Endocrine ( 10% )

Question 1

Insulin

• Is secreted by the α cells in the islets of Langerhans.
• Is a triple helical polypeptide.
• Is synthesized as a prohormone
• Binds at cytoplasmic receptor sites
• Causes K to leak out of the cells.

Answer 1

Is synthesized as a prohormone

Pre-proinsulin->proinsulin->insulin

• Is secreted by the beta cells in the islets of Langerhans.
• Is a double helical polypeptide.
• Binds at Cell surface - tyrosine kinase receptor
• Causes K to leak into the cells.

Question 2

The pancreas

• Does not resemble the salivary glands
• Contains digestive enzymes in α granules
• Secretes 500mL of pancreatic juice/d
• Secretes trypsin which activates phospholipase A2
• Is stimulated by secretin to secrete enzyme rich pancreatic juice which is low in volume

Answer 2

Secretes trypsin which activates phospholipase A2​

Resembles salivary glands

Digestive enzymes contained in zymogen granules

Secretes 1500mL of pancreatic juice/day

Secretin stimulates alkaline, watery juice; CCK stimulates low-volume enzyme-rich juice

Question 3

All of the following increase BSL except

• T4
• Cortisol
• Growth hormone
• Somatostatin
• LH

Answer 3

LH

• Somatostatin inhibits insulin and glucagon secretion*
• GH and glucocorticoids are catabolic for fat*

Question 4

Which statement is correct

• Serum glucose is increased by glucagon without increasing serum lactate
• Insulin increases glucose entry into the liver by increasing the number of GLUT4 transporter.
• Cortisol increases serum glucose by increasing hepatic glycogenolysis.
• Insulin secretion is inhibited by glucagons
• Glucagon secretion is stimulated by free fatty acids.

Answer 4

Serum glucose is increased by glucagon without increasing serum lactate

• Insulin increases glucose entry into the liver by inducing glucokinase causing an increase in the phosphorylation of glucose, increasing the concentration gradient for diffusion
  
  • GLUT 4 in skeletal muscle and fat (stimulated by insulin)
  • GLUT2 in pancreas
• Cortisol increases serum glucose by increasing hepatic gluconeogenesis and export of glucose from hepatocytes
• Insulin secretion is stimulated by glucagons
• Glucagon secretion is inhibited by free fatty acids.

Question 5

With respect to insulin

• Increases ketone release in muscles.
• Synthesized in A cells.
• Increased cAMP in cell causes release of insulin by exocytosis.
• GLUT2 transporter controls the entry of glucose into the endocrine pancreas
• Increases the conversion of TG to FFA.

Answer 5

GLUT2 transporter controls the entry of glucose into the endocrine pancreas

• Inhibits ketone release in muscles.
• Synthesized in beta cells.
• Increased calcium in cell causes release of insulin by exocytosis.
• Decreases the conversion of TG to FFA.

Question 6

Concerning the islets of Langerhan

• The B cells make up 90% of the islets
• The D cells secrete the pancreatic polypeptide.
• Beef insulin is structurally more like human insulin than pork insulin
• The release of insulin involves the depolarization of the cell membrane, causing opening of Ca channels
• High K increases the secretion of insulin

Answer 6

The release of insulin involves the depolarization of the cell membrane, causing opening of Ca channels

Glucose enteres cells, generates ATP which inhibitis K channels, causing cellular depolarisation. This causes a calcium influx, which causes exocytosis of granules containing insulin.

• The B cells make up ~75% of the islets
• The F cells secrete the pancreatic polypeptide
  
  • D cells secrete somatostatin
• Hypokalaemia inhibits the secretion of insulin

Question 7

regarding insulin

• α adrenergic stimulation inhibits insulin secretion
• Theophylline inhibits insulin secretion.
• Insulin has a half life of ~ 30 min in the circulation.
• Insulin inhibits K uptake into muscle and adipose cells
• Somatostatin stimulates insulin secretion.

