Revision card/Mistakes Flashcards

1
Q

Which of the following is NOT an endocrine gland?

A

Spleen
Adipose tissue, heart and kidneys have recently been identified as endocrine glands. Parathyroid is an example of a ‘classic’ endocrine gland.

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2
Q

Which statement regarding the endocrine system is correct?

A

hormones can affect more than one target organ

False: hormones are released into the bloodstream via ducts

Unlike the transmission of ‘messages’ by nervous system in which effects are limited to specific innervated cells only, effects of a hormone can be expressed on multiple target organs.

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3
Q

Is POMC a hormone?

A

NO

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4
Q

Choose the best option concerning the synthesis of steroid hormones.

A

NOT: StAR proteins transport synthesised cholesterol towards the cell membrane for secretion

cholesterol is obtained from the transport products of LDL via the action of esterase.
StAR proteins transport cytoplasmic cholesterol towards mitochondria for further modification to give cortisol. Fatty acid esters are broken down in the cytoplasm by esterase. Since steroid hormones are lipophilic, they diffuse through the cell membrane..

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5
Q

Is this statement true

thyroglobulin is used to transport ACTH.

A

ACTH is a protein/polypeptide hormone, hence does not need transporters.

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6
Q

Concerning the mechanism of action of ACTH, which statement is true?

is this false or true:
ACTH receptors are intracellular in nature

A

ACTH receptors are linked to G-proteins.

Energy is obtained from the dephosphorylation of ATP to cAMP by adenylate cyclase. Activated PKA up-regulates levels StAR proteins and fatty acid esters in the cell. ACTH receptors are located on the plasma membrane, unlike steroid hormones receptors which are found in the cytoplasm.

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7
Q

The lack of this substance during fetal development results in cretinism if untreated.

A

Cretinism occurs if untreated within a few months of birth. Fetal development and growth are some of the roles of iodothyronines. Iodothyronines are produced by the thyroid gland which is in turn stimulated by thyrotrophin.

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8
Q

Which of the following is NOT an effect of high circulating levels of prolactin?

A

erythropoiesis.

NOT:

  • breast lactogenesis
  • stimulation of T cells
  • renal water reabsorption
  • reduction in LH released
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9
Q

Which of the following suppresses the circulating levels of prolactin?

A

dopamine.

Thyrotrophins, suckling and oestrogens increase levels of prolactin while SS decreases levels of growth hormones.

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10
Q

Vasopressin (VP):

and oxytocin synthesis involve different neurophysins

A

Neurophysin is also breakdown product of pre-provasopressin in addition to glycopeptide and VP. VP stimulates water reabsorption. VP and oxytocin differ by 2 amino acids in their sequence and both are nonapeptides i.e. consist of 9 amino acids.

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11
Q

Vasopressin (VP):

and oxytocin synthesis involve different neurophysins

A

Neurophysin is also breakdown product of pre-provasopressin in addition to glycopeptide and VP. VP stimulates water reabsorption. VP and oxytocin differ by 2 amino acids in their sequence and both are nonapeptides i.e. consist of 9 amino acids.

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12
Q

Which physiological effect is NOT due to vasopressin?

A

insulin release

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13
Q

Oxytocin and its actions.

A

one stimulus of oxytocin release is mechanical i.e. suckling
Oxytocin acts on the myoepithelial cells of the breast (post partum i.e. during lactation) and the myometrium during partuition (contraction of the uterus).

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14
Q

With reduced insulin action,

A

hepatic glucose output is increased via glycogenolysis and gluconeogenesis.
Concerning the 2nd option: lipolysis is increased (not decreased) especially in omental fatty tissues, glycerol and NEFAs are produced. Concerning the 4th option: Atheroma formation is more widespread.

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15
Q

GLUT-4.
is this true:
consists of hydrophobic components in the cell membrane

A

is present in muscle and adipose tissue.
GLUT-4 is a channel (consisting of hydrophilic interior and hydrophobic exterior) carrying glucose INTO the cells. It is responsive to insulin and its actions are enhanced by insulin. Glucose uptake into cells is enhanced by a factor of 7.

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16
Q

In the liver

A

glycerol-3-phosphate is converted to glucose via gluconeogenesis

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17
Q

Which of the options is also known as thyroxine?

A

3,5,3’,5’-tetra-iodothyronine

18
Q

Identify one of the two substances that undergo the coupling reaction to give T3 and T4.

A

T1 + T2 give a T3 while 2 T2s give a T4.

3,5,3’-tri-iodothyronine is T3, 3,5,3’,5’-tetra-iodothyronine is T4, 3-monoiodotyrosine globulin is T1 and 3,5-diiodotyrosine is T2.

19
Q

This substance is the main product of the thyroid glands

A

3,5,3’,5’-tetra-iodothyronine

20
Q

Deiodonation of this substance from its biologically reactive to inactive state gives the compound reverse T3 (rT3).

A

It is the deiodination of T4 by the appropriate deiodinase which produces rT3 so correct answer is, yet again, T4.

