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Questions and Answers
Which region of the adrenal gland produces mineralocorticoids?
What is the primary function of the adrenal medulla?
What is the main function of corticoid binding globulin (CBG)?
Which step of steroidogenesis limits the rate of adrenocortical hormone synthesis?
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How are steroid hormones transported in the bloodstream?
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Where does cholesterol conversion into pregnenolone occur during steroidogenesis?
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What percentage of aldosterone in the bloodstream is unbound (in a free state)?
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How do androgens primarily interact with cell receptors?
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What occurs after cholesterol travels into the blood using an LDL in steroidogenesis?
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Which hormone regulates the step of cholesterol conversion into pregnenolone within the mitochondria?
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What is the primary action of aldosterone on the distal tubules of the kidneys?
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Which of the following hormones is responsible for stimulating arteriole constriction and increasing blood pressure?
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What is the effect of aldosterone on potassium in the kidney's distal tubules?
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What happens right after aldosterone's binding to cytoplasmic receptors stimulates transcription within the nucleus of the kidney's distal tubules?
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What is the effect of angiotensin 2 on the neurohypophysis?
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How does aldosterone affect the blood-potassium levels?
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What is stimulated by aldosterone binding to cytoplasmic receptors in the kidneys?
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How does angiotensin 2 affect blood pressure?
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What stimulates renin secretion during RAAS pathway?
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After the neurohypophysis is stimulated by angiotensin 2 to secrete ADH, what does ADH stimulate?
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Which of the following statements about aldosterone is correct?
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Which of the following processes is responsible for the metabolism and excretion of steroid hormones?
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Which of the following is a factor that stimulates aldosterone secretion that works independently of RAAS?
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In the renin-angiotensin-aldosterone system (RAAS), which of the following is the correct sequence of events?
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Which of the following statements about the effects of angiotensin 2 in the renin-angiotensin-aldosterone system (RAAS) is correct?
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Which of the following statements about the regulation of aldosterone secretion is correct?
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Which of the following statements about the effects of ACE inhibitors is correct?
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Which of the following statements about the clearance half-life of steroid hormones is correct?
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What does the cortex region of the adrenal gland include?
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Study Notes
Adrenal Gland Structure and Function
- Located at the cranial poles of the kidneys
- Maintains homeostasis by regulating the adaptive response to stress, balancing water, sodium, and potassium, and controlling blood pressure
- Produces two main hormone families: catecholamines and steroid hormones
Adrenal Medulla
- Produces catecholamines (epinephrine and norepinephrine) in the adrenal medulla
- Originates from ectodermal tissue
Adrenal Cortex
- Produces steroid hormones (glucocorticoids, androgens, and mineralocorticoids) in the adrenal cortex
- Originates from mesodermal tissue with three layers: zona glomerulosa, zona fasciculata, and zona reticularis
- Zona glomerulosa produces mineralocorticoids
- Zona fasciculata produces glucocorticoids
- Zona reticularis produces androgens
Steroidogenesis
- Cholesterol travels in the blood using LDL
- Cholesterol enters the cell via receptor-mediated endocytosis
- Cholesterol is either used immediately or stored in vesicles called "cholesterol ester"
- Cholesterol is converted into pregnenolone within the mitochondria
- ACTH regulates this step, limiting the rate of adrenocortical hormone synthesis
- Steroid hormones are not stored and must be used immediately or secreted by diffusion across the cell membrane
Steroid Hormone Transport
- Hydrophobic steroid hormones require transport proteins
- Transport protein options: corticoid binding globulin (CBG or transcortin) and albumin
- Cortisol transport: 75% use transcortin, 15% use albumin, and 10% are unbound (in a free state)
- Aldosterone transport: 10% use transcortin, 50% use albumin, and 40% are unbound (in a free state)
Hormone-Receptor Interactions
- Steroids bind to intracellular receptors (either within the nucleus or cytosol)
- Cytosol receptors translocate to the nucleus after hormone binding
- Androgens bind to cell surface receptors, allowing for a more rapid cellular response
Aldosterone's Actions on the Kidney's Distal Tubules
- Stimulates tubular NaCl reabsorption, potassium excretion, and water reabsorption
- Increases activity of epithelial sodium channels and synthesizes sodium-potassium pumps
- Active secretion of potassium and synthesizes potassium channels
- Passive reabsorption of water
- Pathway: aldosterone binds to cytoplasmic receptors → stimulates transcription within the nucleus → new protein channels and pumps are synthesized → aldosterone inducing proteins modify existing proteins → increased sodium reabsorption and potassium secretion
Aldosterone Regulation
- Synthesis is stimulated by hypotension, low sodium levels, and high potassium levels
- Not really impacted by ACTH, despite ACTH also having some receptors in the zona glomerulosa
Renin-Angiotensin-Aldosterone System (RAAS)
- Regulates aldosterone production
- Renin secretion is stimulated by:
- Macula densa detecting low sodium concentration in renal filtrate
- Baroreceptors in the afferent arterioles detecting low blood pressure in the kidneys
- Sympathetic stimulation of juxtaglomerular apparatus via beta 1 adrenoreceptors
- High potassium concentration stimulates zona glomerulosa to secrete aldosterone (works independent of RAAS)
- RAAS pathway: liver secretes angiotensinogen, and kidneys secrete renin → renin stimulates the conversion of angiotensinogen to angiotensin 1 → ACE stimulates conversion of angiotensin 1 to angiotensin 2 → angiotensin 2 stimulates adrenal gland cortex to secrete aldosterone
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Description
Learn about the general information, functions, hormone families, and divisions of the adrenal gland. Understand its role in maintaining homeostasis and regulating stress responses.
