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Communication Flashcards

(93 cards)

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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
Explain intracellular receptors
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)
26
Explain cell membrane receptors
Ligands are usually lipophibic (hydrophilic) Ligand does not diffuse through cell membrane Bind to membrane receptors Cause intracellular cascade
27
Give example of lipophilic Ligands Give example of lipophobic Ligands
Steroid hormones Insulin and other peptide hormones
28
What are integrin receptor
Binding ligand stimulates changes in cytoskeleton Cell movement growth and wound healing
29
Explain Receptor channels
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)
30
____ enzymes and ____ both activate amplifier enzymes
Receptor G protein coupled receptor
31
On me ligand is amplified into ___ intracellular molecules
Many
32
Results in signal amplification are
A small amount of ligand creates a large effect
33
Tyrosine Kinase receptor
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
34
What is a specific example of TKR
Insulin receptor
35
Explain the insulin receptor
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
36
Explain the G protein coupled receptors
Hundreds of known GPCR Also called metabotropic receptors 7 transmembrane domain receptor Generate second messengers
37
Why are they called G proteins
Because they bind GDP and GTP
38
What is andenylyl cyclase
The amplifier enzyme that the G protein activates when it diffuses along the inside of the membrane
39
Each G protein activates ___ adenylyl Cyclase
One
40
In andenylyl cyclase the ligand binds to what and does what
G protein receptor | Activates the G protein
41
Once the G protein is activated in Andenylyl cyclase the G protein can _____ along the _____ of the membrane
Diffuse | Inside leaf
42
Adenylyl cyclase converts several hundred _____ into ____
ATP | cAMP
43
What is the second messenger in andenylyl cyclase and can diffuse throughout the cell
cAMP
44
cAMP activates _______
Protein kinase A
45
Protein kinase A diffuses within cell to ______ many other proteins
Phosphorylate Many types of proteins can be phosphorylated giving rise to complex cellular responses
46
What are three examples of GPCR
Andenylyl cyclase Phospholipase C Arachadonic acid
47
What does PL - C stand for
Phospholipase C
48
What does DAG stand for
Diacylglycerol
49
What does PK C stand for
Protein kinase C
50
What does IP3 stand for
Inositol triphosphate
51
What does ER stand for
Endoplasmic reticulum
52
The the ligand binds and activates the G protein receptor it activates _____ which is the ____
Phospholipase C The amplifier enzyme
53
PLC degrades membran phospholipids into two second messengers which are ___ and ___
Diacylglycerol Inositol triphosphate
54
DAG stats associated with the ___
Lipid
55
IP3 is a small polar molecule that ____ through the ___
Diffuses Cytoplasm
56
DAG activates ____
Protein kinase C
57
PLC diffuses within the cell and ____
Phosphorylates other proteins
58
IP3 binds to the ___ receptor on the ___
IP3 Endoplasmic reticulum
59
Activated IP3 receptor allows stores of __ to be released into the ___
Ca | Cytoplasm
60
When Ca is released into the cytoplasm it becomes ____
Another second messenger
61
What are the classic second messengers
cAMP cGMP IP3 DAG
62
What are the novel second messengers
Ca Gasses Lipids
63
Explain Ca as a second messenger
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
Ca binds to the calcium binding protein ___ to activate other proteins
Calmldulin
65
Explain gasses as second messengers
Soluble gasses are now being recognized as second messengers NO (nitric oxide) CO (carbon monoxide) H2S (hydrogen sulfide)
66
CO activates ____
Guanylyl cyclase
67
NO is synthesized by ___
NO synthase
68
NO activates ____ and the production of cGMP leads to ____ of smooth muscles
Guanylyl cyclase Relaxation
69
The arachadonic acid pathway is similar to the ____ pathway
PL-C
70
In arachadonic acid G proteins activate ____ which is the ____
Phospholipase A2 Amplifier enzyme
71
PLA2 degrades phospholipids into ___ which is an ___
Arachadonic acid Eicosanoid
72
Arachadonic acid are ___ within a cell | And diffuse out of the cell and act as a ____ for GPCR cell membrane and adjacent cells
Second messengers Ligand
73
Why does the hormone epinephrine (which is adrenaline) causes some blood vessels to constrict and others to dilate
The presence of receptor isoforms
74
Target response depends on the ___
Target receptor
75
Epinephrine can bind to different isoforms of the _____ receptor
Adrenergic
76
Epinephrine + alpha receptor =
Vessel constricts
77
Epinephrine + beta2 receptor =
Vessel dilates
78
Some Ligands can activate ___ receptors Some receptors are activated by more then ___ ligand
Multiple One
79
Alpha and beta 2 receptors may be activated by either ___ or ___
Epinephrine Norepinephrine
80
Receptors can be ____regulated or ___regulated What are examples
Up Down Development Homeostatic challenges Disease states
81
Receptors can be desensitized | Provide example
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
Control pathways for homeostasis follow and ____
Response and feedback loops
83
Explain negative feedback
``` Initial stimulus To Response To DECREASED STIMULUS To response loop shuts off ```
84
Explain positive feedback
``` Initial stimulus To Response To increased stimulus To Positive feedback cycle back to the response ```
85
How do you shut off the positive feedback cycle
An outside factor is required
86
Negative feedback keeps system ___ a setpoint
Near
87
Negative feedback response acts to __ the stimulus
Negate
88
Negative feedback response can ____ homeostasis but cannot___ the initial perturbation
Restore Prevent
89
Positive feedback brings a system _____ from a setpoint
Further
90
Positive feedback response acts to ____ the stimulus
Reinforce
91
What is the feed forward control
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
Neural control systems speed and specificity
Aimed at specific target Fast acting Shorter lived
93
Endocrine control systems speed and specificity
Target specificity determined by only receptors Longer to act Tends to last longer

Physiology (15 decks)

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