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Human Physiology Bio 340 > chapter six cell communication > Flashcards

chapter six cell communication Flashcards

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1
Q

methods of cell-to-cell communication

A

gap junctions, contact-dependent signals, cells release messengers to ECF

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2
Q

gap junctions

A

direct cytoplasmic transfer between adjacent cells, transfer chemical & electrical signals, made of proteins called connexins

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3
Q

contact-dependent signals

A

surface to surface contact between membranes, require interaction between membrane molecules on two cells, relates to cancer cells

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4
Q

how do cells release messengers to the extracellular fluid?

A

long-distance communication (hormones, neurohormones, neurotransmitters), local communication (paracrine & autocrine)

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5
Q

what are the constraints for gap junctions & contact-dependent signals?

A

distance & small area of communication

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6
Q

how do channels and gap junctions differ?

A

channel connects ICF & ECF (cross one membrane), gap junction connects ICF to ICF (cross two membranes)

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7
Q

cellular messengers

A

long-distance communication & local communication

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8
Q

3 categories of long-distance communication

A

hormones, neurotransmitters, neurohormone

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9
Q

2 categories of local communication

A

paracrine agent & autocrine agent

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10
Q

hormones as cellular messenger

A

released from tissue & travels to target cell through blood

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11
Q

neurotransmitters as cellular messenger

A

released from neurons to adjacent effector (neuron can be measured in feet, message goes long-distance despite being delivered right next door)

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12
Q

neurohormones as cellular messenger

A

released from neuron & travels to target cell through blood

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13
Q

paracrine agent

A

released into interstitial fluid and affects neighboring target cell

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14
Q

autocrine agent

A

released into interstitial fluid and affects the cell that released it

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15
Q

hormones

A

secreted by endocrine glands or cells into blood. only target cells with receptors for the hormone will respond to the signal

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16
Q

neurotransmitters

A

chemicals secreted by neurons that diffuse across a small gap to the target cell. neurons use electrical signals as well

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17
Q

neurohormones

A

chemicals released by neurons into blood for action at distant targets

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18
Q

autocrine signals…

A

act on the same cell that secreted them

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19
Q

paracrine signals…

A

are secreted by one cell & diffuse to adjacent cells

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20
Q

long-distance communication

A

anytime we have the capability of sending it from one part of the body to a different part of the body

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21
Q

receptors

A

protein associated with the membrane or cellular interior which will bind a chemical messenger and exert an effector

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22
Q

what are the 5 characteristics of receptors?

A

highly specific (specificity), high affinity for specific messenger, they can be saturated or blocked, can undergo down-regulation & up-regulation

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23
Q

what influences affinity?

A

type & number of bonds

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24
Q

down-regulation

A

decrease in receptor number in response to chronic elevated levels of messenger

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25
Q

up-regulation

A

increase in receptor number in response to chronic low levels of messenger

26
Q

5 steps of cell communication

A
  1. signal molecule binds to
  2. receptor protein activates
  3. intracellular signal molecules alter
  4. target proteins create
  5. response
27
Q

routes of messenger action: lipophilic messengers

A

diffuse directly through the membrane to an internal receptor (likes lipids)

28
Q

routes of messenger action: lipophobic messengers

A

must enter cell through transport or bind to a surface receptor (bind to the outside, protein flexes, something happens on the inside)

29
Q

transport proteins

A

designed to bind to a lipophilic messenger & carry it though the blood. most are amphipathic molecules. they last longer because they are carried by something else

30
Q

what happens when we change the rate of transcription?

A

the cell is changed & doing something it wasn’t before

31
Q

what do lipophilic signal molecules bind to?

A

cytosolic or nuclear receptors (receptor in cytosol), SLOW- takes a while for message to get into nucleus

32
Q

what do lipophobic signal molecules bind to?

