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Physiology Definition

The study of physiology is the process through which living things work. It is a vast and intricate discipline that covers a variety of subjects, from the behaviour of single cells to the operation of complete organ systems. Fundamentally, the goal of physiology is to comprehend how living things maintain homeostasis, or a state of balance, in the face of continually shifting internal and external circumstances.

Physiology Definition

Ancient Egyptians and Greeks were among the first civilizations to study physiology because they were eager to learn how the human body functions. The area has grown to include a variety of subfields over time, including neurophysiology, endocrinology, cardiovascular physiology, and many others.

The idea of adaptation is a fundamental one in physiology. The goal of the study of physiology is to comprehend how living things adapt to their surroundings on a continuous basis. For instance, when someone starts a new workout routine, their body goes through a number of changes that serve to enhance their physical fitness, such as an increase in muscle mass and a decrease in resting heart rate.

Modern technological advancements have made studying physiology much easier. For instance, the invention of the electrocardiogram (ECG) changed the study of cardiovascular physiology by enabling specialists to identify diseases like arrhythmias and gain a better understanding of how the heart functions.

History of Physiology

The study of physiology has its roots in earlier civilizations like the Egyptians and the Greeks, who were curious about how the human body functioned. For instance, the ancient Egyptians investigated the heart because they thought it was the seat of the soul, while the Greeks researched the human body, including how the brain and circulatory system worked.

The teachings of religious scholars who held the belief that the body was a creation of God and that it was their responsibility to comprehend its workings had an impact on the study of physiology during the Middle Ages. With the work of physicians like Ibn al-Nafis, who was the first to describe the pulmonary circulation of blood, and William Harvey, who made great advancements in the study of the circulatory system, the study of physiology was primarily focused on the human body during this time.

With numerous colleges now providing degree programmes in the topic, physiology is becoming a well-known area of study in the modern era. From the discovery of antibiotics to the creation of novel treatments for chronic diseases, the discipline has been greatly affected by a variety of other sciences, including biology, chemistry, and physics.

Nowadays, physiology covers a vast range of issues, from the operation of individual cells to the functioning of intricate systems like the neurological, endocrine, and immune systems. As fresh investigations are made and new tools are created to aid in our understanding of the human body, the area is continually changing.

Systems under Human Physiology

The human body is an incredibly complex organism, made up of numerous systems that work together to keep us alive and functioning. Each system plays a unique and vital role in maintaining our health and well-being. Here are some of the major systems covered in the study of human physiology.

  • The Nervous System: The nervous system is in charge of regulating and coordinating all bodily processes. It consists of the spinal cord, the brain, and a web of nerves that travels throughout the entire body. This system gives humans the ability to think, feel, move, and speak. Also, it aids in our reaction to environmental cues including touch, sound, and light.
  • The Cardiovascular System: The cardiovascular system moves blood throughout the body. Blood, blood vessels, and the heart are all part of it. Blood is pumped by the heart, which also eliminates waste materials and delivers nutrients and oxygen to the body's tissues.
  • The Respiratory System: The respiratory system controls breathing, which enables us to inhale oxygen and exhale carbon dioxide. It contains the lungs, trachea, bronchi, and alveoli. The lungs take oxygen from the air we breathe in and transmit it to the bloodstream while exhaling carbon dioxide.
  • The Digestive System: This organ is in charge of nutrient absorption and food digestion. It consists of the liver, pancreas, small and large intestines, stomach, oesophagus, mouth, and stomach contents. The body absorbs food into the bloodstream after it has been broken down into smaller molecules.
  • The Endocrine System: The endocrine system is in charge of creating and controlling hormones, which are chemical messengers that command a number of bodily processes. The endocrine system is comprised of the pituitary, thyroid, adrenal, pancreatic, and adrenal glands.
  • The Muscular System: Movement and support are handled by the muscular system. Skeletal, striated, and cardiac muscles are all included. While smooth and cardiac muscles manage unconscious processes like digestion and heartbeat, skeletal muscles enable us to move and maintain posture.
  • The Skeletal System: The body's structure and support are provided by the skeletal system. Together with ligaments, it has bones and cartilage. Moreover, bones act as a container for minerals like calcium and phosphorus and as a shield for internal organs.
  • The Immune system: It is in charge of protecting the body from illnesses and infections. Together with lymph nodes and the spleen, it also contains white blood cells. To locate and eliminate dangerous diseases, these elements cooperate.

