Acid base and blood gas analyser


Vocabulary warm-up

1 Match the words in English with their translations:

1 unknown                                                                     ponořit

2 inner side                                                                 tenká vrstva

3 coated                                                                         dosáhnout

4 immerse                                                                       neznámý

5 plastic jacket                                               nylonová síťka

6 basically                                                                      vnitřní strana

7 nylon net                                                                  plastikový obal

8 uncharged molecules                                               tím

9 pass through                                                            v zásadě

10 thin layer                                                                    projít skrz

11 reach                                                                          nenabité
molekuly, molekuly bez náboje

12 thereby                                                                  potažený



Reading


1 Read the text and complete the gaps with the words from the box:

electrode       uncharged       partial         analysers          diffuse          electrolyte
   solution



Most acid base and blood gas ___________(1) measure pH, pCO[2], pO[2] by means of selective
electrodes.


pH electrode

A pH electrode is a glass ________(2) with a pH-sensitive glass membrane to seal its tip. On the
inner side of the membrane is a buffer solution with constant pH. A silver wire coated with AgCl is
immersed in this solution and, via a plug, connected to the measuring instrument. On the other side
of the glass membrane is a ___________(3) of unknown pH (the sample).


pCO[2] electrode

pCO[2] is defined as the _________ (4) pressure of CO[2] in a gas phase in equilibrium with the
blood, and is measured by a pCO[2] electrode.


A pCO[2] electrode is a combined glass and silver/silver chloride (Ag/AgCl) reference electrode
placed in a plastic jacket, which is filled with a bicarbonate_________ (5). The jacket is covered
with a 20 μm silicon membrane placed on a 50 μm nylon net.


The pCO[2] electrode is basically a pH electrode with a silicon membrane added. This membrane
allows only ___________(6) molecules (i.e. CO[2], O[2], N[2]) to pass through it. Charged ions,
such as H^+, will not pass. Consequently, dissolved CO[2] from the sample will __________(7) into
the thin layer of bicarbonate electrolyte until equilibrium is reached.


2 Now answer these questions:

1 What are the electrodes made of?

2 Where on the electrode is the glass membrane?

3 Does the pH in the buffer solution change?

4 What is the role of the silver wire?

5 Where is the bicarbonate electrolyte situated?

6 What is the difference between a pCO[2] electrode and a pH electrode?

7 What kind of molecules pass through the silicon membrane?

8 How long do the CO[2] molecules move into the bicarbonate electrolyte?


Grammar Point

A Adjectives and Adverbs – Comparison

 Complete the sentences using comparative or superlative forms:

1. This coffee is very weak. I like it a bit …. .........

2. The hotel was surprisingly big. I expected it to be …. ……………

3. The hotel was surprisingly cheap. I expected it to be …. ………………

4. Don’t worry. The situation isn’t so bad. It could be …. …………….

5. This is the …. film I have ever seen.

6. You were a bit depressed yesterday, but you look …............... today. (good)

7. My mother is ……………….. than my father. (old)

8. Our shop has the …. …………….prices. (low)

9. Frying is the ……………... way of cooking. (healthy)

10. Spring is …………………. of the four seasons. (beautiful)



B Expressing “už ne/ještě ne” in English

Translate into English:

1. Už mi nepíše_____________________________________________________________.

2. Už to nechci slyšet!________________________________________________________

3. Už spolu nechodí.___________________________________________________________

4. Chceš znát odpověď? Ne, ještě ne._____________________________________________

5. Ještě na tom nepracuji._______________________________________________________