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Questions and Answers
What defines the interaction of peptide hormones with target cells?
What defines the interaction of peptide hormones with target cells?
Which characteristic is unique to cells producing steroid hormones?
Which characteristic is unique to cells producing steroid hormones?
In the classification of endocrine glands, what distinguishes unicellular glands from multicellular glands?
In the classification of endocrine glands, what distinguishes unicellular glands from multicellular glands?
What is the primary role of autocrine activity in cell communication?
What is the primary role of autocrine activity in cell communication?
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Which type of hormones are derived from cholesterol and where are they primarily produced?
Which type of hormones are derived from cholesterol and where are they primarily produced?
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Which hormone primarily encourages the motility of the digestive tract?
Which hormone primarily encourages the motility of the digestive tract?
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What is the main function of entero-endocrine cells in the Crypts of Lieberkühn?
What is the main function of entero-endocrine cells in the Crypts of Lieberkühn?
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The hypophyseal portal system connects which two structures?
The hypophyseal portal system connects which two structures?
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Which of the following is a characteristic of the adenohypophysis?
Which of the following is a characteristic of the adenohypophysis?
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Which hormone stimulates the secretion of bicarbonate by the pancreas?
Which hormone stimulates the secretion of bicarbonate by the pancreas?
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Which of the following describes sensory input to the adenohypophysis?
Which of the following describes sensory input to the adenohypophysis?
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What type of glands are characterized by a morphological arrangement of follicles?
What type of glands are characterized by a morphological arrangement of follicles?
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What is the primary role of follicular cells in the thyroid?
What is the primary role of follicular cells in the thyroid?
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Which factor primarily regulates the activity of C cells in the thyroid?
Which factor primarily regulates the activity of C cells in the thyroid?
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What is the effect of calcitonin produced by parafollicular cells?
What is the effect of calcitonin produced by parafollicular cells?
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What is the function of parathyroid hormone (PTH) in calcium metabolism?
What is the function of parathyroid hormone (PTH) in calcium metabolism?
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When are abnormalities in the production of thyroid hormones typically assessed in newborns?
When are abnormalities in the production of thyroid hormones typically assessed in newborns?
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What is the role of T3 and T4 hormones produced by follicular cells?
What is the role of T3 and T4 hormones produced by follicular cells?
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Which of the following cells are primarily responsible for producing parathyroid hormone?
Which of the following cells are primarily responsible for producing parathyroid hormone?
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How does parathyroid hormone affect kidney function?
How does parathyroid hormone affect kidney function?
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What is the state of colloid in the thyroid when hormones are not actively released?
What is the state of colloid in the thyroid when hormones are not actively released?
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What effect does hypophyseal gigantism have on a child's growth?
What effect does hypophyseal gigantism have on a child's growth?
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What is the function of the hormone produced by the pineal gland?
What is the function of the hormone produced by the pineal gland?
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Which cell type is specifically responsible for producing calcitonin in the thyroid gland?
Which cell type is specifically responsible for producing calcitonin in the thyroid gland?
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What is the primary characteristic of Herring bodies within the endocrine system?
What is the primary characteristic of Herring bodies within the endocrine system?
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What key feature distinguishes acromegaly from hypophyseal gigantism?
What key feature distinguishes acromegaly from hypophyseal gigantism?
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In the context of the pineal gland, which neurotransmitter is a precursor to melatonin?
In the context of the pineal gland, which neurotransmitter is a precursor to melatonin?
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What role does calcitonin play in the human body?
What role does calcitonin play in the human body?
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What structure is characteristic of the thyroid gland?
What structure is characteristic of the thyroid gland?
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Which condition is a result of hyposecretion of growth hormone during infancy?
Which condition is a result of hyposecretion of growth hormone during infancy?
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Study Notes
Endocrine Glands
- Endocrine glands communicate with distant cells via hormones.
- Hormones are classified as steroid, derived from cholesterol (gonads, adrenal cortex), or protein-based (thyroid, pituitary, pancreas—insulin).
- Hormones interact with specific receptors on target cells (membrane-bound or intracellular).
- Peptide hormones bind to membrane receptors, initiating a cascade reaction (no cell entry).
- Steroid hormones enter the cell and bind to intracellular receptors, directly affecting gene expression.