A

receptors on surface of cell membrane, QUICK response (milliseconds)

33
Q

signal transduction

A

message is conveyed from outside of cell to a new signal inside of the cell which then creates a cellular response

34
Q

transducters

A

convert extracellular signals into intracellular messages which create a response

35
Q

signal transduction benefits the cell through

A

signal amplification & multi-tasking

36
Q

signal amplification

A

like a snowball, as we move along we get bigger and bigger all coming from one tiny messenger

37
Q

multi-tasking

A

we can do multiple different things, one protein / response can create lots of different effects in the cell (kinase can phosphorylate different things in the cell)

38
Q

lipophobic messengers act on 4 types of membrane receptors

A
  1. ligand-gated receptor channels
  2. receptor enzymes
  3. GTP-binding proteins
  4. integral receptors
39
Q

ligand-gated receptor channels

A

receptor proteins that act as an ion channel. gated channel, ligand is our messenger, opened the channel

40
Q

receptor enzymes

A

receptor acts as enzyme and messenger binding initiates enzymatic activity resulting in cellular response (activated the enzyme)

41
Q

GTP-binding proteins

A

messenger activates a G-protein which opens an ion channel or activates an enzyme (most complex). the G protein either opens the channel or activates the enzyme, middle man

42
Q

integrin receptors

A

messenger binding causes a change in the cytoskeleton

43
Q

mechanisms of signal transduction

A
  1. messenger binds to a ligand-gated channel
  2. receptor enzymes
  3. GTP-binding proteins
44
Q

messenger binds to a ligand-gated channel

A

nicotinic (most common receptor in body), GABA, glycine

45
Q

receptor enzymes

A

when activated, receptor enzymes act as enzymes to alter cytoplasmic proteins

46
Q

kinase receptors

A

include many families of growth factors (insulin receptors, fibroblasts)

47
Q

GTP-binding proteins (2nd messenger systems or G protein coupled receptors)

A

intracellular messenger (1st messenger) binds non-covalently to a surface protein & activates a G-protein that initiates an internal chemical (2nd messenger) that initiates the cell’s response (second messenger inside the cell and causes response)

48
Q

what is the cells response in second messenger systems?

A

either opening a channel or activating an enzyme

49
Q

second messenger systems

A
  1. cyclic AMP system
  2. phospholipase-C pathway
50
Q

cyclic AMP

A

chops off two phosphates (adenylyl cyclase enzyme) and attaches them to itself

51
Q

cyclic AMP steps

A
  1. signal molecule binds to G-protein & activates it
  2. G protein turns on adenylyl cyclase
  3. adenylyl cyclase converts ATP to cyclic AMP
  4. cAMP activates protein kinase A
  5. protein kinase A phosphorylates other proteins, leading to a cellular response
52
Q

GPCR

A

the phospholipase C system

53
Q

GPCR steps

A
  1. signal molecule activates receptor & associated G-protein
  2. G protein activates phospholipase C (PL-C amplifier enzyme)
  3. PL-C converts membrane phospholipids into DAG (remain in membrane), IP3 diffuses into cytoplasm
  4. DAG activates protein kinase C (PK-C) (phosphorylates proteins)
  5. IP3 causes release of Ca2+ from organelles creating a Ca2+ signal
54
Q

agonist

A

chemical messenger that binds to a receptor and triggers a cell’s response

55
Q

antagonist

A

molecule that competes with another for a receptor and binds to the receptor but does not trigger a cellular response (when it binds) (also called inhibitor, blockers)

56
Q

what does the target response depend on?

A

the target receptor

57
Q

epinephrine (adrenaline)

A

hormone, the messenger & receptor matters in terms of the type of response the body will have

58
Q

signal termination

A

after the cell’s response has been initiated, the first messenger must be stopped & the second messenger must be removed

59
Q

first messengers can be:

A

degraded by extracellular enzymes (destroy messenger using enzymes) or endocytosis of receptor- ligand complex (broke down the messenger by bringing it in, binds to lysosol which brings destructive enzymes)

60
Q

second messenger must be removed by

A

cannot degrade the second messenger when it is calcium, pumping ions out of the cytoplasm

Human Physiology Bio 340 (6 decks)

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