Lesson 1A (Part 2) Flashcards
What is iodine essential for?
The formation of the thyroid hormones
T4
Thyroxine
T3
Tri-iodothyronine
Why are they labeled T4 and T3?
They are numbered as these molecules contain four and three atoms of the element iodine respectively
What is the body’s main dietary source of iodine? (3)
- Seafood
- Vegetables grown in iodine-rich soil
- Iodinated table salt
What is the recommended minimum intake of iodine per day?
150ug/day
Iodine trapping
The thyroid gland selectively takes up iodine from the blood
What is the release of T4 and T3 into the blood stimulated by?
By the thyroid stimulating hormone
- TSH
Where is the TSH released from?
The anterior pituitary gland
What is secretion of TSH stimulated by?
Thyrotrophin releasing hormone
- TRH
Where is TRH released from?
The hypothalamus
What kind of feedback loop are the thyroid hormones involved with?
Negative feedback
- increase T3, decrease T4 (and vice versa)
How does T3and T4affect most cells of the body by? (3)
- Increasing the basal metabolic rate
- Increasing heat production
- Regulating metabolism of carbohydrates, proteins and fats
What is T4 and T3 essential for?
Normal growth and development
- especially of the skeleton and nervous system
What is influenced by thyroid hormones?
Most other organs and systems
- heart, skeletal muscles, skin, digestive and reproductive systems
Hyperthyroidism
Increased levels of T3 and T4 secretions
What are the common effects of hyperthyroidism? (7)
- Increased basal metabolic rate
- Weight loss, good appetite
- Anxiety, physical restlessness, mental excitability
- Hair loss
- Warm sweaty skin, heat, intolerance
- Diarrhoea
- Exophthalmos in Graves’ disease
What factors affect the thyroid hormones? (6)
- Exercise
- too much or too little - Diet
- malnutrition - Age
- Stress
- Low blood glucose
- Lack of sleep
Exophthalmos
Bulging of the eyes in Graves’ disease
Hypothyroidism
Decreased levels of T3 and T4 secretion
What are the common effects of hypothyroidism? (7)
- Decreased basal metabolic rate
- Weight gain, anorexia
- Depression, psychosis, mental slowness, lethargy
- Dry skin, brittle hair
- Constipation
- Bradycardia
- Dry cold skin, prone to hypothermia
What is the first test for assessment of the thyroid function?
TSH
- thyroid stimulating hormone
What is the TSH test monitoring?
The patients who are on thyroid replacement or suppressive therapy
What is the good thing about patients on thyroid replacement or suppressive therapy?
They are more sensitive than free T4 to alterations of thyroid status in patients with primary thyroid disease
