ANP Chapter 22: Respiratory system

Name the organs of the upper respiratory system and lower respiratory system

Upper respiratory system:
nose, nasal cavity, paranasal sinuses, pharynx

Lower respiratory system:
larynx, trachea, bronchi, bronchioles, lungs, alveoli

Which organs compose the conducting zone and respiratory zone? What are the general functions?

Conducting zone:
nose, pharynx, larynx, trachea, bronchi, bronchioles up to the terminal bronchioles

Functions:
transports air, filters/cleans air, warms air, humidifies air

Respiratory zone:
respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli

Function:
gas exchange

Trace a molecule of oxygen through the respiratory organs and structures as it is inhaled and trace carbon dioxide as it exits.

Oxygen in:
nose/nostrils → nasal cavity → pharynx (nasopharynx → oropharynx → laryngopharynx) → larynx → trachea → primary bronchi → secondary bronchi → tertiary bronchi → bronchioles → terminal bronchioles → respiratory bronchioles → alveolar ducts → alveoli

Carbon dioxide out:
alveoli → alveolar ducts → respiratory bronchioles → bronchioles → bronchi → trachea → larynx → pharynx → nasal cavity → nose

What are the two regions of the nose? What are the functions of the nose?

Two regions:
external nose and nasal cavity

Functions of nose:
airway for respiration, warms air, moistens air, filters air, resonance for speech, smell

Where are paranasal sinuses located, and what are their functions?

Located in:
frontal, sphenoid, ethmoid, and maxillary bones

Functions:
lighten skull, help warm and moisten air

What are the three regions of the pharynx?

Nasopharynx
Oropharynx
Laryngopharynx

Where is the larynx located? What are its functions?

Location:
between the laryngopharynx and trachea, attached to the hyoid bone

Functions:
keeps airway open, routes air and food into proper channels, voice production

Where are the thyroid, cricoid, and epiglottis cartilages located in the larynx? What is the function of the epiglottis?

Thyroid cartilage:
large anterior cartilage, forms Adam’s apple

Cricoid cartilage:
ring-shaped cartilage inferior to thyroid cartilage

Epiglottis:
elastic cartilage above laryngeal inlet

Function of epiglottis:
covers laryngeal inlet during swallowing so food does not enter airway

What is the difference between the vocal folds and vestibular folds? What is the glottis?

Vocal folds (true vocal cords):
vibrate to produce sound

Vestibular folds (false vocal cords):
do not produce sound; help close glottis during swallowing

Glottis:
opening between the vocal folds

What is the location of the trachea? What are the three layers?

Location:
inferior to larynx, extends to mid-sternal level, then splits at the carina

Three layers:

Mucosa
Submucosa
Adventitia

What is the function of the ciliated epithelial tissue?

Cilia move mucus and trapped debris upward toward the pharynx for removal

This is the mucociliary escalator

What are the main structures in the bronchial tree, and where do they disperse air?

Trachea → primary bronchi → secondary (lobar) bronchi → tertiary (segmental) bronchi → bronchioles → terminal bronchioles → respiratory bronchioles → alveolar ducts → alveoli

They disperse air deeper and deeper into the lungs until it reaches the alveoli

What are the alveoli? What are the functions of the Type I and Type II alveolar cells and macrophages? What is the function of surfactant?

Alveoli:
microscopic air sacs, main site of gas exchange

Type I alveolar cells:
simple squamous cells forming most of alveolar wall; allow gas exchange

Type II alveolar cells:
produce surfactant

Macrophages:
remove debris and pathogens

Surfactant:
reduces surface tension and helps prevent alveolar collapse

Where are the main areas of the lung?

Apex: superior tip
Base: broad inferior surface resting on diaphragm
Root: area where bronchi, vessels, nerves connect to lung
Hilum: entry/exit point on mediastinal surface for bronchi, blood vessels, lymphatics, nerves
Cardiac notch: indentation in left lung for heart

What are the differences between the right lung and left lung?

Right lung:
3 lobes, wider, shorter

Left lung:
2 lobes, cardiac notch, slightly smaller because of heart

What are the four main steps of respiration?

Pulmonary ventilation
External respiration
Gas transport
Internal respiration

What processes occur during inspiration, expiration, and forced expiration?

Inspiration: active

Muscles: diaphragm, external intercostals

During heavy breathing: sternocleidomastoid and scalenes assist

Thoracic cavity volume increases, intrapulmonary pressure drops, air flows in

Expiration: usually passive

Inspiratory muscles relax

Thoracic volume decreases, lungs recoil, intrapulmonary pressure rises, air flows out

Forced expiration: active

Uses internal intercostals and abdominal muscles

Define intrapulmonary pressure and atmospheric pressure

Intrapulmonary pressure: pressure inside lungs/alveoli

Atmospheric pressure: pressure of outside air

Describe Boyle’s law

Pressure and volume are inversely related

If volume increases, pressure decreases

If volume decreases, pressure increases

How does intrapulmonary pressure change during inspiration and expiration?

