Exercise Phys 2

Lec 1

What is the primary purpose of the respiratory system?

To deliver O₂ to tissues and remove CO₂ from the body.

What are the four major respiratory processes?

1. Pulmonary ventilation

2. Pulmonary diffusion (external respiration)

3. Transport of gases in blood

4. Capillary diffusion (internal respiration)

What drives gas movement in the body?

Pressure gradients (movement from high → low pressure).

Define partial pressure.

The pressure a gas would exert if it occupied the volume alone.

Boyle’s Law states:

Pressure is inversely proportional to volume (↑ volume → ↓ pressure).

Dalton’s Law states:

Total pressure = sum of individual gas partial pressures.

Henry’s Law states:

Gas dissolves in liquid proportional to its partial pressure.

Fick’s Law of Diffusion depends on what variables?

• Surface area ↑

• Partial pressure gradient ↑

• Diffusion constant ↑

• Membrane thickness ↓

What is pulmonary ventilation?

Movement of air into and out of the lungs.

What is anatomical dead space?

Conducting zone where no gas exchange occurs

List the airflow pathway.

Nose/mouth → pharynx → larynx → trachea → bronchi → alveoli

Is inspiration active or passive?

Active.

Primary muscles of inspiration?

Diaphragm and external intercostals

What happens to pressure and volume during inspiration?

Lung volume ↑, intrapulmonary pressure ↓.

Is expiration active or passive at rest?

Passive

Muscles used during forced expiration?

Internal intercostals and abdominal muscles.

What tool measures lung volumes?

Spirometry

Tidal Volume (TV)?

~0.5 L

Inspiratory Reserve Volume (IRV)?

~3.0 L

Expiratory Reserve Volume (ERV)?

~1.2 L

Residual Volume (RV)?

~1.2 L

Vital Capacity (VC)?

~4.8 L

Total Lung Capacity (TLC)?

~6.0 L

What is FEV₁?

Volume of air exhaled in the first second of forced expiration

Normal FEV₁/FVC ratio?

~85%

What does a ratio ≤70% indicate?

Obstructive lung disease (e.g., COPD)

Where does gas exchange occur in the lungs?

Alveoli and pulmonary capillaries.

What is the respiratory membrane?

Alveolar wall + capillary wall + basement membranes

Why is the respiratory membrane efficient?

Large surface area and very thin thickness.

Alveolar PO₂?

~105 mmHg

Pulmonary artery PO₂?

~40 mmHg

What drives O₂ into the blood?

A ~65 mmHg partial pressure gradient.

How does exercise improve diffusion?

Increased capillary recruitment and ventilation.

How much O₂ is bound to hemoglobin?

>98%

What is oxyhemoglobin?

Hemoglobin bound to oxygen.

What affects the O₂–Hb dissociation curve?

pH, temperature, PO₂ (Bohr effect)

What causes a rightward shift of the curve?

↓ pH, ↑ temperature → more O₂ unloading

Where is myoglobin found?

Muscle cells.

How does myoglobin differ from hemoglobin?

Higher affinity for O₂ and not affected by pH or temperature.

Why is myoglobin important?

Enhances O₂ delivery to mitochondria.

Primary form CO₂ is transported in blood?

Bicarbonate ions (60–70%).

Enzyme that converts CO₂ to bicarbonate?

Carbonic anhydrase

What is carbaminohemoglobin?

CO₂ bound to hemoglobin.

Why does CO₂ diffuse easily despite a small gradient?

CO₂ has a diffusion constant ~20× greater than O₂

Where are respiratory centers located?

Medulla oblongata and pons

Central chemoreceptors respond to what?

Increased CO₂ (via CSF pH)

Peripheral chemoreceptors detect what?

PO₂, PCO₂, and H⁺

What causes increased ventilation during exercise?

Central command + afferent feedback + chemoreceptors

External respiration?

Gas exchange between alveoli and blood

Internal respiration?

Gas exchange between blood and tissues

a–v O₂ difference represents what?

Amount of O₂ extracted by tissues