I’ve been an undergraduate of human physiology since 2015, and I will tell you it has been a wonderful experience of study. But the question is what Physiology?, why do I have interest in, what elicit my interest, and what does it has to do with you.
First I will answer the question “what elicit my interest?”. I developed an interest for human physiology during my second year in my senior secondary school (2012). It happens to occur when a young graduate of human physiology was posted for his NYSC service in my school as a biology teacher. According to the syllabus, the classes were to cover areas of human body, its part and function. This young guy is sound and eloquent that his expression made us imagine and picturize how human body function; as various cells come together to form tissues and different tissues to system; and the different systems work together to make a whole organism. So these imaginations create curiosity to know what is more to this until I found myself studying this for a degree at Olabisi Onabanjo University, Ogun State. What have I been doing? What is Human physiology? 
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<h2><center>What is Human physiology?</center></h2>
Physiology is the branch of the biological sciences that deals with the study of functions and processes of living organisms. It is the most fascinating and ancient branch of science, as it unfolds the mystery of complicated functional aspects of individual organs in the body. Physiology is the science that describes how the body of living organism work, and the ways in which their integrated activities maintain life and health of the individual. The study of physiology aims to understand the study of normal mechanisms, and their interactions within a living system. It deals with the understanding of the connection and relationship between one’s life in the world and the inner life of one’s body.
<h3>How are you concerned?</h3>
We all experience different reactions in our body like fatigue, thirst, hunger, pain, sexual arousal, anger, fear; all these reactions are not just random occurrence, they are as a result of something, and are referring to something. For example, most people hate pain because they think it is harmful to their body; this is a big misconception.
<p> <center><div class="pull-right">https://steemitimages.com/0x0/https://tfc.edu/wp-content/uploads/2016/11/BIO-214-1.jpg<br> <a href="https://steemitimages.com/0x0/https://tfc.edu/wp-content/uploads/2016/11/BIO-214-1.jpg">image source</a></div></center> Pain is neither an enemy of the body nor harmful to it, but the body’s best friend who will never want the body to get harmed. What do I mean? Pain is not what causes the harm but just a language telling you there is a biological tissue damage or threat meaning you are getting hurt. Consider this, when you place your hand on a hot object, you withdraw your hand immediately just because you felt a pain. Do you know, if not for the pain you wouldn’t have noticed anything until the hand is completely burnt. Many people are ignorant of this phenomenon, therefore they find themselves attacking the pain, multiplying their dose of analgesics just to kill it. In this case the major point is to know the cause of the pain, and this is why it is essential to “Know Yourself”
<h3>History of physiology</h3>
Physiology is as old as creation of man, it exists ever since the origin of life. The first creature or man knew about hunger, thirst, pain and fear even before knowing things like relationship, culture or language. The study of human physiology began back in 420 BC in Ancient Greece, with philosophers like Hippocrates and Aristotle, who applied critical thinking and emphasis on the relationship between structure and function. Claudius Galenus (c. 130-200 AD) was the first to use experiments to derive information about the body's functions.
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Modern physiology began with physician of the Renaissance (c. 1400-1600 AD) who attempted to understand the workings of the human body by observing and experimenting on living organisms while they function. The term physiology was introduced by the French physician Jean Fernel (1497–1558). In the 17th century, William Harvey (1578–1657) described the pumping action of the heart and the circulation of blood, pioneering the combination of <em><strong>close observation with careful experiment</strong></em>. In the 19th century, physiological knowledge began to accumulate at a rapid rate with the cell theory of Matthias Schleiden and Theodor Schwann in 1838, that organisms are made up of cells. Claude Bernard (1813–1878) created the concept of the <em><strong>milieu interieur</strong></em> (internal environment), which Walter Cannon (1871–1945) later said was regulated to a steady state in <em><strong>Homeostasis.</strong></em>
 In the 20th century, the physiologists have extended their studies to comparative physiology and Ecophysiology, Evolutionary physiology, Exercise physiology and many more distinct subdisciplines and since then medical science has really experience a fast growth. 
<h3>The study of physiology</h3>
Physiology can be said to be a primitive science that birth other science because the goal of an organism is to survive and maintain a physiologic function (good health). For instance, the idea of building the first house or shelter would have been prompted by a need for protection against wild weather that can make the body deviate from its normal function. Many other technologies also evolve in order to heed the comfort of the body and make life easy.
