The processes which maintain body functions and are necessary for survival such as nutrition, transportation, metabolism, reproduction, respiration, and excretion are called life processes. In the organisms, we can find two types of nutrition. The first is autotrophic nutrition and the second is heterotrophic nutrition. The food we eat is digested in our human body. Digestion is the process of breaking down complex food materials into smaller simpler particles. There are two kinds of respiration – Aerobic and Anaerobic. We will learn about the human respiratory system, the human heart, and its function in the human circulatory system, lymphatic system, excretory system, and functioning of kidneys.

We will understand that the energy requirements of the autotrophic organism are fulfilled by food made by photosynthesis. To perform photosynthesis, plants have requirements of carbon dioxide, water, chlorophyll, and sunlight. They get water through their roots, carbon dioxide from the air, and light energy from the Sun and chlorophyll in cells of the leaf as an output, they make glucose as their food and release oxygen.

In heterotrophic nutrition, organisms use complex forms of food. These complex substances break down into simpler forms before they can be used for the growth of the body. A Single-celled heterotroph Amoeba exists with the Intracellular digestion, in which digestion takes place within the cytoplasm of the organism. 

The human digestive system consists of many different organs and glands with their different functions for the digestion of food molecules. The alimentary canal consists of the mouth, tongue, esophagus, liver, gallbladder, pancreas, stomach, small intestine, large intestine, and anus.

Aerobic respiration occurs in the presence of Oxygen, Aerobic respiration takes place in the mitochondria of the cell and requires oxygen and glucose which produces carbon dioxide, water, and energy. But when low oxygen is present atoms of glucose produce lactic acid and energy by anaerobic respiration in muscle cells.

The human respiratory system is a series of organs like nostrils, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, lungs, and diaphragm responsible for taking in oxygen and expelling carbon dioxide. The primary organs of the respiratory system are the lungs, which carry out this exchange of gases as we breathe.

The human heart is an organ that pumps blood throughout the body via the circulatory system. The heart receives deoxygenated blood from vena cava. From the heart, blood passes to the lungs and oxygenated blood from the lungs returns to the heart. The heart aorta supplies blood to the whole body. 

We will understand in this virtual tour about the transport and exchange of oxygen and carbon dioxide in humans. While external respiration, the gas exchange takes place in the millions of alveoli in the lungs. The oxygenated blood from the lungs comes to the heart. From the heart, arteries carry blood to all parts of the body. Arteries divide into capillaries. While cellular respiration, from capillaries cells, takes oxygen and releases carbon dioxide in the blood. The deoxygenated blood is carried to the heart through veins.

The Lymphatic system is a network of vessels and body parts that collect fluids that leak out of the cells and blood. The lymphatic system consists of lymph vessels, ducts, nodes, and other tissues. The lymph vessels form a network that reaches most of the body’s tissues. The lymphatic system helps the body to get rid of toxins, waste, and other unwanted materials.

Plants have xylem for the transportation of water. Xylem transports water from the roots to different parts of the plants. Transport of food in plants occurs via the phloem. It transports food from the leaves to different parts of the plants.

Excretion is a process by which metabolic waste is eliminated from an organism. The excretory system consists of the kidneys, two ureters, the urinary bladder, and the urethra. Blood flows through the kidneys where waste such as urea is filtered out. The urine produced by the kidneys goes through the ureters. It then waits in the urinary bladder, until it goes out through the urethra.

Kidneys play an important role in excretion by removing extra water and harmful metabolic wastes from the body.  Several factors like infections, injury, or restricted blood flow to kidneys reduce the activity of kidneys. This leads to the accumulation of poisonous wastes in the body, which can even lead to death. Dialysis is a treatment that filters and purifies the blood using a machine. This process helps to keep the fluids and electrolytes in balance when the kidneys can’t do their job.

Plants produce two gaseous waste products like oxygen during photosynthesis and carbon dioxide during respiration. They also excrete resin and gum from the old xylem. Waste materials are also removed in the falling leaves, or excreted into the surrounding soil.

Respiration in the absence of oxygen is known as anaerobic respiration. It is also known as fermentation. It is the ability of an organism to produce energy without using oxygen. Also when we perform physically exhausting work, our muscle cells don’t have enough oxygen and they respire with anaerobic respiration and produce lactic acid. 

We will understand in this virtual tour, anaerobic respiration in yeast. Yeast doesn’t need oxygen to derive energy. In the absence of oxygen, food is oxidized anaerobically without utilizing oxygen. Anaerobic respiration is also known as fermentation because organic compounds are also produced as byproducts.