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Musculoskeletal system > Calcium and signalling > Flashcards

Calcium and signalling Flashcards

1
Q

What is cell signalling?

A

Communication for cells to respond

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2
Q

What is chemotaxis?

A

Neutrophils responding to bacterial signal

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3
Q

What is necrosis?

A

Disorganised cell death

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4
Q

What is apoptosis?

A

Organised cell death

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5
Q

What is endocrine signalling?

A

Hormone is secreted into blood which travels to the target cells

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6
Q

What is paracrine signalling?

A

Cells communicate with adjacent cells, e.g. by cytokines

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7
Q

What is direct contact signalling?

A

Some cells pack closely together to inhibit proliferation, e.g. pores in a cell membrane

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8
Q

What is synaptic signalling?

A

Neurotransmitter released from one neutron and binds to receptors on another

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9
Q

What is the suffix for a steroid?

A

-one

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10
Q

What are the four types of receptors?

A

Steroid, G-protein, ligand gated ion channels, enzyme

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11
Q

What is signal transduction?

A

Steps that occur once a receptor has received its signal that leads to changes in a cell

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12
Q

How is a resting membrane potential maintained?

A

Calcium moves from a higher concentration outside cell to a lower concentration inside cell
Sodium moves from a higher concentration outside cell to a lower concentration inside cell
Potassium moves from a lower concentration outside cell to a higher concentration inside cell

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13
Q

How many sodium move out for potassium moving in?

A

3 sodium out for every 2 potassium in
Calcium ATPase
Electrochemical gradient

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14
Q

What kind of receptor is found at neuromuscular joint?

A

Ligand gated ion channels - nicotinic ACh

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15
Q

What chemical binds to the ligand gated ion channels in neuromuscular junctions?

A

Nicotinic ACh

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16
Q

Process of synaptic transmission at neuromuscular junction

A

Action potential travels down neuron
Sodium enters membrane which opens calcium channels
Synaptic trafficking of vesicles
Releases acetylcholine into cleft to bind with nicotinic ACh receptor to open pore
Sodium enters the muscle fibres

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17
Q

How does a steroid receptor work?

A

Receptors found within the cytoplasm of cells
When steroid added, steroid receptors translocate to nucleus
Steroids are lipids - can diffuse across membrane
They bind to cytoplasmic receptors and move to nucleus
This causes gene and protein expression
In the nucleus, they bind to the enhancer region of DNA
(each steroid binds to a particular region of DNA)
Proteins (transcription factors) form a transcription imitation complex in promoter region
Causes transcription and translation of proteins
Many cells have many different receptors for steroids (SPECIFICITY)

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18
Q

How do steroids work?

A

Bind to elements within DNA and can switch genes on and off and regulate transcription factors

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19
Q

What are all steroids derived from?

A

Cholesterol

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20
Q

Characteristics of G-protein coupled receptors

A

Involved in fight or flight
800 receptors
Mediate variety of signals, e.g. adrenaline
Lots of alpha helices spanning membranes 7 times

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21
Q

What are G-protein couples receptors?

A

Membrane spanning receptors occurring on cell membranes

22
Q

Flow chart of response

A

Signal - receptor - transduction - response

23
Q

On what cells can direct signalling occur?

A

On cells next to each other

24
Q

On what cells can paracrine signalling occur?

A

On cells near each other

25
Q

On what cells can endocrine signalling occur?

A

Travels in bloodstream to target cells

26
Q

On what cells can synaptic signalling occur?

A

Neurones release neurotransmitters

27
Q

On what cells can autocrine signalling occur?

A

Bind to receptors on own membrane

28
Q

How long does it take for ligand-gated ions channels to work?

A

Milliseconds

29
Q

How long does it take for G-protein coupled receptors to work?

A

Seconds

30
Q

How long does it take for kinase linked receptors to work?

A

Hours - the kinase cascade takes time

31
Q

How long does it take for steroid receptors to work?

A

Hours (kinase cascade)

32
Q

How do enzyme linked receptors work?

A

Chemical binds to receptor - leads to two ligand monomers joining together
Kinase domain of receptor phosphorylates other monomer of receptor
Activates Ras - a GTPase
Activates kinase cascade - phosphorylates the transcription factor
Translocates to nucleus and switches on genes involved in growth, proliferation and cell division
Herceptin blocks receptor and stops cascade - stops cell growth

33
Q

What do tyrosine kinase inhibitors do?

A

Stops phosphorylation between two domains

34
Q

What do MAP kinase inhibitors do?

A

Stop kinase cascade

35
Q

What do enzyme linked receptors do?

A

Target systems involved in cell death/survival
Activate kinase cascade - proteins get phosphorylated and change shape, activating transcription factors to turn other genes off

36
Q

What impact does adrenaline have on skeletal and cardiac muscle?

A

More energy
Increased vasodilation
Weaker contraction of smooth muscle
Stronger contraction of cardiac muscle

37
Q

What impact does adrenaline have on gut/skin?

A

Less energy
Vasoconstriction
Stronger contraction of smooth muscle

38
Q

What are the two types of adrenaline receptor?

A

Alpha and beta

39
Q

Where is adrenaline receptor beta I?

A

Heart

40
Q

Where is adrenaline receptor beta ii?

A

Lungs

41
Q

What doe kinases do?

A

Add phosphate to things

42
Q

How do beta receptors work?

A

Adrenaline binds to receptors and leads to G-protein receptor signalling pathway (or G-alpha-S)
G proteins are receptors - GTPase
Hydrolyse GTP bound to them into GDP
Switched on by GTP and off by GDP
Bound to two sub-units (heterotrimeric)
G-alpha-S produces cAMP, which activates adenyl cyclase to convert ATP to cAMP
cAMP is the second messenger and goes to activate kinases
Activates kinase A which adds phosphate to proteins

43
Q

What does the S in G-alpha-S stand for?

A

Stimulatory

44
Q

How do alpha receptors work?

A

Ligand binding site
GTP binding site on cytoplasmic domain
G-alpha-q leads to IP3, which is a ligand
IP3 binds to receptors found on stores (ER/SR)
IP3 receptor is ligand gated calcium channel
Activates protein kinase C
IP3 increases calcium levels in cell G proteins switch off signal by converting GTP to GDP

45
Q

What kind of molecule is IP3?

A

A lipid

46
Q

What are beta-blockers?

A

Drugs that block beta adrenaline receptors on heart

Very similar structure to adrenaline

47
Q

What does protein kinase A do?

A

When activated by cAMP, it activates glycogen phosphorylase

Breaks down glycogen to glucose for energy

48
Q

What impact does protein kinase A have on cardiac muscle?

A

Can also phosphorylate L-type calcium channel to increase its likelihood of opening
Calcium floods into cardiomyocytes more frequent
Increases heart rate and muscle contraction

49
Q

How does PDE switch off a signal in a cell?

A

Breaks down cAMP into AMP
Switches signal off
cAMP leaves PKA
Can inhibit PDE - signal continues for longer

50
Q

What does PDE stand for?

A

Phosphodiesterase

Musculoskeletal system (24 decks)

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