed when a specific group of cells with similar functions come together.

Tissues combine to form organs, groups of organs combine to form organ systems, and finally, a complete organism.

Cells -> Tissues -> Organs -> Organ System -> Organism

Human Anatomy



The human body moves in various ways, including walking, running, crawling, jumping, and climbing. The skeleton is the framework that allows us to carry out all of these activities. Humans are born with up to 300 bones. With age, however, the bones begin to fuse. The total number of bones in an adult is reduced to 206.

The skeleton also protects vital organs like the heart, lungs, and liver. Ligaments, fibrous connective tissue, connect bones to other bones.

Joints are the points where two or more bones come together. They allow for various movements such as rotation, abduction, adduction, protraction, and retraction. Joints are further classified as movable or immovable based on flexibility and mobility. Because the bones are fused, movable joints are flexible, whereas immovable joints (also known as fixed joints) are not.



Muscles are specialized tissues that help the bones move. Tendons connect the muscles to the bones. The contraction and relaxation of the corresponding muscles in that region cause limb movement. Although joints aid in bone flexibility, a bone cannot be bent or stretched unless a muscle acts on it. To put it another way, the muscles attached to that bone pull it in the direction of movement.

Furthermore, the majority of movement involves muscles that work in tandem. When we bend our arm, for example, the muscles in that region contract, become shorter and stiffer and pull the bones in the direction of movement. Muscles in the opposite direction must pull the bones towards it for relaxation (stretching).

List of Human Body Parts

List of Human Body Parts
List of Human Body Parts
  • Human body parts include a head, neck, and four limbs connected to a torso.
  • The skeleton, which is made up of cartilage and bone, gives the body its shape.
  • Internal human body parts such as the lungs, heart, and brain are encased within the skeletal system and housed within the various internal body cavities.
  • The spinal cord is the nerve that connects the brain to the rest of the body.

Human Body Structure

The human body is divided into cavities that house various organ systems.

  • The cranial cavity is the space within the skull that protects the brain and other central nervous system components.
  • The pleural cavity protects the lungs.
  • The intestines, liver, and spleen are all housed in the abdominal cavity.

Humans evolved independently from other animals, but because we share a distant common ancestor, we have a body plan that is most similar to other organisms, with only the muscles and bones in different proportions.

For example, we may believe that giraffes have more vertebrae in their neck than humans. No, despite their enormous size, giraffes have the same number of vertebrae as humans, with seven vertebrae on their necks.

One of the most noticeable characteristics is our ability to use our hands, particularly for tasks requiring skill, such as writing, opening a bottle of water, opening a doorknob, and so on.

This is because humans’ ancestors began walking on their hind limbs rather than all four limbs. The dissection of corpses (cadavers) provided the majority of our anatomical insight, and for a long time, it was the only way we could gain anatomical knowledge about the human body. It was a grotesque affair, but it dominated medical literature for centuries. Human anatomy can now be studied at the microscopic level thanks to technological advancements.

Even today, scientists are discovering new organs previously overlooked or misidentified as other existing tissues. In 2018, scientists found the Interstitium, a new body-wide organ directly beneath the skin.

Human Physiology

It refers to human physical, mechanical, and biochemical functions. This ties health, medicine, and science together by investigating how the human body adapts to physical activity, stress, and disease.

A physiologist is someone who has been trained to study human physiology. Claude Bernard is known as the “Father of Physiology” because of his groundbreaking research.

Human Body Parts and their Functions

Because the standard definition of an organ is still up for debate, the list of human body parts varies. To date, an estimated 79 organs have been identified. We also have organs that have “lost” their function as we have evolved. Vestigial organs are such organs.

Some of these organs collaborate to form specialized systems to perform a single or a set of functions. These are referred to collectively as organ systems.

And, of these 79 organs, five are critical for survival, and any damage to these five organs may result in death. The brain, heart, liver, lungs, and kidneys are the five most crucial human body parts. Continue reading to learn more about these body parts and their functions in-depth:

Circulatory System

The cardiovascular system is another name for the circulatory system. It consists of the heart and all blood vessels, including arteries, capillaries, and veins. Circulation consists primarily of two components:

  • Systemic circulation
  • Pulmonary circulation
Circulatory System
Circulatory System

Aside from these two types of circulation, there is a third type of circulation known as coronary circulation. Because blood is the body’s connective tissue, it aids in the transport of essential nutrients and minerals to cells while also transporting waste byproducts away from them.

As a result, it is also referred to as the body’s “transport system.” The human heart is anatomically similar to other vertebrate hearts in the animal kingdom, making it a homologous organ.

Digestive System

Diagram showing the digestion process

The digestive system digests food and absorbs nutrients, which the body then uses for growth and cell repair.

