INTRODUCTION
There are several factors hidden inside the human body. Are you aware of how our body functions properly? What are the essential things required for the development and functions of the body? Secretions of hormones are the key factor behind it.
Hormones are the bearers or carriers, secreted by the organs of the body in to the blood stream; the blood carries the message to the target organs for the growth and development of the body.
Here let us see what are the hormones secreted in the body through one of the gland since there are two types of glands.
Now we know that hormones secreted in the body. From where does the hormones are secreted? The answer is Gland.
What is a Gland?
A gland is an organ, which produces or secretes and releases the substances that performs certain tasks in the targeted human body parts.
There are two types of glands.
- EXOCRINE GLAND
Here we will discuss about the Exocrine Gland.
These are glands with ducts (passage or a tube). This gland referred as external secretion gland, since it secretes the substance on the external surface of the body parts via the ducts.
This gland are found in the intestinal wall, gastrointestinal tract, or outside such as salivary glands, liver, pancreas, etc.
Exocrine glands secrete enzymes, ions, water(salt water), mucins, mucous and other substances into the digestive tract.
Some of the exocrine glands are salivary glands, mammary glands, sweat glands, lacrimal glands, sebaceous glands, prostate glands and mucous.
The organs Liver and Pancreas functions as exocrine as well as endocrine glands. Pancreas is the largest exocrine gland, which is 99% it functions as exocrine and 1% it functions as endocrine.
STRUCTURE OF EXOCRINE GLAND
Exocrine gland has two portions
- Ductal portion
- Glandular portion
Ductal portion : The duct is either a simple structure or a complex. The simple structure does not have any branches. The duct can be a complex structure with many branches. This is tubular in shape. The portion is single, thick, cuboid cell wall, which helps in the movement of the secretion.
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| Structure of Exocrine Gland |
Glandular portion : This portion is tubular or acinar in structure, or may be blend of the two referred as tubuloacinar. Glandular portion looks after the productions of secreted substances. It is circular or elongated group of cells. The cells of this portion rely up on the secreted substances. E.g., serous cells secretes proteins, mucous cells secretes fluids.
TYPES OF EXOCRINE GLAND
Based on the method of secretion the exocrine gland classified into three types.
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| Types of Secretions |
Image Source : Wikimedia Commons
- Apocrine glands
- Holocrine glands
- Merocrine glands or Eccrine Glands
Apocrine glands : This gland release their secretion by budding off in the part of their cytoplasm or cell membrane. This bud has secreted substance and it release in to the ductal system.
Holocrine glands : The entire cell blasts to excrete its substances. The secreted substances released when the plasma membrane disintegrates and secrete the substances in the lumen.
Merocrine glands or Eccrine Glands : This release the substances directly in to the duct via the cellular channels without any loss of cell membrane i.e., no rupture of cell wall.
WHAT DOES EXOCRINE GLAND SECRETES?
- The Serous cells secrete proteins.
- The Mucous cells secrete mucus.
- The mixed gland secretes both proteins and mucus eg Salivary Glands.
- The Sebaceous glands secrete sebum. This gland also referred as Oil glands.
FUNCTIONS OF EXOCRINE GLAND
- Regulates or controls the body temperature (in the form of sweat)
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Lubrication (like tears, saliva)
- Lactation
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Helps in digestion (saliva)
- Helps in reproduction
Glands present in the Exocrine Gland
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| Presence of Sweat and Oil gland in the skin |
Image Source : Wikimedia Commons
- Lacrimal Glands : Present in each eye, it is tear duct, secretes tears.
- Mammary Glands : Lactation - secretes Breast Milk.
- Eccrine Sweat Glands : excretes salty water in the form of sweat.
- Salivary Glands : This secretes saliva along with the digestive fluids or enzymes.
- Sebaceous Glands : This gland secretes sebum. This gland also referred as Oil glands.
- Pancreas : This secretes pancreatic juice along with the digestive fluids or enzymes in to the stomach.
- Liver : This secretes bile, green-brown fluid, which contains salt and digestive substances.
CONCLUSION
Exocrine gland releases substances externally, which are essential for the body to perform certain tasks as if excreting sweat keeps the body in normal temperature, excretion of tears keeps us calm down in certain stress situation. Therefore, this gland is one of the significant glands in the human body.
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