Anatomy of the Endocrine System

Question 1

Define an exocrine gland

Answer 1

Exocrine glands have ducts and secrete onto a surface e.g the sebaceous glands of the skin.

Question 2

Define an endocrine gland

Answer 2

Do not have ducts and secrete hormones directly into the blood stream e.g thyroid

Question 3

What hormones does the thyroid gland secrete?

Answer 3

Thyroxine (T4)
Triiodothyronine (T3)
Thyrocalcitonin

Question 4

What do T3 and T4 do?

Answer 4

Increase metabolic activity

Question 5

What does thyrocalcitonin do?

Answer 5

Lowers the levels of blood calcium

Question 6

What does the isthmus of the thyroid do?

Answer 6

Connects it’s two lateral lobes

Question 7

What is the pyramidal lobe?

Answer 7

Remnant of embryological development of the thyroid gland

Question 8

What cells secrete parathyroid hormone?

Answer 8

Chief cells

Question 9

Where are the parathyroid glands located?

Answer 9

4 small endocrine glands found on the posterior of the thyroid

Question 10

What does parathyroid hormone do?

Answer 10

Increases blood calcium levels

Question 11

How does parathyroid hormone increase blood calcium levels?

Answer 11

1. Mobilises bone calcium to increase calcium levels in the blood.
2. Stimulates absorption of dietary calcium from the small intestine.
3. Stimulates the reabsorption of calcium in the kidney

Question 12

When does embryological thyroid development begin?

Answer 12

Week 3

Question 13

Explain the embryological development of the thyroid.

Answer 13

1. Endodermal thickening at the back of the tongue
2. Thickening leads to a diverticulum
3. Diverticulum grows inferiorly into the mesenchyme where it forms the thyroglossal duct.
4. Thyroglossal duct elongates and grows becoming bilobed.
5. Thyroglossal duct solidifies becoming a solid cord of cells
6. Bilobed portions grow to form the thyroid gland

Question 14

What is a diverticulum?

Answer 14

Outgrowth

Question 15

What is the remnant of the thyroglossal duct known as?

Answer 15

Pyramidal lobe

Question 16

What is the foramen cecum?

Answer 16

Site of origin of the thyroid gland, located at the back of the tongue.

Question 17

How do thyroglossal cysts form?

Answer 17

Thyroglossal duct fails to close properly allowing secretion of mucus down the duct, this forms a cyst which usually needs to be removed surgically.

Question 18

What proportion of the pancreas has an endocrine function?

Answer 18

5%

Question 19

Where are the endocrine cells of the pancreas located?

Answer 19

Islets of langerhans

Question 20

What are the primary hormones secreted by the pancreas?

Answer 20

1. Gastrin
2. Glucagon
3. Insulin
4. Somatostatin
5. Vasoactive intestinal polypeptide

Question 21

What does gastrin do?

Answer 21

Stimulates the secretion of gastric acid by parietal cells of the stomach.

Question 22

What does glucagon do?

Answer 22

Raises blood glucose through gluconeogenesis and glycogenolysis in the liver.

Question 23

What does insulin do?

Answer 23

Promotes absorption of glucose form the blood into liver, fat and skeletal muscle cells.

Question 24

What does somatostatin do?

Answer 24

1. Inhibitory hormone that suppresses the release of gastrointestinal hormones and pancreatic hormones.
2. Reduces smooth muscle contractions and blood flow to the small intestine.
3. Suppresses appetite and digestion.

Question 25

What does VIP do?

Answer 25

1. Induces smooth muscle relaxation, and secretion of water in pancreatic juice and bile. 2. Potent vasodilator

Question 26

Where is erythropoetin produced?

Answer 26

JGA in the kidneys

Question 27

What does EPO cause?

Answer 27

Causes HSC differentiation into RBC's

Question 28

What does HSC mean?

Answer 28

Haemopoeitic stem cell

Question 29

When is EPO used?

Answer 29

In the end stage of kidney failure to treat anaemia. Performance enhancing drugs - cyclists

Question 30

What is anaemia?

Answer 30

Lack of iron in the blood leads to a lack of production in the number of RBC's

Question 31

What is the RAAS system?

Answer 31

1. Renin is produced by the kidneys in response to decreased blood pressure. 2. Renin travels to the liver where it converts angiotensinogen into angiotensin 1. 3. Angiotensin 1 travels in the blood to the lungs. 4. ACE is present in the lungs and converts angiotensin 1 into angiotensin 2. 5. Angiotensin 2 causes vasoconstriction and stimulates aldosterone production in the adrenal gland.

Question 32

What does aldosterone do?

Answer 32

Aldosterone acts on the kidneys causing increased sodium and water retention. This increases blood volume which in turn increase blood pressure.

Question 33

What does angiotensin 2 do?

Answer 33

1. Potent vasoconstrictor 2. Acts on g-protein coupled receptors in the kidneys stimulating Na+ reabsorption. 3. Stimulates aldosterone production in the adrenal gland.

Question 34

What is the shape of the right adrenal gland?

Answer 34

Pyramid shaped

Question 35

What is the shape of the left adrenal gland?

Answer 35

Crescent shaped

Question 36

What is produced by the cortex of the adrenal gland?

Answer 36

Mineralcorticoids such as aldosterone Glucocorticoids such as cortisol Androgens involved in the development of the male sex organs

Question 37

What are the three regions of the adrenal cortex? | in order

Answer 37

Zona glomerulosa Zona fasciculata Zona reticularis

Question 38

What does the zona glomerulosa release?

Answer 38

Mineral corticoids such as aldosterone

Question 39

What does the zona fasciculata produce?

Answer 39

Glucocorticoids such as cortisol

Question 40

What does the zona reticularis produce?

Answer 40

Androgens such as DHEA

Question 41

What is produced by the adrenal medulla?

Answer 41

The catecholamines Epinephrine and Norepinephrine

Question 42

What is the blood supply to the pituitary gland?

Answer 42

Superior and inferior hypophyseal arteries (branches of the internal carotid) Hypophyseal veins

Question 43

Where do the hypophyseal veins of the pituitary gland drain into?

Answer 43

Cavernous sinuses

Question 44

How does communication from the hypothalamus to the anterior and posterior pituitary differ?

Answer 44

Anterior pituitary sends hormones in the nervous system directly to the anterior pituitary in the blood stream. Posterior pituitary - receives inhibitory or stimulatory impulses from nerve cells in the hypothalamus.

Question 45

What does the pineal gland do?

Answer 45

Secrete melatonin and establish circadian rhythms