Revision card/Mistakes

Question 1

Which of the following is NOT an endocrine gland?

Answer 1

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

Question 2

Which statement regarding the endocrine system is correct?

Answer 2

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.

Question 3

Is POMC a hormone?

Answer 3

NO

Question 4

Choose the best option concerning the synthesis of steroid hormones.

Answer 4

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..

Question 5

Is this statement true

thyroglobulin is used to transport ACTH.

Answer 5

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

Question 6

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

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

Answer 6

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.

Question 7

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

Answer 7

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.

Question 8

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

Answer 8

erythropoiesis.

NOT:

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

Question 9

Which of the following suppresses the circulating levels of prolactin?

Answer 9

dopamine.

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

Question 10

Vasopressin (VP):

and oxytocin synthesis involve different neurophysins

Answer 10

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.

Question 11

Vasopressin (VP):

and oxytocin synthesis involve different neurophysins

Answer 11

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.

Question 12

Which physiological effect is NOT due to vasopressin?

Answer 12

insulin release

Question 13

Oxytocin and its actions.

Answer 13

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).

Question 14

With reduced insulin action,

Answer 14

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.

Question 15

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

Answer 15

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.

Question 16

In the liver

Answer 16

glycerol-3-phosphate is converted to glucose via gluconeogenesis

Question 17

Which of the options is also known as thyroxine?

Answer 17

3,5,3’,5’-tetra-iodothyronine

Question 18

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

Answer 18

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.

Question 19

This substance is the main product of the thyroid glands

Answer 19

3,5,3’,5’-tetra-iodothyronine

Question 20

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

Answer 20

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

Question 21

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

Answer 21

vasopressins

Question 22

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

Answer 22

prolactins

Question 23

The thyroid gland originates from

Answer 23

Thyroglossal duct.

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

Question 24

Which of the following is a clinical feature of myxoedema:

Answer 24

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

Question 25

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

Answer 25

``` 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). ```

Question 26

The adrenal medulla is associated with production of:

Answer 26

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)

Question 27

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

Answer 27

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.

Question 28

One of the actions of aldosterone in the kidney is:

Answer 28

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.

Question 29

The macula densa cells are found in:

Answer 29

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.

Question 30

Renin release is stimulated by:

Answer 30

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

Question 31

One of the physiological actions of cortisol is:

Answer 31

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

Question 32

The enzyme that inactivates cortisol to cortisone is:

Answer 32

11 β hydroxysteroid dehydrogenase 2

Question 33

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

Answer 33

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)

Question 34

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

Answer 34

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

Question 35

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

Answer 35

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.

Question 36

Which of the following is a principal action of oestrogens

Answer 36

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

Question 37

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

Answer 37

Myxoedema is primary hypothyroidism.

Question 38

Which option is responsible for directly stimulating the production of cortisol

Answer 38

ACTH

Question 39

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

Answer 39

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.

Question 40

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

Answer 40

Plasma Ca, Plasma PO4, and PTH | low, high, low

Question 41

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

Answer 41

low, high, high

Question 42

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

Answer 42

low, low, high