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BIOL *1080 > Lecture 7 > Flashcards

Lecture 7 Flashcards

1
Q

What are the 2 types of intercellular communication?

A

1) direct communication
2) indirect communication

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2
Q

What are the three forms of direct communication?

A

1) Gap junctions
2)Membrane (tunneling) nanotubes
3) Mechano signals

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3
Q

What is the form of indirect communication

A

Chemical messengers

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4
Q

What are cell-cell junctions

A

When cells link to eachother to regulate homeostasis and critical cell processes

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5
Q

Where do cell-cell junctions occur

A

Large multiprotien complexs

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6
Q

What are the three types of cell-cell junctions

A
  1. Tight junctions
  2. Anchoring junctions
  3. Gap junctions
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7
Q

Where are gap junctions found

A

Dispersed in the plasma membrane

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8
Q

What are the roles of gap junctions

A
  • Act as communication channels between adjacent cells in animal cells
  • Allow molecules and ions ot pass through
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9
Q

What is the structure of gap junctions

A

Made of transmembrane protein connexin’s
- 6 connexin = 1 connexon
- 6 connexon = 1 protien connexon

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10
Q

Explain homemeric vs hetromeric connexon

A
  • Homemeric connexon = 6 copies of the same connexin protiens
  • Hetromeric connexon = 6 copies of different connexin protiens
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11
Q

Gap junctions - how are protein channels made

A

When a connexon in one cell membrane meets with a connexon in another cell membrane, they pair to make a protein channel

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12
Q

What do gap junctions allow to pass through

A

Ions, sugars, secondary messengers, other small molecules between molecules

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13
Q

What regulates the opening and closing of gap junctions

A

1) Voltage
2) Ion concentration
3) pH

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14
Q

What are the 2 main parts of gap junctions

A

1) Connexons
2) Intercalated disks

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15
Q

Which is smaller; connexons or intercalated disks

A

Intercalated disks

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16
Q

What are intercalated disks

A

Type of gap junction found in cardiac muslce

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17
Q

What is the role of intercalated disks

A

Allow rapid and coordinated propagation of action potentials into rhythmic contractions

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18
Q

How are intercalated disks regulated

A

Phosphorylation and dephosphorlyation

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19
Q

Where are connexons NOT found

A

Mature skeletal cells

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20
Q

What are membrane nanotubes formed from

A

Plasma membranes

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21
Q

How big are membrane nanotubes in comparison to gap junctions

A

Longer and larger pore diameter then gap junctions

22
Q

What do membrane nanotubes transfer

A

Nucleic acids, and small organelles between cells

23
Q

What are the purpose of membrane nanotubes

A

To transfer cell components from stressed to healthy cells

24
Q

What is mechano signal transduction

A
  • A direst physical stress on cells, electing a chemical or metabolic response
  • Conversion of mechanical stimuli to cellular response
25
What are examples of mechano signal transduction (name 1)
- Mechanical stress to muscle fibres from weight lifting resulting in increased protein synthesis - Remodelling of bone and cartilage through physical stress (such as weightlifting) - Conversion of pressure on skin into neural (electrical) impulse
26
What are the 4 main types of chemical messangers
1) Paracrines 2) Neurotransmitters 3) Hormones 4) Neuroendocrines
27
what do paracrines do
Allow cells to communicate with each other by releasing signalling molecules that bind to and activate surronding cells
28
Whats an example of paracrines
Clotting factors, growth factors (eg. estrogen)
29
How can secreted hormones act
In paracrine and endocrine matters
30
How does endocrine signalling work
Uses circulatory system to transport ions or molecules
31
What is the purpose of neurotransmitters
Neurons relayed by neurotransmitters from presynaptic to postsynaptic neuron to propagate electrical impulses
32
What size are the synapse in neurotransmitters
Short distances
32
In which direction do neurotransmitters allow information
Unidirectional information transfer
32
What are the 3 conditions for hormones
1) Must be water or lipid soluble 2) Must cross cell boundaries or membranes 3) Must have target specificity (receptors - targets they have to connect with and act on for a chemical signal to move forward)
32
How are neurotransmitter signals controlled
1) Must not release too many molecules 2) Needs auto shutoff (reuptake or degradation)
32
Examples of hydrophillic messengers
Insulin, epinephrine, seritonin
32
What are the 2 types of hormone messangers
1) Hydrophilic messangers 2) Hydrophobic messangers
33
Where are hydrophilic messengers stored
Secretory cells
34
Do hydrophilic cells need a carrier
No, dissolve in plasma
35
Can hydrophilic cells easily pass lipid membranes
Crossing a lipid membrane presents a barrier - so generally secreted by fusing secretory vesicles to membrane and releasing (exocytosis)
36
Examples of hydrophobic messengers
Steroids, sex hormones
37
Where are hydrophobic messengers stored
Storage limited, made on dement
38
Do hydrophobic messengers need messengers
Cannot dissolve in plasma, need messengers
39
Can hydrophobic cells easily pass lipid membranes
Yes, crossing membrane doesn't cause barrior
40
What is autocrine communication
Cell signalling where cell secretes autocrine signals that bond to receptors in same cell, leading to changes in said cell
41
When is autocrine communication possible
When messenger acts back on the cell that produced the chemical messenger, but would be considered direct communication
42
Do cells only have one time of receptor
No, cells express many different types of receptors. May be 100s or 1000s of receptors on cells surface (ie. amplification)
43
Can the amount of receptors in a cell be controlled
Yes, it can be: 1) Can be up or down regulated 3) Gene regulation
43
What is the goal of chemical signal transduction
Goal to change overall profile of cellular protein/enzymatic activity
44
What is an example of issues with chemical signal transduction
Lactose intolerance - chemical signals do not communicate with body to produce enough of lactase enzyme to digest with the lactose consumed

BIOL *1080 (19 decks)

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