Exercise Physiology Knowledge check 2 (Respiration)

What is partial pressure?

The pressure exerted by an individual gas in a mixture of gases.

What is Dalton's Law?

Each gas in a mixture exerts its own pressure; the total pressure is the sum of all partial pressures.

What is the total atmospheric pressure at sea level?

Approximately 760 mmHg.

What gases contribute to atmospheric pressure?

Nitrogen, oxygen, carbon dioxide, and other gases.

What is Henry's Law?

The solubility of a gas in a liquid depends on its partial pressure and temperature.

What is an example of Henry's Law in the body?

Oxygen and carbon dioxide dissolving in the blood.

What is Boyle's Law?

At constant temperature, pressure and volume have an inverse relationship.

What happens to pressure when volume increases?

Pressure decreases.

What happens to pressure when volume decreases?

Pressure increases.

How does Boyle's Law affect breathing?

Changes in lung volume create pressure differences that move air in and out.

What happens when the diaphragm contracts?

Lung volume increases and lung pressure decreases, allowing air to enter.

What is external respiration?

Gas exchange between the lungs and blood.

What is internal respiration?

Gas exchange between the blood and body tissues.

What three factors influence gas exchange?

Membrane thickness, surface area, and pressure gradient.

How does membrane thickness affect gas exchange?

Thinner membranes allow gases to diffuse more easily.

How does surface area affect gas exchange?

Larger surface area allows more gas exchange.

How does a pressure gradient affect gas exchange?

Gases move from higher partial pressure to lower partial pressure.

How is oxygen transported through the blood?

Primarily bound to hemoglobin.

What is hemoglobin?

A quaternary protein that transports oxygen in red blood cells.

How many oxygen molecules can one hemoglobin molecule bind?

Four oxygen molecules.

Where does oxygen bind on hemoglobin?

To the iron-containing heme groups.

How is most carbon dioxide transported?

As bicarbonate ions (approximately 70%).

What enzyme helps convert carbon dioxide into bicarbonate?

Carbonic anhydrase.

How does bicarbonate help regulate acid-base balance?

It can bind hydrogen ions, helping combat metabolic acidosis.

What is cooperative binding?

Oxygen binding becomes more likely as additional oxygen molecules bind to hemoglobin.

What does the oxyhemoglobin dissociation curve show?

The relationship between oxygen partial pressure and hemoglobin oxygen saturation.

What is a-vO2 difference?

The difference in oxygen content between arterial and venous blood.

What happens to a-vO2 difference during exercise?

It increases as working tissues extract more oxygen.

Why is a-vO2 difference small at rest?

Tissues have lower metabolic demand and extract less oxygen.

What is the Bohr effect?

Increased oxygen unloading from hemoglobin due to a rightward curve shift.

What happens to the oxyhemoglobin curve when it shifts right?

Hemoglobin releases oxygen more readily to tissues.

What four factors shift the oxyhemoglobin curve right?

Decreased pH, increased temperature, increased PCO2, and increased 2,3-DPG.

What brain regions regulate breathing?

The medulla and pons.

What are the inputs that help regulate breathing?

Respiratory neurons, peripheral chemoreceptors, Hering-Breuer reflex, temperature, and central command.

What is integrated regulation of breathing?

Multiple stimuli work together to control breathing.

What controls Phase 1 of exercise breathing?

Central command and active muscles cause the initial increase in ventilation.

What happens during Phase 2 of exercise breathing?

Ventilation rises exponentially toward steady state.

What controls Phase 2 of breathing?

Central command, active muscles, and respiratory neuron input.

What controls Phase 3 of exercise breathing?

Peripheral chemoreceptors detect blood chemistry changes and fine-tune breathing.

What is VT (ventilatory threshold)?

The point where ventilation increases disproportionately during intense exercise.

When does VT occur relative to lactate threshold?

After the lactate threshold.

Why does ventilation increase at VT?

To help offset metabolic acidosis by removing CO2.

What does OBLA stand for?

Onset of Blood Lactate Accumulation.

When does OBLA occur relative to VT?

After VT as exercise intensity increases.

What happens during OBLA?

Hydrogen ions accumulate because ventilation can no longer keep up with removing them.

How does training affect the oxygen cost of breathing?

Training decreases the oxygen cost of breathing.

What percentage of cardiac output may support respiratory muscles initially in untrained individuals?

Nearly 15%.

Why does training decrease the oxygen cost of breathing?

Respiratory muscles become more efficient, leaving more blood flow available for skeletal muscles.