Signalling Processes Flashcards by Ade Akintunde

What is cell signalling?

Complex system communication that:Governs basic cell activitiesCoordinates cell actionsThis ability is the basis of development, tissue repair, immunity and homeostasis

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`List examples of what signalling is important for?

Development and growthMaintaining homeostasisFighting infectionsRepairing injured tissueInitiating and coordinating movementCognition

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What diseases can be caused by cell signalling gone wrong?

CancerAutoimmune diseasesDiabetesMSParkinson’sSchizophreniaEpilepsyHuntington’sALS/ Motor neurone disease

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How does signalling occur in the body?

Chemically or electrically, using a variety of messengers

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What are the types of messengers involved in cell signalling?

IonsAmino acids, peptidesCytokinesNeurotransmittersHormonesNeurohormones

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What is a hormone?

A messenger released by a cell/ gland that binds with specialised receptors on a target cell

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What is a neurohormone?

Any hormone produced and released by neurons.

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What does the signalling cell initially do?

Secretes a substance which acts as a chemical messenger

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What is the role of the chemical messenger/ ligand in signalling?

Binds with specialised receptors on the target cell.

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What part of the signalling process produces a response in the target cell?

Binding of the messenger to the receptor

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What are the short-range signals?

Direct, Intracrine, Autocrine, Juxtacrine

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What is a type of medium-range signal?

Paracrine

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What is a type of long-range signal?

Endocrine

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What are direct signals?

Substance passes freely between adjacent cells through channels

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True or false? Direct signals are a type of juxtacrine signalling?

True

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Give an example of a direct signal

Gap Junctions

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What are intracrine signals?

The substance acts within the cell

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Give an example of intracrine signals

Steroid hormones

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What are autocrine signals?

Substance acts upon the cell that secreted it

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What are examples of autocrine signals?

Growth factor hormonesImmune cells

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What are juxtacrine signals?

Substance acts upon adjacent cells in direct contact with it

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What are examples of juxtacrine signals?

Notch signallingGap Junctions

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What are paracrine signals?

Substance acts upon cells nearby

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What are examples of paracrine signals?

Clotting factorsAllergic responseNeurotransmitters

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What is the difference between paracrine and direct/ juxtacrine signals?

Paracrine signals are medium-range while the others are short-range

What are endocrine signals?

Substance acts upon cells throughout the body (long-distance)

What is an example of an endocrine signal?

ADH

What is a nexus?

A gap junction (synonym)

Give examples of where gap junctions can be found

Heart - In intercalated disksRetina - Interconnecting horizontal cells

True or false? Juxtacrine action does not require physical contact between the two cells involved

False

True or false? The same substance can act across a variety of distances?

True

How can neurotransmitters allow for distant signalling throughout the body?

Nerve Conduction

What travel process do neurotransmitters and hormones have in common?

Diffusion

Approximately how long do nerve signals take to travel?

Milliseconds

Are target effectors involved in the endocrine pathway or the neurohormone pathway?

Both

If you are Schizophrenic you have high levels of... what?

Dopamine

If you have anxiety you typically have low levels of... what?

Dopamine

If you are happy you typically have high levels of... what?

Serotonin

If you have depression you typically have low levels of... what?

DopamineSerotonin

If you are in love you typically have high levels of... what?

DopamineSerotoninOxytocin

In the fight/flight response, you typically have high levels of... what?

NoradrenalineAdrenaline

How do hormones reach their target cells?

Via the bloodstream

What is actually responsible for the hydrophobicity in the bilayer?

Acyl chains

Are hormones water-soluble or lipid-soluble?

Both- depends on the type of hormone

Are neurotransmitters water-soluble or lipid-soluble?

water-soluble

Are growth factors water-soluble or lipid-soluble?

Water-soluble

Are cytokines water-soluble or lipid-soluble?

Water-soluble

Is insulin water-soluble or lipid-soluble?

water-soluble

Is glucagon water-soluble or lipid-soluble?

water-soluble

Is adrenaline water-soluble or lipid-soluble?

water-soluble

True or false? Acetylcholine, glutamate and cortisol are all water-soluble?

False- Cortisol is lipid- soluble

True or false? Testosterone, Oestrogen and Progesterone are all lipid-soluble?

True

True or False? Histamine, Thyroxine and Prostaglandins are all lipid soluble?

False- Histamine is water-soluble.

What is a term used to describe steroid hormones?

Lipophilic/ Hydrophobic

How does signal binding to a specific receptor on the target cell lead to a response?

Binding activates cytoplasmic enzymesThese enzymes alter cell behaviour and functions

What is cytosol?

Intra-cellular fluid present inside cells, the part of the cytoplasm that is not held by any of the organelles in the cell.

What is the difference between cytosol and the cytoplasm?

Cytosol is the part of the cytoplasm that is not held by any of the organelles in the cell.Cytoplasm is the part of the cell which is contained within the entire cell membrane.

What receptors do water-soluble signal molecules bind to?

Receptors at the cell surface

What are the three main classes of cell surface receptors?

* Ligand gated ion-channels * G-protein coupled receptors * Kinase linked receptors

What are ligand-gated ion channels? Where can they be found?

Gated pores for Na, K, ClTriggered by neurotransmittersIn the nervous system

How do ligand gated ion-channels work?

Recieve the signalAct by letting ions through the membrane

How do G-protein coupled receptors work?

Recieve the signalRely on G-protein to pass the signal to an effector enzyme

How do kinase linked receptors work?

Recieve the signalPass on the signal through intrinsic enzyme activity or by activating a kinase

What do GPCRs and kinase linked receptors trigger?

Intracellular signalling cascades

What causes altered cell behaviour?

Cytoplasmic machinery is affected

What is the second messenger in signalling?

Often the first product transiently formed to transduce the signal into the cell

What are 3 types of effector proteins?

* Metabolic enzyme * Gene regulatory protein * Cytoskeletal protein

What is the purpose of intracellular signalling cascades?

To amplify the initial signal

What are common second messengers?

CalciumCyclic nuclotidesPhosphoinositolsLipids

What are the two types of kinases?

Serine/ Threonine kinasesTyrosine kinases

What are G-proteins?

Molecular switches

What are the two types of G-proteins?

Monomeric small molecular weight GTPasesHeterotrimeric G proteins