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Year 2 Semester 2 > Repro & Endocrine > Flashcards

Flashcards in Repro & Endocrine Deck (74)
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31

What is an advantage of using an oral antihyperglycaemic over exogenous insulin?

Does not stimulate insulin secretion so does not cause hypoglycaemia

32

Which channels does glipizide (anti-diabetic agent) block?

ATP-sensitive potassium channels

33

Name a drug you could use to treat hyperinsulinism
How does it work?

Diazoxide
Activates potassium channels causing inhibition of voltage-gated Ca2+ channels
Inhibits insulin secretion

34

What is the hormone relaxin produced by?
What does it do?

Produced by ovary and placenta in preparation for parturition
Softens the broad ligament, pelvic ligaments and sacroiliac joint

35

Where is the thyroid located?

Two lobes located either side of the trachea just below the larynx

36

Where is thyroid stimulating hormone released from?

Anterior pituitary gland

37

Explain the thyroid hormone feedback loop

Thyroid stimulating hormone (TSH) is released by anterior pituitary in response to TRH secreted into the portal system from the hypothalamus. TSH causes the synthesis and secretion of T3 and T4 into the blood from follicular cells in thyroid. Elevated T3 inhibits release of TRH and TSH.
TSH also inhibits release of TRH from the hypothalamus

38

What are the 5 functions of thyroid hormones?

Increase BMR
Normal growth and development (T3 causes increased GH secretion, maintenance of nerve function, hair growth)
Cardiovascular stimulant (increased CO)
Enhances CHO utilisation and lipolysis (increases LDL uptake by liver)
Promotes milk production

39

Give some signs of hypothyroidism

Poor exercise tolerance
Weight gain with no change in appetite
Intolerance to cold and hypothermia
Mental dullness
Increased blood cholesterol
Decreased heart rate
Bilateral symmetrical alopecia

40

How much should T4 increase by after injecting TSH?

1.5 times

41

T3 is how many times as active as T4?

3-5

42

In thyroid hormone replacement therapy, what is used to replace:
T3
T4

T3= Liothyronine
T4= Levothyroxine

43

Explain the metabolism of thyroid hormones

30-40% T4 is converted to T3 in peripheral tissues
50% T4 is converted to reverse t3 (inactive)
20% T4 and 100% T3 form conjugates of glucoronide and sulphur in liver and are excreted in bile

44

How are thyroid hormones transported and bound?

Transported bound to plasma proteins
Free protein binds to target receptors. Bound fraction provides a depot that lasts several days, as when free molecules bind to their target receptors, more molecules dissociate from bound protein.

45

What are the 4 sigs of hyperthyroidism?

Weight loss with increased appetite
Hyperthermia
Increased heart rate
Excitable

46

How can you test for hyperthyroidism?

Test for serum T4 levels (will be high)

47

Describe the T3 suppression test when testing for hyperthyroidism

Take basal TT4 (total T4).
Give oral T3 for 3 days.
Resting T4 should be suppressed by >50%.
If little/no suppression -> producing excess T4 from thyroid gland.

48

Which drugs can be used to treat hyperthyroidism?

Felimazole
Methimazole- inhibits synthesis of T3 and T4
Carbimazole (metabolised to methimazole)

49

What is an alternative to surgical thyroidectomy?
What considerations are there?

Radioactive iodine
Destroys radioactive follicles
Treated animals need to be hospitalised for 1-4 weeks
Treated animals and excrete need to be handled carefully until radioactivity is gone

50

What is a goitre?
What could cause it?

Enlarged thyroid gland
Could be due to tumour, or iodine deficiency

51

Explain how an iodine deficiency could lead to an enlarged thyroid gland and hyperthyroidism

Lack of iodine in diet (eg lack in soil-sheep)/ substances that inhibit uptake
Can't make thyroid hormones. Continually high TSH stimulates thyroid follicular cell growth. No negative feedback
Enlarged thyroid

52

All steroid hormones from the adrenal cortex are formed from which molecule?
What is this then converted to?

Cholesterol
Pregnenalone

53

How are steroid hormones transported?

Bound to plasma proteins
Lipid-soluble

54

What is the mechanism of action of corticosteroids?

Act on intracellular receptors to alter mRNA synthesis

55

What type of corticosteroid is aldosterone?

Mineralocorticoid

56

What are the 3 normal functions of cortisol?

Increased blood glucose
Increased protein catabolism
Increased lipolysis

57

What are the clinical signs of hyperadrenocorticism?

Hyperglycaemia
PU and secondary PD
Tissue wasting
Muscle weakness
Pot belly
Increased skin pigment (synthesis of ACTH involves a precursor: POMC which stimulates MSH -> increases melanin production)

58

What would you see on a stress leucogram?

Lymphocytopenia (decreased lymphocytes)
Monocytosis (increased monocytes)
Eosinopenia (decreased eosinophils)
Neutrophilia (increased neutrophils)

59

What is a stress leucogram caused by?

Stress response or corticosteroid induced

60

How you would distinguish a functioning adrenal tumour from pituitary-dependant hyperadrenocorticism?

Pituitary tumour- increased ACT
Adrenal tumour- decreased ACTH