Hypothyroidism

Question 1

Triiodothyronine (T3)

Answer 1

A thyroid hormone. It affects physiological processes in the body including growth, development, body temperature, metabolism and heart rate. 20 percent is secreted straight into the blood by the thyroid gland and the rest is made through a conversion process (deiodination) in the tissue, liver or kidney.

Question 2

How is T3 and T4 made? What do they do?

Answer 2

Thyroid takes iodine found in the diet and combines it with the amino acid tyrosine. T3 contains 3 iodine atoms. T4 contains 4 iodine atoms. T4 can be converted to T3 by deiodination I’m the liver, tissue or kidney. An iodine is removed from T4 leading to T3. They both increase the basal metabolic rate making cells work harder so they need more energy.

Question 3

What factors effect deiodination?

Answer 3

Inhibit: 
Stress 
Starvation
Beta blockers
Increase:
Cold temperatures

Question 4

How is deiodination regulated?

Answer 4

T3 and T4 production is regulated by the thyroid stimulating hormone (TSH) secreted by the pituitary gland. This is maintained by a negative feedback loop. Low levels of T3 and T4 leads to more TSH released. Once the normal level is restored the pituitary gland decreases TSH production. If levels get too high TRH is not secreted leading to the shutdown of the thyroid gland.

Question 5

Difference between T3 and T4?

Answer 5

T3 is an active form whereas T4 is converted to T3 to make T3. T4 is made by the thyroid gland.

Question 6

How do T3+4 effect the body?

Answer 6

Enter the blood. Reach the target cells and the target receptors are intracellular and are on the nucleus. T3 has a higher affinity. This then alters the cellular activity.

Question 7

What causes hashimotos?

Answer 7

Leukocytes attack the thyroid gland. It is an autoimmune disease. This is a condition were your body can’t identify its own cells from foreign cells causing the body to attack healthy cells.

Question 8

What is radioactive iodine therapy?

Answer 8

Radioactive iodine is taken up by the thyroid gland and destroys the cells in the thyroid gland. This reduces the amount of thyroxine made by the thyroid gland. Taken is tablet form and slightly increases the risk factor of cancer.

Question 9

RIA

Answer 9

Radioimmunoassay. Used antibody to detect and quantiate the amount of antigen in a sample. The test uses radioactive antigens (known as tracers) to compete with antigens for a fixed number of antibodies. The displacement is measured to find out what antigen is present and how much.

Question 10

RIA steps

Answer 10

A quantity of antigen is made radioactive by labelling it with gamma radioactive isotopes of iodine attached to tyrosine.
The radiolabelled antigen is then mixed with a known amount of antibody for that antigen so the two chemically bind together.
A sample containing an unknown quantity of that same antigen is added. This causes the sample to compete with the two radiolabelled antigen for the antibody binding site. The displacement is then measured.

Question 11

Levothyroxine

Answer 11

Hormone replacer so is synthetic (man made)

Question 12

Endocrine system

Answer 12

Released hormones into the blood to maintain homeostasis

Question 13

Pituitary gland

Answer 13

Known as the master gland. Secretes multiple hormones e.g. FSH which stimulates oestrogen

Question 14

Anterior lobe

Answer 14

Recieves signals from the hypothalamus and in response it synthesizes and secretes 7 different hormones

Question 15

Posterior lobe

Answer 15

Doesn’t produce its own hormones but stores and secretes two hormones made by the hypothalamus.

Question 16

Pancreas

Answer 16

Dual organ (endo/exocrine). Secretes the hormones insulin and glucagon. Maintains blood glucose levels which is controlled by the hypothalamus.

Question 17

Islets of langerhans

Answer 17

Contains beta cells that produce insulin and alpha cells that produce glucagon.

Question 18

Glycogenolysis

Answer 18

Glycogen is converted back to glucose by the hormone glucagon.

Question 19

Glycogenesis

Answer 19

Formation of glycogen from glucose stimulated by insulin.

Question 20

Virus

Answer 20

Very simple organism made up of a protein coat and a strand of genetic material. Smallest of all living things. It is a parasite that causes disease (lives in a host cell) and can only reproduce within a host cell or living organism.

Question 21

What treats viruses?

Answer 21

Anti-viral medicine which inhibit the growth of viruses. Vaccines help to prevent them causing harm or illness.