EXAM 2 - Respiratory System 2 Flashcards
Tidal Volume
- Amount of air inhaled & exhaled with each breath under normal/resting conditions
- 500ml
- TV
Inspiratory reserve volume
- Amount of aid that can be forcefully inhaled after a normal tidal volume inhalation
- 3100ml
- IRV
Expiratory reserve volume
- Amount of air that can be forcefully exhaled after a normal tidal volume exhalation
- 1200ml
- ERV
Residual Volume
- Amount of air remaining in the lungs after a forced exhalation
- 1200ml
- RV
Inspiratory Capacity (IC)
- Tidal volume + Inspiratory reserve volume (TV + IRV)
- 3100ml + 500ml
= 3600ml
Vital Capacity (VC)
- Tidal volume + inspiratory reserve volume + expiratory reserve volume
- TV + IRV + ERV
- 3100 + 500 + 1200
= 4800ml
Functional Residual Capacity (FRC)
Expiratory reserve volume + residual volume (ERV + RV)
= 1200 + 1200 ml
= 2400 ml
Total lung capacity (TLC)`
All volumes added up
= 6000ml
Spirometry
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
How is Oxygen Transported in Blood (2)
- Bound to the hemoglobin of RBC’s (98.5%)
- Dissolved in plasma (1.5%)
How Blood is transported by hemoglobin
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
Influence of PO2 on hemoglobin Saturation
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
Why is there an S-Shaped curve
- 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
Factors affecting Hemoglobin saturation (5)
- PO2 MAIN ONE More PO2, curve moves to the LEFT
- PCO2
- Temperature
- pH
- 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
Transport of CO2 by Blood (3)
- Diffused in plasma (7-10%)
- Chemically bounded to hemoglobin (105)
carbaminohemoglobin (cause it binds to globin protein chain, not actual heme - 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-
How does bicarbonate ion leave RBC into plasma
CHLORIDE SHIFT:
outrush of HCO3 – from the RBCs is balanced as Cl– moves in from the plasma
Carbonic acid–bicarbonate buffer system
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
Neural controls of respiration
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
Factors influencing rate & depth of breathing (5)
- Arterial pH
- Arterial PCO2
- Arterial PO2
- Reflexes
- Higher brain centres
Chemical factors (top 3 factors) = most important
PCO2 = most influential
Hyperventilation
Hyperventilation: Breathing that is deeper & faster than necessary for normal gas exchange (more CO2 exhaled than normal)
- Decrease in CO2 = Decreases H+ availability = Increase in pH
- Low CO2 = Central chemoreceptors send fewer impulses to respiratory centres
- High pH - Peripheral chemoreceptors send fewer impulses to respiratory centres
- Respiratory centres –> send fewer impulses to respiratory muscles
- Breathing rate & depth decrease, returns arterial gases and pH to normal
Hypoventilation
Hypoventilation: When breathing rate & depth are too low to maintain normal blood gas levels. (not enough CO2 exhaled)
