ICPP S1 Biological Signalling Molecules

Question 1

What are three main signalling methods in the body?

Answer 1

Endocrine, paracrine and autocrine.

Question 2

What is meant by endocrine communication?

Answer 2

Secretion of hormones from (ductless) glands directly into blood, to be carried throughout the body to attach to complementary target receptor(s) far from site of secretion into blood.

Question 3

Endocrine signalling molecules production is described as ‘feedback regulating synthesis’, what does this mean?

Answer 3

Feedback regulating synthesis is the process by which the pro cuts of a metabolic pathway influences its own production, by controlling one or more of the enzymes involved in its pathway.
This type of feedback is usually inhibitory.

Question 4

What are the 3 types of endocrine signalling molecules in terms of their properties?

Answer 4

Hydrophilic 1
Hydrophilic 2
Lipophillic

Question 5

What are the types of endocrine signalling molecules?

Answer 5

Amines - AA derivatives with modified groups - small charged.
Peptides and proteins - short to long chains
Steroids - derived from cholesterol.

Question 6

Describe the differences between receptor location between the 3 endocrine signalling molecules types.

Answer 6

Amines and peptides act of CSM receptors.

Steroids act on intracellular or nuclear receptors.

Question 7

Describe the differences between mechanisms of action for each of the 3 types of endocrine signalling molecules.

Answer 7

Amines - cause change in membrane potential and trigger synthesis of cytosolic second messengers.
Peptides and proteins - trigger synthesis of cytosolic second messengers and tigger protein kinase activity.
Steroids - controls transcription, translation and overall expression of genes and stability of mRNAs.

Question 8

Give some examples of exogenous molecules and their therapeutic uses.

Answer 8

Adrenaline - A&E - treat anaphylaxis - causes vasoconstriction and helps to increase blood pressure whilst also relaxing smooth muscle in respiratory tract.
Insulin derivatives - control of blood sugar - diabetes
Steroids - anti-inflammatories

Question 9

Describe action of paracrine signalling molecules.

Answer 9

Paracrine signalling molecules are released into extracellular environment inducing changes in nearby cells.
Signal is coupled cell to cell to cells within a certain volume .

Question 10

What are the 3 major groups of NT?

Answer 10

Exception - ACh

Amino acids
Monoamines
Peptides

Question 11

What are 2 major signalling roles of NTs?

Answer 11

Inhibitor of excitatory.

Question 12

Name 4 monoamine neurotransmitters and there signalling function.

Answer 12

Adrenaline - excitatory
Noradrenaline - excitatory
Dopamine - excitatory and inhibitory.
Serotonin - excitatory

ANDS

Question 13

Name 3 amino acid NTs and their signalling function.

Answer 13

Glutamate - Excitatory
Glycine - Mainly inhibitory
G-amino butyric acid - Inhibitory

Question 14

Name some other paracrine signalling molecules other than transmitters.

Answer 14

Cytokines - Cell signalling molecules that aid cell to cell communications in immune response. For example interleukins, interferons, histamine and chemokines.

Eicanoids - derived from polyunsaturated fats. For example prostaglandins, leukotrienes and thoboxanes.

Others includes bradykinin, nitric oxide and certain neuropeptides.

Question 15

Name some exogenous paracrine signalling molecules and their therapeutic uses.

Answer 15

Propranolol - hypertension
Dopamine precursors - Parkinson’s
Fluoxetine - Depression
GABA receptor modulators - epilepsy 
Serotonin - migraine

Question 16

Describe the action of autocrine signalling molecules.

Answer 16

Chemicals released by cells which bind to their own receptors acting over very short distances.

Question 17

What are the 4 main groups of drug targets?

Answer 17

Receptors
Ion channels
Transporters
Enzymes

Question 18

What are the 4 types of receptors?

Answer 18

Kinase linked receptors
Ligand-gated ion channels
Nuclear/ Intracellular
G-protein coupled receptors.

Question 19

Describe the actions of kinase linked receptors.

Answer 19

Act via the phosphorylation of specific groups, start a cascade that leads to gene transcription.

Question 20

What are the 4 roles of enzymes?

Answer 20

Signal processing
Transformation aka isomerisation
Synthesis - anabolism
Degradation - catabolism

Question 21

Describe the action of transporters and carriers.

Answer 21

If favourable gradient present - can transport small ions and molecules into cell via facilitated diffusion.
High polar species or species going against a gradient can be actively transported in.