The digestive system’s major components are as follows:

  • Tongue
  • Oesophagus
  • Stomach
  • Rectum
  • Liver
  • Small and large intestines
  • Gastrointestinal tract
  • Pancreas
  • Mouth
  • Teeth

Mastication is the first step in the digestion process (chewing food). The saliva then combines with the food to form a bolus, a small rounded mass that can be easily swallowed. Food travels down the esophagus and into the stomach after being swallowed. The stomach secretes strong acids and enzymes that break down food into a paste.

Explore More: Diagram Of Digestive System

It then moves into the small intestine, where the food is further broken down by bile secreted by the liver and powerful pancreatic digestive enzymes. This is the stage at which nutrients from food are absorbed.

The leftover materials (stool) are then transported to the large intestine, where they change from liquid to solid as water is removed. Finally, it is pushed into the rectum, where it is expelled from the body.

Reproductive System

The human reproductive system, also known as the genital system, consists of internal and external reproductive organs. It differs between males and females. Hormones, fluids, and pheromones are all connective tissues that allow the reproductive organs to function properly.

Female Reproductive System

The female reproductive system is made up of the following components:

Ovaries: These organs produce ovum, or female eggs, as well as the hormone estrogen.
Uterine tubes: Other names for uterine tubes include oviducts and fallopian tubes.

The uterus, also known as the womb, is a pear-shaped organ in which the fetus develops. The cervix is the pathway to the vagina and the entry point for sperm. The vaginal opening allows the penis to enter during intercourse and the fetus to exit during delivery.

Female Reproductive System

Male Reproductive System

The male reproductive system is made up of testicles, which serve as sperm storage. These oval-shaped organs are housed in a pouch known as the scrotum.

Male Reproductive System

The accessory ducts for the male sexual system are located next to the testis. When sperm is formed, it is mixed with the fluids of the seminal gland, prostate gland, and Cowper’s gland. The primary function of the Cowper gland is to increase sperm volume and lubrication during coitus.

Respiratory System

The respiratory process entails the inhalation of oxygen and exhalation of carbon dioxide from the body. The ventilatory system, gas exchange system, or respiratory apparatus are all names for this system. Vertebrates, like humans, have lungs for breathing. The process of respiration begins with the inhalation and exhalation cycle.

Inhalation causes oxygen to enter the body, while exhalation causes carbon dioxide to leave the body. The respiratory system is made up of the following organs:

  • Trachea
  • Bronchi
  • Bronchioles
  • Lungs
  • Diaphragm
human Respiratory System
human Respiratory System

Carbon dioxide and oxygen molecules are exchanged passively among blood cells and the surrounding environment via diffusion. This exchange occurs through the lungs’ alveoli (air sacs).

Nervous System

The central nervous system maintains and manages voluntary and involuntary actions. It aids in transmitting signals to and from various parts of our bodies. The nervous system is divided into two categories:

  • Central Nervous System
  • Peripheral Nervous System
Human Nervous System
Human Nervous System

The central nervous system consists of the brain and spinal cord, whereas the peripheral nervous system consists of nerves and ganglia found outside of the brain and spinal cord. Every part of the body is linked by the axons.

The Central Nervous System is made up of the following components:

  • The cerebrum, hypothalamus, and thalamus make up the forebrain. The cerebrum is the largest part of the brain. The main functions of this section of the brain are thinking, perceiving, controlling motor function, receiving and processing information, and understanding language. Additionally, sexual development and emotional functions are linked to the forebrain.
  • The midbrain is located between the hypothalamus and the thalamus. The midbrain is linked to the brain stem. The midbrain regulates auditory and visual responses.
  • The medulla, pons, and cerebellum are all linked together in the hindbrain. The Hindbrain connects different parts of the brain’s surface to help accommodate neurons and connect them to the spinal column.

The Peripheral Nervous System is made up of the following components:

  • The primary function of the somatic nervous system is to transmit motor and sensory impulses from the CNS to the body. It is connected to all sensory organs, limbs, and the skeletal system. Consider the following scenario: you are riding your bicycle when you notice an obstacle (say, a dog) on the road. Your ability to immediately swerve out of the way of the obstacle and avoid a collision is the result of the somatic nervous system acting.
  • The autonomic nervous system works without the person’s conscious effort. The system aids in the transmission of impulses from the central nervous system to smooth muscles and involuntary organs such as your heart and lungs. It also prepares the body for violent attacks or abnormal conditions such as high body temperature during a fever or rapid breathing and blood pressure after strenuous exercise.

Key Points About the Human Body

Cells, the fundamental unit of life, make up every human being, including tissues, human body parts, and organ systems. Anatomy is the study of the structure and components of living organisms. Physiology, on the other hand, is concerned with the internal mechanisms and processes that help to sustain life.

These can include biochemical and physical interactions between our body’s various factors and components. Organisms began to exhibit advanced characteristics and features as evolution progressed, allowing them to be more efficient and thrive in their respective environments.