The study of physiology has the ultimate goal of understanding the intact Human or whole organism, but this is done by actual study and understanding of the different integral units that makes up the organism and their interactions with one another. The study of the body is usually considered in terms of individual physiological systems, each of which consists of different organs and structural elements that work together to serve a common functional purpose.
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<h3>The human Body</h3>
The human body is like an incredible technical and complex machine that is understandable by the study of its working parts. It operates as a single entity but is made up of a number of systems that work interdependently. Within the body are different structural organization and complexity but the basic functional unit is known as <em><strong>CELL</strong></em>. Cells are microscopic structures that carry the functionality of life. The cells of the body (of about trillions of them) become specialized for performance of specific function. Similar cells aggregate to form tissues. Tissues consist of cells that share similar structure and cooperate to perform a common basic function. Tissues work together to form organs and organs work together to form system, each system is associated with specific or similar functions that are essential for the well being of the body. Every human is made up of the same structural and functional constituents, that is everybody has the same biological make-up.
<h3><center>Sub-disciplines of physiology</center></h3>
The study of physiology encompasses a wide array of many sub-disciplines which are categorized:
<ul>
	<li><strong>Based on taxonomy:</strong> human physiology, animal physiology, plant physiology, microbial physiology, viral physiology</li>
	<li><strong>Based on the level of organization:</strong> cell physiology, molecular physiology, systems physiology, organ physiology, ecological physiology, integrative physiology</li>
	<li><strong>Based on the process that causes physiological variation:</strong> developmental physiology, environmental physiology, evolutionary physiology</li>
	<li><strong>Based on the ultimate goals of the research:</strong> applied physiology (e.g. medical physiology), non-applied (e.g. comparative physiology)</li>
</li>
	<h3><center>What do physiologists do?</center></h3>
Physiologists work both inside the laboratory and outside observing, hypothesizing, experimenting, and analyzing, to give answers to questions pertaining to human survival in his environment due to internal homeostatic regulation. They make research on how the internal environment of the body is regulated and how this regulation is altered by physical, ecological or emotional changes and how this alteration can be balanced to suit the organism. They explain how parts of the body work at various level of organization, how living systems respond to physical activities, how living systems respond to environmental conditions, how the genomes translate into functions at different levels.
The knowledge of physiology also form an important part of the basis of medicine and other related health fields and medical sciences like dentistry, pharmacology, pathology, pharmacy. 
<h3>Physiology and technology</h3>
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Physiology as a science, has compared the working of the body to other natural and artificial processes and has used these processes to understand the science of the body. With the emergence of the technological era and the development of complex machines, physiology has gained great improvement has it understands the body as a machine that could be studied by taken apart and if kept under favorable conditions the different parts could continue to work.
A further revolution in physiology came with the discovery of radioactivity with the availability of radioisotopes. With the knowledge of radiography, it is possible to trace the fate and movement of atoms and molecules in the body. Due to progressive development, physiologist can now predict the working of the body by using mathematical equations and evaluations, and  even use computerized or specialized machines to test and monitor metabolic processes.
<h3><center>Conclusion</center></h3>
Man is a living being in dynamic interaction with the organic and inorganic elements of a complex ever-changing environment. Physiological state is considered the normal biological state of the body and any deviation from this is known as <em><strong>Unhealthy State</strong></em> of the body. Developing a healthy lifestyle is as good as  <em><strong>knowing yourself.</strong></em> This doesn't mean you would be your own doctor, but it does mean you can be your doctor's partner.

<h4>Reference and Futher Reading</h4>
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- https://en.wikipedia.org/wiki/Physiology
- https://www.medicalnewstoday.com/articles/248791.php
- https://www.prospects.ac.uk/careers-advice/what-can-i-do-with-my-degree/physiology

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<center>This articled is posted to educate on the concept of Physiology (the science of human function). It is also serving the purpose of an introduction of upcoming series of articles that explains the physiology of different metabolism and functional organs of the Body in relation to the function of the entire organism (Man).
Referential source links for this article are included for further reading and all illustrative images are credited to their various sources. If you find it helpful and interesting kindly take a fraction of your time to <strong>UPVOTE, COMMENT</strong> and <strong>RESTEEM</strong>. Thank you.
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