Answer 7

α adrenergic stimulation inhibits insulin secretion

• Theophylline s**timulates insulin secretion
• Insulin has a half life of ~ 5 min in the circulation (most metabolic hormones are 5-10 mins)
• Insulin stimulates K uptake into muscle and adipose cells
  
  • Which is why you use it in hyperkalaemia
• Somatostatin inhibits insulin secretion

Question 8

actions of glucocorticoids include all of the following except

• gluconeogenesis in the liver
• maintenance of myocardial contractility
• inhibition of glucose uptake by muscle and adipose tissue
• permissive effect on angiotensin II
• decrease in vascular resistance

Answer 8

decrease in vascular resistance

Question 9

regarding insulin

• it increases amino acid uptake
• it causes reduced K uptake in cells.
• its absorption is not affected by the site of injection
• it increases protein catabolism
• it is secreted by the α cells in the islets of Langerhan.

Answer 9

it increases amino acid uptake

Increases uptake of glucose, AA, and potassium

• it causes increased K uptake in cells
• its absorption is not affected by the site of injection
  
  • Not specifically noted but almost certainly - different blood flows etc, IM vs SC
• it increases protein synthesis
• it is secreted by the beta cells in the islets of Langerhan

Question 10

Which does not utilize the same type of receptor in its mechanism of action

• Insulin
• Glucagons
• PTH
• ACTH
• None of the above

Answer 10

Insulin.

Tyrosine kinase. Rest are GPCRs

Question 11

Insulin secretion is stimulated by all of the following except

• Mannose
• Glucagons
• Noradrenaline.
• Leucine
• Acetylcholine

Answer 11

Noradrenaline.

and adrenaline

Net result is inhibition as the alpha effects overcome the beta effects.

Question 12

Regarding insulin

• It increases protein catabolism in muscles
• Secretion is inhibited by somatostatin
• Secretion is stimulated by phenytoin
• It causes decreased K uptake into adipose tissue
• It causes decreased protein synthesis

Answer 12

Secretion is inhibited by somatostatin

• It increases protein synthesis in muscles
• Secretion is inhibited by phenytoin
• It causes increased K uptake into adipose tissue
• It causes increased protein synthesis

Question 13

29. Regarding glucagons

• a. It is secreted by the pancreatic B cells
• b. It increases glycogen formation
• c. It has a half life of 30 minutes
• d. Secretion is stimulated by glucose
• e. It stimulates insulin secretion

Answer 13

e. It stimulates insulin secretion

• a. It is secreted by the pancreatic alpha cells
• b. It increases glycogen breakdown
• c. It has a half life of 30 minutes
  
  • probably more like 5-10min
• d. Secretion is inhibited by glucose

Question 14

24. Insulin secretion is stimulated by all of the following EXCEPT:

• a. Mannose
• b. Glucagons
• c. Noradrenaline
• d. Leucine
• e. Acetylcholine

Answer 14

c. Noradrenaline

As with adrenaline, the alpha effects (inhibition) outweigh the beta effects (secretion)

Question 15

19. Insulin

• a. Increases the number of glucose transporters on the cell surface
• b. Regulates intracellular glucose metabolism

Answer 15

a. Increases the number of glucose transporters on the cell surface

• GLUT 4 in skeletal muscle and adipose*
• GLUT 1 and 3 in brain, kidneys, placenta etc does not require insulin to take in glucose*
• GLUT 2 is in the beta cells -> helps regulate insulin secretion*

Question 16

12. Glucose reabsorption by the kidney

• a. Is independent of glucose load
• b. Occurs in the distal convoluted tubule
• c. Involves potassium reabsorption
• d. Occurs through passive diffusion
• e. Occurs through secondary active transport

Answer 16

e. Occurs through secondary active transport

• SGLT Sodium-Glucose co-transporter*
• Occurs in early PCT*

Question 17

13. Insulin

• a. Is synthesized in the Golgi apparatus of beta cells
• b. Is released mostly in its proinsulin form
• c. Has a half-life of 50 minutes
• d. Binds to intracellular receptors
• e. Is mostly degraded in the liver and kidneys

Answer 17

e. Is mostly degraded in the liver and kidneys

(40% kidneys, 60% liver; reversed in exogenous insulin administration)

• a. Is synthesized in the RER of beta cells
• b. Is released mostly in its pre-proinsulin form
• c. Has a half-life of 5 minutes
• d. Binds to cell-surface (tyrosine kinase) receptors

