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Cardio-respiratory Studies 1 > Scenario 5 - Respiration > Flashcards

Scenario 5 - Respiration Flashcards

(51 cards)

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1
Q

what are the two types of alveolar cells? what do they do?

A

Type I cells - squamous pulmonary epithelium - form continuous lining of wall - MAIN SITE OF GAS EXCHANGE

Type II (Septal) Cells - between the type I cells - rounded cuboidal epithelium - free surfaces contain microvilli - SECRETE ALVEOLAR FLUID

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2
Q

What is the alveolar fluid?

A

keeps the surface between the cells, and the air, moist

produce surfactant - that maintains airway patency

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3
Q

what are the alveolar macrophages?

A

found within the wall of the alveolus - phagocytose fine dust and other debris

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4
Q

what is the role of fibroblasts in the alveolar wall?

A

production of reticular and elastic cells

under the type I pnuemocytes to produce the elastic basement membrane

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5
Q

What is the respiratory membrane?

A

where gaseous exchange occurs

  1. alveolar wall (type I and II pneumocytes, macrophages)
  2. epithelial basement membrane of the alveoli
  3. capillary basement membrane (usually fused with (2))
  4. capillary endothelium
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6
Q

What is the pore of Kohn?

A

collateral ventilation between the alveoli

inter-alveolar

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7
Q

what is the Channel of martin?

A

interbronchiolar colateral ventilation

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8
Q

what is the channel of Lambert?

A

bronchioalveolar colateral ventilation

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9
Q

what factors effect the rate of gaseous exchange

A 
Concentration gradient determined by:
- partial pressure gradient
- solubility of the gases
Surface area
respiratory membrane thickness
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10
Q

What is the effect of solubility of a gas on rate of exchange?

A

if dissolved in water, diffusion is more efficient

so more soluble = faster diffusion across the respiratory membrane

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11
Q

what is the percentage of nitrogen in:

(i) dry air
(ii) alveolar air

A

(i) 79%

(ii) 75%

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12
Q

what is the percentage of oxygen in:

(i) dry air
(ii) alveolar air

A

(i) 21%

(ii) 14%

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13
Q

what is the percentage of carbon dioxide in:

(i) dry air
(ii) alveolar air

A

(i) 0.04%

(ii) 5.3%

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14
Q

what is the percentage of water vapour in:

(i) dry air
(ii) alveolar air

A

(i) 0

(ii) 6.2%

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15
Q

What is the partial pressure of oxygen in the alveoli?

A

13.3 kPa

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16
Q

what is the partial pressure of carbon dioxide in the alveoli

A

5.3 kPa

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17
Q

how is oxygen transported?

A

mainly through binding to haemoglobin

1.5% disolved in plasma

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18
Q

what effects oxygen binding to haemaglobin

A

partial pressure of oxygen

  • when PO2 is high - in the lungs - O2 binds to Hb
  • when PO2 is low - in the respiring tissues - O2 dissociates from oxyHb
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19
Q

what does haemoglobin saturation mean?

A

the amount of haemoglobin with O2 bount

i.e. when Hb is low saturated - not a lot of O2 is bound to Hb

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20
Q

What is affinity of Hb?

A

the tightness with which Hb binds O2
i.e. high affinity - more tightly bound to O2
low affinity - O2 is released more readily

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21
Q

what does an oxygen dissociation curve show?

Study These Flashcards
A

how saturated Hb is at different partial pressures of O2

so when PO2 is low, such as in deoxygenated blood - Hb is not very saturated

when PO2 is high - eg. oxygenated blood in systemic circulation, saturation of Hb is high

22
Q

what is the effect of acidity on the oxygen dissociation curve?

Study These Flashcards
A

when pH decreases - suggests CO2 in the blood is high

causes Hb affinity for O2 to decrease - so O2 is released more readily

CURVE SHIFTS TO RIGHT

23
Q

what is normal pH?

24
Q

how does the shift caused by acidity help to return pH to normal?

