The Respiratory System

What is a conducting zone?

brings air in and out of the lungs

What is the respiratory zone?

where gas exchange occurs

What is pulmonary ventilation?

movement of air into and out of the lungs

What is external respiration?

exchange of O2 and CO2 between lungs and blood

What is circulatory transport?

of O2 and CO2 in the blood

What is internal respiration?

exchange of O2 and CO2 between blood and tissues

What is the roof of the nose formed from?

formed by the ethmoid and sphenoid bones

What is the floor of the nose formed by?

formed by the hard palate and the soft palate

What can infected adenoids cause?

blockage in air passageway in the nasopharynx causing the air to not be warmed, moistened and filtered before reaching the lungs

What are vocal ligaments?

form core of vocal folds (true vocal cords) and contain elastic fibers that appear white because of a lack of blood supply.

How is speech produced?

The intermittent release of expired air during opening and closing of glottis - pitch is determined by tension and length of vocal cords and loudness is determined by force of air.

What does the alveolar sac contain?

Clusters of alveoli where gas exchange occurs.

Where does the respiratory zone begin?

at the terminal bronchioles and includes the respiratory bronchioles, alveolar ducts, and alveolar sacs where gas exchange takes place.

What is thyroid cartilage?

Large, shield-shaped cartilage that resemble an upright open book.

How are lungs perfused?

Via two circulation systems: pulmonary and systemic.

What is the upper respiratory system?

The structures from the nose to the larynx that filter, warm, and humidify incoming air.

What is the lower respiratory system?

Includes the larynx, airways and alveoli that facilitate gas exchange and deliver oxygen to the bloodstream.

What does the pharynx connects?

the nasal cavity and the mouth

What is the function of the nose in respiration?

The nose filters, warms, and moistens air; provides sense of smell and resonance for speech.

Where are the paranasal sinuses located and what do they do?

Located in frontal, sphenoid, ethmoid, and maxillary bones; they lighten the skull, produce mucus, and enhance voice resonance.

What are the three parts of the pharynx and their functions?

Nasopharynx (air only), oropharynx and laryngopharynx (air and food); all aid in respiration, swallowing, and speech.

What structures are part of the conducting zone?

Nose to terminal bronchioles; includes nasal cavity, pharynx, larynx, trachea, bronchi, and bronchioles

What structures are part of the respiratory zone?

Respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.

What is the main function of the respiratory zone?

Gas exchange between air and blood.

What are the functions of the larynx?

Air passageway, prevents food entry (via epiglottis), and voice production.

What keeps the trachea open and what is its function?

C-shaped cartilage rings; conduct air to lungs, lined with cilia to trap particles.

How do bronchi function in respiration?

Distribute air to each lung and branch into smaller airways for airflow regulation.

What makes up the respiratory membrane?

Alveolar epithelium, fused basement membranes, and capillary endothelium.

Why is the respiratory membrane structure ideal for gas exchange?

It’s extremely thin and has a large surface area to allow rapid diffusion of gases.

How many lobes do the lungs have?

Right lung has 3 lobes, left lung has 2 lobes (and a cardiac notch).

What are the pleurae and their function?

Serous membranes (visceral and parietal) that reduce friction and keep lungs inflated via surface tension.

Why is the partial vacuum in the intrapleural space important?

It prevents lung collapse by maintaining negative pressure relative to alveolar pressure.

How does Boyle’s Law explain breathing?

As thoracic volume increases (inspiration), pressure decreases → air flows in; opposite for expiration.

Which muscles are involved in normal inspiration?

Diaphragm and external intercostals.

What causes expiration at rest?

Passive elastic recoil of lungs and thoracic cage

What is tidal volume (TV)?

Amount of air inhaled or exhaled in a normal breath (~500 mL).

What is residual volume (RV)?

Air remaining in lungs after forced expiration (~1200 mL).

What is vital capacity (VC)?

TV + IRV + ERV — total air that can be exhaled after a full inhale (~4800 mL).

What is total lung capacity (TLC)?

VC + RV — maximum air the lungs can hold (~6000 mL).

How does alveolar air differ from atmospheric air?

It has less O₂ (~13%) and more CO₂ (~5–6%) due to gas exchange and mixing with residual air.

What does Dalton’s Law state and how does it apply to respiration?

Total pressure = sum of partial pressures; O₂ and CO₂ move based on their pressure gradients.

What does Henry’s Law state?

Gas dissolves in liquid proportionally to its partial pressure and solubility — CO₂ dissolves more easily than O₂.

How is most oxygen transported in the blood?

Bound to hemoglobin (98.5%) as oxyhemoglobin.

What factors increase O₂ unloading from hemoglobin?

↑ Temp, ↓ pH, ↑ CO₂, ↑ BPG — these cause a right shift in the dissociation curve.

What are the three forms of CO₂ transport in blood?

Bicarbonate ions (70%), carbaminohemoglobin (20%), dissolved in plasma (10%).

What is the chloride shift?

Exchange of Cl⁻ and HCO₃⁻ to maintain charge balance during CO₂ transport.

What part of the brain controls respiratory rhythm?

Medulla oblongata (VRG & DRG) and pons (pontine respiratory group)

What do chemoreceptors monitor to regulate breathing?

Central chemoreceptors detect CO₂ and pH; peripheral detect O₂, CO₂, and pH.

What is hyperpnea?

Increased breathing during exercise that matches metabolic demand (normal CO₂ levels)

What is hyperventilation?

Breathing in excess of demand → decreased CO₂ → respiratory alkalosis.

What happens initially when exposed to high altitude?

Increased ventilation and respiratory alkalosis.

What are long-term adaptations to high altitude?

increased EPO → more RBCs, increased BPG, angiogenesis, and more mitochondria/myoglobin in tissues.