Homeostasis/Signalling Molecules

Question 1

What single does of paracetamol can kill someone? Chronic dosing can affect the function of which organ?

Answer 1

10g

Liver function

Question 2

What are endogenous signalling molecules?

Answer 2

Signalling molecules within the body

Question 3

What are the two classes of exogenous signalling molecules?

Answer 3

Exogenous I = natural (e.g. Plant based)

Exogenous II = synthetic

Question 4

Give two examples of endogenous I drugs

Answer 4

Morphine

Aspirin

Question 5

What is the normal core body temperature?

Answer 5

37 degrees Celsius

Question 6

What acts as the ‘controller’ in body temperature regulation?

Answer 6

Hypothalamus

Question 7

Which responses would be seen after an increase in core body temperature? (2)

Answer 7

Sweat glands activated

Peripheral vessels dilate (vasodilation)

Question 8

Which responses would be seen after a decrease in core body temperature?

Answer 8

Skeletal muscle contraction (shivering)

Peripheral vessels constrict (vasoconstriction)

Question 9

Below which temperature is considered hypothermia?

Answer 9

35 degrees Celsius

Question 10

Above which temperature is considered hyperthermia?

Answer 10

38 degrees Celsius

Question 11

Endocrine signalling molecules (hormones) can be categorised into which 3 categories?

Answer 11

Hydrophilic 1 - CATECHOLAMINES
Hydrophilic 2 - PEPTIDES & PROTEINS
Lipophilic - STEROIDS

Question 12

Give an example of a catecholamine signalling molecule

Answer 12

Noradrenaline

Question 13

Give an example of a peptide and a protein signalling molecule

Answer 13

Oxytocin

Insulin

Question 14

Give an example of a steroid signalling molecule

Answer 14

Testosterone

Question 15

Where are the receptors for catecholamines?

Answer 15

In the plasma membrane

Question 16

Where are the receptors for peptide/protein signalling molecules?

Answer 16

In the plasma membrane

Question 17

Where are the receptors for steroid hormones?

Answer 17

Intracellular (cytosolic or nuclear)

Question 18

What is the plasma half-life of catecholamines, peptides/proteins and steroids respectively?

Answer 18

Catecholamines = seconds 
Peptides/proteins = minutes 
Steroids = hours

Question 19

What response do catecholamines result in after binding to its receptor?

Answer 19

Causes a change in membrane potential

Triggers synthesis of cytosolic second messengers

Question 20

What response do peptide/protein hormones cause after binding to its receptor?

Answer 20

Triggers synthesis of cytosolic second messengers

Triggers protein kinase activity

Question 21

What is autocrine signalling?

Answer 21

Signalling molecules released, act on receptors on the same cell causing Intracellular changes

Question 22

What is paracrine signalling?

Answer 22

Signalling molecules released into nearby extracellular environment and bind to receptors on nearby cells, causing their effects

Question 23

What is an example of a paracrine signalling molecule?

Answer 23

A neurotransmitter

Question 24

What distance and timeframe do neurotransmitters typically work over?

Answer 24

~20nm

Milliseconds

Question 25

What does an excitatory neurotransmitter do?

Answer 25

Increases firing rate post synaptically

Question 26

What does an inhibitory neurotransmitter do?

Answer 26

Decreases firing rate post synaptically

Question 27

Neurotransmitters can be grouped into which 3 categories with which exception?

Answer 27

Amino acids Monoamines Peptides Exception = ACh

Question 28

Is acetylcholine excitatory or inhibitory?

Answer 28

Excitatory

Question 29

Name 4 monoamine neurotransmitters. | State whether they are excitatory, inhibitory or both.

Answer 29

Adrenaline (excitatory) Noradrenaline (excitatory) Dopamine (both) Serotonin (excitatory)

Question 30

Name 3 amino acid neurotransmitters. | State whether they are excitatory, inhibitory or both.

Answer 30

Glutamate (excitatory) Glycine (largely inhibitory) GABA (inhibitory)

Question 31

Apart from neurotransmitters, which are the other local chemical mediators used in paracrine signalling?

Answer 31

Cytokines - e.g. Interleukins, histamine Nitric Oxide Eicosanoids - e.g. Prostaglandins

Question 32

Which signalling molecules does autocrine signalling use?

Answer 32

Shares many paracrine signalling molecules - e.g. Cytokines and growth factors

Question 33

What distance do autocrine signalling molecules typically work over once released from the cell?

Answer 33

Microns

Question 34

What is RITE a mnemonic for? What does each letter stand for? What is an exception to this mnemonic?

Answer 34

Describing DRUG TARGETS Receptors Ion channels Transporters Enzymes Chemotherapy drugs are an exception - work on structural proteins/dna

Question 35

What is KING a mnemonic for? What does each letter stand for?

Answer 35

Describing different drug target RECEPTORS Kinase-linked receptors Ion channels (ligand-gated) Nuclear/intracellular receptors G protein coupled receptors

Question 36

What is an example of a kinase linked receptor? How do they cause an effect?

Answer 36

Cytokine receptor Binding results in phosphorylation of proteins ---> signalling cascade ---> gene transcription

Question 37

What is an example of a nuclear receptor? How does it cause an effect?

Answer 37

Oestrogen receptor (lipid soluble molecule e.g. Steroids) Binds to gene transcription factors ---> activates/inactivates a gene

Question 38

What sorts of molecules bind to ligand gated ion channels?

Answer 38

'Fast' neurotransmitters e.g. ACh, GABA, NMDA

Question 39

What sorts of molecules bind to GPCRs?

Answer 39

Hormones Opiates Slow neurotransmitters e.g. Muscarinic ach, serotonin, dopamine, adrenaline, noradrenaline

Question 40

What are the three types of GPCR? What is the difference between them?

Answer 40

Gs, Gi and Gq They activate different intracellular signalling pathways

Question 41

What are the 4 major ion currents in cells?

Answer 41

Na+ K+ Cl- Ca2+

Question 42

How can phosphorylation help to facilitate/inhibit the activity of ion channels?

Answer 42

Phosphorylation of intracellular sites on the channels by PKA/PKC PKA/PKC can be activated by GPCR pathways

Question 43

Transporters are important in the re-uptake of neurotransmitters such as... How is this done?

Answer 43

Noradrenaline Serotonin Glutamate Co-transported with Na+ (symported)