Regulating Flow, Biological Signalling + Calcium Flashcards Preview

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Flashcards in Regulating Flow, Biological Signalling + Calcium Deck (18)
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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


3 roles of transport processes

- Maintain pH and ion concentrations
- Regulate Cell volume
- Excretion of waste and toxic products


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


How does PMCA work?

Hydrolyses ATP to transport Ca2+ out of the cell


How does the Na-K Pump work?

ATP Hydrolysed
3Na+ are transported out
2K+ are taken into cell


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


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


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


How is Na used to move Glucose into the cell?

Na gradient
Causes Na to move into cell, along with Glucose
Through a Symport


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


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


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


How does SERCA work?

Uses ATP to release Ca into cytoplasm


What is the [Ca] inside the SR/ ER?

0.2 mMolar


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)


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


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


Compare Paracrine, Autocrine, Endocrine Signalling

Para: Signalling molecule affects adjacent cells
Auto: Signalling molecule affects cell that it was released from
Endo: Signalling molecule released directly into blood to distant target cells