Question 18

8. Insulin secretion is increased by

• a. Thiazide diuretics
• b. Glucagon
• c. Potassium depletion
• d. Adrenaline
• e. Somatostatin

Answer 18

b. Glucagon

Question 19

4. Insulin release

• a. Is inhibited by raised cyclic AMP in pancreatic beta cells
• b. Is not stimulated by blood glucose levels below 6mmol/L
• c. Is increased by beta adrenergic stimulators
• d. Is inhibited by phosphodiesterase inhibitors
• e. Is increased by somatostatin

Answer 19

c. Is increased by beta adrenergic stimulators

Question 20

with regard to thyroid physiology

• T3 and T4 are metabolized in the spleen and bone marrow.
• T3 and T4 bind and act at the same cell membrane receptor.
• T4 is synthesised from tyrosine held in thyroglobulin
• T3 is bound to a complex polysaccharide in the plasma
• T4 is more active than T3

Answer 20

T4 is synthesised from tyrosine held in thyroglobulin

• T3 and T4 are metabolized in the “Liver, kidneys and other tissues”
• T3 and T4 act at a n**uclear receptor
• T3 is bound to proteins (albumin and TBG) in the plasma.
• T4 is less active than T3

Question 21

regarding the thyroid hormones in plasma

• glucocorticoids decrease free plasma T4
• concentration of binding proteins are increased in HTN
• oestrogens decrease total plasma T4
• free T3 levels are normal in hyperthyroidism
• plasma TSH is high in hypothyroidism

Answer 21

plasma TSH is high in hypothyroidism

TSH is high to try and stimulate T4 release (except in hypothalamic or pituitary failure)

• glucocorticoids increase free plasma T4
• free T3 levels are high in hyperthyroidism

Question 22

Under physiological condition most circulating T4 is bound to

• Thyroxine binding prealbumin
• Tramothynetim
• Thyroxine binding globulin
• Α2 globulin
• Iodothyronine

Answer 22

Thyroxine binding globulin

T4: TBG >> TBPA > albumin

T3: Albumin >/= TBG >>> TBPA (1%)

Question 23

With respect to the thyroid gland which is false

• Serum iodide is passively transported into the colloid
• MIT and DIT are not secreted
• The action of T4 on tissues is faster than T3
• Albumin has the largest capacity to bind T4
• Free T3 and T4 exert a negative feedback effect on both the anterior pituitary and the hypothalamus

Answer 23

The action of T4 on tissues is slower than T3

T3 is less bound, and thus has a shorter half-life, and a more rapid action on tissues

Serum iodide is actively transported into the thyrocytes, but passively diffuses into the colloid

Albumin binds the lowest proportion of T4 (13%), but its concentration is nearly 2000x that of TBG hence its capacity is higher

Question 24

In the thyroid

• Passage of iodide from the thyroid cells into the colloid is an active process.
• RT3 is inert
• Most T4 is metabolized to T3.
• Thyroglobulin is formed in the colloid.
• Thyroxine binding globulin has the highest capacity to bind thyroid hormones in the plasma.

Answer 24

RT3 is inert

• Passage of iodide from the thyroid cells into the colloid is a passive process.
  
  • Uptake into thyroid is active, but then to colloid is passive
• Most T4 is metabolized to RT3.
  
  • 1/3 metabolised to T3, ½ metabolized to RT3
• Thyroglobulin is Synthesized in thyrocytes and then secreted into colloid
• Albumin has the highest capacity to bind thyroid hormones in the plasma.
  
  • Ganong states albumin has the highest capacity (as there is much more of it), whilst TBG has the highest affinity and carries the most T4

Question 25

The following effects of thyroid hormone include all of the following except

• Increased activity of Na/K ATPase
• Increased nitrogen excretion
• Increased levels of catecholamines
• Increased carbohydrate absorption from the gut
• Increased α myosin heavy chains in cardiac muscle fibres

Answer 25

Increased levels of catecholamines.

Increased responsiveness to catecholamines but not the levels of catecholamines

Question 26

thyroxine (T4)

• secretion is regulated by positive feedback at the hypothalamus
• is transported principally by albumin in the blood.
• causes increased LDL in plasma.
• is physiologically more active than T3.
• increases β receptors in the cardiovascular system.

