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Questions and Answers
What is the primary difference between peptide hormones and steroid hormones?
What is the primary difference between peptide hormones and steroid hormones?
Peptide hormones are water-soluble and act on cell surface receptors, while steroid hormones are lipid-soluble and can pass through cell membranes to act on intracellular receptors.
How does negative feedback regulation function in hormone secretion?
How does negative feedback regulation function in hormone secretion?
Negative feedback regulation occurs when rising hormone levels trigger a biological response that inhibits further hormone release.
What role do the hypothalamus and pituitary gland play in the endocrine system?
What role do the hypothalamus and pituitary gland play in the endocrine system?
The hypothalamus releases hormones that regulate the pituitary gland, which in turn secretes hormones that control other endocrine organs.
What is the significance of routes of hormone action in endocrine signaling?
What is the significance of routes of hormone action in endocrine signaling?
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What distinguishes positive feedback regulation from negative feedback regulation in hormone control?
What distinguishes positive feedback regulation from negative feedback regulation in hormone control?
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What type of secretion is involved when a hormone stimulates the release of gastric juices in the stomach?
What type of secretion is involved when a hormone stimulates the release of gastric juices in the stomach?
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How does secretin function in digestion?
How does secretin function in digestion?
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What is the primary role of erythropoietin in the body?
What is the primary role of erythropoietin in the body?
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What distinguishes the paracrine route of hormone action?
What distinguishes the paracrine route of hormone action?
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Identify one hormone produced by the hypothalamus and its main function.
Identify one hormone produced by the hypothalamus and its main function.
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What is the primary distinction between the anterior and posterior lobes of the pituitary gland?
What is the primary distinction between the anterior and posterior lobes of the pituitary gland?
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In what way does the exocrine route differ from the endocrine route?
In what way does the exocrine route differ from the endocrine route?
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What is the role of releasing hormones from the hypothalamus?
What is the role of releasing hormones from the hypothalamus?
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What are the two main thyroid hormones, and what is their primary function?
What are the two main thyroid hormones, and what is their primary function?
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How do peptide hormones differ from steroid hormones in their mechanism of action?
How do peptide hormones differ from steroid hormones in their mechanism of action?
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What is the role of calcitonin in calcium regulation?
What is the role of calcitonin in calcium regulation?
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What hormones are secreted by the adrenal cortex, and what is their primary function?
What hormones are secreted by the adrenal cortex, and what is their primary function?
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What is the function of parathyroid hormone (PTH) in blood calcium and phosphate levels?
What is the function of parathyroid hormone (PTH) in blood calcium and phosphate levels?
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What is the primary role of insulin in glucose metabolism?
What is the primary role of insulin in glucose metabolism?
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What are catecholamines, and what is their primary effect on the body?
What are catecholamines, and what is their primary effect on the body?
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How does the hypothalamus interact with the pituitary gland to regulate endocrine functions?
How does the hypothalamus interact with the pituitary gland to regulate endocrine functions?
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Study Notes
Atypical Hormones
- Gastrin is secreted by the wall of the stomach and stimulates the release of gastric juices from gastric glands.
- Secretin is secreted by the wall of the small intestine and stimulates the secretion of intestinal and pancreatic juices.
- Erythropoietin secreted by the kidneys stimulates bone marrow.
Routes of Hormone Action
- Endocrine route: Hormones are transported via the blood to a target organ.
- Exocrine route: Hormones are secreted to the exterior of the body where they interact with a target organ.
- Paracrine route: Hormones are secreted into the space between cells and are carried to the target organ by interstitial fluid.
- Autocrine route: Hormones produced by a cell regulate the activity of that same cell.
- Neurocrine route: Hormones diffuse through synaptic clefts similar to neurotransmitters.
- Epicrine/Juxtacrine route: Hormones pass through gap junctions between cells to alter the function of adjacent cells.
Endocrine Organs/Glands
- The endocrine system includes the hypothalamus, pituitary gland, thyroid gland, parathyroid glands, adrenal glands, and pancreas.
Hypothalamus
- Releasing hormones (CRH, GnRH, GHRH, TRH) stimulate the release of various hormones from the adenohypophysis (anterior pituitary).
- Oxytocin and antidiuretic hormone are produced by the hypothalamic nuclei but stored in the neurohypophysis (posterior pituitary).
Pituitary Gland
- The pituitary gland is often referred to as the "master gland".
- The pituitary gland consists of two distinct tissues: the adenohypophysis (anterior lobe) composed of epithelial tissue and the neurohypophysis (posterior lobe) composed of neural tissue.
Hormones of the Pituitary Gland
- The pituitary gland secretes hormones that affect the function of many organs in various systems.
Anterior Pituitary (Adenohypophysis)
- Growth hormone (GH): Promotes growth and development.
- Thyroid-stimulating hormone (TSH): Stimulates the thyroid gland to release thyroid hormones (T3 and T4).
- Adrenocorticotropic hormone (ACTH): Stimulates the adrenal cortex to release cortisol.
- Follicle-stimulating hormone (FSH) and luteinizing hormone (LH): Regulate the development and function of gonads.
- Prolactin: Stimulates milk production.
Posterior Pituitary (Neurohypophysis)
- Oxytocin: Stimulates contractions of the uterus during labor and milk ejection.
- Antidiuretic hormone (ADH): Regulates water reabsorption by the kidneys.
Thyroid Gland
- Thyroid hormones (T4 & T3): Tyrosine-based hormones that contain iodine, increase basal metabolic rate (BMR) and have receptors in almost all tissues.
- Calcitonin: A peptide hormone that helps control calcium levels in the blood by inhibiting osteoclasts.
Parathyroid Gland
- Most domestic animals have two pairs of parathyroid glands associated with the thyroid gland.
- The parathyroid gland secretes parathyroid hormone (PTH).
- Parathyroid hormone (PTH): Increases blood calcium levels and decreases blood phosphorus levels, stimulates the release of calcium and phosphorus from bone, increases osteocyte and osteoclast activity, and promotes the formation of vitamin D in the kidneys.
Adrenal Gland
- Adrenal cortex: Secretes glucocorticoids, which enhance glucose production, and mineralocorticoids, which regulate sodium and potassium levels in the blood.
- Adrenal medulla: Secretes catecholamines (epinephrine and norepinephrine) which prepare animals to "fight" or "flight".
Pancreas
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Pancreatic islets:
- Insulin (β cells): Decreases blood glucose levels, increases glucose transporter receptors on cells, and converts excess glucose into glycogen.
- Glucagon (α cells): Increases blood glucose levels by breaking down glycogen into free glucose molecules and forming new glucose from amino acids.
Hormone Regulation
- Negative feedback regulation: Rising levels of a hormone cause a biological response that inhibits further release of that hormone.
- Positive feedback regulation: Hormones cause a biological response that increases the release of hormone.
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Description
Explore the various atypical hormones and their functions within the body. Learn about the different routes of hormone action and how these hormones influence various physiological processes. This quiz will test your understanding of hormone secretion and transport mechanisms.
