Body Systems L20 Flashcards

1
Q

Describe what gases are transported from which systems / organs in the blood. (Major 2 paths)

A

• Transportation of Gas:
- O2 -> Alveoli to systemic tissues
- CO2 -> Systemic tissues to alveoli
Via Transportation -> Blood.

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2
Q

Describe the features required for efficient gas exchange in the blood

A
•	Gas Transportation -> Blood:
-	Diffusion 
 Surface area 
    >> Large 
    >> Moist 
 Diffusion distance
    >> Short
 Conc. gradient / Diff. -> Partial pressure
    >> Alveolar air & blood
 Solubility of gases
 Coordination -> Blood & Air flow
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3
Q

What are the partial pressures of N2 in the lungs alveoli & pulmonary veins?

A
-	Atmosphere
	N2 -> 78.6% -> 597mmHg
-	Alveoli
	N2 -> 75.4% -> 573mmHg
-	Pulmonary Veins
	N2  -> 12.5 ml/L
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4
Q

What are the partial pressures of O2 in the lungs alveoli & pulmonary veins?

A
-	Atmosphere
	O2 -> 20.9% -> 159mmHg
-	Alveoli
	O2 -> 13.2% -> 100mmHg
-	Pulmonary Veins
	O2 -> 3 ml/L
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5
Q

What are the partial pressures of CO2 in the lungs alveoli & pulmonary veins?

A
-	Atmosphere
		CO2 -> 0.04% -> 0.3mmHg
-	Alveoli
	CO2 -> 5.2% -> 40mmHg
-	Pulmonary Veins
	CO2 -> 26 ml/L
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6
Q

What is the partial pressures of water in the atmoshpere vs. the alveoli of the lungs?

A

Atmoshpere
 H2O -> 0.46% -> 3.7mmHg
Alveoli
 H2O -> 6.2% -> 47mmHg

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7
Q

What is Dalton’s Law?

A

• Dalton’s Law of Partial Pressure:

 Total pressure exerted by mixture of gases = Sum of pressures exerted independently by each gas in mixture.

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8
Q

What is the partial pressure (Dalton’s Law)

A

 Partial pressure
 Pressure exerted by each gas
 Directly proportional to % in total gas mixture
Eg. Partial pressure of O2 -> Sea Level
&raquo_space; 20.9% of gases at sea level
&raquo_space; Atmospheric pressure = 760mmHg
-» 20.9 x 760 = 159mmHg (Partial Pressure)

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9
Q

Describe the relationship between atmospheric pressure & altitude

A

• Atmospheric pressure decr. with incr. altitude above sea level.

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10
Q

What are the partial pressures found in the capillaries & alveoli in the pulmonary circuit?

A
-	Pulmonary Circuit:
>> External Respiration 
	Capillary: 
P(O2) = 40
P(CO2) = 45 
	Alveolus:
P(O2) = 100
P(CO2) = 40
	Capillary :
P(O2) = 100
P(CO2) = 40
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11
Q

What are the partial pressures found in the capillaries & alveoli in the systemic circuit?

A
-	Systemic Circuit:
>> Internal Respiration
	Capillary: 
P(O2) = 95
P(CO2) = 40
	Tissues:
P(O2) = 40
P(CO2) = 45
	Capillary :
P(O2) = 40
P(CO2) = 45
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12
Q

What is Henry’s Law?

A

• Henry’s Law:
- The amount of gas that dissolves in water determined by
 Solubility in water
 Partial pressure in air

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13
Q

Describe the conditions of equilibrium of Henry’s Law

A
  • At equilibrium:
     Vol. -> Dissolved gas in solution proportional to partial pressure of gas.
    Eg. Incr. P(Gas) -> Incr. # gas molecules in solution
    Incr. P(O2) -> Incr. amount of O2 in solution.
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14
Q

Outline the gas diffusion requirements of the human body

A
•	Gas Diffusion Requirements:
-	At alveolar P(O2) -> (100mmHg)
	1L plasma dissolves 3ml O2
	Blood Flow -> Tissues = 5 L/min
                     >> 15 ml/min O2
-	Requires >200 ml/min (200-3000 ml/min)
-	1 L blood -> 195ml O2
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15
Q

Describe the structure of Haemoglobin

A
•	Haemoglobin:
-	4 globular protein subunits
>> 2 alpha 
>> 2 Beta
-	Each subunit 
>> Protein -> Globin
>> Non-protein group -> Haem
                                             --> Fe2+ -> Porphyrin ring
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16
Q

State the reaction which occurs at haemoglobin & 2 properties of this reaction

A

Hb + O2 HbO2
Hb -> Deoxy-haemoglobin ; HbO2 -> Oxyhaemoglobin
&raquo_space; Rapid & reversible

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17
Q

How many oxygen molecules does each Hb molecule bind with?