Answer 26

increases β receptors in the cardiovascular system.

• secretion is regulated by negative feedback at the hypothalamus
• is transported principally by TBG (thyroid binding globulin) in the blood.
• causes decreased LDL in plasma
• is physiologically less active than T3.

Question 27

regarding thyroid hormone, which is false

• they increase plasma cholesterol
• they increase the activity of Na/K ATPase
• they increase the number/affinity of β receptors
• they alter the proportion of α myosin heavy chains
• they have a calorigenic action

Answer 27

they decrease plasma cholesterol

Question 28

16. Regarding thyroid disease

• Thyrotoxicosis reflects excessive leakage of hormone out of a non-hyperactive gland
• Secondary hyperthyroidism may be due to a thyroid gland abnormality.
• A common cause for hyperthyroidism is iodide-induced hyperthyroidism.
• d. TSH levels are a reliable indicator of thyroid function caused by hypothalamic and primary pituitary disease.
• e. Secondary hypothyroidism accounts for the vast majority of causes of hypothyroidism

Answer 28

b. Secondary hyperthyroidism may be due to a thyroid gland abnormality.

R&C considers thyroid infl disorders to be a 2’ cause

• a. Thyrotoxicosis reflects excessive leakage of hormone out of a hyperactive gland
• c. A common cause for hyperthyroidism is iodide-induced hyperthyroidism.
  
  • Iodide seems to be a treatment for hyperthyroidism, not a cause
• d. TSH levels are a reliable indicator of thyroid function caused by thyroid disease - this is because of the negative feedback. Central causes have their effect their alterations in TSH levels so are not reflective of the actual thyroid function.
• e. Primary hypothyroidism accounts for the vast majority of causes of hypothyroidism

Question 29

11. Hashimoto’s thyroiditis

• a. Has high levels of triiodothyronine (T3) and thyroxine (T4).
• b. The skin becomes moist, warm and flushed.
• c. Is associated with diffuse toxic hyperplasia.
• d. Is the most common form of goitrous hypothyroidism in regions with sufficient iodine
• e. Has a marked infiltrate of eosinophils

Answer 29

d. Is the most common form of goitrous hypothyroidism in regions with sufficient iodine

Autoimmune hypothyroidism - occurs due to loss of self-tolerance to thyrocyte antigens ->CD8 T cell mediated damage (T4 HSR)

• a. Has low levels of triiodothyronine (T3) and thyroxine (T4).
  
  • Hashimotos = hypo; Graves = Hyper
• b. The skin becomes moist, warm and flushed. Hyperthyroidism can be seen early but is transient. Then presents with varying degrees of hypothyroidism
• c. Is associated with diffuse toxic hyperplasia. Different disease process
• e. Has a marked infiltrate of eosinophils. Mononuclear cell infiltrate

Question 30

10. The commonest cause of thyroid carcinoma is

• a. Medullary
• b. Follicular
• c. Papillary
• d. Anaplastic
• e. Squamous

Answer 30

c. Papillary <- 85%

b. Follicular - 10%

Question 31

9. Hypothyroidism is associated with all of the following EXCEPT:

• a. Cretinism
• b. ?
• c.
• d. decreased hair growth
• e. cold intolerance

Answer 31

Probably B or C

Maybe D) if they make a distinction between decreased growth and hair loss.

Question 32

3. With regard to the effect of thyroid hormone on the cardiovascular system, which of the following is TRUE?

• a. Levels of noradrenaline are increased.
• b. Beta adrenergic receptor affinity is decreased in heart muscle
• c. Circulating adrenaline levels are decreased
• d. Thyroid hormone levels alter the ratio of cardiac myosin isoform types
• e. None of the above

Answer 32

d. Thyroid hormone levels alter the ratio of cardiac myosin isoform types

• a. Levels of noradrenaline are unchanged - Beta receptor number and sensitivity is increased
• b. Beta adrenergic receptor affinity is increased in heart muscle
• c. Circulating adrenaline levels are unchanged

