ENDOCRINOLOGY - Overview and Calcium Homeostasis

Question 1

What are the two classes of hormones?

Answer 1

Steroid hormones
Peptide hormones

Question 2

Where are steroid hormones synthesised?

Answer 2

Liver

Question 3

What are steroid hormones synthesised from?

Answer 3

Cholesterol

Question 4

In vertebrates, which tissues secrete steroid hormones?

Answer 4

Gonads
Adrenal glands
Placenta

Question 5

Where are steroid hormones metabolised and ultimately secreted?

Answer 5

Steroid hormones are metabolised in the liver and kidneys and excreted in urine, faeces and skin

Question 6

What are peptides hormones synthesised from?

Answer 6

Amino acid chains

Question 7

What are tropic hormones?

Answer 7

The hormones secreted from the anterior pituitary gland which stimulates hormone release from target organs

Question 8

What is the function of the hypothalamus in hormone regulation?

Answer 8

The hypothalamus regulates the secretion of tropic hormones from the anterior lobe of the pituitary gland

Question 9

What is the function of the anterior lobe of the pituitary gland in hormone regulation?

Answer 9

Secretion of tropic hormones

Question 10

What is the function of the posterior lobe of the pituitary gland in hormone regulation?

Answer 10

The posterior lobe is made up of axons extending from the hypothalamus which produce hormones, these hormones are secreted by the posterior lobe

Question 11

List the six physiological processes requiring ionic (free) calcium

Answer 11

Muscle cell contraction
Nerve cell activity
Enzyme activation
Release of hormones and neurotransmitters via exocytosis
Coagulation cascade
Cell membrane stability

Question 12

List the physiological process requiring bound calcium

Answer 12

Maintaining bone and teeth strength

Question 13

What are the four pools of calcium found in the body?

Answer 13

Bone calcium
Intracellular calcium
Extracellular calcium
Gastrointestinal tract

Question 14

How is calcium stored in the bone calcium pool?

Answer 14

Calcium is stored as hydroxyapatite crystals

Question 15

List the organs involved in calcium homeostasis and their function

Answer 15

Small intestine (absorbs calcium)
Bone (stores calcium)
Kidney (excretes calcium)

Question 16

What are the glands involved in calcium homeostasis and their function

Answer 16

Parathyroid gland
Thyroid gland

Question 17

Which hormone is secreted by the parathyroid gland?

Answer 17

Parathyroid hormone

Question 18

Which hormone is secreted by the parafollicular cells of the thyroid gland?

Answer 18

Calcitonin

Question 19

List the hormones involved in calcium homeostasis

Answer 19

Parathyroid hormone
Calcitonin
Calcitriol

Question 20

Which organ secretes calcitriol?

Answer 20

Kidneys secrete calcitriol

Question 21

Which hormone is stimulated by decreased blood calcium levels?

Answer 21

The parathyroid hormone

Question 22

Which hormone is stimulated by increased blood calcium levels

Answer 22

Calcitonin

Question 23

What are the three processes stimulated by the parathyroid hormone to maintain calcium homeostasis in response to decreased blood calcium levels?

Answer 23

1. Increases calcium reabsorption in the kidneys
2. Stimulates calcitriol release from the kidneys to stimulate calcium absorption in the small intestine
3. Stimulates osteoclasts to mobilise calcium storage in the bone

Question 24

What are the three processes stimulated by the calcitonin hormone to maintain calcium homeostasis in response to increased blood calcium levels?

Answer 24

1. Inhibits calcium reabsorption into the kidneys thus increasing calcium urinary excretion
2. Inhibits calcium absorption in the small intestine
3. Stimulates osteoblasts to take up circulating calcium to store in the bone