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BIOL 385 > CH 06 — Communication, integration, and homeostasis > Flashcards

CH 06 — Communication, integration, and homeostasis Flashcards

1
Q

What are the three forms of local communication?

A
  1. gap junctions: form direct cytoplasmic connections between adjacent cells for smaller molecules (created by linked membrane proteins)
  2. contact-dependent signals: require interaction between membrane molecules on two cells (CAMs)
  3. diffusing chemicals: chemicals that diffuse through the extracellular fluid to act on cells close by (autocrines & paracrines)
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2
Q

What is an autocrine?

A

act on the same cell that secreted them (local)

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3
Q

What is a paracrine cell?

A

secreated by one cell and diffuse to adjacent cells in the immediate vicinity

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4
Q

What are the 2 forms of long-distance communication?

A
  1. blood transport (hormones)
  2. Neurochemicals (also neurocrine): neurotransmitters, neuromodulators, and neurohormones
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5
Q

What are neurotransmitters?

A

chemicals secreated by neurons that diffuse across a small gap to the target cell — influences the neurons target cell

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6
Q

What are neurohormones?

A

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

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7
Q

What are neuromodulators?

A

chemicals that alter the response of a neuron more slowly than neurotransmitters

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8
Q

What are the characteristics of protein binding of chemical signals?

A

specificity, affinity, competition, and saturation

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9
Q

What are the 5 steps of the signal pathways?

A

signal molecule —> membrane receptor protein —> intracellular signal molecules —> target proteins —> response

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10
Q

Where are receptor proteins?

A
  • can be inside cell or on membrane
  • intracellular vs. cell membrane receptors
  • can be in nucleus or cytosolic
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11
Q

What are the four types of cell membrane receptors?

A
  1. Receptor channel
  2. G protein-coupled receptors
  3. Receptor-enzyme
  4. Integrin receptor
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12
Q

What are receptor- channels?

A
  • ligand binding
  • opens/closes the channel
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13
Q

What are g-protein coupled receptors?

A

ligand binding to a g-protein-coupled receptor (GPCR) opens an ion channel or alters enzyme activity

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14
Q

What are the 2 catalytic receptors?

A
  1. receptor-enzyme
  2. integral proteins
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15
Q

What are receptor-enzymes?

A

ligand binding to a receptor-enzyme activates an intracellular enzyme

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16
Q

What are integrin receptors?

A

ligand binding to integrin receptors alters enzymes or the cytoskeleton

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17
Q

What is signal transduction?

A

transducer convers a signal from one form to another
- convers signal from outside cell to a different form inside cell

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18
Q

What is the first messenger in signal transduction?

A

extracellular signal —> activated protein kinases and amplifier enzymes

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19
Q

What is the second messenger for signal transduction?

A

intracellular signal —> alter gating of ion channels, increase intracellular calcium, change enzyme activity (ED: protein phosphates

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20
Q

What are the steps for basic signal transduction (5)?

A
  1. signal molecule
  2. membrane receptor protein
  3. intracellular signal molecules (converts)
  4. target proteins
  5. response
    (look at slide 20 for transduction pathways in more depth!)
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21
Q

Signal transduction cascade — slide 22

A

signal amplification allows a small amount of signal t have a large effect (one ligand amplified into many intracellular molecules

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22
Q

What are some examples of second messengers in signal pathways?

A
  1. cAMP
  2. cGMP
  3. IP3
  4. DAG
  5. Ca2+
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23
Q

How do rapid signal pathways work? where are they found?

A
  • change ion flow through channels
  • found in nerve & muscle mostly
  • ligand binding to a receptor-channel protein changes permeability to an ion
  • rapid flow of an ion in or out of the cell brings about a rapid response from the cell
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24
Q

What do G proteins do when activated?

A
  • they open ion channels in the membrane
  • they alter enzyme activity on the cytoplasmic side of the membrane
  • most signal transduction uses G proteins
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25
Q

What is the GPCR-Phospholipase C signal transduction?

A

ligand —> g-protein —> phospholipise C —> DAG and IP3
- DAG activated protein kinase C (phosphorilates proteins)
- IP3 releases Ca2+
- they both lead to tissue response
- slide 40

26
Q

How do catalytic receptors work?

A
  • receptor enzymes
  • ligand binding activates intracellular enzyme
  • catalytic receptor enzymes (protein kinases, guanyly cyclase)
27
Q

What does guanylyl cyclase do?

A

converts GTP to cyclic GMP (cGMP)

28
Q

What does tyrosine kinase do?

A

transfers a phosphate group from ATP to a tyrosine (amino acid) of a protein

29
Q

What is an integrin protein? what do they do on the outside and inside of the cell?

A

a membrane spanning protein
- outside the cell they bind to extracellular matrix proteins
- inside the cell they attatch to the cytoskeleton via anchor proteins

30
Q

Slide 49 as general summery map of signal transduction

A
31
Q

What are the 3 novel signal molecules?

A
  • calcium
  • gases
  • lipids
32
Q

What are the 5 ways calcium acts as an intracellular messenger?