Branches Under Human Physiology

Human physiology is a vast field of study that covers the functions and mechanisms of the human body. It can be divided into various sub-disciplines, each of which focuses on a specific aspect of human physiology. Here are some of the main branches of human physiology.

  • The study of the nervous system, which includes the brain, spinal cord, and nerves, is known as This area of research focuses on how the nervous system regulates and synchronises bodily processes as well as how it reacts to various inputs. Neurophysiologists also research how illness and damage affect the neurological system.
  • The study of the blood, blood vessels, and the heart is known as cardiovascular physiology. The mechanisms that control blood flow, blood pressure, and heart rate are the main topics of this subfield of physiology. It also looks at how lifestyle, diet, and exercise affect cardiovascular health.
  • Lungs and the respiratory system are the subjects of respiratory physiology. This area of research focuses on the exchange of oxygen and carbon dioxide in the lungs as well as the regulation of breathing by the respiratory system. Respiratory physiologists also research the impacts of illness and pollution on the respiratory system.
  • Endocrinology is the study of hormones and their effects on the body. Growth, metabolism, and reproduction are just a few of the many biological processes that are regulated by hormones, which are chemical messengers. The production, secretion, and effects of hormones are all topics that endocrinologists research, as well as the diseases that might arise from hormonal imbalances.
  • Immunology is the study of the immune system and how it protects the body from diseases and pathogens. Immunologists investigate the roles of numerous immunological molecules and cells as well as the processes through which the immune system recognises and eliminates infections. They also look into autoimmune diseases and allergies as well as their causes and remedies.
  • The study of the kidneys and the urinary system is called renal physiology. This area of research explores how the kidneys control the body's fluid and electrolyte balance and filter waste materials from the blood. Renal physiologists also research how illnesses and drugs affect the kidneys and urine system.
  • Gastrointestinal physiology is the study of the digestive system, which extends from the mouth to the anus. This area of physiology investigates the processes through which food is digested and absorbed by the body.
  • Reproductive physiology is the study of the reproductive system, including the male and female reproductive organs. It also focuses on the activities of the numerous digestive system organs, such as the stomach, pancreas, and liver. This area of research focuses on the processes of conception and birthing as well as the methods by which sperm and eggs are generated and fertilised. Researchers in reproductive physiology also look into the reasons and cures for infertility and other reproductive problems.

Difference Between Plant and Human Physiology

Plant physiology and animal physiology are two distinct branches of biological science that deal with the functioning of organisms. While both plant and animal physiology involves the study of how living organisms carry out their life processes, there are several key differences between them.

Plant physiology is concerned with the study of the functions of various parts of plants, including leaves, stems, roots, and flowers. Plants are autotrophs, meaning they can produce their own food through the process of photosynthesis, which is a complex biochemical process that occurs in chloroplasts. Photosynthesis involves the conversion of light energy into chemical energy, which is then used to produce carbohydrates that are essential for the survival of plants. In addition to photosynthesis, plant physiology also includes the study of plant growth and development, plant nutrition, and the responses of plants to environmental stimuli such as light, temperature, and water availability.

On the other hand, animal physiology is concerned with the study of the functions of various organs and organ systems in animals. Unlike plants, animals are heterotrophs, which means they cannot produce their own food and must consume other organisms to obtain nutrients. Animal physiology includes the study of the digestive system, which is responsible for the breakdown of food into its constituent molecules, and the circulatory system, which is responsible for the transport of these molecules to different parts of the body. Animal physiology also involves the study of the respiratory system, which is responsible for the exchange of gases between the body and the environment, and the nervous system, which is responsible for the coordination of various bodily functions.

Another key difference between plant physiology and animal physiology is the way in which organisms respond to their environment. Plants are immobile, which means they are not able to move to escape unfavourable environmental conditions. Instead, they have evolved a range of mechanisms to cope with adverse conditions, such as the ability to close their stomata to reduce water loss in response to drought. Animals, on the other hand, are mobile and are able to escape from unfavourable environmental conditions. They also have a range of physiological and behavioural adaptations that enable them to cope with adverse conditions, such as the ability to shiver to maintain body temperature in response to cold.


Human physiology is a vast and multifaceted field of study that covers a wide range of topics. From the nervous system to the digestive system, each branch of physiology focuses on a specific aspect of the human body and its functions. By studying the various branches of human physiology, researchers can gain a deeper understanding of how the body works and how it responds to different internal and external stimuli.

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