Endocrine System 3

Question 1

What are the 3 glands controlled by the Anterior Pituitary Gland?

Answer 1

Thyroid, parathyroid and adrenal gland

Question 2

Where is the thyroid gland found?

Answer 2

Just below the larynx
on the anterior and lateral surface of the trachea

Question 3

What hormones are made and secreted in the thyroid gland? What are their functions?

Answer 3

Thyroid hormone - involved in optimal metabolic activity
Calcitonin - involved in calcium homeostasis

Question 4

In the thyroid gland, these are small spherical sacs

Answer 4

Follicles

Question 5

This is what surrounds the small spherical sacs in the thyroid gland.

Answer 5

Follicular cells (cuboidal epithelial cells)

Question 6

Where is the site of thyroid hormone synthesis?

Answer 6

Follicular cells

Question 7

These cells (in thyroid gland) are found in clusters between the follicles. They are responsible for making the hormone calcitonin (which is mainly involved in calcium homeostasis.

Answer 7

Clear (C) cells

Question 8

How are thyroid hormones stored? Since thyroid hormones are the only lipid soluble hormones that CAN be stored.

Answer 8

Because when iodine enters the follicle cell to react with tyrosine (which forms the thyroid hormone) => the protein this takes place in (TGB) remains in the thyroid gland, and is able to STORE the thyroid hormone.

So when thyroid hormones are needed, they are able to detach from iodised TGB as needed.

Question 9

How do the T4 and T3 hormones (thyroid hormones) travel to target cells?

Answer 9

Via a carrier protein (TBG)

Question 10

What is the purpose of secreting thyroid hormones?

Answer 10

To increase the basal metabolic rate

Question 11

This is the body’s rate of energy expenditure under basal conditions

Answer 11

Basal metabolic rate

Question 12

What does the secretion pathway of thyroid hormone look like?

Answer 12

Hypothalamus secretes TRH (thyroid releasing hormone) to stimulate the Anterior Pituitary

Anterior pituitary secretes TSH (thyroid stimulating hormone) to stimulate the Thyroid Gland

Thyroid gland secretes thyroid hormones into the bloodstream to effector organs

Hormones bind to specific receptors on effector organs

Common effects: Increased metabolic rate
increased: heat production, oxygen consumption and ATP hydrolysis, proteolysis (breakdown of protein)

stimulates carbohydrate metabolism

Question 13

Where is the body’s main store of calcium?

Answer 13

In the bone

Question 14

What 3 hormones are involved in calcium regulation?

Answer 14

Parathyroid hormone, calcitriol, calcitonin

Question 15

This gland secretes parathyroid hormones.

Answer 15

Parathyroid gland

Question 16

Where is the parathyroid gland located?

Answer 16

In the posterior surface of the thyroid

Question 17

What does the secretion pathway for the parathyroid hormone look like?

Answer 17

• this PATHWAY IS NOT CONTROLLED BY THE HYPOTHALAMUS * hence why stimulus directly stimulates parathyroid gland

Stimulus: low blood glucose concentration

Stimulates parathyroid gland to secrete PTH

PTH is released to kidneys and bone

• kidneys: increased bone reabsorption to convert vit. D into calcitriol
• bone: increases bone breakdown => increases release of Calcium into blood

Question 18

How do the kidneys form calcitriol?

Answer 18

By increasing the bone reabsorption to convert it into vit. D.

Question 19

Decrease in plasma Ca2+ leads to:

Answer 19

Increase in PTH release

• regulation of blood calcium concentration is a NEGATIVE feedback system

Question 20

Increase in plasma Ca2+ leads to:

Answer 20

Decrease in PTH release

Question 21

Where are the adrenal glands located?

Answer 21

Superior to each kidney (like little hats)

Question 22

What are the hormones secreted by the adrenal cortex? What type of hormone are they?

Answer 22

Aldosterone, cortisol and androgens (these are steroid hormones)

Question 23

What are the hormones secreted by the adrenal medulla? What type of hormone are they?

Answer 23

Adrenalin and noradrenalin (there are water soluble hormones)

Question 24

What are the two separate glands of the adrenal glands?

Answer 24

Adrenal medulla and adrenal cortex

Question 25

These are secreted as a part of the sympathetic nervous system’s response to stress.

• secreted in response to neural signals and causes increased use of stored energy

Answer 25

Adrenalin and noradrenalin from adrenal medulla