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Medicine > Cell Physiology of Ions 2 > Flashcards

Cell Physiology of Ions 2 Flashcards

1
Q

Hypo

A

Too little

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2
Q

Hyper

A

Too much

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3
Q

Hypocalcaemia

A

Too little calcium in plasma. Causes too much activity; arrhythmias, over-reactive reflexes, seizures

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4
Q

Hypercalcaemia

A

Too much calcium n plasma. Leads to too little activity; constipation, psychological depression

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5
Q

Paraesthesia

A

An abnormal sensation of pins and needles or numbness

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6
Q

Tetany

A

Intermittent muscular spasms

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7
Q

Chvostek’s sign

A

One sign of tetany seen in hypocalcaemia. Abnormal reaction to stimulation of facial nerve; when facial nerve is tapped at angle of jaw, facial muscles on that side of the face will contract momentarily, typically twitch of nose or lips

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8
Q

Cytosol

A

The aqueous component of cytoplasm of cell

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9
Q

What is the second messenger for fertilisation of egg cell

A

High free Ca2+ content in cell is second messenger.

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10
Q

Excitable cells, with examples

A

Cells that can propagate an action potential/ cells that can produce or respond to electrical signals. Neurons and myocytes and fertilisable egg cells

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11
Q

Non-excitable cells, with examples and counterexamples

A

Cells without action potentials. Not muscle or nerve. Epithelial cells

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12
Q

Relationship in terms of movement between Na+, Cl- and H2O

A

Na+ gets pumped or moves through ion channels, Cl- tends to follow Na+ (and other permeable cations) and water follows Cl-

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13
Q

Which is higher in total cations, intracellular or extracellular fluid? Why are these cations needed in that compartment?

A

Intracellular. To balance out all the anionic proteins.

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14
Q

Which fluid compartment has the highest Cl- concentration but the lowest electrolyte concentration?

A

Interstitial fluid

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15
Q

Which fluid compartment has the highest electrolyte concentration?

A

Intracellular

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16
Q

Why is intracellular fluid highly negative?

A

Because some negative ions (Cl-) are not paired with positive ions (K+) because K+ leaks out without any anions following

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17
Q

What conditions must Calcium be in to partake in reactions?

A

Free, ionised, in solution in cytosol

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18
Q

Another name for free intracellular calcium

A

Cytosolic calcium

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19
Q

Action potential triggers muscle contraction via……?

A

A cytosolic calcium increase

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20
Q

If action potential in muscle cells is too weak, ……….?

A

Not enough Ca2+ is released so no muscle contraction

21
Q

Action potential is a change in voltage. It can lead to other changes inside the cell:

A

Second messengers; calcium, kinases, phospholipases. Muscle contraction. Change in voltage in one cell can lead to change in voltage in other cells; synaptic transmission

22
Q

Explain in terms of action potentials and ions how involuntary muscle contractions occur.

A

In pathological situations, AP not needed for Calcium ion release so unwanted contractions.

23
Q

Give the 3 rules of ionic balance. What is the importance of the rules of ionic balance?

A

Charge must balance, ions must be replaced, energy maintains ionic gradients. Ion transport depends on these rules

24
Q

Explain ‘charge must balance’ law

A

Concentration of positive and negative ions must nearly balance. If +ve ion crosses membrane, charge imbalance corrected by either -ve ion following or another _ve charge going in opposite direction. “Nearly” means that there can be tiny amounts of unbalanced cations on one side of a membrane that are near to anions on the other side of the membrane

25
Q

Explain ‘ions must be replaced’ law. Give an example and explain the importance of the law in the example

A

Any ion that leaves the cell must be replaced soon by another ion of that same type coming into cell. When cells in salivary gland secret K+ into saliva, K+ ions replaced by K+ from blood. This is fundamental to homeostasis; otherwise the salivary cells would run out of K+.

26
Q

Explain ‘energy maintains gradients’ rule. Give an example

A

Energy is always being used to re-establish the ionic gradients across membranes. e.g. Na-K pump

27
Q

Changes in blood pH mainly corrected by……?

A

Kidneys and lungs

28
Q

pH is a measure of the concentration of…….?

A

Free H+ ions

29
Q

Carbonic anhydrase is used for homeostasis in many systems. Give 4 examples.

A

Red Blood Cells: Chloride shift for removing H+/ CO2 from muscle. Lungs: removing CO2 from blood. Gastric Parietal Cells: Secreting acid into stomach. Pancreas: secreting bicarbonate.

30
Q

Describe Chloride shift in RBC for muscles.

A

Need to remove CO2 and H+ from respiring tissue. CO2 produced by respiring cell diffuses into RBC where CA reacts it to make H+ and HCO3-. H+ binds to RBC which acts as a buffer and HCO3- in RBC enters blood plasma in exchange for a Cl-. OPPOSITE AT LUNGS

31
Q

Why is Cl- content of RBC in veins higher than that of arterial RBC?

A

Because venous RBC uses cloride shift to remove H+ and CO2 from cells.

32
Q

What is the purpose of gastric pits and what key cells are found in them?

A

Increases surface area of stomach lumen. Full of gastric parietal cells.

33
Q

What inhibits chloride shift?

A

Acetazolamide

34
Q

Another name for parietal cell?

A

Oxyntic cell

35
Q

What inhibits proton pumps?

A

Omeprazole

36
Q

How are bicarbonate ions removed from gastric parietal cells?

A

Chloride-bicarbonate exchanger (passive)

37
Q

How are protons removed from gastric parietal cells?

A

Proton pumps (active)

38
Q

What inhibits chloride-bicarbonate exchangers?

A

Oxonol dyes

39
Q

What ion is brought in simultaneously by the proton pump (in parietal cell)?

A

K+

40
Q

How do K+ ions leave parietal cell?

A

Passive potassium channels

41
Q

How does Cl- brought into gastric parietal cell by chloride-bicarbonate exchanger leave the cell?

A

Chloride channels, passive.

42
Q

What does Cl- make once it has left the gastric parietal cell?

A

Combines with H+ from proton pump to make HCl in lumen of stomach

43
Q

Where on the gastric parietal cell is the chloride-bicarbonate exchanger?

A

Basal side.

44
Q

Where on the gastric parietal cell is the potassium channel found?

A

Basal and apical

45
Q

Where on the gastric parietal cell is the chloride channel found?

A

Apical side

46
Q

Where on the gastric parietal cell is the proton pump found?

A

Apical side

47
Q

How does the gastric parietal cell ensure that it is not depleted in terms of K+ concentration?

A

Sodium-potassium pump, which pumps 3 Na+ out and 2K+ in, actively

48
Q

Where on the gastric parietal cell is the sodium-potassium pump found?

A

Basal side

49
Q

What inhibits the sodium-potassium pump?

A

Ouabain and digitalis

Medicine (18 decks)

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