Endocrine System - Pituitary Hormone 2

Question 1

What is the location, function and hormone of the zona glomerulsa (adrenal cortex)?

Answer 1

• Location: The outermost layer, just beneath the capsule.
• Function: Produces mineralocorticoids, primarily aldosterone.
• Hormone: Aldosterone regulates sodium and potassium balance and
  maintains blood pressure.

Question 2

What is the location, function and hormone of the zona fasciculata (adrenal cortex)?

Answer 2

• 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.

Question 3

What is the location, function and hormone of the zona reticularis (adrenal cortex)?

Answer 3

• 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

Question 4

What hormones do choffamin cells produce and their function (adrenal medulla)

Answer 4

• 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.

Question 5

What are the functions of aldersterone?

Answer 5

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.

Question 6

What is step 1 to stimulation of aldersterone secretion?

Answer 6

*Increased Plasma Potassium ([K+]): Directly stimulates aldosterone release to promote potassium excretion

Question 7

What is step 2 to aldersterone secretion?

Answer 7

*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.

Question 8

What is step 3 to aldersterone secretion?

Answer 8

Independence from Hypothalamus-Pituitary Axis: Aldosterone secretion is
largely independent of ACTH and primarily regulated by plasma potassium levels
and the RAAS system

Question 9

What is hypoaldersteronism?

Answer 9

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

Question 10

What are clinical features of hypoaldosteronism?

Answer 10

*Hyperkalaemia: High potassium levels.
*Hyponatraemia: Low sodium levels.
*Hypovolemia: Decreased blood volume.
*Hypotension: Low blood pressure.
*Other Symptoms: Metabolic acidosis, fatigue, and weakness

Question 11

What is hyperaldesteronism?

Answer 11

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.

Question 12

What are the clinical features to hyperaldesteronism?

Answer 12

*Hypokalaemia: Low potassium levels.
*Hypernatremia: High sodium levels.
*Hypertension: High blood pressure.
*Other Symptoms: Metabolic alkalosis, polydipsia (excessive thirst) and
polyuria (excessive urination).

Question 13

What is dehydroepiandrosterone?

Answer 13

Dehydroepiandrosterone (DHEA) and its derivatives are steroid hormone that
regulates the development and maintenance of MALE characteristics
(masculinisation)

Question 14

What is DHEA regulated by +lack of feedback axis?

Answer 14

*regulated by ACTH
*lack of feedback axis to ACTH or CRH

Question 15

What is hypoandrogensim?

Answer 15

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.

Question 16

What are the symptoms to hypoandrogenism?

Answer 16

Loss of energy, erectile dysfunction, reduced libido, loss of muscle and bone
mass, mood changes, cognitive impairment, and increased body fat.

Question 17

What is hyperandrogenism?

Answer 17

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.

Question 18

What are the functions of cortisol?

Answer 18

*glucose metabolism, protein metabolism, lipid metabolism
*immune response (anti-inflammatory +immune supression
*stress response (fight or flight, adaptation)
*bp regulation, bone health + mood/cognition

Question 19

What are the symptoms of hyperandrogenism in women?

Answer 19

*Excess hair growth (hirsutism), masculinisation (virilisation), acne and oily skin,
menstrual irregularities, hair thinning and baldness.

Question 20

What is the zona fasciculate of the adrenal cortex responsible for?

Answer 20

Zona Fasciculata: The middle layer of the adrenal cortex is responsible for
the production of cortisol.

Question 21

What hormones does the HPA release and what do they do?

Answer 21

• 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.

Question 22

What type of negative feedback loop is seen in terms of cortisol and CRH, ACTH?

Answer 22

Elevated cortisol levels inhibit the release of CRH and ACTH, maintaining
homeostasis

Question 23

What is the primary cause (10%) of Cushing’s syndrome?

Answer 23

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.

Question 24

What are the secondary causes (80%) for Cushing’s syndrome?

Answer 24

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

Question 25

What are the ectopic causes (10%) of Cushing's syndrome?

Answer 25

Ectopic ACTH Production (10%) * Bronchial Tumour: Small cell lung carcinoma or bronchial carcinoid tumours can produce ACTH. * Other Ectopic Sources: Tumours in locations such as the thymus or pancreas may also produce ACTH. * Mechanism: These tumours secrete ACTH independently of the hypothalamic-pituitary axis, leading to increased cortisol production by the adrenal glands.

Question 26

What are the clinical features of Cushing's syndrome In terms of general appearance?

