Option D.6 Transport and Respiratory Gases (AHL)

Question 1

What is the pressure of a gaseous mixture equivalent to?

Answer 1

sum of pressure of the component gases

Question 2

What is the pressure of a specific gas in a mixture called?

Answer 2

partial pressure

Question 3

What is partial pressure defined as?

Answer 3

fraction of total gas pressure exerted by particular gas

Question 4

What is a hemeoglobin composed of

Answer 4

interlocking subunits like:

• globular proteins
• non protein heme group

Question 5

What is measured on an oxygen dissociation curve?

Answer 5

affinity of haemoglobin for oxygen (measured through percentage saturation with oxygen)

Question 6

Why is the oxygen dissociation curve s-shaped?

Answer 6

• first oxygen molecule attaches with difficulty
• second combines easy
  all becomes saturated

Question 7

Why does an oxygen dissociating curve S-line showed me?

Answer 7

the amount of oxygen held by hemeoglobin depend on partial pressure of oxygen

Question 8

How does partial pressure affect our lungs?

Answer 8

• air saturated; partial pressure of component gases is different from outside

Question 9

What is the effect of CO2 on oxygen transport?

Answer 9

Bohrs effect

• increased CO2 shifts oxygen curve to right
• oxygen released more easily
• useful for tissues

Question 10

Give another example (except from indo) of a reverse of oxygen

Answer 10

MYOGLOBIN:

• found in skeleton muscles
• reserve/store used during intense muscle contraction
• higher affinity for oxygen (not hemoglobin)
• acts as oxygen store

Question 11

What happens when oxygen concentration in muscle falls?

Answer 11

oxymyglobin dissociates to supply oxygen;
allows aerobic respiration;
if reserve is used up by extended muscle contraction;
anarobic respiration

Question 12

How does a fetus obtain oxygen?

Answer 12

mother’s blood through placenta;

maternal and fetus characteristics are not similar, they do not touch;

Question 13

Do fetal and maternal blood circulation ever mix?

Answer 13

No. come very close but never mix

Question 14

Why do fetal and maternal blood circulation never mix?

Answer 14

Hemoglobins are different. Fetal hemoglobin combines with oxygen more readily at same partial pressure

Question 15

How can CO2 be transported in blood plasma?

Answer 15

• dissolved as CO2
• reversibly converted to biocarbonate ions that are dissolved; by red blood cell enzyme carbonic anhydrase
• bound to plasma proteins

Question 16

What property does blood have to keep it from being acidic?

Answer 16

hydrogen ions are buffered by plasma proteins and hemoglobins

Question 17

How is CO2 converted into hydrogen carbonate ions?

Answer 17

red blood cells and catalysed by carbonic anhydrase (enzyme); lowers pH of blood

Question 18

When is the reaction of CO2 conversion to HCO3 used?

Answer 18

in tissues, CO2 is generated; so need to be trnasported to lungs via dissolving as HCO3;

Question 19

When is the conversion of HCO3 into CO2 used?

Answer 19

In lungs, CO2 needs to leave blood; CO2 is stored as HCO3 in blood and must be converted

Question 20

What controls the rate of our ventilation?

Answer 20

respiratory control centre in medulla oblongata; two nerve cells bring about ventilation movement by reflexive action; involuntary action

Question 21

What are the two sets of nerves in our medulla oblongata?

Answer 21

intercostal nerves: rate and depth of breathing;

expiratory nerves: inhibit inspiratory centre, stimulate expiration

Question 22

Outline how breathing is controlled in body?

Answer 22

• intercostal nerves stimulate intercostal muscles of the thorax;
• phrenic nerves stimulate diaphragm;
• lungs expand, stretch receptors in chest and lung send signal to respiratory centre
• triggers cessation leading to inspiration until exhalation;
• new signal

Question 23

What is the main stimulus that affects breathing?

Answer 23

concentration of blood carbon dioxide (drop in blood pH);

Question 24

What detects changes in blood pH?

Answer 24

chemoreceptors are sensitive to pH changes and concentration of blood CO2

Question 25

What occurs when blood pH is low?

Answer 25

chemoreceptors in artery/aorta detet this;
send message to medulla oblongata (centre);
medulla sends imulse to diaphragm and intercostal muscles;
ventilation rate increased
more gas exchange

Question 26

Why is regulation of blood pH important?

Answer 26

pH of blood must stay within NARROW range of 7.35 to 7.45

Question 27

How does blood regulate pH so narrowly?

Answer 27

has buffers that help keep blood resistant to small changes of pH, include HCO3 and amino acids/proteins

Question 28

What ways can blood over come pH changes quickly?

Answer 28

Hyperventilation (removed CO2);
in kidney H+ secreted into urine bound;
tubules reabsorb HCO3 to neutralize;
HCO3 secreted into distal convulated tubule of kidney
buffers cannot remove acid/base, but minimize effect

Question 29

What are 3 major components of cigarettes?

Answer 29

Carcinogen, Nicotine and carbon monoxide

Question 30

What are carcinogens?

Answer 30

any agent that can cause cancer by damaging DNA molecules and chromosomes

Question 31

What is nicotine?

Answer 31

stimulates relaxation; cross blood brain; releases dopamine; experience of pleasure;
on long term can cause depressing ability to feel pleasure;
more nicotine needed to satisfy

Question 32

Why is carbon monoxide dangerous from smoking?

Answer 32

less oxygen transported; strain on heart circulation

Question 33

Why is passive smoking dangerous?

Answer 33

fumes have higher concentration of toxins

Question 34

What is emphysema?

Answer 34

lung condition where walls between alveoli break down (lose elasticity get holes); accumulation of macrophages; release enzymes that break more elastic fibres
become big; less surface area; less gas exchange;

Question 35

What are causes of emphysema?

Answer 35

long term exposure to tabacco smoke; air pollution (coal); damage by:

• oxidative reactions produced by high concentration of chemicals
• inflammation due to body responding to irritation
• free radical and other components of smoke diminish activity of enzymes that maintain elasticity of lungs

Question 36

How can emphysema be alleviated?

Answer 36

oxygen therapy: supplies oxygen enriched air to patient;
training breathing that
- reduces breathlessness
- improve ability of patient to exercise;
quitting smoking (prescription medicine sometimes needed to facilitate);
surgery to remove damaged lung tissue;
lung transplants also possible;
ATT proteins

Question 37

Describe use for ATT protein and how can it be manufactured?

Answer 37

found in milk from GMO sheep;
ATT is a special human blood protein;
enables us to maintain vital lung elasticity;
people with emphysema cannot produce ATT;
human gene for ATT isolated and used for cloning with promoter gene;
sheep produces human protein in milk

Question 38

Why do gaseous exchange problems arise in high altitudes?

Answer 38

partial pressure of oxygen falls;
becomes more difficult for hemoglobin in lungs to load oxygen;
percentage of saturation for hemoglobin is lowered;
chemoreceptors detect this;
respiratory system stimulates lungs to take extra deep breaths;
more CO2 lost from body; rise in pH of blood;
chemoreceptors become ineffective;
ventilation regulation is hampered

Question 39

As the body cannot adapt to high altitudes immediately, prolonged exposure can be fatal, but over time what can happen?

Answer 39

• a more alkaline urine secreted by kidney; pH of blood returns to normal; CO2 chemoreceptors become sensitive (normal ventilation)
• bone marrow tissue produced; releases more red cells; enhanced oxygen carrying capacity
• muscles produce more myoglobin to ensure delivery of oxygen to tissues
  population in high altitude have greater lung surface area