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Physiology > Communication > Flashcards

Communication Flashcards

1
Q

There are 3 mechanisms for local signalling

A

Gap junction dependent communication

Contact dependent signals

Paracrine and autocrine

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2
Q

Explain gap junctions

A

Channels that connect adjacent cells

Water filled pore allows same molecules and ions to diffuse from one cell to the next

Cells are connected by cytoplasmic bridges

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3
Q

Two adjacent cells express channel proteins in gap junctions called ____

A

Connexins

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4
Q

What are common places for gap junctions

A

Common in heart smooth muscles and some neurons

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5
Q

Two ____ form a functional gap junction between two adjacent cells

A

Connexons

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6
Q

Each connexon is made of __ connexin monomers

A

6

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7
Q

Explain contact dependent signalling

A

A molecule (ligand) in the Extracellular matrix of one cell binds to a receptor in the membrane of the adjacent cell

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8
Q

What are common places for contact dependent signalling

A

Immune system

Development

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9
Q

Explain local communication

A

A signalling molecule is released

Paracrine - signalling to cells in the immediate vicinity

Autocrine - signalling to self

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10
Q

Signalling to self is what type of local communication

A

Autocrine

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11
Q

Signalling to cells in the immediate vacinity is what type of local communication

A

Paracrine

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12
Q

What’s an example of long distance communication

A

Endocrine system
Neurotransmitters
Neurohormones

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13
Q

What does the endocrine system do

A

Secretes hormones

Chemicals secreted into the blood that affect cells in other parts of the organism

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14
Q

What does endocrine refer to

A

The substance secreted in to the blood such as insulin

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15
Q

What does exocrine refer to

A

Substances secreted into a duct such as digestive enzymes from pancreas

Into pancreatic duct then digestive system

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16
Q

___ cells with ___ for the hormone responds to the signal sent out by the endocrine glands or cells

A

Target

Receptors

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17
Q

Explain neurotransmitters

A

An electrical signal travels distance along a nerve cell

Causes release of a chemical. The chemical travels across a small gap onto a target

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18
Q

Explain neurohormones

A

An electrical signal travels the distance along a nerve cell

Causes release of a chemical. The chemical is released into the blood and acts at distant targets

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19
Q

_____ are chemicals secreted by neurons that diffuse across a small gap to the target cell

A

Neurotransmitters

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20
Q

____ are chemicals released by neurons into the blood for action at distant targets

A

Neurohormones

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21
Q

Except for gap junction signalling

Cell to cell signalling requires what

A

Signal (ligand)

Receptor

Way to transduce the message intracellular signalling pathways

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22
Q

Explain how intracellular signal pathways are activated

A

Signal molecule binds to a receptor protein and ACTIVATES intracellular signal molecules which ALTERS target proteins to CREATE a response

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23
Q

Are intracellular signal pathways ubiquitous

Why are these important

A

All cells have some pathways

Only certain cells have specific pathways

Amplify signals

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24
Q

Two main categories of ligand receptor interaction

Based on receptor location

A

Intercellular receptors

Cell membrane receptors

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25
Q

Explain intracellular receptors

A

Ligands are usually lipophilic (hydrophobic)

Able to diffuse through cell membrane and bind to receptors in the nucleus of cytosol

Often alter gene expression (slow but long lasting)

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26
Q

Explain cell membrane receptors

A

Ligands are usually lipophibic (hydrophilic)

Ligand does not diffuse through cell membrane

Bind to membrane receptors

Cause intracellular cascade

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27
Q

Give example of lipophilic Ligands

Give example of lipophobic Ligands

A

Steroid hormones

Insulin and other peptide hormones

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28
Q

What are integrin receptor

A

Binding ligand stimulates changes in cytoskeleton

Cell movement growth and wound healing

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29
Q

Explain Receptor channels

A

Also known as an ion channel

Often called ligand gated ion channel
Neurotransmitter gated ion
Ionotropic receptors

The ligand is often a neurotransmitter

When the ligand binds the channel opens and allows ions to enter and leave cells (synaptic)

Allow Ca into cells (calcium is an important intracellular signal)

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30
Q

____ enzymes and ____ both activate amplifier enzymes

A

Receptor

G protein coupled receptor

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31
Q

On me ligand is amplified into ___ intracellular molecules

A

Many

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32
Q

Results in signal amplification are

A

A small amount of ligand creates a large effect

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33
Q

Tyrosine Kinase receptor

A

Transfers a phosphate group from ATP to a tyrosine residue (an amino acid) of a protein

Signal molecule binds to surface receptor the tyrosine kinase is on the cytoplasmic side and phosphorylated tyrosines on proteins

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34
Q

What is a specific example of TKR

A

Insulin receptor

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35
Q

Explain the insulin receptor

A

The alpha subunit binds insulin (which is the ligand)

Binding of insulin causes receptors to dimerize and autophosphorylate. The bets subunit transmits a signal from the bound insulin to the cytoplasm

The dimerization and autophosphorylation activate a kinase domain in the cytoplasm

Kinase domains on the the receptor phosphorylate insulin receptor substrate triggering other responses inside the cell

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36
Q

Explain the G protein coupled receptors

A

Hundreds of known GPCR

Also called metabotropic receptors

7 transmembrane domain receptor

Generate second messengers

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37
Q

Why are they called G proteins

A

Because they bind GDP and GTP

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38
Q

What is andenylyl cyclase

A

The amplifier enzyme that the G protein activates when it diffuses along the inside of the membrane

39
Q

Each G protein activates ___ adenylyl Cyclase

A

One

40
Q

In andenylyl cyclase the ligand binds to what and does what

A

G protein receptor

Activates the G protein

41
Q

Once the G protein is activated in Andenylyl cyclase the G protein can _____ along the _____ of the membrane

