Anatomy and Physiology of Human Body

Introduction 

Human Anatomy is the discipline of science that focuses on the structural composition of humans. It is a Greek word wherein “ana” is (up) and “tome” is (cutting). Anatomy is the study of how the human body is arranged and made up of cells, tissues, organs, and organ systems. Human physiology is a branch of science that deals with the activities and functions of the vital life processes within the human body. There are various types of physiology such as Cell physiology, Special physiology, Systemic physiology, and Pathophysiology. The human body is comprised of multiple organ systems such as the respiratory system, digestive system, nervous system, cardiovascular system, urinary system, and reproductive system.

Learn More about Anatomy and Physiology of Human Body. Check out more videos in Science Class 6 Lesson no 08.

Circulatory system

The human circulatory system is made up of the heart, arteries, veins, and capillaries. This system is used to transport blood and lymph throughout the body. It also provides nutrition and removes nitrogenous waste from the body. It is also called the cardiovascular system. Humans have a closed circulatory system, where blood flows in specific blood vessels. Below given are the components of the circulatory system and their function.

Organ	Structure and Components	Functions
Heart	The human heart contains four chambers: the right and left atrium, and the right and left ventricle. It has specialized cardiac muscle with many valves.	It pumps blood throughout the body.
Arteries(blood vessels)	Thick-walled, valveless.	Transport blood from the heart to other parts of the body (exception- the pulmonary artery).
Veins   (blood vessels)	Thin-walled and have valves.	Transport blood from the other parts of the body to the heart (Exception- for the pulmonary vein).
Capillaries	Thinnest blood vessels.	Connects arteries and veins.
Blood	50–55 % of blood is made up of plasma and 45-50% is made of blood cells like RBC, WBC, and platelets.	Act as the medium of transport of nutrients, gases, and nitrogenous wastes.

Respiratory System

• Respiration is the process of oxidation of food materials to liberate energy. 
• There are two types of respiration internal and external respiration. The inhalation and exhalation of air with the help of the lungs are known as external respiration. Here carbon dioxide is exhaled and oxygen is inhaled.
• Internal respiration is also known as cellular respiration which occurs in the mitochondria and produces energy in the form of ATP. 
• The human respiratory system is made up of the Nostrils, pharynx, Larynx, a pair of lungs, and Diaphragm. 
• The lungs are made up of Trachea, Bronchi, Bronchioles, and Alveoli.

Digestive system

• Digestion is the breakdown of complex food substances into simpler nutrients such as carbohydrates, proteins, etc. which are easily absorbed by the body. 
• The digestive system secretes various enzymes which assist in the digestion of food material. Digestion occurs in 5 steps given as follows-

Steps	Involved organs	Function
Ingestion	teeth, tongue, and palate.	Intake of food materials such asrice, fruits, vegetables, etc.
Digestion	Mouth, salivary glands, liver, stomach, pancreas, small intestine.	Food is digested and broken down into simpler soluble and absorbable forms such as sugars, amino acids, fatty acids, etc.
Absorption	Villi of the small intestine.	The food thus broken into simpler substances is absorbed in the blood and transported to various organs of the body.
Assimilation	Cells, tissues	Absorbed food is utilized by cells and tissues for their cellular activities.
Egestion	Large intestine and anus.	Excretion of unusable or undigested material from a cell.

Reproductive System

• Humans are sexually dimorphic. They perform sexual reproduction and give rise to the next generation. 
• The human reproductive system is different for males and females. 

Female reproductive system–

• The female reproductive system is situated in the pelvic girdle.
• It produces eggs that are haploid and fuse with the sperm to form the zygote and then the fetus.

The female reproductive system is made up of the following-

Sex organs	Functions
Pair of Ovaries	That Contain eggs and perform Oogenesis and ovulation.
Genital Tract (Fallopian Tubes, Uterus, Vagina)	Fertilisation, ovulation, carrying a baby, and giving birth.
External Genitalia	Respond to sexual stimulation.
Mammary Gland	Produces milk for the newborn child.

Male reproductive system –

• The male reproductive system is situated in the pelvic girdle and produces sperm.
• They contain the penis which is an ejaculatory organ that transfers sperm in the female body.

The male reproductive system is made up of the following organs

Sex organs	Functions
Pair of Testis	Secreting testosterone and producing sperm.
Epididymis	Develop the sperm.
Ejaculatory ducts	Transport mature sperm to the urethra.
Urethra	Ejaculating semen.

Nervous system

• The body’s primary controlling, regulating, and communication system is the nervous system.
• The ability to move, breathe, see, think, learn, remember, and more is controlled by this system,
• The nervous system is made up of neurons, nerves, and ganglia which carry messages to the brain and the entire body.
• Neurons are made up of axons, dendrons, and a  cell body.
• The brain and spinal cord make up the central nervous system.
• The Somatic Nervous System and the Autonomic Nervous System make up the Peripheral Nervous System.

Urinary system

• The urinary system of the body is used for expelling waste products from the body. The waste products are in the form of urine. 
• A pair of kidneys perform the function of excretion. Its structural and functional unit is a nephron. 

Following are the parts of the urinary system.

Organ	Function
A pair of Kidney	Performs ultrafiltration of the blood and removes waste products from the body in the form of urine. It also performs the function of osmoregulation.
A pair of Ureter	Carries the urine downward.
Urinary Bladder	Storage organ which stores urine temporarily.
The urethra	Passes the urine outside the body.

Immune system

• The immune system of an organism protects the body from infection.
• The immune system fights the antigen (pathogen) by forming antibodies. These antibodies kill the pathogen and thus the steady state of the body is maintained.
• The organs of the immune system are-spleen, thymus, lymph nodes, blood, etc.
• The cells of the immune system include-Stem cells, T-lymphocytes, B-lymphocytes, Monocytes, Cytotoxic and Helper cells, Neutrophils, etc.

Summary

Anatomy of the human body is the study of the structure and relationship between all organs of the body. However, the physiology of the human body explains how each organ performs. The body’s organ systems collaborate to carry out a certain activity or set of duties. The respiratory system, digestive system, nervous system, cardiovascular system, urinary system, and reproductive system are various organ systems in the body that operate together and support healthy body development, growth and reproduction.

Frequently Asked Questions

1.State the types of anatomy.
Ans: The different types of anatomy are-

• Gross anatomy- Gross anatomy entails the dissection of organs on a larger scale for examination.
• Cellular anatomy- Investigating cells and cellular components under a microscope are called “cellular anatomy.”
• Molecular anatomy- DNA, RNA, proteins, and other biochemical components are studied in molecular anatomy.

2. How is the human body organized?
Ans: Cells are the structural and functional unit of life. The human body is made of cells. These cells combine and form tissues, tissues form organs, organs form organ system and all these systems together build the human body.

3. What are primary and secondary sex organs in humans?
Ans. The primary sex organs are those organs that produce gametes. In females, the primary sex organ is the ovaries which produce egg cells. In males, the primary sex organ is the testes which produce sperm.

Secondary sex organs are those that transport and store the gametes and nourish the growing baby. Male secondary sex organs are Epididymis, vasa deferentia, penis, etc. Female secondary sex organs are- the fallopian tube, vagina, uterus, etc.