Question 33

10. Increased T4 and T3 levels

• a. Causes CSF protein to increase
• b. Causes O2 consumption of the thyroid to increase
• c. Are not caused by starvation
• d. Suppresses formation of LDL receptors
• e. Delays epiphyseal closure

Answer 33

c. Are not caused by starvation

• ​Hypothyroidism causes an increase in CSF protein
• d. Increases formation of LDL receptors and thus reduces serum cholesterol
• e. Hypothyroidism delays epiphyseal closure

Question 34

15. Hypothyroidism causes

• a. Cretinism
• b. Myxoedema.
• c. Early genital development
• d. Hair loss

Answer 34

a. Cretinism

• If congenital/genetic*
• b. Myxoedema - Also true but seen in Grave’s disease as well

Question 35

a deficiency of parathyroid hormone is likely to lead to

• low PO4
• kidney stone formation
• a self limiting illness
• neuromuscular hyperexcitability.
• cystic bone disease

Answer 35

neuromuscular hyperexcitability.

Due to hypocalcaemia.

A, B and E are all hyperparathyroid effects (stone, groans, and moans are symptoms of hypercalcaemia)

Question 36

In calcium metabolism

• Gastrin, glucagons and secretin inhibit calcitonin secretion
• Human calcitonin has a half life of 30 min
• Calcitonin increases bony resorption.
• PTH increases PO4 excretion in the urine
• 1,25 dihydroxycholecalciferol decreases Ca absorption from the intestine.

Answer 36

PTH increases PO4 excretion in the urine

• Calcitonin increases bony Formation
• 1,25 dihydroxycholecalciferol increases Ca absorption from the intestine

Question 37

With respect to Ca metabolism

• PTH decreases urinary reabsorption of Ca.
• PTH decreases urinary PO4 secretion.
• Calcitonin increases bone resorption of Ca.
• 24,25 dihydrocycholecalciferol has 15% the activity of 1,25 dihydroxycholecalciferol
• PTH also inhibits PO4 resorption in the kidneys

Answer 37

PTH also inhibits PO4 resorption in the kidneys

• PTH increases urinary reabsorption of Ca.
• PTH increases urinary PO4 secretion.
• Calcitonin increases bone Formation

Question 38

Concerning Ca metabolism

• The net effect of PTH is to decrease serum PO4
• Vitamin D decreases renal excretion of both Ca and PO4. Increases
• Calcitonin is secreted by parathyroid chief cells. Thyroid parafollicular cells
• Insulin decreases bone formation.
• Thyroid hormones decrease Ca excretion in urine

Answer 38

The net effect of PTH is to decrease serum PO4

• Vitamin D decreases renal excretion of only calcium as far as I can tell
  
  • ​Works to increase serum calcium levels
• Calcitonin is secreted by Thyroid parafollicular cells
• Insulin increases bone formation.
• Thyroid hormones decrease Ca excretion in urine
  
  • ?thyroid hormones have no effect
  • Calcitonin is technically from the thyroid and this increases calcium excretion in the urine

Question 39

with regard to Ca metabolism

• approximately 60% of filtered Ca is reabsorbed by kidney.
• absorption of Ca in the GIT is mainly by passive diffusion.
• the extent of Ca binding by plasma proteins is inversely proportional to the plasma protein level
• levels of 1,25 dihydroxycholecalciferol fall in the presence of increased plasma Ca
• the majority of Ca present in bone is readily exchangeable.

Answer 39

levels of 1,25 dihydroxycholecalciferol fall in the presence of increased plasma Ca

Vitamin D works to increase calcium, so falls if already high

• approximately 99% of filtered Ca is reabsorbed by kidney
• absorption of Ca in the GIT is mainly by Active transport
• the extent of Ca binding by plasma proteins is proportional to the plasma protein level
• the minority of Ca present in bone is readily exchangeable

Question 40

regarding Ca metabolism

• the adult human body contains 15% of its body mass as Ca
• Ca is passively absorbed from the intestinal brush border.
• Oestrogen inhibits osteoclasts
• TNF inhibits osteoclasts
• Corticosteroids stimulate osteoblasts. Inhibit osteoclasts in short term

