The anatomy of man is the study of the structures of the human body. The term anatomy derives from the ancient Greek word meaning ‘dissection’ or ‘to dissect’. It involves the study of the structure of the human body. The human body comprises 206 bones and 79 organs. Anatomy focuses on how different body structures look and work at different levels.  

The structuring of the Human Body

The cell is the smallest unit of an organism. It comprises three parts: the cell membrane, nucleus, and cytoplasm. The core contains nucleolus and cell DNA. A group of cells makes tissues. There are around four types of tissues:

• Connective Tissue: It supports other tissues and binds bone, blood, and lymph tissues together.
• Epithelial Tissue: A group of cells provides skin and lining to the various internal cavities and forms glands.
• Muscle Tissue: It helps the body in movement.
• Nerve Tissue: is neurons that transmit messages/information to the brain.

A group of tissues makes up an organ. It performs certain functions. The human body has nine central organ systems:

1. the integumentary system
2. the musculoskeletal system
3. the respiratory system
4. the circulatory system
5. the digestive system
6. the excretory system
7. the nervous system
8. the endocrine system 
9. the reproductive system

1.THE INTEGUMENTARY SYSTEM

The integumentary system is the largest organ of the body that provides an outermost layer to the body and provides immunity, acts as a barrier, and protects the body. The system includes:

• The skin (epidermis and dermis).
•  Hypodermis.
•  Associated glands.
•  Hair.
•  Nail.

2.THE MUSCULOSKELETAL SYSTEM

The musculoskeletal system helps the human in motion. It also provides support, and stability to the body. It is divided into two parts:

•   MUSCULAR SYSTEM: It includes all the muscles of the body and helps body joints to create movement. Tendon is also the part of the muscular system which joins the muscles to the bone. They also store minerals like calcium.

•   SKELETAL SYSTEM: Its main part is bone, which forms the joints providing our body with a hard-core and mobile structure. It stores the body’s majority of carbohydrates in the form of glycogen.

3.THE RESPIRATORY SYSTEM

The respiratory system helps our body to breathe without which we’ll die. It  includes:

• Mouth and nose: They help in intaking air and breathing out carbon dioxide 
• Pharynx (throat):  They deliver air to the trachea/windpipe. 
• Trachea: It is a passage that connects the throat with the lungs.
• Bronchial tubes: Tubes at the bottom of the trachea that connect into each lung.
• Lungs: It removes oxygen from the air and then passes it into the blood. They filter air into oxygen and carbon dioxide. It then passes the filtered oxygen into the blood and removes the carbon dioxide from the body. 

• Diaphragm: It helps to pull and push air out of the lungs.
• Ribs: These are the bones that surround and protect lungs and heart.

4.THE CIRCULATORY SYSTEM

The circulatory system helps in circulating blood to all the different parts and consists of the heart, blood, and blood vessels, and their functions are: 

THE HEART

The heart consists of four chambers, and each has its functions.

• Two on top (atrium and plural atria) 
• Two on the bottom (ventricles), one on each side.

• RIGHT ATRIUM- two large veins carries the deoxygenated blood to the right atrium. The superior vena cava transports blood from the upper body, and the inferior vena cava carries blood from the lower body.  Then the right atrium pumps blood to the right ventricle.
• RIGHT VENTRICLE- Then, deoxygenated blood is pumped into the lungs through the pulmonary artery from the lower right chamber. The lungs make the blood oxygenated. 
• LEFT ATRIUM- The pulmonary veins transports the blood to the left atrium. It then transports the blood to the left ventricle. 
• LEFT VENTRICLE- left ventricle is more significant than the right one. It transports the oxygenated blood back to the rest of the body parts.

THE BLOOD 

• The blood is made up of red blood cells and white blood cells, plasma, and many platelets.

THE BLOOD VESSELS

• The blood vessels include arteries, veins, and capillaries that carry blood throughout the body.

5.THE DIGESTIVE SYSTEM 

The digestive system’s function is to digest food and liquids. The digestive system includes:

• MOUTH

It helps in intaking food and with the help of teeth and tongue and saliva, it breaks down the food into small parts and turns it into sugar.

• PHARYNX

The food moves from the mouth to the stomach through the pharynx.

• THE STOMACH

The stomach is a large, bag-like organ that stores food. It first churns the food and mixes it with gastric acid. The paste of mixed acids and partially digested food is known as chyme.

• THE SMALL INTESTINE

The bile, pancreatic enzymes, and other digestive enzymes secreted by the inner wall of the small intestines help in the complete breakage of the food.

• THE LARGE INTESTINE

It is the largest organ in the human body and helps in the digestion of minerals and water.

• RECTUM

It connects to the anus and is a part of the lower gastrointestinal tract. It is in sacrum shape. It stores faeces until it is released through the anus.

• ANUS

The anus is the end part of the gastrointestinal tract. The faeces are released through the anus.

6.THE EXCRETORY SYSTEM

The function of the Excretory system is to remove waste materials from the body. These waste materials include water, Co2, salts, nitrogen along with heat.

The various parts are:

•  Lungs – Through the process of respiration, it removes co2 and water from the body 
•  Skin – it helps remove urea, water, and salt from the surface of the body through sweat.
•  Liver – it stored sugar until it is needed for the blood to be utilised. Urea is a substance in the urine that is released from the body through the urethra.
•  kidneys- it removes excess water from the body and filters impurities out of the body.

7.THE NERVOUS SYSTEM

The nervous system gathers information, monitors changes inside the body, and takes actions if needed. It consists/is divided into two parts: the central nervous system(CNS) and the peripheral nervous system(PNS).

THE BRAIN

• The brain is the main and most integral part of the central nervous system. 
• It is divided into three sections/parts cerebrum, cerebellum, and brainstem.  
•  Cerebrum: It is the largest part and consists of the right and left hemispheres. Its functions are interpreting touch, vision and hearing, speech, logic, emotions, learning, and control over movements of the body.
• The cerebellum: is situated under the cerebrum. It coordinates muscle movements, maintains posture, and provides balance.
• Brainstem: It joins the cerebrum and cerebellum with the spinal cord. It performs many non-voluntary functions like breathing, heartbeats, body temperature, sleep cycles, digestion, sneezing, vomiting, and swallowing.

THE SPINAL CORD

• It is formed by nervous tissues.
• It has a long, thin tube-like structure.
• It covers the central canal of the spinal cord that contains cerebrospinal fluid.

Conclusion

In this topic, we learned about the comparative anatomy of man, how different body functions and parts work.  And then, we studied the comparative anatomy of the heart. We also looked at the comparative anatomy of the brain. These notes are helpful for students appearing in other competitive exams. This topic is crucial for biology students and students studying anthropology.