Flashcards in Regulating Flow, Biological Signalling + Calcium Deck (18)
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1
What 2 factors does Passive Diffusion depend on?
Rank the Permeability levels of
- Hydrophobic
- Small uncharged
- Large uncharged
- Ions
Ionic gradient + Permeability
Most permeable - Hydrophobic
Highly Permeable - Small Uncharged
Low Permeability- Large Uncharged
Impermeable- Ions
2
3 roles of transport processes
- Maintain pH and ion concentrations
- Regulate Cell volume
- Excretion of waste and toxic products
3
What are the Intra AND Extracellular concentrations for
1. Ca
2. K
3. Cl
4. Na
Ca: 1.5 mM outside, 0.1 microMolar inside
K: 4mM outside, 155mM Inside
Cl: 123mM outside, 4.2 mM Inside
Na: 145mM outside, 12nM Inside
4
How does PMCA work?
Hydrolyses ATP to transport Ca2+ out of the cell
5
How does the Na-K Pump work?
ATP Hydrolysed
3Na+ are transported out
2K+ are taken into cell
6
How does the Na-Ca-Exchanger (NCX) work?
What effect does depolarisation have on this process?
- Uses Na gradient from Na-K Pump
- 3Na into cell, 1Ca out of cell
Activity reversed, as NCX depends on membrane potential
7
How does Ischaemia affect the NCX exchanger?
-ATP is depleted, so Na-K Pump stops and Na gathers in cell
- Activity is reversed, so Na is moved out of cell and Ca is moved into cell, which is toxic
8
How does the Na-H-Exchanger (NHE) work?
- Uses Na gradient from Na-K Pump
- One Na moves into cell, One H moved out of cell
9
How is Na used to move Glucose into the cell?
Na gradient
Causes Na to move into cell, along with Glucose
Through a Symport
10
Which 3 co-transporters are involved in regulating intracellular pH
How do they work?
- NHE ( Na in, H out)
- NBC ( Na, HCO3- in. H, Cl- out) Alkanises the cell
-Anion Excanger (HCO3- out, Cl- in) acidifies the cell
11
At the Set Point pH, which two transporters have equal activity?
Which transporter has a higher activity, what is the effect on pH of cell?
NHE and AE
NBC works more, Alkanises the cell
12
What are 4 process involved in increasing [Ca] inside the cell?
- Ligand Gated Calcium Channels
- Voltage Operated Calcium Channels
- IP3R open when binded to IP3, allowing Ca to leave SR/ER to enter cytoplasm
- CICR/ Ryanodine receptors detect high cytoplasmic Ca, allowing more Ca to enter cytoplasm, from SR/ER
13
How does SERCA work?
Uses ATP to release Ca into cytoplasm
14
What is the [Ca] inside the SR/ ER?
0.2 mMolar
15
Which 3 factors oppose an increase in Cytoplasmic Calcium?
- Impermeability of Membrane to Ca2+
- Ca transporters, proteins move Ca out of cytoplasm
- Ca buffer proteins (Decrease Free Ca Level)
16
How do Nuclear/ Intracellular Receptors work?
Hydrophobic ligand binds to receptor
Ligand-receptor complex binds to gene transcription factor
Activates/ inactivates a gene/ set of genes
17
Explain how a Kinase-linked receptor works
1. Agonist binds to a receptor, activating Tyrose Kinase
2. Autophosphorylation: TK Phosphorylates the adjacent chain of same molecule
3. Enzymes bind to phosphorylated TK and gets phosphorylated itself
18
