Describe the abundance of iodine?
High abundance in sea
Low abundance on land
What is the RDI for iodine?
What is iodine required for in the body?
Synthesis of thyroid hormones T3 and T4
What can iodine deficiency lead to?
Decreased thyroid hormone synthesis > feedback to increase production of TSH > induces thyroid cell proliferation > goitre
What is the cause of cretinism?
Congenital condition due to maternal iodine defciciency
Which radioactive substance can destroy the thyroid?
Radiation from I-131
Why are iodine deficiencies common in humans and land animals?
Absence from soils
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
Can iodine be used as an antibiotic, antiseptic, or disinfectant?
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
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
Why is iodine used as an X-ray contrast material?
High atomic number
Ease of attachment to organic compounds
Is iodine a major mineral or a trace mineral in the body?
Trace mineral (20mg/body)
Which substance has the highest concentration of iodine?
What is the recommended upper level of iodine intake per day?
What are the most significant sources of iodine in the human diet?
Briefly describe the symptoms of iodine deficiency?
Underactive thyroid gland
Describe the symptoms associated with iodine toxicity?
Underactive thyroid gland
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
How many people in the world are affected by iodine deficiency?
How many people are affected by goitre?
How many people worldwide are affected by cretinism?
Most common form of mental retardation
Also most preventable
What is the most common and also most preventable form of mental retardation?
Describe the hypothalamic-pituitary-thyroid axis?
What controls the release of thyroid hormones?
TSH from pituitary
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
Why does every cell in the body rely upon thyroid hormones?
Required for regulation of metabolism
Describe the proportion in which the normal thyroid produces T3 and T4?
Describe the relative activity of T3 and T4 in the body?
T3 has about four times the activity of T4
Describe the half-lives of T3 and T4?
T3: 6-9 days
T4: 24-36 hours