Answer 40

Oestrogen inhibits osteoclasts

• the adult human body contains 15% of its body mass as Ca
  
  • Seems way too high
• Ca is actively absorbed from the intestinal brush border.
• Corticosteroids inhibit osteoclasts in short term (and hence lower serum calcium) - long term cause osteoporosis

Question 41

2. regarding 1,25 dihydroxycholecalciferol (calcitriol)

• a. it is formed by the action of sunlight on pre-vitamin D3
• b. it exerts its actions via stimulation of adenylyl cyclase.
• c. it decreases calcium reabsorption from kidneys.
• d. its formation is increased with elevated plasma Ca2+ levels.
• e. it causes increased formation of calbindin-D proteins

Answer 41

e. it causes increased formation of calbindin-D proteins

• a. it is formed by the action of sunlight on pre-vitamin D3
  
  • Sunlight converts 7-dehydrocalciferol to cholecalciferol, which is converted in the liver to calcidiol
• b. it exerts its actions via a nuclear receptor (as a lipid homrone this is much more likely)
• c. it increases calcium reabsorption from kidneys.
• d. its formation is decreased with elevated plasma Ca2+ levels.

Question 42

7. Regarding the role of vitamin D in calcium metabolism, which of the following is INCORRECT?

• a. It increases renal tubular calcium phosphate reabsorption
• b. It causes an increase in synthesis of calcium-binding protein
• c. It increases bone resorption
• d. It decreases bone formation
• e. It increases intestinal calcium and phosphate absorption

Answer 42

d. It increases bone formation

Causes an increase in bone formation. This increased osteoblast activity stimulates increased osteoclast activity.

Question 43

9. With regards to calcium regulation and metabolism

• a. 98% of calcium is reabsorbed in the proximal tubule.
• b. the transport of calcium out of the intestine into the circulation involves a calcium dependent ATPase
• c. a decrease in plasma calcium level will decrease 1,25 dihydroxycholecalciferol level
• d. calcium absorption is increased by high levels of phosphates and oxalates
• e. distal tubule reabsorption is not regulated by parathyroid hormone

Answer 43

b. the transport of calcium out of the intestine into the circulation involves a calcium dependent ATPase

• a. 98% of calcium is reabsorbed in total and 60% in PCT
• c. a decrease in plasma calcium level will increase 1,25 dihydroxycholecalciferol level
• d. calcium absorption is decreased by high levels of phosphates and oxalates
• e. distal tubule reabsorption is regulated by parathyroid hormone

Question 44

17. Regarding Ca2+ metabolism, which is INCORRECT?

• a. 1,25 dihydroxycholecalciferol is formed in the liver
• b. PTH acts on the distal tubule to decrease phosphate absorption

Answer 44

a. 1,25 dihydroxycholecalciferol is formed in the kidneys

25-OH vit D is formed in the liver (calcidiol)

Question 45

temperature regulation

• is integrated by cortical pathways
• systems result in hypothermia when the anterior hypothalamus is stimulated
• is mediated by endogenous pyrogens produced by monocytes, macrophages and Kupffer cells
• is deranged due to a mutation in the ryanodine receptor resulting in excess Na released in malignant hyperthermia
• results in the maintenance of a constant body temperature over 24 hours

Answer 45

is mediated by endogenous pyrogens produced by monocytes, macrophages and Kupffer cells

• is integrated by ?subcortical pathways
• systems result in hypothermia when the anterior hypothalamus is stimulated
  
  • Cold response activated by posterior pituitary
  • Heat response activated by anterior pituitary - act to reduce a high temp but unlikely to cause hypothermia
• is deranged due to a mutation in the ryanodine receptor resulting in excess calcium released in malignant hyperthermia
• Body temperature fluctuates over 24 hours - lowest at 0600

Question 46

Which is false

• The suprachiasmatic nuclei of the hypothalamus is responsible for producing the diurnal secretion of ACTH
• Free serum cortisol has a direct negative feedback on the pituitary but not on the hypothalamus
• Aldosterone and glucocorticoid secretion is increased by haemorrhage
• Aldosterone secretion is only found in the zona glomerulosa
• Testosterone exerts a negative feedback on pituitary LH secretion

Answer 46

Free serum cortisol has a direct negative feedback on the pituitary but not on the hypothalamus

Question 47

All of the following are secreted by the anterior pituitary except

• ACTH
• Prolactin
• β lipoprotein
• FSH
• Oxytocin

Answer 47

Oxytocin

PP secretes oxytocin and ADH only. Everything else is AP.

