The endocrine system II

Question 1

What characteristics of a hormone does their transport in the blood depend on?

Answer 1

Their chemical composition and hydrophilicity

Question 2

What kinds of hormones are transported dissolved in plasma?

Answer 2

Protein and peptide hormones

Question 3

Why are protein and peptide hormones usually transported dissolved in the plasma?

Answer 3

They are water soluble

Question 4

What are the temporal characteristics of protein and peptide hormones?

Answer 4

Fast acting, short half-life, rapidly eliminated

Question 5

How are steroid and thyroid hormones transported in the blood?

Answer 5

Bound to plasma proteins

Question 6

Why are steroid and thyroid hormones transported via being bound to plasma transport proteins?

Answer 6

They are hydrophobic and so not water soluble

Question 7

If something is hydrophobic, what is is soluble in?

Answer 7

lipids

Question 8

What are the temporal characteristics of steroid and thyroid hormones?

Answer 8

Slower action, longer half-life, slower elimination

Question 9

What is the total hormone concentration?

Answer 9

Sum of free hormone and bound hormone

Question 10

What can free hormones do that bound hormones cannot?

Answer 10

Interact with target cells and organs

Question 11

What is the reversible reaction involving free hormone, carrier plasma protein and hormone-protein complex

Answer 11

Free hormone + Carrier plasma protein<—-> hormone-protein complex

Question 12

What is the total mass of a hormone usually?

Answer 12

micrograms (10-6 g), nanograms (10-9 g) and picograms (10-12 g)

Question 12

Difference between intracrine and autocrine hormone action

Answer 12

Autocrine hormones are secreted, intracrine are not

Question 13

What is intracrine hormone action?

Answer 13

The hormone acts inside the cell from which it was produced

Question 13

What is paracrine hormone action?

Answer 13

Hormone is secreted and acts on a neighbouring cell

Question 13

What is special about intracrine hormones?

Answer 13

They are not secreted

Question 14

What is autocrine hormone action?

Answer 14

Hormone is secreted and binds to the cell from which it was released

Question 15

What does the location of the hormone (in or on the cell) depend on?

Answer 15

The water solubility of the hormone

Question 15

Why do only some tissues respond to specific hormones?

Answer 15

They have receptor proteins in or on their cells that are specific to a certain hormone(s)

Question 15

What is neuroendocrine action?

Answer 15

Neurons secrete endocrine hormones

Question 16

What is endocrine hormone action?

Answer 16

Hormone is secreted and acts on a cell far away

Question 17

If a hormone is water soluble, where is its receptor?

Answer 17

On the plasma membrane of the receptor cell

Question 18

How does the signal of a water soluble hormone reach the inside of a receptor cell?

Answer 18

Via second messengers which are activated by the receptor on the plasma membrane

Question 19

How does the receptor for water soluble hormones receive a signal from the outside and cause a 2nd messenger reaction inside the cell?

Answer 19

They span the plasma membrane

Question 20

If a hormone is water insoluble where is its receptor?

Answer 20

Inside the nucleus of the receptor cell

Question 21

Why can water insoluble hormones enter the receptor cells?

Answer 21

They are hydrophobic (so lipid soluble) and so can cross the lipid bilayer of the plasma membrane

Question 22

What is a typical outcome of a water soluble hormone?

Answer 22

An enzyme in the cytoplasm may be activated

Question 23

What is a typical outcome of a water insoluble hormone?

Answer 23

Transcription factors (etc) activated and so specific proteins will be synthesised