Part 1 Science - TEAS

Order of airflow through the respiratory system

Nasal cavity → Pharynx → Larynx → Trachea → Primary bronchi → Secondary bronchi → Tertiary bronchi → Bronchioles → Alveoli

Function of the nasal cavity

Warms, humidifies, and filters air using mucus and cilia.

Function of the pharynx

Common passageway for air and food.

Another name for the larynx

Voice box.

Function of the epiglottis

Prevents food from entering the trachea during swallowing.

Function of tracheal cartilage rings

Keep the airway open.

Right lung vs. left lung

Right lung: 3 lobes. Left lung: 2 lobes and a cardiac notch.

Site of gas exchange

Alveoli.

Conducting zone

Trachea, bronchi, bronchioles, and terminal bronchioles; no gas exchange.

Respiratory zone

Respiratory bronchioles, alveolar ducts, and alveoli; gas exchange occurs here.

Why is the conducting zone called anatomical dead space?

Because no gas exchange occurs there.

Function of alveoli

Oxygen enters the blood and carbon dioxide leaves the blood.

Function of red blood cells in the lungs

Pick up oxygen and release carbon dioxide.

Primary muscles of inspiration

Diaphragm and external intercostal muscles.

What happens during inspiration?

Diaphragm contracts and flattens, ribs move up and out, thoracic volume increases, pressure decreases, air flows into the lungs.

Is inspiration active or passive?

Active.

What happens during normal expiration?

Diaphragm and intercostal muscles relax, thoracic volume decreases, pressure increases, air flows out.

Is normal expiration active or passive?

Passive.

When does expiration become active?

During forced breathing, such as exercise or coughing.

Ventilation

Movement of air into and out of the lungs.

Perfusion

Flow of blood through pulmonary capillaries around the alveoli.

Ideal ventilation-perfusion relationship

Airflow and blood flow are matched for efficient gas exchange.

Hypoventilation

Too little ventilation causing ↑ CO₂ (hypercapnia) and ↓ O₂ (hypoxia).

Hyperventilation

Too much ventilation causing ↓ CO₂ (hypocapnia) and respiratory alkalosis.

How does increased CO₂ affect blood pH?

Increases H⁺ concentration, making the blood more acidic.

How does the body respond to high CO₂ levels?

The brain increases the rate and depth of breathing to restore blood pH to about 7.4.