Communication, Integration, Homeostasis Flashcards

1
Q

Cell to cell communication(short distance)

A

Gap junctions, juxtacrine (contact dependant), autocrine and paracrine

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2
Q

2 key control systems

A

Endocrine and Nervous

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3
Q

Gap juctions

A

channels that produce a direct pathway between cytoplasm of one and another cell, for electrical or chemical signals
- Direct cytoplasmic transfer

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4
Q

Contact dependant

A

Juxtacrine: one end is stuck in the membrane of one cell and receptor is stuck in another cells membrane. They have to come in contact with receiving cell.
- cell to cell dependant

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5
Q

Autocrine

A

Cell is signaling itself, same cell releases signal and bind to receptor on the same cell
- release signal

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6
Q

Paracrine

A

Release signal to neighboring cell and binds

- release signal

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7
Q

communication via long distance: hormone

A

hormone: endocrine cells
released by endocrine cells and travels through the blood to target cells. Target cells need to have correct receptors to be activated

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8
Q

communication via long and short distance: neurons

A

use local and long distance. Neurons secrete signals = neurocrines
1- neurohormone: transported like hormone, through the blood
2- neurotransmitter: something secreted by neuron into neighboring cell
3- neuromodulator: substances released by neurons, modifies how neuron responds to normal primary signal

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9
Q

Electrical signaling

A

Excitable cells use e- signals for communication
ex; nerves, muscles, some endocrine cells.
- due to changes in membrane potential. [ difference in charge is only along the membrane]

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10
Q

Membrane potential

A

All cells have it
electrical potential difference = Vm = voltage = stored energy
** reported inside relative to outside. Use absolute value when determining the largest potential difference

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11
Q

How do membrane potentials arise?

A

1- unequal distribution of ions

2- selective membrane permiablity

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12
Q

Chemical (diffusional ) forces

A

Concentration of gradient principle, ECF vs ICF

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13
Q

Electrical force

A

ionic charge vs membrane charge

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14
Q

electrochemical equilibrium

A

= no net electrochemical force

- 2 forces(chemical and electrical) are equal but opposite = equilibrium potential.

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15
Q

Nerst equation, what you need to know

A
Nerst = Eion = 61/z *( [ion]out/[ion]in)
Z= valence electrons, if anion use a (-)
log(#>1)= +
log(1)= 0
log(#<1)= -
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16
Q

Ex of different Ions

A
k+ = -90mv
Na = +60 mV
Cl- = -63 mV
Ca+ = +240
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17
Q

Membrane potentials influenced by equilibrium potentials

A

due to multiple ions
reality of how much charge is unequally distributed.
unequeal distributions give us ion equilibrium potentials(Ex).

18
Q

Equilibrium potentials

A

each ions desired value.

- ions want to move Vm towards ions Ex to be at equilibrium.

19
Q

What is the driving force?

A

Membrane potential - Equilibrium potential = driving force

(Vm-Ex) = determines ion flow in/out of a cell

20
Q

Membranes permeability to certain ions

A

Leakage (open), but a small drop in the ocean

K+>Cl->Na+, K+ has more votes

21
Q

Resting membrane potential equation

A
Vm = pK(Ek)+ pNa(Ena) + pCl(Ecl)
Px = permeability
22
Q

How are concentration gradients maintained over time?

A

Active transporters, Like the Na+/K+ ATPase. 3 Na for 2K, always running and controls the “leak” of potassium

23
Q

types of gated channels

A
chemically  gated: 
1- ligand(lock and key)
2- ATP channel (Na/K)
Voltage: activated by depolarization
Mechanically gated: Activated with stretch or pressure
24
Q

How can changes to a membrane’s permeability depolarize or hyperpolarize a cell?

A

ion channels display specificity and allow rapid flow of ions
- ions flow to change membrane potential of cell (Vm) towards their equilibrium potential(Ex)

25
Depolarize vs repolarize vs hyperpolarize
Depolarize; making more positive(|Vm decreases|) Repolarization; returning, making more negative hyperpolarization; too negative, pass the threshold. |Vm increases|
26
What does chemical signaling rely on?
ligand- receptor interactions ligand- ex, insulin receptor: have binding sites for ligand (specificity, competition, saturation)
27
intracellular vs vs membrane receptors
intracellular: lipophilic, hydrophobic membrane: lipophobic, hydrophilic,
28
Lipophobic receptors:
receptor channels: simplest, most rapid (neurotransmitter) **** confused based on the learning goals
29
GPCR
Most signal transduction uses GPCR - membrane-spanning protein - extracellular binding sites - cytoplasmic tail linked G protein (3 parts to it) - when activated, they can open ion channels, or alter enzyme activity inside cell [ protein kinase/phosphatases (amplifier enzymes).]
30
What is amplification?
allows a small amount of signal to have a large effect. 2 most common amplifier enzymes: -adenylylcyclase - phospholipase C
31
Step one of cAMP
``` ligand (1st messenger) binds to GPCR. - G-protein activated -> exchanges GDP for GTP. functions like molecular switch -GTP = active - GDP = inactive ```
32
step 2 of the cAMP
activated G Protein activates adenylyl cyclase | - adnyl cyclase converts ATP => cyclic amp(secondary messenger)
33
step 3 of cAMP
cAMP activates protein kinase A and then that has multiple functions
34
What does protein kinase A do?
cAMP dependant, can influence many factors, including opening ion channels and regulating gene transcription.
35
What stops the cAMP pathway?
G protein: GTPase: converts GTP back to GDP cAMP:phosphodiesterase: breaks down cAMP Protein kinase A:phosphatases, unphosphorylated things
36
Phospholipase C pathway
- instead of adenylyl cyclase there is phospholipase C. - instead of cAMP, there is DAG and IP3 - -> DAG is made from membrane phospholipids and then continues to protein kinase C on the membrane - -> IP3 activates Ca+ storage
37
can receptors have more than one ligand?
yes; | ex; adrenergic receptors bind to both epinephrine and norepinephrine, ligands compete
38
endogenous
into, from within. something that is provided from within the body
39
exogenous
drugs, come from the outside that can also bind to receptors. They block activity.
40
upregulation vs down regulation
upregulation: mechanism to increase cell response, increase # of receptors downregulation: mechanism to decrease cell response decrease # of receptors or binding affinity or receptors
41
Antagonistic vs tonic control
antagonistic is faster, both branches(S7P) are active | tonic = volume dial
42
how is a signaling molecule turned off?
- degrade/inactive signal (1st or 2nd messenger): GTPase or phosphodiesterase - remove signal: 1st or second mess, by transporting it, ex; pumping Ca+ back into ER - endocytosis of receptor-ligand complex.