Pharmacology

Question 1

Describe the difference between the endocrine and exocrine systems

Answer 1

Endocrine - hormones secreted into Extra-cellular fluid

Exocrine - secretes hormones into duct system which then empties hormones into various parts of body

Question 2

Name the main endocrine glands in the body

Answer 2

Pineal gland
Hypothalamus
Pituitary

Thyroid
Parathyroid
Thymus

Adrenal Glands
Pancreas

Ovaries
Testes

Question 3

Name the four main chemical groupings of hormones

Answer 3

Modified Amino Acids
Steroid
Peptide
Protein

Question 4

What substance is the precursor for steroid hormones?

Answer 4

Cholesterol

Question 5

Adrenaline, T3 and T4 are examples of what type of hormone?

Answer 5

Modified amino acids

Question 6

Give examples of steroid hormones

Answer 6

Cortisol
Progesterone
Testosterone

Question 7

Adrenocorticotrophic hormone (ACTH) and anti-diuretic hormone are members of what group of hormones?

Answer 7

Peptides

Question 8

Give one example of a protein hormone

Answer 8

Insulin

Question 9

Describe the difference between Autocrine, Paracrine and Endocrine

Answer 9

Autocrine - cell that releases the signal also receives the signal

Paracrine - cell that sends the signal is adjacent to the cell which recieves the signal

Endocrine - cell sends signal into bloodstream and signal is recieved at an organ distal to the original cell site

Question 10

It is possible for hormones to act in more than one manner (e.g. both paracrine and endocrine). TRUE/FALSE?

Answer 10

TRUE

e.g. somatostatin = paracrine in pancreas
BUT endocrine in brain

Question 11

Hormones act at very high concentrations. TRUE/FALSE?

Answer 11

FALSE

Act at very low concentrations
=> act with very high potency

Question 12

What occurs when a hormone binds to its target receptor?

Answer 12

• biological response is triggered
• signal transduction cascade
• causes amplification of the original signal

Question 13

How is hormone action terminated?

Answer 13

• enzyme-mediated metabolic inactivation in the liver

- or terminated at sites of action

Question 14

Give an example of hormones which work together in a complementary manner

Answer 14

Adrenaline, cortisol, glucagon

Prevent hypoglycaemia and hypokalaemia in short term intense exercise

Question 15

What hormones work in an antagonistic manner?

Answer 15

INSULIN and GLUCAGON

Insulin:
- lowers plasma glucose levels

Glucagon:
- increases plasma glucose levels

=> opposite effects

Question 16

How are amine hormones released from cells?

Answer 16

• pre-synthesised
• stored in vesicles
• released by Ca2+ dependent exocytosis

Question 17

Are amine hormones hydrophilic or hydrophobic? Can they be transported freely in plasma?

Answer 17

Amines are hydrophilic

=> transported mainly free in plasma

Question 18

Are peptide hormones hydrophilic or hydrophobic? Can they be transported freely in blood plasma?

Answer 18

hydrophilic

=> transported mainly free in plasma

Question 19

How are peptide hormones released from cells?

Answer 19

• pre-synthesised usually longer precursors
• stored in vesicles
• released by Ca2+-dependent exocytosis

Question 20

How are steroid hormones synthesised and released from cells?

Answer 20

• synthesised and secreted upon demand

Question 21

How do stimuli increase the production/secretion of steroid hormones?

Answer 21

Stimuli increase:

(i) cellular uptake and availability of cholesterol
(ii) rate of conversion of cholesterol to pregnenolone (rate limiting step)

Question 22

Are steroid hydrophilic or hydrophobic?

Answer 22

• hydrophobic
  => transported in plasma mainly bound (~90%) to plasma proteins

only ‘free’ steroid hormone is biologically active

Question 23

What are the main functions of carrier proteins?

Answer 23

• increase amount transported in blood
• provide a reservoir of hormone
• extend half-life of the hormone in the circulation

Question 24

Give examples of specific carrier proteins

Answer 24

cortisol-binding globulin (CBG) – binds cortisol in a selective manner (also some aldosterone)

thyroxine-binding globulin (TBG) – binds thyroxine (T4) selectively [also some triiodothyronine (T3)]

sex steroid-binding globulin (SSBG) – binds mainly testosterone and oestradiol

Question 25

Give an example of a general carrier protein

Answer 25

albumin – binds many steroids and thyroxine

Question 26

Why do peptide and protein hormones not last as long?

Answer 26

They do not have carrier proteins to prolong their half life

Question 27

How do carrier proteins prevent surges in hormone?

Answer 27

bind free hormone to buffer surge in concentration

Question 28

If hormone is eliminated from the plasma, what is the role of carrier proteins?

Answer 28

To dissociate from hormone and create more "free" to enter plasma and maintain concentration

Question 29

What elements of the HPA axis can cortisol negatively feedback on?

Answer 29

Hypothalamus | Anterior Pituitary

Question 30

What external factor can have a positive effect on the HPA pathway, causing it to be stimulated more?

Answer 30

Stress at level of hypothalamus | elicits sudden burst in secretion

Question 31

How are hormones usually eliminated

Answer 31

metabolism locally, by the liver | excretion by the kidney

Question 32

How is the plasma concentration of a hormone defined?

Answer 32

plasma conc. = rate of secretion – rate of elimination

Question 33

Roughly how long are the half lives of each hormone group?

Answer 33

amines t½ = seconds proteins and peptides t½ = minutes steroids and thyroid hormones - t½ = hours to days

Question 34

What types of receptors do hormones usually bind to?

Answer 34

G-protein coupled (GPCR) Receptor kinases Nuclear receptors (Class 1, Class 2 and Hybrid class)

Question 35

What hormone receptors are found on the cell surface?

Answer 35

GPCR | Receptor Kinases

Question 36

How are the classes of Nuclear Receptor different?

Answer 36

class 1 - activated mainly by steroids - located in the cytoplasm - bound to inhibitory heat shock proteins (HSP) - move to the nucleus when activated class 2 - activated mostly by lipids - present in the nucleus hybrid class - activated by thyroid hormone (T3) etc - similar in function to class 1

Question 37

What type of hormone activates GPCRs?

Answer 37

activated by amines and some proteins/peptides

Question 38

What types of hormone activate receptor kinases?

Answer 38

activated by some proteins/peptides

Question 39

What effect does Gs have on the formation of adenylyl cyclase?

Answer 39

Causes it to convert more ATP to cAMP

Question 40

What effect does Gi have on adenylyl cyclase?

Answer 40

Negative effect on production of cAMP from ATP

Question 41

What hormones signal via GPCR Gs?

Answer 41

Adrenaline Glucagon Corticotrophin Releasing Factor (CRF)

Question 42

What hormone signals via GPCR Gi?

Answer 42

Melatonin | for sleep => causing cellular effects to lessen

Question 43

What hormones signal via GPCR Gq?

Answer 43

Angiotensin II Gonadotrophin releasing hormone Thyrotropin releasing hormone

Question 44

Describe the mechanism of receptor kinases

Answer 44

``` Target Hormone Binds Autophosphorylation of tyrosine residues Recruitment of phosphorylated adapter proteins Stimulate Protein kinase B Metabolic effects ```

Question 45

Describe the basis of Class 1 nuclear receptor signalling

Answer 45

- lipophilic molecules diffuse across plasma membrane - combine with intracellular receptor - HSP dissociate - receptor steroid complex moves to nucleus - dimer forms and binds to DNA hormone response elements - transcription either ‘switched-on’ or ‘switched off’ => alters mRNA levels/rate of synthesis of proteins