Pharmacology

Question 1

what do endocrine glands do?

Answer 1

Secrete hormones into interstitial fluid. It is then taken up by the capillary circulation and taken to the site of action around the body.

Question 2

How do exocrine glands differ from endocrine glands?

Answer 2

Exocrine glands release the hormones straight into the site of action whereas endocrine glands use the bloodstream.

Question 3

Name the major endocrine organs

Answer 3

Pituitary gland
Parotid
Hypothalamous
Thyroid gland
Parathyroid
Endocrine pancreas
Adrenal gland
Ovaries
Testes
Thymus

Question 4

Describe the chemical nature of hormones

Answer 4

Hormones can be derived from amino acids e.g. tyrosine, thyroid hormones and adrenaline.
They can be steroids derived from cholesterol e.g. cortisol, progesterone and testosterone
They can be peptides derived from larger proteins e.g. ADH
Or they can be proteins e.g. insulin

Question 5

Name the three types of chemical signalling

Answer 5

Autocrine
Paracrine
Endocrine

Question 6

Autocrine

Answer 6

Signalling molecule/hormone released by a cell acts on that same cell

Question 7

Paracrine

Answer 7

Signalling molecule/hormone acts locally on surrounding cells

Question 8

Characteristics of endocrine hormones

Answer 8

Concentration of the hormone may be very low but the receptors for the hormone are highly specific.
Once bound, there is often an amplification reaction where more receptors are activated.

Question 9

How are amines (amino acid derivatives) released into the blood?

Answer 9

A ligand binds to a receptor. This causes calcium influx which triggers pre-formed vesicles containing the amine to fuse with the membrane of the cell.
The amine is then released into the insterstitial fluid and then the blood stream.

Question 10

Describe the process of storing peptides and proteins

Answer 10

They are from larger precursor protein molecules. They are enzymatically cleaved to produce smaller hormones by convertases. They are then packaged into storage vesicles.

Question 11

How are peptides and proteins released into the blood?

Answer 11

A ligand binds to a receptor on the cell. This causes calcium influx causing the vesicle containing the peptides/proteins to fuse with the membrane. The peptides/protein is released into the interstitial fluid and then moves into the blood

Question 12

Why do you not need a transporter to get the protein molecules into the blood?

Answer 12

Proteins are mainly hydrophillic and therefore can travel in the plasma.

Question 13

How are steroid hormones synthesised and how are they released into the blood?

Answer 13

Steroid hormones are synthesised on demand (e.g. when the ligand binds to the receptor).
Cholesterol is imported into the cell and is converted to a different hormone via pregnenolone.
The hormone is released straight into the blood (no storage vesicles used for steroid hormones).

Question 14

How are steroids carried in the blood?

Answer 14

The hormone is carried in the blood plasma bound to plasma proteins due to it being hydrophobic. When bound to plasma proteins- the hormone is pharmacologically inert.
Only the proportion of steroid unbound to plasma proteins will cause a biological action.

Question 15

How do carrier proteins help with hormone function

Answer 15

They provide a reservoir of hormone and act as a buffer.

Question 16

Explain the relationship between bound hormone and unbound hormone

Answer 16

There is an equilibrium set up between the proportion of bound hormone to plasma proteins and unbound. As the bound hormone cannot move across the capillary membrane to reach the target receptors, only the unbound hormone shifts across disturbing the equilibrium (decreasing the free concentration).
It therefore shifts to counteract this change and more of the hormone dissociates from the proteins.

Question 17

Name some important carrier proteins

Answer 17

Cortisol binding globulin (CBG)- binds cortisol in a selective manner
Thyroxine binding globulin- binds thyroxine
Sex steroid binding hormone- binds testosterone and oestrial.
Albumin- binds many steroids

Question 18

Describe the ways in which hormonal levels can be controlled

Answer 18

Negative feedback
Neuroendocrine- a sudden burst of secretion to meet a specific stimulus
Diurnal (circadian) rhythm- Secretion rate fluctuates in relation to time (day or night)

Question 19

Three types of hormone receptors

Answer 19

G protein coupled receptors
Receptor kinases
Nuclear receptors

Question 20

G protein coupled receptors

Answer 20

Bind mainly to amines and some peptides/proteins

Major signalling pathways are Gs, Gi or Gg

Question 21

Receptor kinases

Answer 21

Activated by proteins/peptides

Question 22

Nuclear receptors

Answer 22

Divided into three subtypes- class 1, 2 or hybrid class.

Question 23

What type of receptors are G protein and receptor kinases?

Answer 23

Cell surface receptors

Question 24

What type of receptors are nuclear receptors?

Answer 24

Intracellular receptors because the substance binding to them is lipophillic it can pass the cell membrane.

Question 25

Class 1 nuclear receptor

Answer 25

Mainly binds steroid hormones.
In the absence of stimuli found in cytoplasm bound to inhibitory heat shock proteins.
When stimulated moves to nucleus.

Question 26

Class 2 nuclear receptors

Answer 26

Activated mostly by lipids. Present in the nucleas

Question 27

Hybrid class receptors

Answer 27

Bind to thyroid hormone (T3) and other hormones.