The human body is bipedal, with hair covering the body, mammary glands, and a set of exceptionally well-developed sense organs. In terms of human anatomy, we have a specialized circulatory system that allows for the efficient transport of materials and nutrients throughout the body.

A well-developed digestive system aids in the extraction of essential nutrients and minerals required by the body. A well-developed respiratory system ensures efficient gas exchange, and a well-developed nervous system allows coordination and interaction within the body as well as with the external environment, ensuring survival.

Frequently Asked Questions on Human Anatomy And Physiology

What exactly do you mean by “human anatomy”?

Anatomy is the study of an object’s structure. Human anatomy is concerned with how the various parts of humans interact to form a functional unit.

What exactly do you mean by human physiology?

Human physiology is concerned with human mechanical, biochemical, and physical functions. It is the cornerstone of modern medicine. It is the study of how human organs work.

Who is considered the father of human physiology?

The father of human physiology is Claude Bernard. He is also known as the father of modern experimental Physiology.

What role does human physiology play?

Human physiology serves as the foundation for our understanding of life. It teaches us how to treat diseases and how to deal with stress caused by various environments.

Who is the originator of human anatomy?

Andreas Vesalius is widely regarded as the father of human anatomy. He was a Belgian born into a medical family. Fabrica of Andreas Vesalius, his most famous work, received widespread acclaim.

What are the various types of anatomy?

Anatomy is classified into two types: gross anatomy and microscopic anatomy. Gross anatomy is concerned with things that can be seen with the naked eye, whereas microscopic anatomy is concerned with things that can only be seen through a microscope.

What role does human anatomy play?

Human anatomy helps us understand the structure and relationships of all body parts. It also assists us in understanding the characteristics of various body parts.

What are the differences between anatomy and physiology?

Anatomy teaches us about the structure of various body parts, whereas physiology studies the functions and relationships of body parts.

What are the most vital organs in the human body?

The brain, lungs, heart, kidney, liver, stomach, intestines, and bladder are all vital organs.

What are our body’s various systems?

Our body’s systems include the cardiovascular system, the endocrine system, the digestive system, the respiratory system, the excretory system, the lymphatic system, the nervous system, the muscular system, and the skeletal system.

How Many Ribs Are in the Human Body

Most adult humans have 12 pairs of ribs, for a total of 24 ribs. These ribs attach to the vertebral column (spine) in the back and curve around to connect to the sternum (breastbone) in the front. The first seven pairs of ribs are often referred to as “true ribs” because they attach directly to the sternum, while the remaining five pairs are called “false ribs” because they either attach to the sternum indirectly or do not attach to the sternum at all. The last two pairs of false ribs are sometimes also called “floating ribs” because they do not attach to the sternum or any other bones in the front of the body.

What Is the Strongest Muscle in the Human Body

The strongest muscle in the human body is the masseter muscle, which is one of the muscles responsible for jaw movement during chewing. The masseter muscle is located in the jaw and is often used in activities such as biting and chewing food. It is considered the strongest muscle in the human body because of its ability to generate the greatest force of all the muscles in the body.

However, it’s worth noting that when it comes to overall strength, the human heart may be considered the strongest muscle, as it works continuously throughout our lives to pump blood and oxygen to the body’s tissues and organs.

How Many Nerves Are in the Human Body

It’s difficult to provide an exact count of the number of nerves in the human body, as the nervous system is highly complex and constantly changing. However, the human nervous system is estimated to contain billions of nerve cells, also known as neurons, that transmit signals throughout the body to control and coordinate various functions.

The human nervous system is divided into two main parts: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS is made up of the brain and spinal cord, while the PNS includes all the nerves that extend from the brain and spinal cord to the rest of the body.

The PNS is further divided into the somatic nervous system, which controls voluntary movements and sensation, and the autonomic nervous system, which regulates involuntary functions such as heart rate, digestion, and breathing. The autonomic nervous system is also divided into the sympathetic and parasympathetic nervous systems, which work together to maintain a balance in bodily functions.

Overall, the human nervous system is a vast and intricate network of nerve cells and fibers that enable us to perceive and interact with the world around us.

What Is the Only Jointless Bone in the Human Body

The only bone in the human body that does not articulate, or form a joint with any other bone, is the hyoid bone. The hyoid bone is a U-shaped bone located in the neck, just above the larynx, or voice box. It is suspended by muscles and ligaments and does not directly attach to any other bones in the body.

The hyoid bone plays an important role in speech and swallowing. It serves as an attachment point for muscles of the tongue, neck, and pharynx, which are involved in these functions. It also provides support for the larynx and helps to maintain the airway during breathing. Because it is not connected to any other bones, the hyoid bone is free to move and is sometimes used as a marker in forensic investigations to help identify the position of the neck and head at the time of death.

