Gas Exchange

Question 1

What 2 laws relate to gas exchange?

Answer 1

1. Dalton’s Law of Partial Pressures
2. Henry’s Law
   
   • gas solubility

Question 2

What is Dalton’s Law of Partial Pressures?
What are the percentages and pressures related to this?

Answer 2

Total pressure exerted by a mixture of gases
= sum of pressure by each gas w/in the mixture

N2 = 78% P(N2) = 597mmHg
O2 = 21% P(O2) = 160mmHg
CO2 = 0.04%
P(CO2) =0.3mmHg

Question 3

Why is Dalton’s Law of Partial Pressure important?

Answer 3

• PASSIVE exchange of gases by diffusion
• Gases flow down the concentration gradient
  [H] —> [L]
• diffusion occurs until reaching equilibrium

Question 4

What is Henry’s Law?
What 2 things affect the aspects of this law?

Answer 4

How gas dissolves in a liquid
==> gas SOLUBILITY

1. Pressure
   
   • ⬆️ P => ⬆️ Solubility
   • ⬇️ P => ⬇️ Solubilty
2. Temperature
   
   • ⬆️ Temp => ⬇️ Solubility
   • ⬇️ Temp => ⬆️ Solubility

Question 5

How does O2 transport ?

Answer 5

1. Dissolved in blood plasma
   =>1.5 %
2. Bound to Hemoglobin
   =>98.5%
   - Hemoglobin saturation depends on PO2
   - Hb + O2 => HbO2

Question 6

What is the structure of hemoglobin?

Answer 6

= 4 subunits
Subunit:
1. Heme group
- organic ring structure
- pigament
2. Iron Atom
- the middle of the heme group
- where O2 binds
3. Wrapped in Globin
- 3D protein shell where CO2 binds
- Hb + CO2 => HbCO2 Carbaminohemoglobin

Question 7

What is O2 affinity & what influence

Answer 7

Rapid & reversible
How much O2 & Hb will want to bind
Cooperative Binding
Influenced by:
- Temp
- P(CO2)
- pH
- 2,3 Biophosphoglyerate

Question 8

What is the Oxegen Hemoglobin Association/ Disacciation Curve? What does this show?

Answer 8

This is a curve showing saturation of Hb vs. P(O2)
Sigmoid curve (not linear)
Going up the curve:
- association
- loading O2 at the lungs
Going down the curve:
- disassociation
- unloading O2 at the tissues

*Shows Cooperative Binding
*Can be sat w/ O2 at a variety of atms
*Large reserve of O2 btwn 20-40 mmHg more sat then btwn 40-100mmHg
* Deoxegenated blood = 75% sat w/ O2

Question 9

What will shift the oxegen hemoglobin association right & left?

Answer 9

RIGHT Shift:
(↓ O2 affinity)
- ↑ Temp
- ↑ P(CO2)
- ↓ pH -> more acidic
- ↑ 2, 3 Biophosphoglyerate (BPG)

LEFT Shift:
(↑ O2 affinity)
- ↓ Temp
- ↓ P(CO2)
- ↑ pH -> more alkaline
- ↓ 2, 3 Biophosphoglyerate (BPG)

Question 10

Why do you sufficate for rapid transfer to higher pressures ?

Answer 10

-Partial pressure of O2 in atm becomes less than P(O2) in your body & O2 diffuses out of your blood
-P(CO2) in body also decreases and diffuses out increasing pH. and chemoreceptors don’t tell you to breath & instead decrease RR = Hypocapnia

Question 11

What is are causes of a right shift on the oxegen hemoglobin association curve?

Answer 11

Rt Shift => ↓ O2 affinity
1. Exercise
- ↑ Temp,
- ↑ products of ATP metabolism = CO2, 2,3 biophosphoglyerate (BPG)

2. thyroid hormone
   - ↑ cell metabolism => ↑ products, ↑ temp
3. Hyperthyroid
   - respiratory issues because lower O2 affinity
4. Testosterone/ Estrogen
   - ↑ cell metabolism
5. Growth Hormone
   - ↑ cell metabolism
6. Epinephrine/ Norepinephrine
   - flight or fight
   - ↑ O2 delivery to tissues
   - ↑ atp metabolism

Question 12

Where do right and left shifts in the oxegen hemoglobin association curve usually occur? Exceptions?

Answer 12

Right shift = tissues
Left shift = lungs
Exception:
- in freezing pond/ hypothermia
=> left shift shift all over
(bc ↓↓↓ temp)

Question 13

What is cooperative binding?

Answer 13

↑ sat of Hb (amt molecules bonded to Hb)
=> ↑ O2 affinity

↓ sat of Hb (amt molecules bonded to)
=> ↓ O2 affinity

1st O2 binds -> ↑ affinity
2nd O2 binds ->↑↑ affinity
3rd O2 binds-> ↑↑↑ affinity
- reversible