Lecture 19- The Thyroid Gland

Question 0

List 5 signs/symptoms of Hashimoto’s disease

Answer 0

• bradycardia-less hormone and neurotransmitter receptor synthesis, therefore less responsiveness to regulatory factors.
• weight gain- less catabolism
• tiredness and weakness-again, less catabolism
• decreased BMR
• constipation- poor bowel movements
• lack of concentration and memory-CNS affected if insufficient T3/T4

Question 1

What is Hashimoto’s disease?

Answer 1

Hypothyroidism caused by autoimmune destruction of thyroid follicles or production of an antibody that block TSH receptors on follicular cells.

Question 2

What is the treatment of Hashimoto’s disease?

Answer 2

Oral thyroxine. Dose adjusted to suit signs and symptoms and TSH levels.

Question 3

What is Grave’s disease?

Answer 3

Hyperthyroidism. An autoimmune disease in which antibodies are produced that stimulate TSH receptors on follicular cells, causing more T3and T4 synthesis and secretion.

Question 4

List 5 signs and symptoms of Grave’s disease

Answer 4

• increased BMR
• hyperactivity and hypermobility
• weight loss- due to increased catabolism and BMR
• tachycardia- due to increased hormone and neurotransmitter receptor synthesis
• exophthalmos- bulging of the eye
• increased appetite and bowel movements
• osteoporosis- increased bone turnover
• muscle wasting and weakness- increased myopathy (muscle disease)
• Heat intolerance- due to increased BMR.

Question 5

Describe the location of the thyroid gland

Answer 5

In front of (anterior to) the lower larynx and upper trachea

Question 6

Describe the structure of the thyroid gland

Answer 6

It is an exocrine gland shaped like a butterfly.

Each of its two lobes are associated with 2 parathyroid glands.

Question 7

What is secreted from the follicular and para follicular cells respectively?

Answer 7

T3/T4 and Calcitonin.

Question 8

Outline the synthesis of T3 and T4.

Answer 8

Iodide ions are transported into the epithelial cells against a concentration gradient.
Thyroglobulin is secreted in the epithelial cells and exocytosed into the lumen.
Peroxidase activates iodide to an iodinating species.
Iodinating species binds to/iodinates tyrosine side chains of thyroglobulin.

Question 9

What is the name of the protein that T3 and T4 bind to for transportation?

Answer 9

Thyronine binding globulin (TBG)

Question 10

What are some of the effects of T3?

Answer 10

-increased BMR
-increased heat production
-increased O2 consumption
Due to increased catabolism of proteins, glucose and fatty acids.
-CNS- myelination, development, cellular processes of nerve cells etc
-ovulation cannot occur without it