Secretion and Excretion

The movement or flow of items in the body is aided by excretion and secretion. Both the processes are necessary for the upkeep of the homeostasis of the body. The primary distinction between excretion and secretion is that secretion involves the transport of materials from one region of the body to another, whereas excretion involves the elimination of waste material that is no longer useful to living organisms. Excretion is a passive process, while secretion is an active one. The animal body excretes tears, perspiration, carbon dioxide, urine and feces, whereas saliva, enzymes and hormones are secreted by the organisms.

Secretion and Excretion

Secretion is the production and release of chemicals from a cell, organ or a gland. Humans produce secretory products such as enzymes, saliva and hormones. Hormones are produced by endocrine glands, whereas enzymes are produced by gastric glands in the stomach lining. Hormones are secreted into the bloodstream and delivered to their target sites. Hormones and enzymes help to speed up and regulate biological reactions. Saliva helps in providing lubrication, protection and moisture to the mouth. Within the cells, the Golgi apparatus is engaged in the production and release of secretory chemicals.

Pathways for the process of secretion are as followed-

1. Lysosomes- These organelles are commonly assumed to be just vital for dehydration, however they also play a significant role in the biological process of secretion. Certain specialized cell types, such as blood stem cells and pigment cells, typically use the lysosome secretory pathway. Lysosomes, like secretory vesicles, can fuse with the membrane of the cells to discharge their contents, but the fusion process requires a different type of protein.
2. Transport through membrane- In some circumstances the proteins in the cytosol migrate through the cell membrane via transporter proteins. So, in this situation, the products are not packed in vesicles, instead, they are delivered separately by specific proteins in the cell membrane.
3. Porosomes and the Golgi pathway- the products which are secretory are firstly synthesised in the endoplasmic reticulum, then put into spherical container like vesicle, known as transport vesicle, that are formed of the lipid bilayer. These products are then modified in the Golgi apparatus before being packaged into a specialized secretory vesicle.

The process through which metabolic waste products such as CO₂ and urea are expelled from the body is known as excretion. It is helpful to control the osmotic pressure by balancing the water and inorganic ions and by maintaining the acid-base balance. The primary goal of excretion is to ensure homeostasis in the internal environment of the organism. In humans, the lungs, liver and skin are all involved in performing the process of excretion.

Diffusion is the process through which protozoans such as Amoeba dispose of their waste. Higher multicellular species, on the other hand, have excretory organs that are more specialized. Kidneys are the primary excretory organs of vertebrates that maintain the water balance while excreting waste from the body of the organism.

The excretion process also happens in  plants to get rid of their waste products. Small plants excrete wastes through their surface cells, but large vascular plants have an excretion system in which the plant’s leaf plays an important part.

Distinction between Excretion and Secretion

• Process- Excretion is the elimination of waste material from the living organisms, whereas secretion is the transport of material from one part of the body to another.
• Excretion process is passive whereas the secretion process is active.
• In terms of the materials- The body secretes materials such as saliva, enzymes, and hormones, while materials such as sweat, CO₂, feces, and urine are excreted from body.
• Organs that are involved- For secretion, the organs like endocrine glands, gallbladder, liver, digestive glands and the salivary glands are involved whereas for the process of excretion organs like skin, lungs, tea ducts and rectum is involved.
• Function- Secreted materials play a role in the body’s metabolism. Excretion, on the other hand, is primarily responsible for the removal of waste from the body.

Conclusion

Secretion and the biological process of excretion are the two ways for the transport of materials inside the body. The organs and the glands in the body produce and secrete metabolically essential chemicals. Excretion is primarily responsible for the removal of wastes from the body, such as urea and carbon dioxide. As a result, the primary distinction between these two processes is their function in the organism.