Question 48

Concerning ADH

• Diabetes insipidus is characterized by polydipsia and polyuria
• Secretion of ADH is stimulated by alcohol.
• Surgical stress inhibits secretion of ADH
• Preprooxyphysia is the precursor of ADH
• ADH is absent in hippopotamuses

Answer 48

Diabetes insipidus is characterized by polydipsia and polyuria

• Secretion of ADH is inhibited by alcohol - this is why it is a diuretic
• Surgical stress stimulates secretion of ADH - hence post-surgical SIADH and hyponatraemia in half the fucking patients.

Question 49

Which of the following is true regarding temperature regulation

• Vaporization of sweat accounts for 70% heat loss.
• Increased TSH is an important response to the cold.
• Anterior hypothalamic stimulation causes shivering
• Bacterial toxin act on the OVLT to produce fever
• None of these

Answer 49

None of these

• Radiation accounts for 70% heat loss - Sweat is about 25%
• Increased TSH is not an important response to the cold
• Posterior hypothalamic stimulation causes shivering.
  
  • PP = cold; AP = heat response
• Bacterial toxin act on monocytes, macrophages, and Kupffer cells, which produce cytokines/pyrogens, which act on the OVLT to produce fever

Question 50

with respect to thirst, which is true

• angiotensin II acts on the supraoptic nucleus to stimulate thirst
• drinking and ADH secretion are regulated much the same
• dry mucous membranes stimulate thirst via the hypothalamus
• secretion of oxytocin causes thirst due to its similarity to vasopressin
• ACE inhibitors decrease thirst in response to Hypovolaemia by deceasing angiotensin II

Answer 50

ACE inhibitors decrease thirst in response to Hypovolaemia by deceasing angiotensin II

• Osmoreceptors for thirst are in the anterior hypothalamus*
• Ang II acts on subfornical organ to stimulate thirst*

Question 51

Which pattern of lab findings is most consistent of diabetes insipidus, note that the values are 24 hour urine volumes of ketones, glucose and protein respectively

• 4 0 +
• 6.2 0 2+
• 1.6 4+ 0
• 6.4 0 0
• 5 3+ 0

Answer 51

d) 6.4 0 0

Dehydration 2’ water loss, no glycosuria (cf diabetes mellitus) and no proteinuria (early stage of diabetic nephropathy)

Question 52

he hypothalamus is essential for

• movement
• visual acuity
• renal function

Answer 52

renal function

• Ang II acts on hypothalamus to increase thrist*
• Releases ACTH -> cortisone*

Question 53

t1. Which is true of the pituitary gland?

• a. Anterior-LH-basophils
• b. Posterior-vasopressin-basophils
• c. Anterior-GH-basophils
• d. Posterior-prolactin-acidophils

Answer 53

a. Anterior-LH-basophils

Question 54

2. Pituitary adenoma may cause

• a. Graves disease
• b. Hypothyroidism
• c. Acromegaly

Answer 54

c. Acromegaly

Question 55

With regard to adrenal physiology

• The only glucocorticoid secreted in significant amounts is cortisol
• Dopamine is secreted by the adrenal medulla
• The largest steroid molecules are oestrogens
• Cortisol has negligible Mineralocorticoid activity
• Glucocorticoids exert their action by cGMP activation

Answer 55

Dopamine is secreted by the adrenal medulla

Along with adrenaline and noradrenaine

• Cortisol is the primary glucocorticoid, but there are others - steroids are on a spectrum of MC:GC effects
• The largest steroid molecules are oestrogens
  
  • Looking at pictures, all seem to have the same core size with different add-ons (-H and -OH etc)
• Cortisol has weak Mineralocorticoid activity
• Glucocorticoids exert their action by cAMP activation via adenylyl cyclase

Question 56

With regard to adrenal function

• The zona fasciculate secretes mainly aldosterone
• The adrenal medulla is not essential to life
• ACTH is the prime controller of secretion from zona glomerulosa
• More than 85% of adrenal medullary secretion is NA
• Hypernatraemia is associated with Mineralocorticoid deficiency

Answer 56

The adrenal medulla is not essential to life

After adrenalectomy, some catecholamines appear in the blood, under the same controls as the adrenal glands. I cannot find the specific words above in Ganongs.