Study These Flashcards
A

oxy-Hb becomes deoxy-Hb - releasing oxygen

in the process, the oxygen binding site is replaced by binding of H+ ions - thus removing them from circulation and increasing pH

25
What is the effect of haemaglobin binding CO2?
causes affinity for O2 to decrease - O2 dissociates more readily. CURVE SHIFTS RIGHT
26
why would there be a high concentration of H+ ions in circulation?
when CO2 is high, it reacts with H20 in the RBCs forming H2CO3 - which is unstable and forms H+ and HCO3- HCO3- remains in RBC H+ moves out into the blood
27
what is the effect of temperature on oxygen dissosiation?
increased temp - faster chemical reactions - more metabolic products - decreased pH - more O2 disossiation CURVE SHIFTS RIGHT
28
What is the effect of BPG on oxygen dissosiation?
BPG formed by RBCs during glycolysis binds to the beta globin chain go Hb decreases affinity for O2 - more O2 released CURVE SHIFTS RIGHT
29
What would cause the oxygen dissosiation curve to shift lefT?
high pH, low temperature, low [BPG]
30
what causes the Bohr Shift?
O2 dissosiates readily from Hb at higher PO2 due to acidity or high concentration of CO2.
31
what are the main ways that CO2 is transported?
Disolved in plasma (7%) Carboamino compounds (i.e. bound to Hb) - 23% As bicarbonate ions (70%)
32
how is carbon dioxide transported as carboamino compounds
CO2 binds to the terminal alpha and beta chains of Hb particularly when PCO2 is high
33
How is CO2 transported as bicarbonate ions?
CO2 + H2O --> H2CO3 --> H+ and HCO3- mainly carried in the RBC as HCO3- some HCO3- diffuses out in exchange with Cl- (THE CHLORIDE SHIFT) to be transported in plasma
34
what is the Haldane effect?
the more oxy-Hb in the circulation, the lower the carrying capacity for CO2 if there is high deoxy-Hb, it can: - bind more CO2 - bind more H+ ions by binding H+, increases the concentration gradient between RBC and blood - so more H+ can be formed from CO2 in the RBC NET EFFECT - when oxygen levels are low, ability to transport carbon dioxide is higher.
35
what is daltons law?
determines partial pressure | a gas exerts its own pressure in a mixture of gases as if no other gases were present
36
what is the rhythm for normal breathing?
2 second burst for inspiration and 3 second relaxation for exhilation
37
where is the inspiratory burst initiated?
DRG - sends impulses to diaphragm via phrenic nerve & sends impulses to external intercostals via intercostal nerves VRG acts as a pacemaker - sending signals to the DRG to initiate inspiration
38
where are the DRG and VRG found
in the medullary respiratory centre
39
what is the role of the VRG
pacemaker to DRG in quiet breakting send impulses to accessory muscles in forceful inhalation and in forced exhalation when DRG is not firing
40
where is the pneumotaxic centre and what is its role?
within the Pons transmit impulses to the DRG in normal breathing Modifies the basic rhythm formed by the VRG during complex breathing - e.g. exercise, speaking, sleeping
41
what is the role of the apneustic centre
increases the length of inspiration when talking by feeding back to DRG - to cause forced inhalation, and VRG to activate accessory muscles.
42
what is the role of chemoreceptors?
detect pH of the blood - if low, then CO2 must be high input to VRG - causing forced exhalation to blow off more CO2
43
where are the central chemoreceptors?
within the medulla - CO2 diffuses into CSF - effects pH - central chemoreceptors feed to VRG directly 80% of response to high CO2
44
where are the peripheral chemoreceptors
in the carotid and aortic bodies
45
how do the peripheral chemoreceptors respond?
monitor pH, O2 and CO2 Carotid body --> glossopharangeal nerve --> DRG Aortic body --> vagus nerve --> DRG
46
what is the role of stretch mechanoreceptors?
found in smooth bronchiole walls detect stretching to prevent over inflation of the lungs feed back to DRG via vagus nerve - causing shorter and shallower breathing
47
what is the role of J receptors?
found in alveolar and bronchiole walls respond to lack of movement in the alveoli or bronchi feed back to DRG via vagus nerve increase rate and depth of breathing
48
what is the role of proprioceptors?
within all respiratory muscles except the diaphragm detect the position and length of the muscles - feed back to DRG to increase rate of breathing if the muscles are excessively stretched - i.e. in exercise
49
what is the role of cortical control in breathing
higher centres detect anxiety, talking exercise etc. input to the pons to modulate breathing
50
what is VO2?
oxygen consumption the amount of oxygen being used by the tissues per minute
51
what is DO2?
oxygen delivery the amount of oxygen being delivered to the tissues per minute

Cardio-respiratory Studies 1 (5 decks)

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