Podcast
Questions and Answers
What is the primary function of the adrenal medulla?
What is the primary function of the adrenal medulla?
Which zone of the adrenal cortex is responsible for producing aldosterone?
Which zone of the adrenal cortex is responsible for producing aldosterone?
What is the primary function of cortisol, produced by the zona fasciculata?
What is the primary function of cortisol, produced by the zona fasciculata?
Which of the following is NOT a function of the adrenal cortex?
Which of the following is NOT a function of the adrenal cortex?
Signup and view all the answers
What is the innermost layer of the adrenal cortex responsible for?
What is the innermost layer of the adrenal cortex responsible for?
Signup and view all the answers
What is the primary role of glucocorticoids in the regulation of blood pressure?
What is the primary role of glucocorticoids in the regulation of blood pressure?
Signup and view all the answers
What is the primary stimulus for the release of corticotrophin-releasing hormone (CRH) from the hypothalamus?
What is the primary stimulus for the release of corticotrophin-releasing hormone (CRH) from the hypothalamus?
Signup and view all the answers
What is the primary difference between Cushing's syndrome and Cushing's disease?
What is the primary difference between Cushing's syndrome and Cushing's disease?
Signup and view all the answers
What is the primary mechanism by which alcohol can mimic Cushing's syndrome?
What is the primary mechanism by which alcohol can mimic Cushing's syndrome?
Signup and view all the answers
What is the primary purpose of the dexamethasone suppression test in the diagnosis of Cushing's syndrome?
What is the primary purpose of the dexamethasone suppression test in the diagnosis of Cushing's syndrome?
Signup and view all the answers
Study Notes
Adrenal Gland Structure and Function
- The adrenal gland consists of two main functional parts: the adrenal medulla and adrenal cortex.
- Adrenal medulla: inner part of the adrenal gland, responsible for producing and secreting catecholamines (adrenaline and noradrenaline), involved in the fight or flight response.
- Adrenal cortex: outer part of the adrenal gland, responsible for synthesizing and secreting steroid hormones necessary for physiological functions.
Adrenal Cortex Zones and Functions
- Adrenal cortex is divided into three distinct zones:
- Zona glomerulosa: outermost layer, produces aldosterone (regulates electrolyte balance, Na and K, and blood pressure).
- Zona fasciculata: middle layer, produces glucocorticoids (mainly cortisol), involved in regulating metabolism, immune function, and stress response.
- Zona reticularis: innermost layer, produces adrenal androgens, contributing to secondary sexual characteristics.
Glucocorticoids Functions
- Glucocorticoids increase protein breakdown, glycogenolysis, and gluconeogenesis.
- They also sensitize arterioles to noradrenaline actions, key to controlling blood pressure.
- Glucocorticoids have an effect on water excretion (diuresis).
ACTH Negative Feedback Loop
- The hypothalamus monitors blood cortisol levels and initiates the regulation process.
- When cortisol levels are low, the hypothalamus secretes corticotrophin releasing hormone (CRH), which stimulates the secretion of adrenocorticotropic hormone (ACTH) in the anterior pituitary gland.
- ACTH stimulates the synthesis and secretion of cortisol in the adrenal cortex.
- As blood cortisol levels rise, cortisol exerts negative feedback on the anterior pituitary and hypothalamus.
Cushing's Syndrome
- Cushing's syndrome: persistent and inappropriately raised plasma cortisol levels, often due to exogenous steroids.
- Cushing's disease: glucocorticoid excess secondary to inappropriate ACTH secretion, caused by an ACTH-producing tumor or pituitary tumor.
- Endogenous causes: Spontaneous Cushing's, pituitary adenoma, ectopic ACTH-producing tumor.
- Adrenal adenomas/carcinomas autonomously produce cortisol, leading to Cushing's syndrome.
- Pseudo-Cushing syndrome: alcohol can mimic Cushing's syndrome clinically and biochemically, resolves upon alcohol cessation.
Clinical Features of Cushing's Syndrome
- Obesity: fat centrally distributed (trunk/abdomen/buffalo hump on neck).
- Plethoric complexion and thin skin, easily bruising due to protein catabolic effect.
- Moon face: round and full face.
- Purple striae (stretch marks) on abdomen/breasts/thigh.
- Pigmentation (melanin) if ACTH dependent.
Investigations for Cushing's Syndrome
- Raised urinary free cortisol.
- Elevated cortisol levels throughout the day, loss of circadian rhythm.
- Dexamethasone suppression test: administer 0.5mg Dex every 6hrs for 48hrs, suppresses endogenous cortisol production in healthy individuals.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge of the adrenal gland, its two main functional parts, and their roles in producing catecholamines and steroid hormones. Learn about the fight or flight response and physiological functions.