21
Q

Corticotrophin releasing hormone (CRH) stimulates secretion of ACTH from the anterior pituitary. Which other substance from the hypothalamus potentiates the action of CRH?

A

vasopressins

22
Q

This hormone is controlled by the neurosecretions dopamine and thyrotrophin releasing hormone (TRH

A

prolactins

23
Q

The thyroid gland originates from

A

Thyroglossal duct.

The thyroid gland originates from the thyroglossal duct which itself originates from the foramen caecum.

24
Q

Which of the following is a clinical feature of myxoedema:

A

Deepening voice is one of the features of primary hypothyroidism (myxoedema). Other common features are weight gain with reduced appetite, depression, tiredness, cold intolerance, bradycardia, and constipation

25
Q

Which of the following is a clinical feature of Graves’ diseases causing hyperthyroidism:

A
Pretibial Myxoedema (not to be confused with myxoedema) is a feature of Graves' disease where TSH receptor antibodies are produced causing activation of dermal fibroblast and stimulation of connective tissue cells causing swelling of the shins. 
Two other common features are the swelling of the thyroid gland due to excessive stimulation causing a goitre and swollen eyes due to the Ab's binding to the muscles behind the eyes causing exophthalmos (bulging eyes).
26
Q

The adrenal medulla is associated with production of:

A

Catecholamines are produced by the chromaffin cells (specialised post synaptic neurones that secrete directly into the blood) in the adrenal medulla. Adrenaline and noradrenaline are the two catecholamines produced (80% A : 20% NA)

27
Q

What percentage of cortisol is found in its bioactive form, free in the blood

A

10%
In blood 75% of cortisol is bound to corticosteroid binding globulin (CBG), 15% is bound to Albumin, and only 10% is free in the blood and bioactive.

28
Q

One of the actions of aldosterone in the kidney is:

A

The actions of aldosterone are that it stimulates re-absorption of sodium in the distal convoluted tubule and cortical collecting duct, and also that it stimulates K+ and H+ ion SECRETION (no reabsorption) in the distal convoluted tubule.

29
Q

The macula densa cells are found in:

A

Distal convoluted tubule.
The distal convoluted tubule contains the macula densa cells, which sense certain changes occurring in the tubule. These are closely associated with juxtaglomerular cells which, when stimulated by the macula densa cells, release renin into the afferent arteriole.

30
Q

Renin release is stimulated by:

A

Decrease in renal perfusion pressure
A decrease in renal perfusion pressure (caused by a decrease in arteriole blood pressure) leads to an increase in production of renin by the juxtaglomerular cells, which in turn leads to an increase in blood pressure via the renin - angiotensin pathway.
Other causes of renin release are increased sympathetic stimulation, and also a decrease in Na+ at the the top of the loop of Henle

31
Q

One of the physiological actions of cortisol is:

A

Lipolysis
Cortisols physiological actions during a normal stress response are as follows:
Peripheral protein catabolism
Hepatic gluconeogenesis
Increases blood glucose concentration
Fat metabolism (lipolysis in adipose tissue)
Enhanced effects of catecholamines and glucagon

32
Q

The enzyme that inactivates cortisol to cortisone is:

A

11 β hydroxysteroid dehydrogenase 2

33
Q

Which of the following is a cause of Cushing’s disease and what causes cushings syndrome:

A

Pituitary adenoma.

Taking steroids by mouth, adrenal adenoma, and ectopic ACTH all cause Cushing’s SYNDROME (Cushing’s disease is a specific type of Cushing’s syndrome)

34
Q

What is the primary hormone responsible for inducing the proliferate phase of the endometrial cycle:

A

Oestradiol is the main oestrogen responsible for the proliferation and vasculisation of the endometrium.

35
Q

In the ovarian cycle which of the following is responsible for producing androgens?

A

Thecal cells.
The thecal cells produce androgens when stimulated by LH ; this is then usually aromatized to oestrogens by the granulosa cells on stimulation by FSH.

36
Q

Which of the following is a principal action of oestrogens

A

Inhibits bone resorption
Oestrogens have many principal actions which include stimulating osteoblasts, increasing salt reabsorption, inducing LH surge,

37
Q

Which option best describes the condition of a person with the following symptoms: increased weight with reduced appetite, tiredness, deepening voice, and bradycardia?

A

Myxoedema is primary hypothyroidism.

38
Q

Which option is responsible for directly stimulating the production of cortisol

A

ACTH

39
Q

which option is primarily responsible for causing Cushing’s disease?

A

ACTH
Cushing’s disease is caused by a pituitary adenoma, which secretes (without regulation) ACTH which in turn stimulates the adrenal glands to produce excessive cortisol.

40
Q

The table shows a differential diagnosis matrix. How would the values in the hypoparathyroidism row compare to normal values?

A

Plasma Ca, Plasma PO4, and PTH

low, high, low

41
Q

The table shows a differential diagnosis matrix. How would the values in the pseudo-hypoparathyroidism row compare to normal values?

A

low, high, high

42
Q

The table shows a differential diagnosis matrix. How would the values in the vitamin D deficiency row compare to normal values?

A

low, low, high