DEFINITIONS AND DIVISIONS OF PHYSIOLOGY

Physiology is defined as the study of the normal function­ing of organs and organ systems, i.e., the study of homeo­stasis and biological functioning of an organism. Human and animal physiology are part of the same discipline and may be covered as one coherent whole.

1.4.1 Cell and Molecular Physiology

Cell and molecular physiology deals with the physiologi­cal mechanisms that occur at the cellular level and these have important consequences for the higher levels of orga­nization. Cell and molecular physiologists study molecular genetics, signal transduction, metabolic biochemistry, and membrane biophysics.

Physiology is the study of how animals work and how they solve the challenges of surviving in the natural envi­ronment. Though we often think of animal physiology as a study of organs, systems, and whole animals, it is important to recognize that the reasons for many of these features can be traced back to underlying rules of chemistry, biochemis­try, and cell biology. Many of the properties of organs and systems emerge from the regulation of cellular processes, such as energy production, membrane transport, cellular anatomy, and gene expression. While the physiology of an animal is much more than the sum of these molecular and cellular processes, an awareness of how cells work is vital to understanding complex physiological processes

1.4.2 Systemic Physiology

Systemic Physiology includes each organ system of the body and its functions. It is the detailed study of individ­ual organ systems like the Respiratory System, Nervous System, Renal System, Digestive System, and Reproductive System.

1.4.2.1 The Integumentary System

The skin and its derivatives are parts of the integumentary system. These consist of many types of glands, hair, and nails. The system is responsible for protecting the body, controlling body temperature, eliminating waste, synthe­sizing vitamin D3 with solar radiation, and responding to different stimuli that are interpreted as pressure, pain, and temperature.

1.4.2.2 The Skeletal System

The term skeleton is derived from the Greek word skeleton, which means “dried up.”Bones, joints, cartilage, and liga­ments are all part of the skeletal system. The joints allow the body to move and provide flexibility. However, from a structural standpoint, the human skeletal system is made up of two forms of supportive connective tissue: bone and cartilage. Skeletal system functions include the following:

1. It serves as the internal structure that supports and anchors all soft organs.

2. Bones protect soft body organs.

3. Movement: Skeletal muscles associated with the skeletal system act as levers to move the body and its parts.

4. Fat storage: Fat is stored in the cavities of bones. Bone is a mineral storage in and of itself. Calcium and phosphorus are two of the most important.

5. Blood cell production happens in the marrow cavi­ties of specific bones

1.4.2.3 The Muscular System

Muscle tissue encompasses all contractile tissues in the body, including skeletal, cardiac, and smooth muscle. The skeletal muscle system, on the other hand, refers to the skeletal muscle tissue and connective tissues that comprise particular muscle organs such as the biceps brachii muscle. Cardiac muscle tissue is found in the heart and is thus a part of the cardiovascular system. The intestines’ smooth muscle tissue is part of the digestive system, while the urine bladder’s smooth muscle tissue is part of the urinary sys­tem, and so on.

1.4.2.4 The Nervous System

Every bodily system depends on the others to function. All of them depend on one another and function as a single entity to enable the body to function normally. The nervous system and the endocrine system are the two main communication networks that allow the body’s billions of cells to be con­trolled. Though they accomplish it in different ways, both systems transfer information from one area of the body to another. The nervous system uses nerve impulses to quickly transfer information from one part of the body to another. The endocrine system uses substances produced into blood­stream by ductless glands and circulated from glands to other regions of the body to relay information more slowly. The main coordinating body is the nervous system.

The nervous system’s function is to react to these internal and external changes, also referred to as stimuli, to help the body adjust to new circumstances. Conditions both within and outside the body are always changing. The nervous system maintains the equilibrium between an individual and their surroundings as well as the internal harmony of the person through the nerve impulses it sends to different organs. The brain and spinal cord serve as switching cen­ters, while the nerve trunks serve as cables that transmit messages to and from these centers. This has led to com­parisons of the nervous system to a telephone exchange.

1.4.2.5 The Endocrine System

The two primary coordinating and governing systems in the body are the neurological system and the endocrine system. These two systems differ in several ways. For instance, the endocrine system has more extensive, slower-acting, and longer-lasting effects than the neurological system, which is primarily activated by chemical and electromagnetic inputs. Additionally, the endocrine system affects more general functions like growth, metabolism, and reproduc­tion. Despite these distinctions, there exists a close relation­ship between the two systems.

1.4.2.6 CardiovascularSystem

The circulatory system is the body’s transport system that transports food, oxygen, water, and other needs to tis­sue cells while also transporting waste products away. It is divided into three sections: 1. The blood, which is the fluid that transports materials to and from the tissue. 2. The heart, which is the driving force behind blood circulation.

3. The blood vessels, which carry blood to and through tis­sues before returning to the heart.

1.4.2.7 RespiratorySystem

Oxygen is a basic necessity for all bodily cell functions and growth. It is also required for the body to obtain energy from meals. The respiratory system’s primary functions are to remove carbon dioxide, a gaseous waste product, from each tissue cell and to deliver oxygen to each one. The inhalation and exhalation of air is referred to as breath­ing or ventilation. The mixture of gases that makes up air includes nitrogen, carbon dioxide, oxygen, and other gases. The pressure of these gases changes with altitude above sea level. The first phase, known as external expiration, only occurs in the lungs, where blood is filled with oxygen from the surrounding air and is subsequently evacuated with car­bon dioxide. Gas exchanges occur between the blood and the body’s cells during the second phase, known as internal respiration. Oxygen leaves the blood and enters the cells at the same time that carbon dioxide exits the cells and enters the blood. Air enters the lungs through the complex network of passages and compartments that make up the respiratory system. The pharynx, which is shared by the respiratory and digestive systems, the voice box, or larynx, the windpipe, or trachea, the nasal cavities, and the lungs themselves, with their conducting tubes and air sacs, are examples of these areas. You could see the entire system as an airway connecting the blood and the atmosphere.

