24.5

Question 1

The thyroid gland secretes ___ hormones to regulate metabolism and secretes ___ to regulate calcium levels.

Answer 1

Thyroid hormones

Calcitonin

Question 2

Thyroid hormones are produced in the ___ of the thyroid gland.

Answer 2

Colloid

Question 3

___ cells in the ___ spaces secrete calcitonin for calcium metabolism.

Answer 3

C cells in interstitial spaces

Question 4

Colloid is a glycoprotein mix filled with ___.

Answer 4

Thyroglobulin

Question 5

___ is a precursor to thyroid hormones.

Answer 5

Tyrosine

Question 6

Free T3 and T4 produced in follicular cells diffuses into circulation because it is ___.

Answer 6

Lipophilic or hydrophobic

Question 7

T3/T4 binds to plasma proteins including ___-___ globulin, ___ and transthyretin.

Answer 7

Thyroid-binding globulin
Albumin
Transthyretin

Question 8

T4 is also called ___ and is a prohormone.

Answer 8

Thyroxine

Question 9

The half-life of T_ is short compared to T_.

Answer 9

T3 is less than T4

Question 10

What are the actions of thyroid hormones?

Answer 10

Increased basal metabolic rate and O2 consumption - calorigenic/heat producing effects
Modulation of metabolism
Sympathomimetic effects (by increasing sensitivity to catecholamines?) - increase HR and CO
ESSENTIAL for GH and IGFs actions

Question 11

Thyroid hormones are ___ for the actions of GH and IGFs

Answer 11

PERMISSIVE

Question 12

Goitres occur because of stimulation of the ___ receptor. ___ or ___ stimulates the production of TH AND growth of the thyroid gland itself.

Answer 12

TSH

TSH or TSIs of Grave’s disease! (BOTH activate the TSH receptor)

Question 13

What are the physiological effects of hypothyroidism?

Answer 13

(Opposite of normal effects of TH.)
Decreased basal metabolic rate and O2 consumption, decreased energy and increased weight
Cold intolerance
Sympathetic effects, decreased HR
Central effects, decreased mentation and reflexes, fatigue
Decreased protein synthesis, accumulation of mucopolysaccharides under skin

Question 14

What is the treatment for thyroid hormone replacement?

Answer 14

Thyroid hormone replacement or increase in dietary iodine intake.

Question 15

A common cause of primary hyperthyroidism is ___ disease.

Answer 15

Grave’s disease

Question 16

In Grave’s disease, there is production of ___-___ ___ that targets ___ receptors resulting in increased production of thyroid hormones AND increased growth of the thyroid gland. There is strong negative feedback to reduce endogenous TRH and TSH levels.

Answer 16

Thyroid-stimulating immunoglobulin
TSH receptors (on the thyroid gland)

Question 17

What are the physiological effects of hyperthyroidism?

Answer 17

Increased basal metabolic rate and O2 consumption
Heat intolerance
Weight loss
Increase in appetite
Muscle weakness
Increase in HR
Increase in alertness, irritability and hyperexcitability

Question 18

In Grave’s disease there can be ___ (bulging of the eyes) do to retention of water by ___ behind the eyes

Answer 18

Exophthalmos

Carbohydrates

Question 19

What is the treatment for hyperthyroidism?

Answer 19

Remove thyroid/tumour
Use radioactive iodine to destroy gland
Anti-thyroid drugs e.g. to block TH synthesis or conversion of T4 to T3