Answer 26

Weight Gain: * Central obesity with fat accumulation around the abdomen, face, and neck. * Thin arms and legs. * Moon Face: * Rounded, puffy face due to fat deposition. * Buffalo Hump: * Fat accumulation on the upper back and neck. Skin and Hair Changes * Skin: * Thin, fragile skin that bruises easily. * Purple striae (stretch marks), especially on the abdomen, thighs, breasts, and arms. * Slow wound healing. * Hair: * Hirsutism: Excessive hair growth on the face, chest, and abdomen in women. * Thinning of scalp hair.

Question 27

What are the clinical symptoms of Cushing's syndrome? (musculoskeletal)

Answer 27

Muscle Weakness: * Proximal muscle weakness, particularly in the thighs and upper arms. * Osteoporosis: * Bone pain and increased risk of fractures due to reduced bone density.

Question 28

What are the clinical symptoms of Cushing's syndrome? (cardiovascular)

Answer 28

Hypertension: * High blood pressure is common due to increased blood volume and sensitivity to catecholamines. * Cardiovascular Disease: * Increased risk of atherosclerosis and other cardiovascular conditions

Question 29

What are the clinical symptoms of Cushing's syndrome? (metabolic)

Answer 29

Hyperglycaemia: * Elevated blood glucose levels, potentially leading to diabetes mellitus. * Dyslipidaemia: * Abnormal lipid levels, including high cholesterol and triglycerides.

Question 30

What are the clinical symptoms of Cushing's syndrome? (reproductive)

Answer 30

* Menstrual Irregularities: * Amenorrhoea (absence of menstrual periods) or oligomenorrhoea (infrequent periods) in women. * Infertility: * Reduced fertility due to hormonal imbalances. * Erectile Dysfunction: * Impotence and reduced libido in men.

Question 31

What are some clinical symptoms of Cushing's syndrome (psychological)?

Answer 31

* Mood Changes: * Depression, anxiety, and irritability. * Cognitive Impairment: * Difficulty concentrating and memory problems.

Question 32

What are some clinical symptoms of Cushing's syndrome (other features)?

Answer 32

* Immune Suppression: * Increased susceptibility to infections due to the immunosuppressive effects of cortisol. * Peptic Ulcers: * Increased risk of developing ulcers in the stomach and duodenum. * Fatigue and Weakness: * Generalised fatigue and decreased physical stamina

Question 33

What is Addisons disease?

Answer 33

Addison's disease, also known as primary adrenal insufficiency, occurs when the adrenal glands do not produce sufficient amounts of cortisol, aldosterone, and androgens. This condition can be life-threatening if not diagnosed and treated properly

Question 34

What are the causes of Addisons disease?

Answer 34

1.Autoimmune Disease: * The most common cause, where the immune system attacks the adrenal cortex, leading to adrenal gland failure. 2.Infections: * HIV/AIDS: Can damage the adrenal glands directly or through opportunistic infections. * Tuberculosis (TB): Historically a common cause, TB can infect the adrenal glands and lead to their destruction. 3.Other Causes: * Genetic disorders, adrenalectomy (surgical removal of the adrenal glands), and certain medications that affect adrenal function

Question 35

What are the clinical features of Addisons disease?

Answer 35

* Hair Loss: * Loss of body hair, particularly in women, due to decreased androgen levels. * Blurred Vision: * Potentially due to hypotension or electrolyte imbalances affecting ocular function. * Abdominal Pain: * Vague, chronic abdominal pain that can be severe during an Addisonian crisis. * Decreased Appetite: * Leading to significant weight loss over time. * Darkening of the Skin (Hyperpigmentation): * Especially noticeable in areas exposed to friction, such as elbows, knees, knuckles, and creases of the hands. * Caused by increased production of melanocyte-stimulating hormone (MSH) due to high levels of ACTH. * Weight Loss: * Progressive weight loss due to decreased appetite and chronic illness. * Hypoglycaemia: * Low blood sugar levels, causing symptoms such as sweating, dizziness, and confusion. * Postural Hypotension: * Low blood pressure, especially when standing up, leading to dizziness and fainting. * Caused by aldosterone deficiency, leading to sodium loss and decreased blood volume

Question 36

Where is ADH stored and what does it do?

Answer 36

Antidiuretic Hormone (ADH), also known as Arginine Vasopressin (AVP), is a crucial hormone produced by the hypothalamus and released by the posterior pituitary gland. It plays a vital role in regulating water balance, blood pressure, and overall fluid homeostasis

Question 37

What is ADH secretion (hypovolemia)?