1.4.2.8 DigestiveSystem

Every cell in the body requires a steady supply of nutrients to provide energy and building blocks for the production of bodily components.

1.4.2.9 The Urinary System

The body’s excretory system, commonly known as the urinary system, is responsible for removing waste materi­als from the blood and expelling them from the body. The two kidneys, which remove waste from the blood, balance bodily fluids, and produce urine, make up the urinary sys­tem. A tube called the ureter transports urine from the kid­neys to the bladder. The urinary bladder: the two ureters deliver urine to this reservoir, which it then stores. The tube known as the urethra transports pee from the bladder to the exterior of the body for excretion.

1.4.2.10 The Reproductive System

Replication is the reproductive system’s function. Sexual reproduction creates new individuals and allows genetic features to be handed down from both parents to their off­spring. Producing and delivering sperm to the female repro­ductive system is the male’s reproductive responsibility. However, a female’s duty in reproduction is to create an ova and carry the developing embryo. The growth and opera­tion of the reproductive organ as well as sexual behaviour and urges are significantly influenced by sex hormones.

1.4.3 Clinical Physiology

Clinical physiology is a discipline of physiology that is con­cerned with functional aspects of a disease’s pathogenesis. Clinical physiology is a diagnostic study where samples are collected from the animals and interpreted. Clinical physi­ology refers to the in vitro study of disease and accessing the functional changes of an organ and an organ system.

1.4.4 Environmental Physiology

Environmental physiology is a branch of physiology about the relationship between an organism and its environment.

1.4.5 Comparative Physiology

Comparative Physiology deals with the comparison of physiological processes of different animals of the same species and also between different species. It is the science concerned with the differences in the vital physiological processes in different species of organisms, particularly relating to the adaptation to the specific needs of the spe­cies, to illuminating the evolutionary relationships among different species, or to establishing other interspecific gen­eralizations and relationships.

Another area of physiology that sheds light on the func­tional mechanisms of many living things is comparative physiology. The discipline itself encompasses a wide range of scientific disciplines, including environmental studies, archaeology, and evolution. Therefore, comparative physi­ology emerged as a result of a necessity and a curiosity. Research on animals that resembled people in many ways was very desirable since doctors needed to find new ways to treat human patients. In the end, the usefulness of com­parisons developed into a general scientific interest in the similarities and differences between different animal spe­cies. Numerous functions in organisms are studied and contrasted by comparative physiologists. Every aspect of an organism’s anatomy has a purpose, and almost all liv­ing things have similar basic needs, such as the ability to breathe, digest food, regulate their body temperature, and sustain their hearts. By examining the mechanisms under­lying these requirements, such as blood circulation and cell-based exchanges, researchers can amass a plethora of comparable data. Only until a scientist comprehends how each organism’s physical makeup enables it to perform the functions necessary for daily existence can accurate com­parisons be made. Therefore, the physiological aspect of comparative physiology could include anything from exam­ining how an organism moves through the use of its limbs or other appendages to researching how it breathes.

Ecophysiology, or the study of the interaction between organisms and their surroundings, is a significant com­ponent of comparative physiology. Diverse species may respond extremely differently to the same physical environ­ment. For example, a fish’s chances of surviving in a desert are far lower than in its native water habitat. On the other hand, because of their anatomical structure, a land-dwell­ing lizard accustomed to colder weather would not be able to survive in an aquatic environment. Therefore, in terms of comparative physiology, ecophysiology and its research of adaptation-related topics can provide a deeper understand­ing of all animal groups.

One area of comparative physiology that has gotten more attention throughout time is the use of phylogenic compara­tive techniques. These methods are used by scientists to investigate potential evolutionary links between various living animals and to chronicle any noteworthy changes that a particular animal group may have undergone since its beginning. Researchers may investigate the physical simi­larities between different creatures or how different organ­isms have evolved comparable functional elements, such as lungs or gills for breathing.

As a result, the investigation may find shared ancestors among various species and establish an evolutionary link. Examination of fossil remnants and other archaeological material may also aid comparative physiologists in under­standing how an animal group has altered and adapted from ancient times to the present.

1.4.6 Pathophysiology

Pathophysiology or physiopathology is a branch of physiol­ogy and is an intersection of pathology and physiology, con­cerning disordered physiological processes that cause, result from, or are otherwise associated with a disease or injury. Pathophysiology generally deals with functional changes happening when the animal is diseased. Pathophysiology is inevitable to diagnose and cure the disease.

1.4.7 Developmental Physiology

Developmental physiology deals with how structures and functions change as animals grow through the various stages of life from the embryo to adult, to senescence and death.

1.4.8 Evolutionary Physiology

Evolutionary physiology deals with explaining how specific physiological traits arise within lineages throughout multi­ple generations. The evolutionary physiologist is interested in studying the origin of variations within the populations of a single species, or the closely related groups of animals.

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