respiratory system week pt: 2 week #8

What muscles are responsible for deep breathing?

The diaphragm and external intercostals.

➡ Diaphragm pulls downward, external intercostals lift ribs up and out.

Which respiratory volumes are affected by deep breathing?

Tidal volume and Inspiratory reserve volume.

What does pulmonary ventilation do?

Moves air in and out of the alveoli (breathing).

What is external respiration vs internal respiration?

• External: Gas exchange between alveoli and blood.

• Internal: Gas exchange between blood and tissues.

What drives gas exchange?

Pressure gradients — gases move from high → low pressure.

What is the partial pressure of O₂ in alveoli vs blood?

• Alveoli: 104 mmHg

• Blood: 40 mmHg

  ➡ So oxygen diffuses into blood.

 What is the partial pressure of CO₂ in blood vs alveoli?

• Blood: 45 mmHg

• Alveoli: 40 mmHg

  ➡ So CO₂ diffuses out of blood.

What are the main gases in the atmosphere and their approximate percentages?

• Nitrogen (N2) is about 78.6 percent
• Oxygen (O2) is about 20.9 percent
• Water vapor (H2O) is about 0.5 percent
• Carbon dioxide (CO2) is about 0.04 percent

What carries most of the oxygen in the blood?

Hemoglobin (Hb) — forms oxyhemoglobin (HbO₂).

How many O₂ molecules can one hemoglobin carry?

Four oxygen molecules per hemoglobin.

 What % of oxygen is dissolved in plasma?

 Only ~1.5% — most is bound to hemoglobin.

What determines how easily gases dissolve?

Pressure and solubility (Henry’s Law).

What happens when pressure increases?

Gas dissolves more in liquid (like soda under pressure).

What affects hemoglobin’s oxygen binding (affinity)?

• Temperature ↑ → less binding (releases O₂)

• Acidity (low pH) ↑ → less binding (Bohr effect)

• 2,3-BPG ↑ → less binding (more O₂ released)

What is the Bohr effect?

Increased CO₂ or acidity → hemoglobin releases O₂ more easily.

Why does fetal hemoglobin grab O₂ from the mother?

It has a higher affinity for oxygen (binds tighter) due to different 2,3-BPG levels.

 How is most carbon dioxide transported in blood?

As bicarbonate ions (HCO₃⁻) — ~70%.

(Small amount dissolved or bound to hemoglobin)

What is the role of the bicarbonate buffer system?

Maintains blood pH balance by converting CO₂ into a neutral buffer.

LY What is Dalton’s Law? What is Boyle’s Law? What is Henry’s Law?

Dalton’s: Each gas in a mixture exerts its own partial pressure.

Boyle’s: Pressure and volume are inversely related — when one goes up, the other goes down.

Henry’s: The amount of gas that dissolves in a liquid depends on pressure and solubility.

 What does “PO₂ = 95 mmHg in tissues” mean?

By the time blood reaches tissues, oxygen pressure has dropped a bit from the lungs (100 → 95 → 40 mmHg at tissues).

How does exercise affect oxygen unloading?

Increased temperature and CO₂ (acidic environment) → promotes oxygen release to muscles.

What happens if pH becomes too acidic?

Hemoglobin releases oxygen faster — less binding.

What happens if body temperature drops (cold)?

Hemoglobin binds oxygen more tightly — less O₂ released to tissues.

What’s the role of 2,3-DPG?

Helps regulate O₂ release — more DPG = easier O₂ release to tissues.