EXAM 2 - Respiratory System 2

Question 1

Tidal Volume

Answer 1

• Amount of air inhaled & exhaled with each breath under normal/resting conditions
• 500ml
• TV

Question 2

Inspiratory reserve volume

Answer 2

• Amount of aid that can be forcefully inhaled after a normal tidal volume inhalation
• 3100ml
• IRV

Question 3

Expiratory reserve volume

Answer 3

• Amount of air that can be forcefully exhaled after a normal tidal volume exhalation
• 1200ml
• ERV

Question 4

Residual Volume

Answer 4

• Amount of air remaining in the lungs after a forced exhalation
• 1200ml
• RV

Question 5

Inspiratory Capacity (IC)

Answer 5

• Tidal volume + Inspiratory reserve volume (TV + IRV)
• 3100ml + 500ml
  = 3600ml

Question 6

Vital Capacity (VC)

Answer 6

• Tidal volume + inspiratory reserve volume + expiratory reserve volume
• TV + IRV + ERV
• 3100 + 500 + 1200
  = 4800ml

Question 7

Functional Residual Capacity (FRC)

Answer 7

Expiratory reserve volume + residual volume (ERV + RV)
= 1200 + 1200 ml
= 2400 ml

Question 8

Total lung capacity (TLC)`

Answer 8

All volumes added up
= 6000ml

Question 9

Spirometry

Answer 9

Common test –> inspire maximally, and then force air out as quickly as possible

• FVC (forced vital capacity) = amount of gas forcibly expelled after taking a deep breath
• Forced expiratory volume (FEV) = amount of gas
  expelled during specific time interval of FVC
• EXMAPLE: FEV1 –> amount of air expelled in 1st second

Question 10

How is Oxygen Transported in Blood (2)

Answer 10

1. Bound to the hemoglobin of RBC’s (98.5%)
2. Dissolved in plasma (1.5%)

Question 11

How Blood is transported by hemoglobin

Answer 11

Binds to the iron molecule within the heme group - 4 x heme groups within a hemoglobin (so when fully saturated, can carry max. 4 O2 molecules)

Oxyhemoglobin (HbO2)
Deoxyhemoglobin (HHb)
HHb + oxygen = (lungs/tissues) = HbO2 + H+

As O2 binds, Hb changes shape, increasing its
affinity for O2 increases
* As O2 is released, Hb shape change causes a
decrease in affinity for O2

Question 12

Influence of PO2 on hemoglobin Saturation

Answer 12

oxygen-hemoglobin dissociation curve
- S-shaped curve

WHy S-Shaped?
- As O2 binds, Hb changes shape, increasing its affinity for O2 increases
- As O2 is released, Hb shape change causes a decrease in affinity for O2

Question 13

Why is there an S-Shaped curve

Answer 13

• Lungs have a high PO2 compared to tissues, so Hb fuses with oxygen quicker at lungs
• The closer the haemoglobin get to the tissues, the less the partial pressure and the quicker they start to unload (drops O2 off faster @ tissues)
• As O2 binds, Hb changes shape, increasing its affinity for O2 increases
• As O2 is released, Hb shape change causes adecrease in affinity for O2

Question 14

Factors affecting Hemoglobin saturation (5)

Answer 14

1. PO2 MAIN ONE More PO2, curve moves to the LEFT
2. PCO2
3. Temperature
4. pH
5. BPG

MOVING CURVE TO THE RIGHT (not as steep): THINK EXERCISE
- increase in body temp
- decrease in pH (more acidic)
- Increase in PCO2
- Higher BPG

Question 15

Transport of CO2 by Blood (3)

Answer 15

1. Diffused in plasma (7-10%)
2. Chemically bounded to hemoglobin (105)
   carbaminohemoglobin (cause it binds to globin protein chain, not actual heme
3. In plasma as bicarbonate ion (70%

CO2 + H2O ⇔ H2 CO3 ⇔ H+ + H CO3 –

Bicarbonate goes to lungs, then equation is reversed
- Carbonic anhydrase used to catalise first bit of reaction.
- because carbonic acid is very unstable, it quickly dissociates into H+ and HCO3-

Question 16

How does bicarbonate ion leave RBC into plasma

Answer 16

CHLORIDE SHIFT:
outrush of HCO3 – from the RBCs is balanced as Cl– moves in from the plasma

Question 17

Carbonic acid–bicarbonate buffer system

Answer 17

If H+ concentration in blood rises:
- excess H+ removed by combining with HCO3 to form carbonic acid,
which dissociates into CO2 and H2O

If H+ concentration begins to drop, carbonic acid dissociates, releasing H+
* HCO3– is considered the alkaline reserve of carbonic acid-bicarbonate buffer system

Question 18

Neural controls of respiration

Answer 18

Lungs have receptors –> Impulses sent via Vagus nerves TO respiratory centres
- Breathing normally regulated by RC involunatrily

HYPOTHALAMIC CONTROL: Respiratory rate & depth –> modified by emotions, pain & temperature

CEREBRAL MOTOR CORTEX–> conscious control over breathing

Pons & Medulla

Question 19

Factors influencing rate & depth of breathing (5)

Answer 19

1. Arterial pH
2. Arterial PCO2
3. Arterial PO2
4. Reflexes
5. Higher brain centres

Chemical factors (top 3 factors) = most important
PCO2 = most influential

Question 20

Hyperventilation

Answer 20

Hyperventilation: Breathing that is deeper & faster than necessary for normal gas exchange (more CO2 exhaled than normal)

1. Decrease in CO2 = Decreases H+ availability = Increase in pH
2. Low CO2 = Central chemoreceptors send fewer impulses to respiratory centres
3. High pH - Peripheral chemoreceptors send fewer impulses to respiratory centres
4. Respiratory centres –> send fewer impulses to respiratory muscles
5. Breathing rate & depth decrease, returns arterial gases and pH to normal

Question 21

Hypoventilation

Answer 21

Hypoventilation: When breathing rate & depth are too low to maintain normal blood gas levels. (not enough CO2 exhaled)