Answer 37

* Decreased blood volume triggers ADH release to conserve water and maintain blood volume

Question 37

What is ADH secretion (hypotension)?

Answer 37

* Low blood pressure stimulates baroreceptors, which signal the release of ADH to increase BV and pressure.

Question 38

What is ADH secretion (hyperosmolarity)?

Answer 38

* Increased plasma osmolality (high concentration of solutes in the blood) stimulates osmoreceptors in the hypothalamus, leading to ADH release.

Question 39

What are the functions of ADH?

Answer 39

*water reabsorption in the kidneys *stimulation of ACTH release *vasconstriction of blood vessels

Question 40

Describe ADH's water reabsorption function

Answer 40

* Increased Permeability: ADH increases the permeability of the distal convoluted tubule (DCT) and the collecting ducts in the kidneys. * Water Reabsorption: This allows more water to be reabsorbed back into the bloodstream, concentrating the urine and reducing urine volume. * Mechanism: ADH binds to V2 receptors on the cells of the renal tubules, triggering the insertion of aquaporin-2 water channels into the cell membranes, facilitating water reabsorption.

Question 41

Describe ADH's stimulation of ACTH release function

Answer 41

* ADH can stimulate the release of Adrenocorticotropic Hormone (ACTH) from the anterior pituitary. * Effect: ACTH stimulates the adrenal cortex to produce cortisol, which helps the body respond to stress and maintain blood pressure and glucose levels

Question 42

Describe ADH's vasoconstriction of bv function

Answer 42

* Higher Concentrations of ADH: At higher levels, ADH causes vasoconstriction (narrowing of blood vessels). * Mechanism: ADH binds to V1 receptors on vascular smooth muscle cells, causing the muscles to contract and the blood vessels to narrow. * Effect: Vasoconstriction increases peripheral resistance, raising blood pressure.

Question 43

What is diabetes insipidus?

Answer 43

Diabetes Insipidus (DI) is a condition characterised by excessive urination (polyuria) and excessive thirst (polydipsia) due to the body's inability to regulate water balance effectively. There are two main types of DI: Pituitary DI (Central DI) and Nephrogenic DI

Question 44

What are the clinical features of diabetes insipidus?

Answer 44

1.Polyuria: * Excessive production of dilute urine. * Patients may produce large volumes of urine, often more than 3 litres per day. 2.Polydipsia: * Excessive thirst and increased fluid intake. * Patients may drink large amounts of water to compensate for fluid loss

Question 45

What are the types of DI?

Answer 45

*pituitary diabetes insipidus (central DI) *nephrogenic diabetes insipidus

Question 46

What are the the cause, mechanism and effect of central DI?

Answer 46

* Cause: Inadequate release of Antidiuretic Hormone (ADH) from the pituitary gland. * Mechanism: Damage to the hypothalamus or pituitary gland due to trauma, surgery, tumours, infections, or genetic disorders leads to insufficient ADH production. * Effect: Low levels of ADH result in decreased water reabsorption in the kidneys, leading to excessive urine output and thirst

Question 47

What are the cause, mechanism and effect leading to nephrogenic DI

Answer 47

* Cause: Dysfunction of ADH receptors in the collecting ducts of the kidneys. * Mechanism: The kidneys are unable to respond to ADH, despite its normal or elevated levels. This can be due to genetic mutations, certain medications (like lithium), chronic kidney disease, or electrolyte imbalances (such as hypercalcaemia or hypokalaemia). * Effect: The inability of the kidneys to respond to ADH results in reduced water reabsorption, causing excessive urine output and thirst

Question 48

What is syndrome of inappropriate antidiuretic hormone secretion (SIADH)?

Answer 48

is a condition characterised by excessive release of antidiuretic hormone (ADH), leading to water retention, highly concentrated urine, and hyponatraemia. Unlike other forms of hyponatraemia, the low sodium levels in SIADH are due to dilution rather than actual sodium loss.

Question 49

What are the causes of SIADH?

Answer 49

1.CNS Pathologies: Conditions such as head injury, infections (e.g., meningitis, encephalitis), strokes, and brain surgery can lead to excessive ADH release. 2.Malignancy: Certain cancers, particularly small cell lung carcinoma, can produce and secrete ADH ectopically. 3.CNS Drugs: Medications affecting the central nervous system, such as antidepressants, antipsychotics, and anticonvulsants, can trigger SIADH

Question 50

What are the clinical features of SIADH?