A
  • Each haem portion -> Haemoglobin

 Binds -> 4 molecules -> O2

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18
Q

Describe the different ways in which oxygen is transported in the blood & the proportions of oxygen transported by these methods.

A

• Transportation of O2:

  • Approx. 97% O2 transported in Blood -> Using Hb
  • Remaining 3% O2 transported in Blood -> Plasma
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19
Q

Describe the uptake of O2 by haemoglobin and what this causes.

A

 Hb changes shape upon binding with O2
&raquo_space; Enables further uptake of O2 -> Positive Feedback
&raquo_space; Binding of O2 mol. to Hb cause change in shape of Hb
> Enables easier successive binding of O2 to Hb.
&raquo_space; As max. limit of O2 binding approaches, affinity decreases.

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20
Q

What is Hb saturation?

A

 Hb Saturation:

 % of haem units per Hb mol containing bound O2

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21
Q

What is Hb saturation affected by?

A
 Affected by:
>> Partial pressure O2  - > P(O2) -> Blood
>> Blood pH
>> Temperature
>> No. of O2 mol. already bound -> haem 
      ---> O2 dissociation Curve
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22
Q

What is the oxygen dissociation curve?

A

 O2 Dissociation (Saturation) Curve

 Graph illustrating Saturation of Hb in relation to P(O2) in blood

23
Q

Describe the shape of the oxygen dissociation curve?

A
Steep portion of curve
    >> Range ->  % saturation within systemic capillaries. 
       > 75 – 100% saturation
         -->> P(O2) ~ 40mmHg 
    >> 100% sat. of Hb within alveoli

Steep rise followed by plateau

24
Q

List the factors which influence the affinity of Hb for O2?

A

 Factors influencing affinity for O2:
% saturation & affinity of Hb for O2:
&raquo_space; Increases with each successive binding of O2 to Hb
&raquo_space; Increases with incr. P(O2)
» Partial pressure O2 - > P(O2) -> Blood
» Blood pH
» Temperature
» No. of O2 mol. already bound -> haem

25
Q

Describe the affinity of Hb for O2 in relation to pH

A

> > Decr. with incr. pH
> Incr. pH (incr. H+ conc.) alters ionic bonds -> protein structure of Hb
> Changes shape of Hb
-> Less able to bind -> O2

26
Q

Describe the affinity of Hb for O2 in relation to CO2

A

> > Decr. with incr. p(CO2)
> Incr. CO2 causes incr. acidity of blood
-> Incr. pH -> change in shape -> proteins of Hb
-> Less able to bind -> O2

27
Q

Describe the affinity of Hb for O2 in relation to temperature

A

> > Decr. affinity with incr. temperature
> Incr. temperature denatures bonds within Hb
> Changes shape of Hb
-> Less able to bind -> O2

28
Q

Describe the Bohr shift in relation to pH & CO2 (unloading of O2 to tissues)

A
Unloading of O2 -> Tissues
   >> Incr. pH & Incr. CO2
o	Curve shifts   -->
>> Bohr Shift 
>> Incr. efficiency of unloading
>> Higher % saturation at lower P(O2)
29
Q

Describe the Bohr shift in relation to the temperature(unloading of (O2 to tissues)

A

> > Incr. temperature
- Higher -> Active tissues
- Incr. 2,3 diphosphoglycerate (2,3-DPG) -> Anaerobic conditions
o Curve shifts –>
Bohr Shift
Incr. efficiency of unloading
Higher % saturation at lower P(O2)

30
Q

Describe the effect of altitude on breathing / o2 as altitude increases

A
•	Altitude & Oxygen Transportation:
 High Altitude:
             Faster, deeper breathing
         V. High Altitude:
             Hypoxia -> V. low blood O2 conc
          Extreme:
             Foggy Brain, Weak muscles.
31
Q

What factors change as altitude increase in relations to gas exchange?

