Physiology: The Major Endocrine Glands and the Classification of Hormones

Question 1

Name the organ which provides the highest level of endocrine control, and integrates activities of nervous and endocrine systems

Answer 1

Hypothalamus

Question 2

Name the hormone which selectively binds cortisol (and some aldosterone)

Answer 2

Cortisol-binding globulin (CBG)

Question 3

What percentage of steroid hormones are biologically active (‘free’)?

Answer 3

10%

Question 4

Amine-derived hormones are derived from _______

Answer 4

Amino acids e.g. tyrosine

Question 5

Name the 3 classes of hormones

Answer 5

Steroid, amine-derived, peptide hormones

Question 6

How are peptide hormones transported around the body?

Answer 6

Hydrophilic and are transported unbound (‘free’) in the blood plasma

Question 7

Describe diurnal (circadian rhythm) control of hormone levels

Answer 7

External cues (light/dark) evoke fluctuations in hormone secretion

Question 8

Which type of hormone accounts for the majority of the hormones produced (secreted by pituitary, parathyroid, heart, stomach, liver, kidneys)?

Answer 8

Peptide hormones

Question 9

Name 4 examples of a peptide hormone

Answer 9

Oxytocin, ADH, growth hormone, insulin

Question 10

How are steroid hormones transported around the body?

Answer 10

Hydrophobic so are transported bound to carrier proteins

Question 11

Name two examples of amine-derived hormones

Answer 11

Adrenaline, thyroid hormones

Question 12

Name the hormone which binds mainly testosterone and oestradiol

Answer 12

Sex steroid-binding globulin (SSBG)

Question 13

Steroid hormones are lipids derived from _________

Answer 13

Cholesterol

Question 14

What is a hormone?

Answer 14

Any substance elaborated by one cell to regulate another cell

Question 15

Describe the formation of peptide hormones

Answer 15

Synthesised as precursor molecules and stored in secretory vesicles

Different end hormones can be made by cleaving a common precursor with a different enzyme

Question 16

Name the hormone which selectively binds thyroxine T4 (and some triodothyronine T3)

Answer 16

Thyroxine-binding globulin (TBG)

Question 17

Name 3 examples of steroid hormones

Answer 17

Cortisol, testosterone, oestradiol

Question 18

Describe the mechanism of action of steroid hormones

Answer 18

1. Steroid hormone passes through plasma membrane
2. Activated hormone-receptor complex forms within the cell
3. The complex binds to DNA and activates specific genes → gene activation leads to production of specific genes

Question 19

Describe the mechanism of action of amine-derived hormones

Answer 19

Bind to bound receptors to evoke cellular response

Question 20

Give an example of hormones interacting in a complementary fashion

Answer 20

Sympathetic response and the actions of adrenaline, cortisol and glucagon on blood glucose levels

Question 21

Describe the structure of a peptide hormone

Answer 21

May be composed of a ring structure due to disulfide bonds e.g. somatostatin

May be composed of 2 chains held together by disulfide bones e.g. insulin

Question 22

How are amine-derived hormones transported around the body?

Answer 22

Most amine-derived hormones are hydrophilic and are transported unbound (‘free’) in blood plasma

Exception: thyroid amine which are bound to carrier proteins

Question 23

Which hormones are transported in the blood via carrier proteins?

Answer 23

Steroid and thyroid hormones

Question 24

What is the hormonal duration of action?

Answer 24

Can vary from hours to days

Question 25

Name the three routes by which hormones can be delivered to their target cell

Answer 25

Autocrine, paracrine or endocrine routes

Question 26

Give an example of hormones interacting in an antagonistic fashion

Answer 26

Hormonal control of glucose homeostasis