How Many Atoms Are in the Human Body

It’s difficult to give an exact number of atoms in the human body, as it can vary depending on several factors such as age, weight, and sex. However, scientists have estimated that the average human body contains approximately 7 octillion atoms (that’s 7 followed by 27 zeros), based on average values for body weight and composition.

The most abundant elements in the human body are oxygen, carbon, hydrogen, and nitrogen, which make up around 99% of the total number of atoms. Other elements that are also present in small amounts include calcium, phosphorus, potassium, sulfur, sodium, chlorine, magnesium, and trace amounts of several other elements.

It’s important to note that these estimates are based on the assumption that the human body is composed entirely of non-radioactive elements. Some radioactive isotopes, such as carbon-14 and potassium-40, are also present in the body in trace amounts, but their contribution to the total number of atoms is negligible.

Pollex Is the Medical Term for Which of These Parts of the Human Body?

Pollex is the medical term for the thumb, which is the first digit of the human hand. The term “pollex” is derived from the Latin word for “thumb.” Similarly, the term “hallux” is used to refer to the big toe, which is the first digit of the human foot.

What Percentage of the Human Body Is Water

Water is a critical component of the human body, and its percentage varies depending on factors such as age, sex, and body composition. On average, the human body is approximately 60% water. This percentage may be slightly higher in infants and young children, as they have a higher proportion of water in their bodies due to their developing tissues and organs.

Water is found in many parts of the body, including the blood, organs, muscles, and bones. It serves a variety of important functions, such as regulating body temperature, lubricating joints, transporting nutrients and oxygen to cells, and removing waste products from the body.

It’s important to maintain proper hydration levels to support these functions and promote overall health. The recommended daily intake of water varies depending on several factors, but a general guideline is to drink at least 8 cups (64 ounces) of water per day.

Weird Facts About the Human Body

Here are some interesting and unusual facts about the human body:

  1. The human nose can detect over 1 trillion different scents, making it one of the most sensitive sense organs in the body.
  2. The acid in your stomach is strong enough to dissolve razor blades, but the stomach lining is replaced every 3 to 4 days to protect it from being digested.
  3. The human body has enough fat to make seven bars of soap.
  4. The human brain can hold up to 2.5 petabytes of information, which is equivalent to 3 million hours of television shows.
  5. The average person produces enough saliva in their lifetime to fill two swimming pools.
  6. The small intestine is about 22 feet long, while the large intestine is only about 5 feet long.
  7. The longest muscle in the human body is the sartorius, which runs from the hip to the knee.
  8. The human body contains enough iron to make a 3-inch nail.
  9. Your eyes are always the same size from birth, but your nose and ears never stop growing.
  10. The fingerprints of identical twins are not identical.

These are just a few of the many fascinating facts about the human body.

How Long Can the Human Body Go Without Food

The human body can go for a period of time without food, but the exact length of time varies depending on several factors such as age, sex, body composition, and overall health status. On average, the body can survive without food for about 3 weeks, although this can be shorter or longer depending on the individual.

When the body is deprived of food, it begins to break down stored glycogen, a complex sugar that is stored in the liver and muscles. After the glycogen is used up, the body starts to break down fat stores to provide energy. If food is still not consumed, the body will eventually begin to break down muscle tissue for energy, which can have serious health consequences.

However, it’s important to note that going without food for extended periods of time can be dangerous and should not be attempted without medical supervision. A lack of nutrients and calories can lead to malnutrition, dehydration, weakness, and other serious health problems. It’s important to maintain a balanced diet and ensure that the body is getting the nutrients it needs to function properly.

Where Are the Kidneys Located in the Human Body

The kidneys are a pair of bean-shaped organs located in the back of the abdominal cavity, on either side of the spine. They are located in the retroperitoneal space, which means that they are positioned behind the peritoneum, a membrane that lines the abdominal cavity.

The kidneys are located near the bottom of the ribcage, with the right kidney usually slightly lower than the left due to the position of the liver. They are located towards the back of the body, just below the diaphragm and above the waistline.

The kidneys are responsible for several important functions in the body, including filtering waste and excess fluid from the blood, regulating blood pressure, producing hormones, and maintaining the balance of electrolytes in the body. It’s important to maintain good kidney health by drinking plenty of fluids, maintaining a healthy diet, and avoiding activities that can damage the kidneys, such as smoking and excessive alcohol consumption.

About The Author

Knowledge Glow

I am Komal Gupta, the founder of Knowledge Glow, and my team and I aim to fuel dreams and help the readers achieve success. While you prepare for your competitive exams, we will be right here to assist you in improving your general knowledge and gaining maximum numbers from objective questions. We started this website in 2021 to help students prepare for upcoming competitive exams. Whether you are preparing for civil services or any other exam, our resources will be valuable in the process.

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