Difference Between Endocrine and Exocrine Glands & Examples

Ans. Glands are organs which secrete certain chemical substances. These may be hormones, digestive juices, sweat or sebum. They are released directly into the bloodstream or even outside the body. 

Ans. Based on the availability or absence of ducts, the glands have been divided into two major categories - 

1. Endocrine glands- these are the glands that don't contain ducts. 
2. Exocrine glands- these glands have ducts present in them.

Ans.

• Pineal glands - The pineal gland is a small gland located in the brain. It releases many hormones including melatonin. Melatonin is responsible for controlling our sleeping patterns. 
• Pituitary glands - The pituitary gland is that of a pea-sized gland located deep inside the skull. It's considered very superior to other glands because it controls them. It even controls our metabolism, reproductive system, blood pressure and sexual growth. The failure of these glands can cause hair loss, anxiety, high blood pressure, irregular menstrual cycles and other problems.
• Thyroid glands - These glands are located in the neck and are important for the development of the brain, muscle growth and body's metabolism. 
• Parathyroid glands - They lie behind the thyroid glands in the neck and release a hormone so as to release calcium into the bones. 
• Adrenal glands - These glands are present in the kidneys and produce many hormones for sustaining the body. A hormone, adrenaline, is also produced. It increases the heart rate, blood pressure or even enlarges the pupil of the eye in response to some external environment movement. This can also be called a stress hormone.
• Pancreas - It plays a great role in digestion. It produces enzymes that break down sugar, fats and starches in the body. They also help the digestive system by producing insulin and glucagon. These help control the blood glucose levels and prevent them from becoming extremely low. 

Ans. These include the lacrimal glands which control tears, mammary glands which produce breast milk, salivary glands which secrete saliva, the liver that secretes bile, and the pancreas which controls the digestive system. 

Ans. There are three types of endocrine glands. These are - 

• Eccrine or merocrine glands
• Apocrine glands, and
• Holocrine glands

Ans. The Pancreas is both an endocrine gland as well as an exocrine gland which is why it is called a mixed gland. It has the functions of both. It produces pancreatic juice which is released into the pancreatic duct. This way it acts as an exocrine gland. It also produces insulin hormone which makes it endocrine. 

Ans. The pineal gland is the smallest gland present in our body. It is located deep in the brain and produces a hormone called melatonin. 

Ans. Exocrine glands play a crucial role in secreting digestive juices. When the glands fail to do so, that is when the pancreas becomes unable to produce enzymes, which can lead to Exocrine pancreatic insufficiency. Such unavailability in the production of enzymes can lead to a loss in weight and a lack of vitamins. 

Ans. Two types of hormones are produced by the hypothalamus: releasing hormones (that stimulate secretion of pituitary hormones) and inhibiting hormones (that inhibit secretion of pituitary hormones).

These hormones are:

1. Thyrotrophin-releasing hormone Adreno-
2. corticotrophin-releasing hormone
3. Follicle-stimulating hormone-releasing hormone
4. Luteinizing hormone-releasing hormone
5. Growth hormone-releasing hormone
6. Growth inhibiting hormone
7. Prolactin releasing hormone
8. Prolactin inhibiting hormone
9. Melanocyte stimulating hormone¬releasing hormone
10. Melanocyte stimulating hormone- inhibiting hormone.

Ans. Adrenal glands have two regions, namely, the outer adrenal cortex and the inner adrenal medulla. Both these regions secrete different hormones.

Hormones of the adrenal cortex are grouped into three categories:

1. Glucocorticoids, e.g., cortisol
2. Mineralocorticoids, e.g., aldosterone
3. Sexcorticoids e.g testosterone. The adrenal medulla secretes two hormones
   (i) Epinephrine (adrenaline)
   (ii)Nor-epinephrine (nor-adrenaline).

Ans. (Folliclestimulatinghormone) being glycoprotein is insoluble in lipids, therefore,

cannot enter the target cells. It binds to the specific receptor molecules located on the surface of the cell membrane to form a hormone-receptor complex. This complex causes the release of an enzyme adenylate cyclase from the receptor site. This enzyme forms the cell cyclic adenosine monophosphate (cAMP) from ATP. The cAMP activates the existing enzyme system of the cell. This accelerates the metabolic reactions in the cell. The hormone is called the first messenger and the cAMP is termed the second messenger. The hormone-receptor complex changes the permeability of the cell membrane to facilitate the passage of materials through it. This increases the activities of the cell as it receives the desired materials.

Ans. Exocrine gland is a gland that pours its secretion on the surface or into a particular region by means of ducts for performing a metabolic activity, e.g., sebaceous glands, sweat glands, salivary glands and intestinal glands.

(b) Endocrine gland is an isolated gland (separates even from epithelium forming it) which secretes informational molecules or hormones that are poured into venous blood or lymph for reaching the target organ because the gland is not connected with the target organ by any duct. Therefore endocrine gland is also called the ductless gland e.g. thyroid gland.