A
	Changes:
>> Arterial Mean P(O2)
>> O2 saturation 
>> Haemoglobin conc
>> O2 content
32
Q

Name the types of haemoglobin

A

Carboxyhaemoglobin
Methaemoglobin
Foetal haemoglobin

33
Q

Describe carboxyhaemoglobin

A
  • Carboxyhaemoglobin:
     Stronger binding -> CO
    » (200x greater)
     Greatly reduces ability of O2 binding to Hb
34
Q

Describe methaehaemoglobin

A
-	Methaemoglobin:
	Fe2+ oxidised -> Fe3+
>> Drugs
	Unable to carry O2
>> Slow reconversion
35
Q

Describe foetal haemoglobin

A
-	Foetal haemoglobin:
	2 alpha & 2 ץ
	Higher affinity -> O2
	Important -> O2 transfer across placenta
	Higher % saturation at lower P(O2)
36
Q

How and where is CO2 produced in the body?

A
  • Generated -> Aerobic metabolism -> Peripheral tissues
37
Q

Name the methods in which CO2 is transported in the blood & what proportion of CO2 is transported in each

A

70% -> bicarbonate ion -> plasma
23% -> bound ->Haemoglobin
7% dissolves -> plasma

38
Q

Describe the most common transportation method of CO2 in the blood

A
  1. 70% converted -> carbonic acid formation -> H2CO3-
    &raquo_space; Carbonic anhydrase enzyme
    -> Transported in plasma -> Bicarbonate ion HCO3-
    &raquo_space; CO2 + H2O -> H2CO3
    H2CO3 -> H+ & HCO3-
    -> Chloride shift
    &raquo_space; HCO3- moves out RBCs & replaced by Cl -
39
Q

Describe the transportation of CO2 in the blood using Hb

A

. 23% Bound -> Haemoglobin
-» Carbahameoglobin
&raquo_space; Hb-(NH2) + CO2  Hb-(NHCOOH)
-> Carbamino group

40
Q

Describe the least common method of transportation of CO2 in the blood

A

. 7% dissolved -> Plasma

41
Q

Describe the chloride shift

A

-> Chloride shift
&raquo_space; HCO3- moves out RBCs & replaced by Cl -

-> Bicarbonate ion (formed as result of carbonic anhydrase reaction with carbonic acid)

42
Q

Write the equation for formation of bicarbonate ions for transportation of CO2 in the blood

A

> > CO2 + H2O -> H2CO3

H2CO3 -> H+ & HCO3-

43
Q

What kind of ion is CO2 transported as in the blood?

A

Bicarbonate

44
Q

What is the name of the complex formed when CO2 is transported using haemoglobin

A

-» Carbahameoglobin

45
Q

What is the equation for the formation of a carbamino group involved in transportation of co2 in the blood/

A

> > Hb-(NH2) + CO2  Hb-(NHCOOH)

46
Q

Describe buffering in RBCs

A

• Buffering in RBCs:
- Every CO2 -> HCO3- reaction yields H+
» Leads to acidic pH
- Consumption / release of H+ minimises incr. pH
» Imidazole groups of histidine residues in haemoglobin
-> Act as buffers.
&raquo_space; Hb-(N)-(NH) + H+  Hb-(N)-(NH2+)
- Deoxygenated Hb -> Strongest affinity for H+

47
Q

What is the purpose of releasing H+ in the buffering of RBCs?

A
  • Consumption / release of H+ minimises incr. pH
    » Imidazole groups of histidine residues in haemoglobin
    -> Act as buffers.
48
Q

Write the equation for formation of Imidazole groups of histidine residues in haemoglobin

A

> > Hb-(N)-(NH) + H+  Hb-(N)-(NH2+)

49
Q

What kind of Hb has the strongest affinity for H+?

A
  • Deoxygenated Hb -> Strongest affinity for H+
50
Q

Describe the Haldane effect in the lungs

A
•	Haldane Effect:
-	Lungs:
	Oxygenation of Hb
>> Conformational change -> Hb
	Lower affinity -> H+
>> Decr. buffering ability 
	H+ released
>> Aids in unloading of O2 -> lungs
51
Q

Describe the Haldane effect in the tissues.

A
-	Tissues:
	Deoxygenation of Hb
>> Conformational change -> Hb
	Higher affinity -> H+
>> Incr. buffering ability
	Uptake of H+
	Transportation of CO2 from tissues
52
Q

What is the name of the molecule formed as a result of incr. temperature & active tissues?

A

. 2,3 diphosphoglycerate (2,3-DPG)

53
Q

In what conditions does formation of 2.3 diphosphoglycerate occur?

A

> > Incr. temperature

                                - Higher -> Active tissues
                                - Incr. 2,3 diphosphoglycerate (2,3-DPG) -> Anaerobic conditions