Answer 50

* Retention of Water: * Excessive ADH causes the kidneys to reabsorb more water, leading to water retention in the body. * Highly Concentrated Urine: * Despite the body retaining water, the urine remains highly concentrated due to the reabsorption process. * Hyponatraemia: * The retained water dilutes the sodium in the bloodstream, leading to low serum sodium levels (hyponatraemia) due to a dilution effect rather than a direct loss of sodium.

Question 51

What are the primary functions of oxytocin?

Answer 51

* Milk Let-Down Reflex: * Stimulation of Milk Ejection: * Oxytocin stimulates the contraction of myoepithelial cells surrounding the alveoli in the mammary glands. * This contraction forces milk into the ducts, facilitating its expression from the nipple during breastfeeding. * Uterine Contraction: * Labour and Delivery: * Oxytocin causes the smooth muscle of the uterus to contract, helping to initiate and sustain labour. * These contractions are essential for childbirth, assisting in the delivery of the baby

Question 52

What is the role of oxytocin in maternal behaviour, sexual behaviour and social bonding?

Answer 52

* Maternal Behaviour: * Bonding with Offspring: * Oxytocin is involved in the establishment of maternal behaviours, such as nurturing and protecting the offspring. * It strengthens the bond between the mother and her baby, enhancing maternal care. * Sexual Behaviour: * Role in Sexual Activity: * Oxytocin is released during sexual activity and is thought to contribute to the feeling of pleasure and emotional bonding between partners. * It enhances sexual arousal and satisfaction. * Social Bonding: * Social Interactions: * Oxytocin is often referred to as the "love hormone" due to its role in promoting social interactions and bonding. * It facilitates trust, empathy, and social recognition, playing a key role in forming social relationships.

Question 53

What are the pancreatic hormones?

Answer 53

*insulin *glucagon *somatostatin *pancreatic polypeptide

Question 54

What are the sources and functions of insulin, glucagon, somatostatin and pancreatic polypeptide?

Answer 54

*Insulin: * Source: Beta (β) cells. * Function: Lowers blood glucose, promotes glucose uptake and storage, and inhibits fat and protein breakdown. *Glucagon: * Source: Alpha (α) cells. * Function: Raises blood glucose by stimulating gluconeogenesis and glycogenolysis. *Somatostatin: * Source: Delta (δ) cells. * Function: Inhibits insulin and glucagon release, and regulates digestion * Source: PP cells (F cells). * Function: Regulates pancreatic functions, gastric motility, and enzyme secretion. * Relevance: Pancreatic tumours, other disorders

Question 55

What is glucose homeostasis?

Answer 55

Glucose homeostasis is the balance of insulin and counter-regulatory hormones to maintain blood glucose levels within a narrow range, typically between 4-8 mmol/L. This balance is crucial for providing a steady supply of glucose to the body, particularly the brain, which relies on glucose as its primary energy source

Question 55

What are the functions of insulin?

Answer 55

*regulation of blood glucose *fat metabolism *protein metabolism *overall anabolic effects (promotes storage of energy and build up of tissues)

Question 56

How is hyperglycaemia balanced?

Answer 56

* Insulin is released to promote the uptake and storage of glucose, lowering blood glucose levels. * Insulin's effects counteract those of glucagon, adrenaline, growth hormone, and cortisol.

Question 57

How is hypoglycaemia balanced?

Answer 57

* Glucagon, adrenaline, growth hormone, and cortisol are released to increase blood glucose levels. * These hormones promote the production and release of glucose into the bloodstream.

Question 58

What is diabetes mellitus?

Answer 58

Diabetes mellitus is a chronic metabolic disorder characterised by hyperglycaemia (high blood glucose levels). It results from defects in insulin production, insulin action, or both. There are two primary types of diabetes mellitus: Type 1 and Type 2.

Question 59

Describe features of Type 1 diabetes mellitus

Answer 59

* Insulin Deficiency: Autoimmune destruction of pancreatic beta cells. * Onset: Typically in children and young adults. * Symptoms: Hyperglycaemia, polyuria, polydipsia, polyphagia, weight loss

Question 60

Describe features of Type 2 diabetes mellitus

Answer 60

* Impaired Beta-Cell Function and Insulin Resistance: * Insulin Resistance: Cells are resistant to insulin's effects. * Beta-Cell Dysfunction: Pancreas produces insufficient insulin. * Onset: Typically in adults over 45, but increasingly in younger individuals. * Symptoms: Hyperglycaemia, polyuria, polydipsia, polyphagia, fatigue, blurred vision, slow healing of wounds