Hormones and Receptors

Question 1

Is the endocrine system ductless or does it contain ducts?

Answer 1

ductless

Question 2

Are glands anatomically distinct?

Answer 2

Yes, but do form functional system

Question 3

What does the anterior pituitary release to cause the adrenal cortex to make cortisol?

Answer 3

ACTH

Question 4

By what three ways is specificity of signalling achieved?

Answer 4

• chemically distinct hormones
• specific receptors for each
• distinct distribution of receptors across target cells

Question 5

Name the 3 main classes of hormones.

Answer 5

Glycoproteins and peptides
Steroids
Tyrosine and tryptophan derivatives

Question 6

Which hormone class is most diverse?

Answer 6

glycoproteins and peptides

Question 7

Give an example of the glycoproteins and peptides class

Answer 7

oxytocin or insulin

Question 8

Give examples of steroids.

Answer 8

Cortisol, testosterone

Question 9

Give examples of Tyrosine and tryptophan derivatives.

Answer 9

adrenaline, melatonin and thyroid hormones

Question 10

Are amines, peptides and proteins hydrophilic or phobic, and are they transported freely or bound?

Answer 10

hydrophilic, freely

Question 11

Are steroids hydrophilic or phobic, and are they transported freely or bound?

Answer 11

hydrophobic, bound to plasma proteins

Question 12

Are steroids and thyroxine soluble or insoluble in plasma?

Answer 12

relatively insoluble

Question 13

What is the function of carrier proteins?

Answer 13

• increase amount of hormone transported in blood

- prevent rapid excretion by preventing filtration at kidney

Question 14

What act as a buffer and ensure free and bound hormones are in equilibrium?

Answer 14

carrier proteins

Question 15

Is albumin a specific or general carrier protein?

Answer 15

general

Question 16

What does albumin bind?

Answer 16

many steroids

thyroxine

Question 17

What does transthyretin bind?

Answer 17

thyroxine

some steroids

Question 18

Do peptides and proteins need carrier proteins and why?

Answer 18

no, are soluble in plasma

Question 19

What type of hormones, free or bound, can cross the capillary wall?

Answer 19

only free

Question 20

What does cortisol bind globulin bind to sometimes as well as cortisol?

Answer 20

aldosterone

Question 21

What does thyroxine binding globulin bind to?

Answer 21

T4 (thyroxine) as well as some triiodothyronine (T3)

Question 22

What does sex steroid binding globulin (SSBG) bind to mostly?

Answer 22

testosterone and estradiol

Question 23

What buffer surges in hormone?

Answer 23

carrier proteins

Question 24

What is the primary determinant of plasma secretion?

Answer 24

rate of secretion

Question 25

What 3 things is rate of secretion subject to?

Answer 25

- negative feedback control - neuroendocrine (sudden bursts of secretion in response to stimulus eg stress) - diurnal rhythm

Question 26

Does rate of elimination contribute to plasma concentration?

Answer 26

Yes

Question 27

How does rate of elimination generally occur?

Answer 27

By liver metabolism and kidney excretion

Question 28

How long does amine elimination take?

Answer 28

seconds

Question 29

How long does protein/peptide elimination take?

Answer 29

minutes

Question 30

How long does steroid elimination take?

Answer 30

hours - days

Question 31

What are the 3 main types of hormone RECEPTOR?

Answer 31

- G protein coupled - receptor kinases - nuclear receptors

Question 32

What is the receptor for insulin an example of?

Answer 32

receptor kinases

Question 33

Which classes are cell surface receptors?

Answer 33

G protein coupled and receptor kinases (nuclear receptors are intracellular)

Question 34

What are G protein coupled receptors activated by?

Answer 34

amines and some proteins/peptides

Question 35

What are receptor kinase receptors activated by?

Answer 35

proteins/peptides

Question 36

How many classes are there of nuclear receptors?

Answer 36

3 (1, 2 and hybrid)

Question 37

What activates class 1 nuclear receptors?

Answer 37

steroid hormones

Question 38

Where are class 1 nuclear receptors when activated and when not?

Answer 38

no activated - cytoplasm, bound to heat shock proteins | activated- nucleus

Question 39

Where are class 2 nuclear receptors?

Answer 39

nucleus mostly

Question 40

What activates class 2?

Answer 40

mainly lipids

Question 41

What activates the hybrid class?

Answer 41

thyroid hormone

Question 42

What class is the hybrid class similar to in function?

Answer 42

class 1

Question 43

What must the ligands be to diffuse across the membrane in nuclear receptors?

Answer 43

lipophilic