Endocrine System - Pituitary Hormone 2 Flashcards
What is the location, function and hormone of the zona glomerulsa (adrenal cortex)?
- Location: The outermost layer, just beneath the capsule.
- Function: Produces mineralocorticoids, primarily aldosterone.
- Hormone: Aldosterone regulates sodium and potassium balance and
maintains blood pressure.
What is the location, function and hormone of the zona fasciculata (adrenal cortex)?
- Location: The middle layer, which is the thickest of the three cortical zones.
- Function: Produces glucocorticoids, mainly cortisol.
- Hormone: Cortisol regulates metabolism, and immune response, and helps
the body respond to stress.
What is the location, function and hormone of the zona reticularis (adrenal cortex)?
- Location: The innermost layer of the cortex, adjacent to the medulla.
- Function: Produces androgens, such as dehydroepiandrosterone (DHEA) and
androstenedione. - Hormone: Androgens are precursors to sex hormones and contribute to
secondary sexual characteristics
What hormones do choffamin cells produce and their function (adrenal medulla)
- Hormones:
- Adrenaline: Increases heart rate, blood pressure, and energy
availability. - Noradrenaline: Works with adrenaline to enhance the fight-
or-flight response by constricting blood vessels and increasing
blood pressure.
What are the functions of aldersterone?
Sodium Reabsorption:
* Increases sodium reabsorption in the kidneys, promoting water
retention and increasing blood volume.
* Potassium Excretion:
* Enhances the excretion of potassium in the urine, maintaining proper
potassium levels in the blood.
* Blood Pressure Regulation:
* Increases blood volume and blood pressure by promoting sodium
and water retention.
* Acid-Base Balance:
* Stimulates the secretion of hydrogen ions, helping to maintain the
acid-base balance in the blood.
What is step 1 to stimulation of aldersterone secretion?
*Increased Plasma Potassium ([K+]): Directly stimulates aldosterone release to promote potassium excretion
What is step 2 to aldersterone secretion?
*Renin-Angiotensin-Aldosterone System (RAAS): Renin release leads to the
formation of angiotensin II, which stimulates aldosterone secretion to increase
sodium reabsorption and blood pressure.
What is step 3 to aldersterone secretion?
Independence from Hypothalamus-Pituitary Axis: Aldosterone secretion is
largely independent of ACTH and primarily regulated by plasma potassium levels
and the RAAS system
What is hypoaldersteronism?
Hypoaldosteronism is a condition characterised by insufficient production of aldosterone.
This can result from a deficiency in the enzymes required for aldosterone synthesis, which
leads to various electrolyte and fluid imbalances
What are clinical features of hypoaldosteronism?
*Hyperkalaemia: High potassium levels.
*Hyponatraemia: Low sodium levels.
*Hypovolemia: Decreased blood volume.
*Hypotension: Low blood pressure.
*Other Symptoms: Metabolic acidosis, fatigue, and weakness
What is hyperaldesteronism?
Hyperaldosteronism is a condition characterised by excessive production of aldosterone,
a hormone that regulates sodium and potassium balance. This condition can lead to
hypertension (high blood pressure) and a range of other symptoms due to the imbalance
of electrolytes.
What are the clinical features to hyperaldesteronism?
*Hypokalaemia: Low potassium levels.
*Hypernatremia: High sodium levels.
*Hypertension: High blood pressure.
*Other Symptoms: Metabolic alkalosis, polydipsia (excessive thirst) and
polyuria (excessive urination).
What is dehydroepiandrosterone?
Dehydroepiandrosterone (DHEA) and its derivatives are steroid hormone that
regulates the development and maintenance of MALE characteristics
(masculinisation)
What is DHEA regulated by +lack of feedback axis?
*regulated by ACTH
*lack of feedback axis to ACTH or CRH
What is hypoandrogensim?
Hypoandrogenism, or androgen deficiency, can occur due to a deficiency in the enzymes
required for the synthesis of DHEA (Dehydroepiandrosterone). DHEA is a precursor to
androgens such as testosterone, and its deficiency can lead to a variety of symptoms
related to reduced androgen levels.
What are the symptoms to hypoandrogenism?
Loss of energy, erectile dysfunction, reduced libido, loss of muscle and bone
mass, mood changes, cognitive impairment, and increased body fat.
What is hyperandrogenism?
Excessive levels of Dehydroepiandrosterone (DHEA) and its sulphated form (DHEA-S) can
lead to hyperandrogenism, particularly affecting women. Elevated DHEA levels can result
in various symptoms due to the increased production of androgens.
What are the functions of cortisol?
*glucose metabolism, protein metabolism, lipid metabolism
*immune response (anti-inflammatory +immune supression
*stress response (fight or flight, adaptation)
*bp regulation, bone health + mood/cognition
What are the symptoms of hyperandrogenism in women?
*Excess hair growth (hirsutism), masculinisation (virilisation), acne and oily skin,
menstrual irregularities, hair thinning and baldness.
What is the zona fasciculate of the adrenal cortex responsible for?
Zona Fasciculata: The middle layer of the adrenal cortex is responsible for
the production of cortisol.
What hormones does the HPA release and what do they do?
- CRH (Corticotropin-Releasing Hormone): Released from the hypothalamus
in response to stress and low blood cortisol levels. - ACTH (Adrenocorticotropic Hormone): Secreted by the anterior pituitary
gland in response to CRH, stimulating the adrenal cortex to produce and
release cortisol.
What type of negative feedback loop is seen in terms of cortisol and CRH, ACTH?
Elevated cortisol levels inhibit the release of CRH and ACTH, maintaining
homeostasis
What is the primary cause (10%) of Cushing’s syndrome?
Adrenal Carcinoma/Adenoma:
* Adrenal Adenoma: A benign tumour of the adrenal cortex that
autonomously secretes cortisol.
* Adrenal Carcinoma: A malignant tumour of the adrenal cortex that produces
high levels of cortisol.
What are the secondary causes (80%) for Cushing’s syndrome?
Pituitary Tumour (Cushing’s Disease):
* Pituitary Adenoma: A benign tumour of the pituitary gland that secretes
excessive Adrenocorticotropic Hormone (ACTH).
* Mechanism: The excess ACTH stimulates the adrenal cortex to produce and
release large amounts of cortisol