L4 & L5 Cell physiology of ions Flashcards

(34 cards)

1
Q

What is a solvent? [3]

A

Fluid present
Biological systems it is water
Organic fluids in lab

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2
Q

What is a solute? [3]

A

particles dissolved in solvent

Can be atoms & molecules
DNA, sugars, proteins and H+ ions

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3
Q

What is an electrolyte?

A

ionized components of living fluid

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4
Q

important ions to remember

A

Na+, K+, Ca2+, H+, Mg2+, OH-, Cl-, HCO3_, SO4-, PO4-& charged proteins

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5
Q

What is PO4- used for?

A

important for reactions involving ATP (enzyme) and structurally in bone

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6
Q

What is SO4- used for?

A

is important structurally in glycosaminoglycan (connective tissue )

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7
Q
Fluid compartments
Plasma 
Interstitial 
Intracellular 
Transcellular
A

Plasma: Na+ based

Interstitial: ~ plasma and lacks blood proteins

Intracellular: K+ based and lots of protein

Transcellular: In the lumen of tubes and organs (CSF, urine in bladder, chyme in GIT)

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8
Q

Methods of transport

A
Channels 
Pumps 
Transporters 
Exchangers
Leak
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9
Q

What are the following?

Channels 
Pumps 
Transporters 
Exchangers
Leak
A

Channels: membrane proteins that open/close and let specific ions flow down a concentration gradient (passive)

Pumps: membrane proteins that use ATP to pump ions across membrane (against concentration gradient)

Transporters = membranes proteins that couple the transport of two different molecules so that both go across membrane together (passive)

Exchangers: membrane proteins that couple the transport of two different molecules (opposite directions) Passive

Leak: Movement of ions across a membrane (passive) no protein to facilitate

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10
Q

Ions - where??

A
Free
Tightly bound 
Sequestered 
Chelated 
Buffered - can go in/out solution 
Teeth and bones
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11
Q

Role of ions [2]

A

Start cellular process - act as 2nd messenger
Involved in muscle contraction - fertilisation and exocytosis

Create energy (ATP), activate enzymes (protein kinase C), move water (kidney) and control transmembrane voltage

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12
Q

Wrong ion concentration can lead to? [4]

A

Cardiac arrhythmias, bone deformities, oedema and seizures

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13
Q

Causes of ionic imbalance [8]

A
Trauma/haemorrhage 
Diabetes
Kidney dysfunction 
Hormonal imbalance 
Extensive D and V 
Dehydration 
Vit D imbalance 
poisons
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14
Q

Voltage [4]

A

Difference in potential energy between 2 points in an electric field
V=IR G = I/V
G = conductance (ability for current to flow at given voltage)

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15
Q

What are the ionic differences in a cell?

A

K+ inside, na+ outside

cell membrane is not permeable to be charged ions, but it is permeable to water and uncharged molecules

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16
Q

What is a chemical force?

A

= Diffusional force
based on concentration difference across membrane
10 x Na+ outside, 30x potassium in intracellular/extracellular

17
Q

What is an electrical force?

A

Based on Vm (membrane potential -> varies over time)
Based on a few positive charges
Same for all ions

18
Q

What is a net force?

A

chemical + electrical force

19
Q

What happens at equilibrium, in terms of charges?

A

-1 x electrical force

net force = 0

20
Q

What is hypocalcaemia?

A

Low calcium

Can lead to ECG abnormalities and arrhythmyia

21
Q

Level of ions maintained in

A

Cytosol of cell

22
Q

Excitable cells can…

A

Propagate action potential (amplified voltage response)

Neurons and muscle cells

23
Q

Non-excitable examples

A

Skin and liver (esp epithelial cells)

24
Q

Plasma composition

A

Highest in Na+ concentration (to balance protein anions)

Is slightly more negative in electric potential than the Extracellular Fluid (ECF)

25
Intracellular fluid composition
Highest in total cations Highest in proteins Highest electrolyte concentration (milliEquivalents) Most negative voltage
26
Free Calcium summary
Calcium ionised AND in solution -> free to activate enzymes Found in bone of insoluble solid, bound to protein or sequestered inside cellular organelles
27
Cytosolic calcium amount in cytosol vs extracellular
Low in cytosol ~ 100 nanoM Cf extracellular is +1.2milliM
28
Change in voltage can lead to...
Second Messenger: Calcium, kinases, phospholipases Contaction in muscles
29
3 rules
The concentration of positive and negative ions must “nearly” balance Any ion that leaves the cell must be replaced soon by another ion of that type coming into the cell Energy is always being used to re-establish the ionic gradients across membranes
30
pH
extracellular fluid (7.40 ± 0.05) cytosol (7.20, although this can vary based on the cell type). Changes in blood pH are corrected by the actions of the kidneys and the lungs.
31
Carbonic anhydrase
Create base or acid Indirectly contribute to H+ crossing membrane and epithelia Indirectly transport CO2 around body (CO2 is poorly soluble in blood)
32
Carbonic Anhydrase in Homeostasis
Red Blood Cells: “Chloride shift” for removing H+ from muscle Lungs: for eliminating CO2 source from blood Gastric Parietal cells: secreting acid into stomach Pancreas: secreting bicarbonate
33
What does the Sodium-potassium pump (Na / K ATPase) do?
maintains the intracellular K+ concentration. It is inhibited by ouabain and digitalis
34
What inhibits the H+ / K+ ATPase “Proton Pump” ? | active, uses up ATP energy
Inhibited by omeprazole (a proton pump inhibitor PPI)