• The zona fasciculate (middle) secretes mainly cortisol
  
  • ​Zona granulosum (exterior) secretes aldosterone
  • Zone reticularis (interior) secretes androgens
• ACTH is the prime controller of secretion from zona fasciculata
  
  • ​Zona granulosum (aldosterone) also under Ang II and vasopressin control
• More than 85% of adrenal medullary secretion is adrenaline
• Hyponatraemia is associated with Mineralocorticoid deficiency

Question 57

Which is false

• The suprachiasmatic nuclei of the hypothalamus is responsible for producing the diurnal secretion of ACTH
• Free serum cortisol has a direct negative feedback on the pituitary but not on the hypothalamus
• Aldosterone and glucocorticoid secretion is increased by haemorrhage
• Aldosterone secretion is only found in the zona glomerulosa
• Testosterone exerts a negative feedback on pituitary LH secretion

Answer 57

Free serum cortisol has a direct negative feedback on the pituitary and the hypothalamus

“The inhibitory effect is exerted at both the pituitarty and hypothalamic levels”

Question 58

8. Cushing syndrome is associated with

• a. Osteoporosis
• b. General obesity
• c. Hypotension

Answer 58

a. Osteoporosis

Central obesity, hypertension, poor wound healing, poor musculature, striae, insulin resistence, fluid retention

Question 59

17. Regarding Cushing Syndrome

• a. It is called Cushing disease if it is caused by a primary pituitary lesion with decreased ACTH production
• b. The basic lesion is in the adrenal and pituitary glands.
• c. Diffuse atrophy in the adrenal gland is found in 60-70% of cases
• d. It is found more frequently in men aged 20-30 years.
• e. Primary adrenal neoplasm is responsible for 60% of cases

Answer 59

c. Diffuse atrophy in the adrenal gland is found in 60-70% of cases

this might be correct, as the vast majority of cases of Cushing Syndrome are from exogenous steroids and this is the finding

• a. It is called Cushing disease if it is caused by a primary pituitary lesion with increased ACTH production
• b. The basic lesion is in the adrenal and pituitary glands.
  
  • Can be exogenous steroid, or a hypothalamic lesion too
• d. It is found more frequently in men aged 20-30 years.
  
  • Unlikely given this group don’t often take steroids
• e. Exogenous steroids most common cause of Cushings
  
  • ​Primary adrenal neoplasm = 10% endogenous cases
  • ACTH hypersecretion due to pituitary or hypothalamic lesion = 70% endogenous cases

Question 60

20. With regard to cortisol, which is INCORRECT?

• a. It is predominately metabolized in the liver
• b. It has a permissive action on vascular reactivity
• c. It has greater mineralocorticoid activity than glucocorticoid activity

Answer 60

c. It has Less mineralocorticoid activity than glucocorticoid activity

• a. It is predominately metabolized in the liver
  
  • Phase I + II reactions (cf aldosterone just phase II)
• b. It has a permissive action on vascular reactivity
  
  • Needed in low amounts for catecholamines to exert their effect

Question 61

26. With regard to the renin-angiotensin system

• a. Prorenin has 50% of the activity of renin.
• b. Renin secretion will be increased by propranolol. Decreased
• c. Angiotensinogen is synthesized in the liver
• d. Angiotensin I is a potent vasoconstrictor
• e. Angiotensin II acts at receptors in the nucleus

Answer 61

c. Angiotensinogen is synthesized in the liver

Renin = kidney, angiotensinogen = liver, ACE = lungs

• a. Prorenin has “little if any biologic activity”
• b. Renin secretion will be decreased by propranolol.
• d. Angiotensin II is a potent vasoconstrictor
  
  • Ang I has no biologic activity
• e. Angiotensin II acts at GPCRs