week 5

Question 1

What is the purpose of respiration?

Answer 1

Remove oxygen from the air for use at the body tissues
remove carbon dioxide from body tissues and eliminate it in expiration

Question 2

What happens in external respiration?

Answer 2

exchange of oxygen at alveoli
exchange of carbon dioxide at alveoli

Question 3

What happens in internal respiration?

Answer 3

exchange of oxygen and carbon dioxide at the tissue

Question 4

What does atmospheric air consist of?

Answer 4

nitrogen
oxygen
water
carbon dioxide

Question 5

What is Dalton’s Law of partial pressures?

Answer 5

the total pressure in a gas mixture is the sum of the partial pressures of each individual gas

Question 6

What is the partial pressure of a gas?

Answer 6

The pressure contributed by a single gas in a mixture of gases

Question 7

What do English texts use as units for gas pressure?

Answer 7

KPa

Question 8

How do you work out Kpa from mmHg?

Answer 8

Kpa = mmHg / 7.5

Question 9

What unit do paediatrics use to measure gas pressure?

Answer 9

mmHg

Question 10

What is Henry’s law?

Answer 10

The amount of gas in solution depends on the partial pressure of the gas and its solubility

Question 11

What does oxygen move along the conducting zone by?

Answer 11

Bulk flow

Question 12

What does oxygen move by in the respiratory zone?

Answer 12

diffusion

Question 13

Name some factors controlling the rate of diffusion

Answer 13

area of the barrier
diffusing ability of the gas
inversely proportional to the thickness of the barrier
partial pressure difference

Question 14

What is Fick’s Law?

Answer 14

diffusion is proportional to (surface area x difference in concentration)/diffusion distance

Question 15

Name some influencing factors to diffusion

Answer 15

temperature
movement of molecules
partial pressure of the gas in the 2 areas

Question 16

What is the partial pressure of oxygen in mixed venous blood?

Answer 16

40mmHg

Question 17

What is the partial pressure of oxygen in alveoli air?

Answer 17

104mmHg

Question 18

How long does equilibration take between venous blood and alveoli air?

Answer 18

about 0.25 seconds

Question 19

Does oxygen combined with haemoglobin contribute to the partial pressure within the capillary blood?

Answer 19

NO

Question 20

What happens to oxygen once haemoglobin is saturated?

Answer 20

Oxygen collects in the plasma

Question 21

What limits transfer of oxygen at the alveoli?

Answer 21

It is perfusion limited i.e. by lack of blood supply

Question 22

What is the partial pressure of carbon dioxide in mixed venous blood?

Answer 22

45mmHg

Question 23

What is the alveolar partial pressure of carbon dioxide?

Answer 23

40mmHg

Question 24

Why does carbon dioxide reach equilibrium in the same time as oxygen despite a small gradient?

Answer 24

Carbon dioxide is more soluble

Question 25

Describe the shape of a red blood cell

Answer 25

Biconcave disc shaped

Question 26

What cellular structures does a red blood cell lack?

Answer 26

nuclei, mitochondria and ribosomes

Question 27

In what two ways is oxygen carried in the blood?

Answer 27

majority of oxygen is combined with haemoglobin Once all available haemoglobin has been saturated with oxygen, the remaining oxygen is dissolved in plasma

Question 28

Describe the structure of haemoglobin

Answer 28

2 alpha polypeptide chains 2 beta polypeptide chains each chain forms a protein subunit with single haem group

Question 29

How much oxygen does each haem group combine with?

Answer 29

1 molecule of oxygen

Question 30

How many oxygen molecules can 1 haemoglobin combine with?

Answer 30

4

Question 31

What is a saturated/fully loaded haemoglobin molecule called?

Answer 31

oxyhaemoglobin

Question 32

What is a haem group that is not combined with oxygen called?

Answer 32

deoxyhaemoglobin

Question 33

What happens to haemoglobin once the first oxygen molecule binds to a haem group?

Answer 33

Haemoglobin molecule begins to change shape, this increases the affinity of haemoglobin for oxygen and oxygen molecules 2,3 and 4 easily bind

Question 34

How do you work out the percentage of haemoglobin saturation?

Answer 34

(oxygen bound to Hb) / (Oxygen capacity of Hb) x 100

Question 35

What is the Henderson Hasselback equation?

Answer 35

water + carbon dioxide <- -> carbonic acid <- -> hydrogen ion + bicarbonate ion

Question 36

How does bicarbonate maintain the pH of blood?

Answer 36

Acts as a buffer

Question 37

What is the Bohr effect?

Answer 37

High levels of CO2 produce more hydrogen when converted to bicarbonate An excess of hydrogen ions leads to a low pH causing the blood to become more acidic In acidic environments Hb dissociates from oxygen This shifts the oxygen dissociation curve to the right

Question 38

What type of relationship do Hb and oxygen have?

Answer 38

reversible relationship

Question 39

What is carbon dioxide transported mainly as?

Answer 39

bicarbonate ions

Question 40

What is PaO2?

Answer 40

The partial pressure of oxygen dissolved in the blood and is measured in mmHg or Kpa

Question 41

What is pH?

Answer 41

An expression of the hydrogen ion concentration. A scale used to define whether a liquid is acidic or alkaline

Question 42

What is the pH of the body?

Answer 42

7.35-7.45

Question 43

What does SaO2 represent?

Answer 43

The percentage of available haemoglobin which is combined with oxygen

Question 44

What can SaO2 be analysed and measured from?

Answer 44

Directly from an arterial blood sample

Question 45

What is spO2?

Answer 45

The percentage of available haemoglobin which is saturates, but measure non invasively using a pulse oximeter

Question 46

How does a pulse oximeter measure SpO2?

Answer 46

Haemoglobin changes shape when bound to oxygen so absorbs and reflects light differently The finger probe can detect the change in the way oxyhaemoglobin and deoxyhaemoglobin absorbs and reflects light it then quantifies this

Question 47

What percentage of haemoglobin are normally saturated with oxygen in arterial blood?

Answer 47

97.5%

Question 48

What is the normal value of PaO2?

Answer 48

11-14 Kpa

Question 49

What is the normal value of SaO2?

Answer 49

>94%

Question 50

What is the normal value of SpO2?

Answer 50

>94%

Question 51

What are the advantages/purpose of pulse oximetry?

Answer 51

non invasive/painless used for continuous monitoring during treatment or exercise as an outcome measure post treatment aid exercise prescription identify the need for additional/supplementary oxygen

Question 52

What are the limitations of saturation probes?

Answer 52

limited usefulness if patient has low blood pressure, cold peripheries, hypothermia, PVD, anaemia may be low in the elderly, during sleep and with COPD the sensor is affected by movement, nicotine stains, clubbing, bruising, nail polish

Question 53

What are ABG's?

Answer 53

A diagnostic test performed on blood taken from an artery - most commonly from the wrist or the ear with some anaesthetic cream. Tested in a machine which produces the results in minutes

Question 54

What do ABG's give accurate information on?

Answer 54

pH, PaO2, SaO2 and the partial pressure of carbon dioxide in arterial blood

Question 55

What changes can result in a change to the normal levels of oxygen and carbon dioxide in the blood?

Answer 55

changes in respiratory mechanics (disorders of ventilation) and changes in the respiratory system that impedes diffusion (disorders of oxygenation) result in a change to the normal levels of oxygen and carbon dioxide in the blood

Question 56

What are some of the complications of ABG's?

Answer 56

Arteriospasm Haematoma nerve damage fainting or vasovagal response decreased blood pressure sweating

Question 57

Where do they collect arterial blood from?

Answer 57

radial (1st choice) brachial femoral