During inspiration:
intrapulmonary pressure becomes less than atmospheric pressure, so air flows into lungs

During expiration:
intrapulmonary pressure becomes greater than atmospheric pressure, so air flows out of lungs

Explain Dalton’s law and Henry’s law

Dalton’s law:
total pressure of a gas mixture equals the sum of the partial pressures of each gas

Henry’s law:
gases dissolve in liquids in proportion to their partial pressures and solubility

Be able to compare partial pressures of gases in blood and alveolar lung tissue to judge which direction the gases will move during respiration

In lungs:

Alveolar PO₂ ≈ 100 mm Hg
Venous blood PO₂ ≈ 40 mm Hg

Oxygen moves from alveoli into blood

Venous blood PCO₂ ≈ 45 mm Hg
Alveolar PCO₂ ≈ 40 mm Hg

Carbon dioxide moves from blood into alveoli

How is oxygen transported in the blood?

98.5% bound to hemoglobin as oxyhemoglobin

1.5% dissolved in plasma

How is carbon dioxide transported in the blood?

70% as bicarbonate ions (HCO₃⁻)

23% bound to hemoglobin as carbaminohemoglobin

7% dissolved in plasma

What percentage of the air we breathe is oxygen, carbon dioxide and nitrogen?

Nitrogen: 78.6%

Oxygen: 20.9%

Carbon dioxide: 0.04%

What is the Haldane effect?

The lower the PO₂ and hemoglobin saturation, the more CO₂ blood can carry

Deoxygenated hemoglobin carries CO₂ more easily

Be able to compare partial pressures of gases in blood and body tissue cells to judge which direction the gases will move during respiration

At tissues:

Arterial blood PO₂ ≈ 100 mm Hg
Tissue PO₂ < 40 mm Hg

Oxygen moves from blood into tissues

Arterial blood PCO₂ ≈ 40 mm Hg
Tissue PCO₂ ≈ 45 mm Hg

Carbon dioxide moves from tissues into blood

What factors influence the rate of O₂ loading and unloading?

PO₂

pH

PCO₂

temperature

BPG (2,3-bisphosphoglycerate)

Explain how PO₂, pH, BPG, PCO₂ & temperature influence whether hemoglobin will keep or give up oxygen

PO₂

High PO₂: hemoglobin holds onto oxygen
Low PO₂: hemoglobin releases oxygen

Low pH (acidic): more O₂ released

High PCO₂: more O₂ released

High temperature: more O₂ released

High BPG: more O₂ released

State what conditions will shift the oxygen-hemoglobin dissociation curves to the left and to the right

Right shift = hemoglobin gives up oxygen more easily

↓ PO₂
↑ temperature
↓ pH
↑ PCO₂
↑ BPG

Left shift = hemoglobin holds oxygen more tightly

↑ PO₂
↓ temperature
↑ pH
↓ PCO₂
↓ BPG

Explain the following volumes

Tidal volume (TV):
air moved in or out during normal breath

Inspiratory reserve volume (IRV):
extra air forcibly inhaled after normal inspiration

Expiratory reserve volume (ERV):
extra air forcibly exhaled after normal expiration

Residual volume (RV):
air left in lungs after forced expiration

Vital capacity (VC):
TV + IRV + ERV

Total lung capacity (TLC):
TV + IRV + ERV + RV

Explain what spirometry is and why it is used in a clinical setting

Spirometry: test using a spirometer to measure lung volumes and capacities

Used to assess lung function and help distinguish obstructive vs restrictive disorders

Define minute ventilation rate and alveolar ventilation rate. Which is a better measure of effective ventilation?

Minute ventilation: total air moved in or out each minute

Alveolar ventilation: air reaching respiratory zone each minute

Better measure of effective ventilation: alveolar ventilation

Define the following terms: pathologies

Eupnea: normal breathing

Dyspnea: difficult/labored breathing

Apnea: no breathing

Hyperpnea: increased depth and rate of breathing

Hypopnea: shallow/slowed breathing

Hypoxia: low oxygen in tissues

Hypercapnia: high carbon dioxide in blood

Hypocapnia: low carbon dioxide in blood

Describe how the medulla controls respiration

Main rhythm center

DRG integrates sensory input

VRG generates respiratory rhythm

Sets normal breathing rate

Describe how the pons controls respiration

Modifies medullary activity

Helps control depth of breathing

Smooths transition between inspiration and expiration

What is the Hering-Breuer Reflex?

Stretch receptors in lungs/airways respond to inflation

Sends inhibitory signals to end inspiration

Helps prevent overinflation of lungs

What are some other factors which can influence rate or depth of breathing?PCO₂ levels

PCO₂ levels

PO₂ levels

blood pH

body temperature

conscious control

stretch receptors and chemoreceptors

Explain the following pathologies

COPD:
chronic obstructive pulmonary disease; reduced ability to force air out

Chronic bronchitis:
chronic inflammation, excess mucus, productive cough, obstructed airways

Emphysema:
destruction of alveolar walls, reduced elasticity, air trapping, hyperinflation

Asthma:
airway inflammation and bronchospasm causing wheezing, dyspnea, chest tightness, coughing

Sleep apnea:
temporary stoppage of breathing during sleep

Obstructive: airway collapse
Central: reduced brainstem respiratory drive

Lung cancer:
often linked to smoking; includes adenocarcinoma, squamous cell carcinoma, and small cell carcinoma

IRDS:
infant respiratory distress syndrome caused by too little surfactant, especially in premature infants