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Questions and Answers
The endocrine system primarily uses positive feedback to regulate hormone secretion, where the effects of the hormone amplify the initial stimulus.
The endocrine system primarily uses positive feedback to regulate hormone secretion, where the effects of the hormone amplify the initial stimulus.
False (B)
The posterior pituitary gland synthesizes antidiuretic hormone (ADH) and oxytocin, then stores and releases them into the circulation.
The posterior pituitary gland synthesizes antidiuretic hormone (ADH) and oxytocin, then stores and releases them into the circulation.
False (B)
Hormones classified as amines include insulin, growth hormone, and calcitonin.
Hormones classified as amines include insulin, growth hormone, and calcitonin.
False (B)
The anterior pituitary's hormone secretions are directly influenced by neural impulses originating from the hypothalamus.
The anterior pituitary's hormone secretions are directly influenced by neural impulses originating from the hypothalamus.
If the effects of a hormone do not reverse the stimulus, its secretion will likely increase.
If the effects of a hormone do not reverse the stimulus, its secretion will likely increase.
In the two-messenger mechanism, the protein hormone directly activates the cell's enzymes to initiate the cell's response.
In the two-messenger mechanism, the protein hormone directly activates the cell's enzymes to initiate the cell's response.
Cyclic AMP (cAMP) functions as the primary messenger, initiating hormonal responses within cells.
Cyclic AMP (cAMP) functions as the primary messenger, initiating hormonal responses within cells.
Steroid hormones bind to membrane receptors to initiate protein synthesis.
Steroid hormones bind to membrane receptors to initiate protein synthesis.
Hormone receptors, regardless of the type of hormone, are exclusively located within the cell membrane of target cells.
Hormone receptors, regardless of the type of hormone, are exclusively located within the cell membrane of target cells.
The steroid-protein complex directly alters gene expression by binding to DNA without entering the cell's nucleus.
The steroid-protein complex directly alters gene expression by binding to DNA without entering the cell's nucleus.
Antidiuretic hormone (ADH) decreases water reabsorption by the kidney tubules, leading to increased urine production.
Antidiuretic hormone (ADH) decreases water reabsorption by the kidney tubules, leading to increased urine production.
Oxytocin stimulates contraction of the myometrium of the uterus and inhibits the release of milk from mammary glands.
Oxytocin stimulates contraction of the myometrium of the uterus and inhibits the release of milk from mammary glands.
Alcohol consumption inhibits ADH secretion, which leads to decreased urinary output.
Alcohol consumption inhibits ADH secretion, which leads to decreased urinary output.
Stretching of the cervix stimulates the hypothalamus to inhibit the release of oxytocin during labor.
Stretching of the cervix stimulates the hypothalamus to inhibit the release of oxytocin during labor.
Growth hormone-releasing hormone (GHRH) inhibits growth hormone secretion, while growth hormone-inhibiting hormone (GHIH) stimulates it.
Growth hormone-releasing hormone (GHRH) inhibits growth hormone secretion, while growth hormone-inhibiting hormone (GHIH) stimulates it.
Thyroid-stimulating hormone (TSH) decreases the secretion of thyroxine (T4) and triiodothyronine (T3) by the thyroid gland.
Thyroid-stimulating hormone (TSH) decreases the secretion of thyroxine (T4) and triiodothyronine (T3) by the thyroid gland.
Adrenocorticotropic hormone (ACTH) secretion is decreased by corticotropin-releasing hormone (CRH) during physiological stress.
Adrenocorticotropic hormone (ACTH) secretion is decreased by corticotropin-releasing hormone (CRH) during physiological stress.
Prolactin secretion is stimulated by prolactin-inhibiting hormone (PIH) and decreased by prolactin-releasing hormone (PRH) from the hypothalamus.
Prolactin secretion is stimulated by prolactin-inhibiting hormone (PIH) and decreased by prolactin-releasing hormone (PRH) from the hypothalamus.
In women, follicle-stimulating hormone (FSH) stimulates the maturation of the corpus luteum.
In women, follicle-stimulating hormone (FSH) stimulates the maturation of the corpus luteum.
Thyroxine (T4) and triiodothyronine (T3) decrease cell respiration
Thyroxine (T4) and triiodothyronine (T3) decrease cell respiration
Calcitonin increases reabsorption of calcium from bones to the blood, elevating blood calcium levels.
Calcitonin increases reabsorption of calcium from bones to the blood, elevating blood calcium levels.
Parathyroid hormone increases blood calcium level & raises the blood phosphate level
Parathyroid hormone increases blood calcium level & raises the blood phosphate level
Glucagon is secreted by beta cells of the pancreas and stimulated by hyperglycemia.
Glucagon is secreted by beta cells of the pancreas and stimulated by hyperglycemia.
Epinephrine decreases the heart rate and stimulates vasoconstriction only in skeletal muscles.
Epinephrine decreases the heart rate and stimulates vasoconstriction only in skeletal muscles.
Aldosterone increases the reabsorption of K+ ions by the kidneys to the blood and increases excretion of Na+ ions in urine.
Aldosterone increases the reabsorption of K+ ions by the kidneys to the blood and increases excretion of Na+ ions in urine.
