Human Physiology

Human physiology is the scientific study of the functions and mechanisms within the human body. It focuses on how organs, systems, tissues, cells, and biomolecules carry out the chemical and physical functions that sustain life. Physiology is a branch of biology that connects anatomy (the body's structure) with biochemistry and molecular biology. By understanding physiology, we learn how the body works under normal conditions and how it responds to internal and external changes.

1.0Homeostasis

The body can maintain a stable internal environment despite changes in the external surroundings. For example, body temperature regulation, blood pH, and glucose levels.

2.0Body Systems

The Digestive System

It is essential for good health because it converts food into the raw materials that build and fuel our body’s cells. Specifically, the digestive system ingests food (takes it in), digests it (breaks it down) into nutrient molecules, absorbs the nutrients into the bloodstream, and then defecates (excretes) to rid the body of the indigestible wastes.

Breathing and Respiration

Respiratory organs in animals (recall only); Respiratory system in humans; Mechanism of breathing and its regulation in humans of gases, transport of gases and regulation of respiration Respiratory volumes: Disorders related to respiration-Asthma, Emphysema, Occupational respiratory disorders.

Body Fluids and Circulation

All living cells require nutrients, oxygen, and other essential substances, while waste and harmful materials need continuous removal for healthy tissue function. Efficient transport mechanisms are essential for moving these substances to and from cells. Simple organisms like sponges and coelenterates circulate water through their body cavities for substance exchange, while more complex organisms use specialized body fluids like blood and lymph. 

Excretory Products and Their Elimination

Animals accumulate ammonia, urea, uric acid, carbon dioxide, water and ions like Na+, K+, Cl–, phosphate, sulphate, etc., either by metabolic activities or by other means like excess ingestion. These substances have to be removed totally or partially. Ammonia, urea and uric acid are the major forms of nitrogenous wastes excreted by the animals. Ammonia is the most toxic form and requires a large amount of water for its elimination, whereas uric acid, being the least toxic, can be removed with a minimum loss of water.

Locomotion and Movement

Movement is one of the significant features of both plants and animals. Locomotion: Voluntary movements that result in a change in place or location. Locomotion. Walking, running, climbing, flying, and swimming are all locomotory movements. Locomotion is generally searching for food, shelter, mating, suitable breeding grounds, favourable climatic conditions and escapes from enemies/predators. All locomotions are movements, but all movements are not locomotion.

Neural Control and Coordination

To maintain the body's homeostasis, the functions of the organs and organ systems must be coordinated. Coordination is the process through which multiple organs interact and complement each other's functions. For instance, during physical exercise, the demand for energy increases to sustain heightened muscular activity, necessitating an increased supply of oxygen. This increased oxygen supply requires a higher respiration rate, faster heartbeat, and enhanced blood flow through the blood vessels.

Chemical Coordination and Regulation

The neural system and the endocrine system jointly co-ordinate and regulate the physiological functions in the body. The neural co-ordination is fast, very exact and short lived, whereas chemical co-ordination is usually slow, widespread and long lasting. All cells of our body are not innervated by nerve fibres but the cellular function needs to be continuously regulated so a special kind of coordination and integration has to be provided. This function is carried out by hormones.

The Immune System: The immune system is a complex network of organs, cells and proteins that defends the body against infection, whilst protecting the body’s own cells.

The Reproductive system: It is the human organ system responsible for the production and fertilization of gametes (sperm or eggs) and carrying of a fetus.