Thyroid Hormone

Question 1

What is the anatomy of the thyroid gland divided into?

Answer 1

clusters of follicles via connective tissues

Question 2

What does a thyroid gland follicle consist of?

Answer 2

Thin layer of epithelial cells and colloid

Question 3

What is the function of the epithelial cells?

Answer 3

they are responsible for the synthesis of thyroid hormones

Question 4

What are four different ways that thyroid hormones can be transported?

Answer 4

99.5% binds to plasma proteins
TBG is a glycoprotein with a high affinity
TBPA is a protein with a low affinity
ALB/ albumin is a protein that also has a low affinity

Question 5

How is thyroid hormone production regulated?

Answer 5

Hypothalamus produces TRH which then acts on the anterior pituitary to release TSH which is neccesary for the release of TH

Question 6

What is the function of TH relating to metabolism?

Answer 6

It increases the overall basal metabolic rate, regulates the rate of O2 consumption and energy expenditure

Question 7

What is the function of TH relating to neural function?

Answer 7

important during foetal life and early brain development/ myelination so it increases axonal speed conduction

Question 8

What is the function of TH relating to the cardiovascular system?

Answer 8

It increases blood flow and cardiac output

Question 9

How does TH effect thermogenesis

Answer 9

It increases heat production and oxygen consumption

Question 10

How does TH effect carbohydrate metabolism?

Answer 10

Stimulates glycogenolysis in the liver

Question 11

What effect does TH have on lipid metabolism?

Answer 11

It stimulates release of free fatty acids by increasing the activity of hormone sensitive lipase in adipocytes

Question 12

What effect does TH have on protein metabolism?

Answer 12

It stimulates the synthesis of proteins mainly involved in oxidative reactions

Question 13

What is hypothyroidism?

Answer 13

sub-optimal levels of TH

Question 14

What is primary hypothyroidism?

Answer 14

relates to the thyroid gland itself, the plasma TH is still high

atrophy of the thyroid gland

Question 15

What is secondary hypothyroidism?

Answer 15

It is related to the pituitary gland, the plasma TSH is low

Question 16

What are some clinical signs of hypothyroidism?

Answer 16

mental retardation, slow metabolism, feeling cold, weight gain, sluggishness, skin issues
skin thickening/ myexdema

Question 17

What is hyperthyroidism?

Answer 17

Excessive production of T3/T4, associated with a high metabolic rate

most common in cats

Question 18

What kind of tumour is hyperthyroidism most commonly associated with?

Answer 18

a benign thyroid tumour

Question 19

What are some clinical signs of hyperthyroidism

Answer 19

Increased body temperature, weight loss
Increased heart rate and work load
loss of skeletal mass

Question 20

What is Exophthalmos?

Answer 20

complex water retaining carbs are maintained behind the eyes which pushes the eyes out

Question 21

What is Goitre?

Answer 21

an enlarged thyroid gland

Question 22

What causes goitre?

Answer 22

iodine deficiency, iodine toxicity, ingestion of certain plants

Question 23

What is thyroglobulin?

Answer 23

Source of thyroid hormone

Question 24

What effect will T3/T4 have on the production of TRH?

Answer 24

Long loop negative feedback

Question 25

What kind of temperatures promote TH release?

Answer 25

Low temperatures

Question 26

What are the primary functions of TH?

Answer 26

Normal development of of body tissue growth, physical/mental wellbeing
Stimulates growth hormone secretion (IGF-1)
Activates nuclear transcription of large numbers of genes

Question 27

What is the more biologically active version of Thyroid hormone?

Answer 27

T3, it can be derived from iodination of T4 in peripheral tissues

Question 28

What are the biochemical actions of thyroid hormone?

Answer 28

Thermiogenesis: increased heat production
Effect on carbohydrate metabolism: Increased breakdown of glycogen to glucose
Effect on lipid metabolism: Stimulates release of free fatty acids, increased oxidation of fatty acids
Effect on protein metabolism: increased production and catabolism of proteins

Question 29

What causes primary hypothyroidism?

Answer 29

Lymphocytic thyroiditis and
idiopathic atrophy of thyroid gland

Question 30

What are some common causes of Goitre?

Answer 30

Iodine deficiency/ iodine toxicity/ ingestion of goitrogenic plants