Which of the following distinguishes endocrine and exocrine glands from another?
A.
The presence or absence of ducts
B.
The effect their secretions have on the target cells
C.
The biochemistry of their secretions
D.
The presence or absence of nerve innervation
The correct answer and Explanation is :
The correct answer is A. The presence or absence of ducts.
Explanation:
Endocrine and exocrine glands are two distinct types of glands in the body that differ primarily in their structure and the way they release their secretions.
Endocrine Glands:
- Lack of Ducts: Endocrine glands do not have ducts. Instead, they release their secretions directly into the bloodstream. These secretions are hormones, which are chemical messengers that travel through the bloodstream to target organs or tissues.
- Function: The hormones produced by endocrine glands regulate various physiological processes such as metabolism, growth, reproduction, and mood. The lack of ducts allows the hormones to enter the circulatory system and exert their effects on distant target cells throughout the body.
- Examples: Examples of endocrine glands include the thyroid gland, adrenal glands, and pituitary gland.
Exocrine Glands:
- Presence of Ducts: Exocrine glands possess ducts through which their secretions are delivered to specific sites, such as body surfaces or cavities. These glands secrete substances directly to their target area rather than into the bloodstream.
- Function: The secretions of exocrine glands often have local effects and include a variety of substances such as enzymes, sweat, saliva, and digestive juices. For instance, sweat glands secrete sweat through ducts onto the skin’s surface to help regulate body temperature.
- Examples: Examples of exocrine glands include salivary glands, sweat glands, and digestive glands like those in the pancreas.
Differences in Secretions:
While the biochemistry of their secretions (Option C) and the effect on target cells (Option B) are important, they are not the primary distinguishing features. Endocrine and exocrine glands may produce various types of substances with different effects, but the key difference lies in the presence or absence of ducts for their secretions. The presence of ducts characterizes exocrine glands, while the absence of ducts is characteristic of endocrine glands.