- Protein-producing cells have well-developed RER and Golgi apparatus for synthesis and modification of proteins.
- Steroid-hormone-producing cells have well-developed SER and lack secretion granules.
- Endocrine glands can be unicellular (e.g., islets of Langerhans) or multicellular (different arrangements of cells, e.g., cords, follicles, interstitial).
Embryogenesis
- Cell communication occurs via direct contact, synaptic communication, endocrine secretion, paracrine activity, and autocrine activity.
- Direct contact: Direct between cells.
- Synaptic: Between neurons.
- Endocrine: Hormones secreted into blood stream. This reaches target cells.
- Paracrine: Secretion affects nearby cells.
- Autocrine: Target organ is the cell that produced the hormone.
Gastrointestinal Diffuse Endocrine System
- Cells in the gastrointestinal tract secrete peptide hormones.
- Gastrin stimulates gastric secretion and intestine motility.
- Serotonin acts on the gastrointestinal motility.
- CCK stimulates pancreatic secretion and bile production.
- Secretin stimulates bicarbonate secretion and pancreatic enzyme production.
- Motilin increases intestine motility.
Pituitary Gland
- Consists of an anterior lobe (adenohypophysis) and a posterior lobe (neurohypophysis).
- Adenohypophysis is regulated by hypothalamic hormones through the hypophyseal portal system. This transports hormones through blood vessels.
Hypothalamus
- The hypothalamus is the control center for many endocrine processes.
- It sends signals to the anterior pituitary through the hypophyseal portal system to release or not release hormones into the blood.
- This triggers the release of regulating hormones.
Anterior Pituitary
- Only secretes regulating hormones that control other glands.
- Regulating hormones can be triggered by hypothalamic hormones
Posterior Pituitary
- Secretes hormones that are directly secreted into the blood without any other intermediaries.
Hormone Types and Functions
- See separate table for a list of hormones and their functions.
Multiple Endocrine Gland Arrangements
- Types of arrangements: cords, islets, follicles, interstitial.
Clinical Points
- Hypophyseal dwarfism: Hyposecretion of growth hormone in childhood leads to slow bone growth and short stature.
- Hypophyseal gigantism: Hypersecretion of growth hormone in childhood results in excessive bone growth and extraordinarily tall stature.
- Acromegaly: Hypersecretion of growth hormone in adulthood causes disproportionate growth of the hands, feet, and face.
Pineal Gland
- Located near the base of the brain (diencephalon).
- It contains pinealocytes and glial cells.
- Photosensitive; regulates day-night cycles.
- Produces melatonin.
Thyroid Gland
- Butterfly-shaped gland in the neck.
- Composed of follicles (that contain colloid) and C cells.
- Follicular cells produce thyroid hormones (T3 and T4).
- C cells produce calcitonin.
- Thyroid hormone regulates metabolism.
- Calcitonin regulates calcium levels.
- The activity of follicular cells is controlled by TSH from the anterior pituitary.
- The activity of parafollicular cells (C cells) is controlled by blood calcium levels.
Parathyroids
- Four small glands posterior to the thyroid.
- Chief cells produce parathyroid hormone (PTH).
- PTH increases blood calcium levels.
- Calcitonin decreases blood calcium levels.
Adrenal Glands
- Located superior to the kidneys.
- Composed of a cortex and medulla.
- Cortex produces steroid hormones (mineralocorticoids, glucocorticoids, androgens).
- Medulla produces catecholamines (epinephrine, norepinephrine).
Islets of Langerhans (Pancreas)
- Endocrine cells within the pancreas.
- Alpha cells produce glucagon (increases blood glucose),
- Beta cells produce insulin (decreases blood glucose).
- Delta cells produce somatostatin.
- PP cells produce pancreatic polypeptide.
Other Endocrine Glands
- Includes testes, ovaries, and other organs.
- Testes produce testosterone (male sex hormone)
- Ovary produces estrogen, progesterone (female sex hormones)
- Other glands produce specific hormones with specialized roles (e.g., heart, kidneys, adipose tissue).
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Description
Explore the fascinating world of endocrine glands and embryogenesis through this quiz. Learn how hormones communicate with cells, the differences between steroid and protein hormones, and the cellular structures involved in hormone production and secretion. Test your knowledge on these critical biological concepts.