A
  1. binds to calmodulin and alters enzyme or transporter activity or gating of ion channels
  2. binds to other regulatory proteins (EX: troponin) and alters movement of contractile or cytoskeleton proteins such as microtubules
  3. binds to regulatory proteins to trigger exocytosis of secretory vesicles
  4. binds directly to ion channels to alter gating state
  5. entry into fertilized egg initiates development of embryo
33
Q

How can calcium enter the cell?

A
  • gated channels
  • released from intracellular compartments by second messengers (stored in ER by active transport)
  • release of Ca2+ creates Ca2+ singal (called the Ca2+ “spark”)
    ** diagram on slide 55
34
Q

What are some advantaged and disadvantages of gaseous second messengers?

A
  • soluable gases are short-acting paracrines or autocrines
  • EX: nitric oxide (NO) which activates guanylyl cyclase (cGMP)
  • advantages:
  • disadvantages:
35
Q

What are some examples of gaseous second messengers?

A
  1. nitric oxide (NO) which activates guanylyl cyclase (cGMP)
  2. Carbon monoxide (CO)
  3. Hydrogen sulfide (H2S)
36
Q

What type of singal molecules are gases?

A
  • ephemeral
  • paracrines or autocrines
37
Q

What type of signals are lipids?

A

some are important paracrine signals

38
Q

Do receptors exhibit specificity, saturation, and competition?

A

yes

39
Q

What is specificity and competition in relation to ligands?

A

multiple ligands for one receptor (EX: norepinephrine and epinephrine)

40
Q

What is the agonist ligand?

A

a different ligand then the primary one that can still bind to the receptor and cause a response

41
Q

What is the antagonist ligand?

A
  • blocks receptor activity
  • causes no response
  • a lot of medicines work like this
  • EX: beta blockers block epinephrine/norepinephrine (i think??)
42
Q

What is a primary ligand?

A

The main ligand that is the normal ligand that binds to the receptor
- causes response
- (most of what has already been talked about)

43
Q

Can one ligand have multiple receptors?

A

yes

44
Q

Does epinephrine dialate or constrict blood vessels?

A

BOTH! (can cause different responses depending on what isoform of adrenergic receptor it binds to)
- released during fight/flight (want blood in skeletal muscles, heart, lungs)
- in the areas we want to increase blood it dialates
- the rest of the body constricts to conserve blood for where we need it

45
Q

Which receptor constricts the blood vessels when epinephrine is binded to it?

A

alpha receptors (EX: intestinal blood vessels)

46
Q

Which receptor dialates the blood vessels when epinephrine is binded to it?

A

beta-2 receptors (EX: skeletal muscles)

47
Q

What is up-regulation?

A

inserts more receptors in cell membrane (receptors are held inside the cell in vesicles)

48
Q

What is down-regulation

A

decrease in receptor number (cell removes receptors — still same number of ligands but not enough receptors —> decreased response)

49
Q

What is desensitization?

A
  • by binding a chemical modulator to receptor
  • phosphorylation a b-adrenergic receptor will desensitize it
  • very fast switch instead of up & down regulation
50
Q

What are the 3 ways to modulate a signal pathway?

A
  1. up-regulation
  2. down-regulation
  3. desensitization
51
Q

Why are signal modulators used?

A

used by cell to regulate itself to try to maintain a cellular homeostasis
- just because a certain amount of ligands have been released doesn’t mean it will produce the same response

52
Q

How can cells terminate signal pathways?

A
  1. removing free ligand (degeneration, transport into cells, sequestering —> (means storing/hiding)
  2. removing bound ligand (receptor-mediated endocytosis)
53
Q

What do diseases and drugs target in the cell?

A

they target the proteins of signal transduction

54
Q

Table 6.1 on slide 77 —> diseases and drugs targeting proteins of signal transduction

A
55
Q

What are Cannon’s 4 postulates?

A
  1. nervous system helps regulate internal environment
  2. some systems are under tonic control
  3. some systems are under antagonistic control
  4. one chemical signal can have different effects in different tissues
56
Q

What is tonic control?

A
  • regulates physiological parameters in an up-down- fashion
  • ONLY 1 system controlling them
  • signal is always present but changes intensity
  • look at def from book as well
57
Q

What is antagonistic control?

A
  • uses different signals to send a parameter in opposite directions
  • EX: antagonistic neurons control HR (some speed it up & others slow it down)
58
Q

What are some examples of sensors?

A

**all receptors are sensors, not all sensors are receptors
- membrane/intracelular receptors
- central receptors: closer or in the brain (eyes, ears, nose, tongue)
- Prerepheral receptors: lie outside of the brain (baroreceptor, proprioreceptors, mechanoreceptors, etc.)

59
Q

go back and add from slide 87-89

A
60
Q

What is the simple neural reflex pathway?

A

internal/external change —> receptor —> input signal (sensory neuron) —> nervous system integrating center —> efferent neuron —> target —> response

61
Q

Why is the simple endocrine reflex pathway?

A

internal/external change —> endocrine system sensor-integrating center —> output signal: hormone —> target —> response

62
Q
A

BIOL 385 (9 decks)

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