Flashcards
Endocrine System
Endocrine System
Major regulating system that maintains body functions and homeostasis.
Hormones
Hormones
Chemical messengers secreted by glands into the bloodstream to regulate body functions.
Negative Feedback
Negative Feedback
Regulatory mechanism that decreases hormone secretion when effects are achieved.
Pituitary Gland
Pituitary Gland
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Posterior Pituitary Gland
Posterior Pituitary Gland
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Two-messenger mechanism
Two-messenger mechanism
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Cyclic AMP (cAMP)
Cyclic AMP (cAMP)
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Hormone receptors
Hormone receptors
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Steroid hormones
Steroid hormones
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Protein synthesis
Protein synthesis
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ADH (Antidiuretic Hormone)
ADH (Antidiuretic Hormone)
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Oxytocin
Oxytocin
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Growth Hormone (GH)
Growth Hormone (GH)
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Thyroid Stimulating Hormone (TSH)
Thyroid Stimulating Hormone (TSH)
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Adrenocorticotropic Hormone (ACTH)
Adrenocorticotropic Hormone (ACTH)
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Prolactin
Prolactin
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Follicle Stimulating Hormone (FSH)
Follicle Stimulating Hormone (FSH)
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Luteinizing Hormone (LH)
Luteinizing Hormone (LH)
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Calcitonin
Calcitonin
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Parathyroid Hormone (PTH)
Parathyroid Hormone (PTH)
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Insulin
Insulin
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Glucagon
Glucagon
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Epinephrine
Epinephrine
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Cortisol
Cortisol
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Study Notes
Endocrine System Overview
- The endocrine system is a major regulatory system, maintaining body functions and homeostasis.
- Endocrine glands are ductless, secreting hormones directly into the bloodstream.
- Hormones include amines (e.g., thyroxine, epinephrine, norepinephrine), proteins (e.g., insulin, growth hormone, calcitonin, ADH, oxytocin), and steroids (e.g., cortisol, aldosterone, estrogen, progesterone, testosterone).
Endocrine Glands & Hormones
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Pituitary Gland (Hypophysis): Plays a role in regulating several body functions. Composed of two parts:
- Anterior pituitary (adenohypophysis): Separate glandular tissue.
- Posterior pituitary (neurohypophysis): Extension of the hypothalamus, storing hormones produced there.
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Hypothalamus: Regulates anterior pituitary hormone secretion through releasing hormones.
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Thyroid Gland: Located on the front and sides of the trachea. Produces thyroxine (T4) and triiodothyronine (T3), crucial for regulating metabolic rate. Also produces calcitonin.
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Parathyroid Glands: Four glands on the back of each thyroid lobe. Secrete parathyroid hormone (PTH), which antagonizes calcitonin. PTH elevates blood calcium levels.
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Pancreas: Located in the upper left quadrant of the abdominal cavity. Contains the islets of Langerhans, which produce hormones. Alpha cells produce glucagon, while beta cells produce insulin.
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Glucagon is released when blood sugar levels are low and stimulates the liver to convert glycogen into glucose.
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Adrenal Glands (Suprarenal): Located on top of each kidney. Composed of two parts:
- Adrenal medulla: Secretes epinephrine and norepinephrine (catecholamines), which are triggered by sympathetic impulses from the hypothalamus. These hormones duplicate and prolong the effects of the sympathetic nervous system.
- Adrenal cortex: Secretes steroid hormones:
- Mineralocorticoids (e.g., aldosterone): Regulate blood pressure and electrolyte balance. Stimulated by low blood sodium and high blood potassium.
- Glucocorticoids (e.g., cortisol): Help the body respond to stress; increases metabolism of fats and proteins, and regulates blood glucose. Stimulated by ACTH.
- Sex hormones (e.g., estrogen, androgens): Involved in reproductive functions and secondary sex characteristics.
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Ovary: Produces estrogen and progesterone, hormones required for reproduction, development of secondary sex characteristics, and the menstrual cycle..
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Testes: Produce testosterone, promoting the maturation of sperm and male secondary sex characteristics. Secrete inhibin, which regulates FSH release from the anterior pituitary.
Hormone Action Mechanisms
- Two-messenger system: Protein hormones bind to membrane receptors, initiating second messenger (e.g., cAMP) which activates other enzymes within the cell.
- Steroid hormones: Diffuse through cell membrane and bind to cytoplasmic receptors. The steroid-receptor complex moves into the nucleus, activating specific genes for protein synthesis.
Hormone Regulation
- Negative feedback: Information on the hormone's effects is sent back to the gland, decreasing hormone secretion when appropriate.
- Positive feedback: Hormone's effects stimulate further production, as seen in oxytocin and childbirth.
Regulation of Hormone Secretion
- Hormone secretion is primarily regulated by negative feedback loops. The effects of the hormone reverse the stimulus and decrease the secretion of the hormone.
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Description
Explore the endocrine system, its major glands, and the hormones they secrete. Understand the role of the pituitary gland, hypothalamus, and thyroid gland in regulating body functions. Learn about different types of hormones, including amines, proteins, and steroids.
