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Questions and Answers
What is the primary function of hormones synthesized by endocrine glands?
Which of the following correctly describes autocrine hormones?
Which organs contain dispersed endocrine cells?
Which hormone type is associated with local cell-to-cell actions?
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What type of tissue primarily supports endocrine glands?
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What role do receptors play in hormone action?
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Which of the following glands is part of the principal endocrine glands?
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How are hormones released from endocrine glands?
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What distinguishes endocrine hormones from other types of hormones?
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Which of the following is a characteristic of endocrine glands?
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Study Notes
Endocrine System
- The endocrine system works with the nervous system to coordinate and integrate bodily functions.
- The endocrine system consists of glands that produce and secrete hormones into the bloodstream.
- Hormones act on specific target organs and cells to elicit physiological responses.
- Endocrine glands lack ducts, hence the term “ductless glands”.
- The hypothalamus, a brain structure, controls the secretion of many endocrine glands.
- Endocrine glands are made up of epithelial cells, supported by vascular connective tissue.
- Hormones are secreted into interstitial spaces and then absorbed into the bloodstream via fenestrated capillaries.
- Endocrine glands are classified into three categories:
- Individual endocrine glands, including the pituitary, thyroid, parathyroid, adrenal, and pineal glands.
- Groups of endocrine cells within organs:
- Pancreas (islets of Langerhans)
- Testes (interstitial cells of Leydig)
- Ovaries (ovarian follicles and corpus luteum)
- Placenta
- Dispersed endocrine cells, for example, APUD cells.
Hormones
- Hormones are chemical substances synthesized and secreted by specific cells.
- They are transported via the circulatory system.
- They exert their effects at very low concentrations.
- They trigger specific responses in distant target tissues.
Types of Hormones
-
Endocrine hormones:
- Synthesized by endocrine glands.
- Transported by blood to target cells.
- Examples: catecholamines and insulin.
-
Paracrine hormones:
- Synthesized near their target cells.
- Act on neighboring cells.
- Examples: alpha and beta cells of the pancreas.
-
Autocrine hormones:
- Exert their actions on the cells that produce them.
- Example: prostaglandins.
Target Cells
- Target cells possess specific receptors for hormones.
- These receptors are proteins.
- Receptors have at least two functional domains:
- A recognition domain that binds the hormone.
- A signaling domain that generates a signal for intracellular function (signal transduction).
Principle Endocrine Glands
- Pituitary gland (anterior and posterior lobes)
- Thyroid gland
- Parathyroid glands
- Adrenal glands (cortex and medulla)
- Islets of Langerhans (in the pancreas)
- Male gonads (testes)
- Female gonads (ovaries)
- Placenta
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Description
Explore the intricate functions of the endocrine system, including the role of glands and hormones in regulating bodily processes. This quiz delves into the types of endocrine glands and their specific functions, emphasizing their ductless nature and interaction with the nervous system.
