Iodine metabolism and thyroid hormones Flashcards Preview

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Flashcards in Iodine metabolism and thyroid hormones Deck (40)
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1

Describe the abundance of iodine?

High abundance in sea

Low abundance on land

2

What is the RDI for iodine?

150 ug

3

What is iodine required for in the body?

Synthesis of thyroid hormones T3 and T4

4

What can iodine deficiency lead to?

 Decreased thyroid hormone synthesis > feedback to increase production of TSH > induces thyroid cell proliferation > goitre 

5

What is the cause of cretinism?

Congenital condition due to maternal iodine defciciency

6

Which radioactive substance can destroy the thyroid?

Radiation from I-131

7

Why are iodine deficiencies common in humans and land animals?

Absence from soils 

8

Describe the difference between an antiseptic and a disinfectant?

Antispetic: antimicrobial that reduces the risk of infection, applied externally to living surfaces

Disinfectant: antimicrobial that is applied to non-living objects

 

9

Can iodine be used as an antibiotic, antiseptic, or disinfectant?

Antiseptic

10

What are the advantages of using iodine as an antiseptic?

Wide spectrum of antimicrobial activity

When brown - can see where it is and inidicates that it is active 

11

Describe why iodine has an antimicrobial action?

Active form, I2, is a potent oxidiser 

Reacts in electrophilic reactions with enzymes of respiratory chain and amino acids in cell membrane and cell wall > cell integrity destroyed 

12

Why is iodine used as an X-ray contrast material?

High atomic number 

Low toxicity

Ease of attachment to organic compounds 

13

Is iodine a major mineral or a trace mineral in the body?

Trace mineral (20mg/body)

14

Which substance has the highest concentration of iodine?

Kelp

15

What is the recommended upper level of iodine intake per day?

1100 ug/day

16

What are the most significant sources of iodine in the human diet?

Iodised salt

Seafood

Bread

17

Briefly describe the symptoms of iodine deficiency?

Underactive thyroid gland

Goitre

Cretinism

18

Describe the symptoms associated with iodine toxicity?

Underactive thyroid gland

Elevated TSH

Goitre 

19

What are goitrogens?

Where are they found?

Substances that inhibit iodide uptake in the thyroid and magnify the severity of any iodine deficiency

Found in soy, cabbage, kale, brussel sprouts

20

How many people in the world are affected by iodine deficiency?

2 billion 

21

How many people are affected by goitre?

200 million 

22

How many people worldwide are affected by cretinism?

6 million 

Most common form of mental retardation 

Also most preventable

23

What is the most common and also most preventable form of mental retardation?

Cretinism

24

Describe the hypothalamic-pituitary-thyroid axis?

25

What controls the release of thyroid hormones?

TSH from pituitary

26

Describe the action of thyroid hormones?

Increase mental alertness

Increase basal metabolic rate

Elevate number of catecholamine receptors > enhance catecholamine effects

Stimulate differentiation and function of brown adipose tissue > generate heat

27

Why does every cell in the body rely upon thyroid hormones?

Required for regulation of metabolism

28

Describe the proportion in which the normal thyroid produces T3 and T4?

80% T4

20% T3

29

Describe the relative activity of T3 and T4 in the body?

T3 has about four times the activity of T4

30

Describe the half-lives of T3 and T4?

T3: 6-9 days

T4: 24-36 hours