Human Physiology


Human Physiology, a part of biology concerned with the functioning of living organisms and their parts, is studying how the body works. The body's structure, function, and chemistry are all closely related to one another. The body comprises many systems that work together to maintain homeostasis. These systems are made up of organs and organ systems that work together in order to maintain a stable internal environment despite changes in external conditions.

Human physiology is a large subject that deals with the functions of animals, including humans. It includes how these animals' bodies work, what is going on inside their bodies, and how they interact with their environments.

The human body is composed of various cells, also known as tissues. It has several organs, which can be classified into four main groups− the integumentary system (skin), skeletal system (bones), muscular system (muscles), and nervous system (nerves). Each organ has its specific function to ensure everything works properly and efficiently in our bodies.

What is Physiology?

Physiology is the scientific study of living organisms and the various mechanisms that allow these organisms to function. In other words, it's what makes humans and animals "tick." The field encompasses a wide variety of topics, including how the central nervous system interacts with our muscles and organs, how the digestive system breaks down food and assimilates the nutrients into our body, how the heart works to pump blood throughout our body, and how we convert chemical energy from food into usable forms of energy.

The field also includes exploring how organisms respond to their environments and understanding how our senses (such as sight or hearing) work. Overall, understanding physiology can help us better understand why things happen in our bodies and facilitate research that could lead to cures or treatments for some diseases and conditions.

In human psychology, the following are the main bodily systems−

The Endocrine System

The endocrine system is an organic network of ductless glands that secretes hormones. The secretion of these hormones directly affects the metabolic activities of cells, tissues and organs in living things. The endocrine system uses a feedback control loop to constantly control the production and release of these hormones. This control loop relies on a specific sequence of events, including hormone production and regulation by the hypothalamus and pituitary gland, subsequent conversion of these hormones into secondary messengers within target cells, and the expression of genetic material that leads to changes in cell function.

The hypothalamus is a large structure located at the brain's base. It is responsible for many vital functions, such as maintaining homeostasis and also links the nervous and endocrine systems by secreting neurohormones. The pituitary gland is attached to the bottom of the hypothalamus and secretes several different types of hormones into the bloodstream. These include luteinizing, follicle-stimulating, thyroid-stimulating hormone, adrenocorticotropic hormone, and growth hormone. These then travel throughout the body, triggering further chemical reactions within target cells that alter the activity of the cells. The pituitary gland also secretes prolactin, which is involved in breast milk production.

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The Nervous System

The body's ability to work relies on the transmission and reception of signals by the nervous system. It comprises a network of nerves connecting the brain and spinal cord to every cell in the human body. The nervous system serves as a conduit for information flow throughout the body. Among its many functions is transmitting information between the brain, spinal cord, and many organs, including the kidneys, intestines, and skin. Movement, digestion, and respiration are all aided by the information carried by these signals.

Communication between the brain and various central nervous system elements is also carried out through nerves (the brain, spinal cord, and retina). This enhances our senses of sight, sound, taste, and touch. Nerves also regulate our muscles, allowing us to move and directing our senses. As a result, they help regulate our blood vessels so that our blood can flow throughout our bodies and reach all of our cells.

The nervous system has three types of nerves− sensory nerves carry messages from specific parts of our bodies to the brain; motor nerves carry messages from the brain to specific parts of our bodies so we can move; autonomic nerves carry messages from the brain to our internal organs so they can function properly without us having to think about each task.

The Immune System

The immune system is a collection of organs and cells that work together to protect the body from foreign invaders, such as bacteria, viruses, and fungi. It is also responsible for fighting cancerous cells, which are similar to infectious agents in that they are abnormal, tend to grow uncontrollably, and spread throughout the body.The immune system is a collection of organs and cells that work together to protect the body from foreign invaders, such as bacteria, viruses, and fungi. It is also responsible for fighting cancerous cells, which are similar to infectious agents in that they are abnormal, tend to grow uncontrollably, and spread throughout the body.

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One key difference between the immune system and other defenses of the body is that it's not one unified defense, but rather it's made up of many different cells and organs that act in concert to produce an overall response. White blood cells (leukocytes) are the most significant cells, and they are formed in the bone marrow in red blood cells by the stem cells. The five types of white blood cells are neutrophils, eosinophils, basophils, monocytes, and lymphocytes.

The first line of defense against foreign invaders is the skin and mucus membranes (which line hollow organs like the lungs). Surfaces of these membranes have tiny hair-like protrusions called cilia that move back and forth or side-to-side in an effort to trap microbes that attempt to enter.

However, microbes can be too small or slimy for these defenses to detect or trap. The next line of defense is a thin layer of mucus that lines the entire respiratory system, including the nose, throat, and lungs. Mucus is a sticky substance that traps bacteria and viruses.


In conclusion, human physiology is the study of how the human body works. It covers a wide range of topics, from the way our cells work to the way our organs work. It is a complex and fascinating subject, and there is still much to learn about it.


1. What is Human Physiology?

Our bodies' physical and chemical functioning are studied in human physiology. You can find it in the same category as animal physiology as a whole.

2. What is a typical day in the life span of a human being?

When a person is born, their life span begins. Children's ages range from birth to two years; then there's childhood, then adolescence, then young adulthood, then middle age, and finally, old age (60+ yrs).

3. How many types of muscles are there?

There are three types of muscles− smooth, cardiac, and skeletal. The skeletal muscle is the most common type of muscle in humans and animals. These contract voluntarily and involuntarily, but only when stimulated by impulses from the nervous system. Skeletal muscles provide movement for our bodies.

4. Why do we need to breathe?

In order to stay alive, we need oxygen from our environment. This is because the air contains oxygen that our bodies need to function properly. The lungs act as a pump that brings oxygen into our bodies so that our cells can use it for energy production.

5. How many bones are there in the human body?

The number of bones in your body depends on whether you are male or female. Women have smaller bones than men, so they have fewer. The average adult has 206 bones.


Simply Easy Learning

Updated on: 13-Oct-2022


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