A

Diffuse

Inside leaf

42
Q

Adenylyl cyclase converts several hundred _____ into ____

A

ATP

cAMP

43
Q

What is the second messenger in andenylyl cyclase and can diffuse throughout the cell

A

cAMP

44
Q

cAMP activates _______

A

Protein kinase A

45
Q

Protein kinase A diffuses within cell to ______ many other proteins

A

Phosphorylate

Many types of proteins can be phosphorylated giving rise to complex cellular responses

46
Q

What are three examples of GPCR

A

Andenylyl cyclase

Phospholipase C

Arachadonic acid

47
Q

What does PL - C stand for

A

Phospholipase C

48
Q

What does DAG stand for

A

Diacylglycerol

49
Q

What does PK C stand for

A

Protein kinase C

50
Q

What does IP3 stand for

A

Inositol triphosphate

51
Q

What does ER stand for

A

Endoplasmic reticulum

52
Q

The the ligand binds and activates the G protein receptor it activates _____ which is the ____

A

Phospholipase C

The amplifier enzyme

53
Q

PLC degrades membran phospholipids into two second messengers which are ___ and ___

A

Diacylglycerol

Inositol triphosphate

54
Q

DAG stats associated with the ___

A

Lipid

55
Q

IP3 is a small polar molecule that ____ through the ___

A

Diffuses

Cytoplasm

56
Q

DAG activates ____

A

Protein kinase C

57
Q

PLC diffuses within the cell and ____

A

Phosphorylates other proteins

58
Q

IP3 binds to the ___ receptor on the ___

A

IP3

Endoplasmic reticulum

59
Q

Activated IP3 receptor allows stores of __ to be released into the ___

A

Ca

Cytoplasm

60
Q

When Ca is released into the cytoplasm it becomes ____

A

Another second messenger

61
Q

What are the classic second messengers

A

cAMP
cGMP
IP3
DAG

62
Q

What are the novel second messengers

A

Ca
Gasses
Lipids

63
Q

Explain Ca as a second messenger

A

Binds the calcium binding protein calmldulin to activate other proteins

Binds to motor proteins and allows action of cytoskeleton and motor proteins

Binds to synaptic proteins to trigger exocytosis

Binds to ion channels to modulate their gating

In fertilized eggs initiates development

64
Q

Ca binds to the calcium binding protein ___ to activate other proteins

A

Calmldulin

65
Q

Explain gasses as second messengers

A

Soluble gasses are now being recognized as second messengers

NO (nitric oxide)

CO (carbon monoxide)

H2S (hydrogen sulfide)

66
Q

CO activates ____

A

Guanylyl cyclase

67
Q

NO is synthesized by ___

A

NO synthase

68
Q

NO activates ____ and the production of cGMP leads to ____ of smooth muscles

A

Guanylyl cyclase

Relaxation

69
Q

The arachadonic acid pathway is similar to the ____ pathway

A

PL-C

70
Q

In arachadonic acid G proteins activate ____ which is the ____

A

Phospholipase A2

Amplifier enzyme

71
Q

PLA2 degrades phospholipids into ___ which is an ___

A

Arachadonic acid

Eicosanoid

72
Q

Arachadonic acid are ___ within a cell

And diffuse out of the cell and act as a ____ for GPCR cell membrane and adjacent cells

A

Second messengers

Ligand

73
Q

Why does the hormone epinephrine (which is adrenaline) causes some blood vessels to constrict and others to dilate

A

The presence of receptor isoforms

74
Q

Target response depends on the ___

A

Target receptor

75
Q

Epinephrine can bind to different isoforms of the _____ receptor

A

Adrenergic

76
Q

Epinephrine + alpha receptor =

A

Vessel constricts

77
Q

Epinephrine + beta2 receptor =

A

Vessel dilates

78
Q

Some Ligands can activate ___ receptors

Some receptors are activated by more then ___ ligand

A

Multiple

One

79
Q

Alpha and beta 2 receptors may be activated by either ___ or ___

A

Epinephrine

Norepinephrine

80
Q

Receptors can be ____regulated or ___regulated

What are examples

A

Up
Down

Development
Homeostatic challenges
Disease states

81
Q

Receptors can be desensitized

Provide example

A

Phosphorylation of alpha and beta receptors can cause them to have lower affinity for Ligands

Mechanism of drug tolerance as a result continuous exposure to an agonist

82
Q

Control pathways for homeostasis follow and ____

A

Response and feedback loops

83
Q

Explain negative feedback

A 
Initial stimulus 
To
Response 
To
DECREASED STIMULUS 
To 
response loop shuts off
84
Q

Explain positive feedback

A 
Initial stimulus 
To
Response 
To 
increased stimulus
To 
Positive feedback cycle back to the response
85
Q

How do you shut off the positive feedback cycle

A

An outside factor is required

86
Q

Negative feedback keeps system ___ a setpoint

A

Near

87
Q

Negative feedback response acts to __ the stimulus

A

Negate

88
Q

Negative feedback response can ____ homeostasis but cannot___ the initial perturbation

A

Restore

Prevent

89
Q

Positive feedback brings a system _____ from a setpoint

A

Further

90
Q

Positive feedback response acts to ____ the stimulus

A

Reinforce

91
Q

What is the feed forward control

A

A small stimulus sets off a chain of events aimed at preventing a perturbation

Requires a complex program

Ie) mouth watering in anticipation of food (psychologists may disagree)

92
Q

Neural control systems speed and specificity

A

Aimed at specific target
Fast acting
Shorter lived

93
Q

Endocrine control systems speed and specificity

A

Target specificity determined by only receptors
Longer to act
Tends to last longer

Physiology (15 decks)

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