The Thyroid Hormones Flashcards Preview

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Flashcards in The Thyroid Hormones Deck (14):
1

What does the hypothalamus recognise as a signal to start the production of TRH?

The signal is a drop in temperature

2

What converts T4 to the T3 ligand?

5-monodeiodooxidase (5-MD)

3

What are the 3 actions of hormones in utero and in children?

1. Lung maturation in utereo
2. Bone maturation
3. Neonatal brain development

4

What are 5 other actions of the thyroid hormones?

1. Increase basal metabolic rate
2. Increased B-adreonceptor production to increase heart rate
3. Skeletal muscle contractility
4. Cardiac muscle contracility to increase heart rate

5

How do they thyroid hormones increase basal metabolic rate?

Increase Na+/K+ pump action, lipolysis and glycogenolysis

6

What is parathyroid hormone?

A hormone secreted by the chief cells in the parathyroid gland the regulates Ca2+ levels

7

How are low Ca2+ levels detected?

By receptors on the parathyroid chief cells

8

What does the parathyroid hormone do to raise the Ca2+ level?

It increases osteoclastic activity

9

Why would an increase in osteoclast activity increase Ca2+ levels?

Osteoclast reabsrob bone and produce calcium phosphate which increase plasma Ca2+ levels

10

Why is osteoclast activity downregulated after ca2+ levels have been restored?

Because phosphate loss inhibit bicarbonate

11

What is calcitonin?

A hormone that decreases calcium levels

12

Where is calcitonin secreted from?

The parafollicular cells of the thyroid

13

Does an increase is Ca2+ levels cause the release of calcitonin?

It is detected by receptors on the parafollicular cells which then secrete calcitonin

14

How does calcitonin decrease Ca2+ levels?

It decreases osteoclast activity which means bone reasborption is inhibited