Respiratory System Notes

Respiratory System

Functions of the Respiratory System

• Two main functions:
  • Brings oxygen in (O2).
  • Helps eliminate carbon dioxide (CO2).
• Other functions:
  • Olfactory sense (sense of smell).
  • Vocal cords (sound production).

Relationship with Circulatory System

• Respiratory systems work closely with circulatory systems.
• Circulatory systems carry gases close to all body cells, facilitating gas exchange.

Respiration Processes

1. Ventilation (breathing): Movement of air into and out of the lungs.
2. Exchange of O2 and CO2 between the air in the lungs and the blood.
3. Transport of O2 and CO2 in the blood.
4. Exchange of O2 and CO2 between the blood and the tissues.

Main Organs of the Respiratory System

• Upper Respiratory Tract:
  • Nasal cavity
  • Pharynx
  • Epiglottis
  • Larynx (voice box)
• Lower Respiratory Tract:
  • Trachea
  • Bronchi
  • Bronchioles
  • Lungs
  • Diaphragm
  • Alveoli

Detailed Organ Functions

Pharynx and Epiglottis

• Air enters the pharynx through the nose or mouth.
• The pharynx is a chamber shared with the digestive tract.
• Air travels from the pharynx through the larynx.
• The epiglottis is a flap of tissue supported by cartilage that guards the opening to the larynx.
• During breathing, the epiglottis is tilted upward, allowing air to flow freely into the larynx.
• During swallowing, the epiglottis folds downward, covering the larynx and directing substances into the esophagus.

Larynx (Voice Box)

• Air enters the larynx, which contains the vocal cords.
• Exhaled air causes the vocal cords to vibrate, producing sound.

Bronchi and Bronchioles

• Air moves into the trachea, which divides into two bronchi (singular: bronchus).
• Each bronchus branches out into many bronchioles.

Alveoli

• The increasingly small bronchioles conduct air to alveoli (singular: alveolus), which are microscopic air sacs where gas exchange occurs by diffusion.
• The thin walls of the alveoli and the capillaries provide a small distance for oxygen and carbon dioxide to diffuse across, making gas exchange efficient.

Gas Exchange

• Diffusion of gases (CO2 and O2) occurs across the alveoli.
• CO2 is exchanged with O2 with the help of blood flowing through nearby capillaries.
• Oxygenated blood returns to the heart, which then pumps it to the body.

Breathing Mechanism

• Air is inhaled actively and exhaled passively.
• Air flow is controlled by the diaphragm, a sheet of skeletal muscle located beneath the lungs.

Diaphragm Function

• In its relaxed state, the diaphragm muscle is expanded and domes upward, reducing the volume of the chest cavity.
• Contracting the diaphragm causes it to become smaller and flatten downward, enlarging the chest cavity.
• During inhalation, the diaphragm is actively contracted, pulling it downward. The rib or intercostal muscles lift the ribs upward and outward.
• Both of these muscular movements actively enlarge the chest cavity.
• Exhalation occurs spontaneously and passively when the muscles that cause inhalation relax.
• As the diaphragm relaxes, it domes upward; at the same time, the ribs move downward and inward.

Respiratory System Diseases and Disorders

Sinusitis

• Inflammation of the sinuses (-itis = inflammation).
• Causes: infections, allergies, a deviated septum.
• Symptoms: facial pain/pressure, congestion.
• The sinuses are small, empty spaces behind your cheekbones and forehead that connect to the inside of the nose.
• The nasal septum is the cartilage and bone in your nose.

Laryngitis

• Inflammation of the larynx (-itis = inflammation).
• Causes: infections, overuse of voice, allergic irritation.
• Symptoms: hoarseness, weak voice, sore throat.

Asthma

• Narrowing of the bronchioles.
• Causes: genetics, allergies, respiratory infections, air pollutants.
• Symptoms: wheezing, chest pain, breathlessness.

Emphysema

• Damage to the walls of the alveoli.
• Chronic and incurable.
• Causes: smoking and vaping.
• Symptoms: shortness of breath, coughing.

Lung Cancer

• Uncontrolled growth of abnormal lung cells.
• Causes: smoking, vaping, exposure to pollutants.
• Symptoms: difficulty breathing, fatigue, coughing blood.

Effects of Smoking and Vaping

• Vapes and cigarettes contain:
  • Carcinogens: substances that cause cancer.
  • Teratogens: substances that cause malformations in fetuses.
  • Mutagens: substances that change the DNA.
  • Nicotine: addictive substance.
• Smoking/Vaping and the Respiratory System:
  • Irritates the airways.
  • Impairs the lung’s ability to clean its tissue, leading to mucus build-up.
  • Airways get inflamed and become more narrow.
  • Destroys alveoli.
  • Reduces lung’s ability to bring O2 into the body and CO2 out of the body.

EVALI

• E-cigarette or Vaping Use-Associated Lung Injury (2019).
• Caused by some of the ingredients that get inhaled.
• Signs and symptoms: Shortness of breath, cough, chest pain, rapid and shallow breathing.
• Patients need to be hospitalized and, depending on the severity, might need continued support.