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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
Q

What are examples of mechano signal transduction (name 1)

A
  • 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
Q

What are the 4 main types of chemical messangers

A

1) Paracrines
2) Neurotransmitters
3) Hormones
4) Neuroendocrines

27
Q

what do paracrines do

A

Allow cells to communicate with each other by releasing signalling molecules that bind to and activate surronding cells

28
Q

Whats an example of paracrines

A

Clotting factors, growth factors (eg. estrogen)

29
Q

How can secreted hormones act

A

In paracrine and endocrine matters

30
Q

How does endocrine signalling work

A

Uses circulatory system to transport ions or molecules

31
Q

What is the purpose of neurotransmitters

A

Neurons relayed by neurotransmitters from presynaptic to postsynaptic neuron to propagate electrical impulses

32
Q

What size are the synapse in neurotransmitters

A

Short distances

32
Q

In which direction do neurotransmitters allow information

A

Unidirectional information transfer

32
Q

What are the 3 conditions for hormones

A

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
Q

How are neurotransmitter signals controlled

A

1) Must not release too many molecules
2) Needs auto shutoff (reuptake or degradation)

32
Q

Examples of hydrophillic messengers

A

Insulin, epinephrine, seritonin

32
Q

What are the 2 types of hormone messangers

A

1) Hydrophilic messangers
2) Hydrophobic messangers

33
Q

Where are hydrophilic messengers stored

A

Secretory cells

34
Q

Do hydrophilic cells need a carrier

A

No, dissolve in plasma

35
Q

Can hydrophilic cells easily pass lipid membranes

A

Crossing a lipid membrane presents a barrier - so generally secreted by fusing secretory vesicles to membrane and releasing (exocytosis)

36
Q

Examples of hydrophobic messengers

A

Steroids, sex hormones

37
Q

Where are hydrophobic messengers stored

A

Storage limited, made on dement

38
Q

Do hydrophobic messengers need messengers

A

Cannot dissolve in plasma, need messengers

39
Q

Can hydrophobic cells easily pass lipid membranes

A

Yes, crossing membrane doesn’t cause barrior

40
Q

What is autocrine communication

A

Cell signalling where cell secretes autocrine signals that bond to receptors in same cell, leading to changes in said cell

41
Q

When is autocrine communication possible

A

When messenger acts back on the cell that produced the chemical messenger, but would be considered direct communication

42
Q

Do cells only have one time of receptor

A

No, cells express many different types of receptors. May be 100s or 1000s of receptors on cells surface (ie. amplification)

43
Q

Can the amount of receptors in a cell be controlled

A

Yes, it can be:
1) Can be up or down regulated
3) Gene regulation

43
Q

What is the goal of chemical signal transduction

A

Goal to change overall profile of cellular protein/enzymatic activity

44
Q

What is an example of issues with chemical signal transduction

A

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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