Chapter 1: Respiration & Phonation Review

Trachea:

• semicircular, U-shaped cartilaginous rings

  • calcify with age

• Lined with ciliated epithelial columnar & goblet cells

• Lower end “bi-furcates” into the mainstem bronchi

Carina:

• trachea bifurcates at the carina → demaracation is not perfectly centered bc of angles

  • the left carina is a bit smaller bc of angle of bronchi

  • right side is more vertical, creating a bigger space at the level of carina

Bronchi:

• composed of cartilaginous rings like the trachea

• left & right mainstem bronchi

Which side of the mainstem bronchi is the “common pathway for aspiration?”

• Right side

  • does NOT mean “all aspiration is on the right side”

  • 55% on right vs. 45% on left

• Mainstem bronchi enter the lungs & further split into secondary (lobar) bronchi

In what order does the bronchi break down?

• Mainstem → Secondary (lobar)→ tertiary (segmental) → bronchus → terminal bronchioles → alveolar sacs → alveolus (inside an alveoli sac)

Lungs:

• 2 lungs

  • Right → 3 lobes

  • Left → 2 lobes

• Made up of spongy material

  • Elastic fibers

  • Surface tension from surfactant

    • lubrication for alveoli expansion

(Lungs) Pleural membrane:

• Visceral pleura

• Pleural cavity

• Parietal pleura

(Lungs) Visceral pleura:

• covers the lung surface & essentially house the lungs

(Lungs) Pleural cavity:

• fluid filled space between the visceral & parietal pleura

• Negative pressure

  • hold the lung tissue against the ribs to form the chest wall

  • Pleural linkage → chest wall & lungs move together

  • Pneumothorax

  • Pleural Effusion

(Lungs) Parietal pleura:

• lines the thorax or inner chest wall

Pneumothorax:

• Collapsed lung (or lobe) when external air leaks into the pleural cavity

What are the causes of a pneumothorax?

• Injury

• Lung Disease (e.g., lung cancer)

• Ruptured air blisters (Blebs)

• Mechanical Ventilation

• Iatrogenic (we caused it trying to fix something else)

• I Love Ralph Macchio Intensely

What are the risk factors for a pneumothorax (MSGAP)?

• Male

• Smoking

• Genetics

• Age (for Blebs)

• Previous Pneumothorax

• MSGAP

Pleural Effusion:

• Excess fluid accumulating in the pleural cavity

• Limits lung expansion

What are the causes of pleural effusion?

• Leakage from other organs (Congestive Heart Disease)

• Cancer

• Infection (e.g., COVID)

• Autoimmune conditions

• Pulmonary embolism

What are the risk factors for pleural effusion (MSGAP)?

• Male

• Smoking

• Genetics

• Age (for Blebs)

• Previous Pneumothorax

• Aspiration PNA does not typically cause this bc it is in the lungs, pleural effusion is AROUND them

Pneumonitis:

• non-infectious inflammation of some type (inflammation for whatever reason)

Opacities, Infiltrates, Consolidations:

• Infection (bacterial or viral)

• Blood

• Exudate (i.e., pus)

• Opacities: ground-glass appearance

• Infiltrates: material infiltrated into lungs & shouldn’t be there (prandial, secretions, reflux, vomitus)

• Consolidations: tumors

Pneumonia:

• infection & inflammation

• impairs gas exchange

Thorax:

• the “mid-section”

• bony thorax is formed by the rib-cage, sternum, spine, & clavicles

• Houses the lungs, heart, diaphragm, & thoracic portion of the esophagus

• Not a rigid structure!

  • expands with inspiration

    • Anterior-Posterior, Lateral, Vertical

    • Breathing changes the diameter of the thorax

Diaphragm:

• the primary muscle of inspiration

• separates the thorax & abdomen

• unpaired muscle, but, is functionally divided into Left & Right diaphragms

• surrounded by the diaphragmatic pleura

(Diaphragm during inspiration) Diaphragm contracts & flattens:

• increases thoracic volume

• compresses abdominal volume → abdominal expansion

• Lungs expand

• Air enters lungs

(Diaphragm during inspiration) Intercostal muscles contract:

• Ribs are elevated

• Increases thoracic volume

(Diaphragm during inspiration) Pectoralis muscles – Accessory respiration muscles:

• sometimes involved in inspiration, but, only when the shoulder girldle & arms are in a fixed position

Abdominal Muscles:

• Relaxed during Inspiration

• Relaxed during Passive Exhalation

• Engaged during Speech

• Engaged during Forced Expiration

• Forced Expiration

  • compress the abdominal contents with push against the diaphragm, assisting in maximum exhalation

Neurology of Phonation (Table 1-4):

• CN X

• CN V

• CN VII

• CN XII

• C1-C3

CN X (vagus nerve):

• intrinsic laryngeal muscles

CN V (trigeminal nerve) & CN VII (facial nerve):

• suprahyoid muscles (digastric, mylohyoid, stylohyoid, geniohyoid)

• remmeber different counselors

CN XII (hypoglossal nerve) & C1-C3:

• Infrahyoid (omohyoid)

Neurophysiology of Breathing:

• Brainstem Central Pattern Generator (CPG)

• Phrenic Nerve (Diaphragm)

  • Bilateral

  • Originates from spinal nerves at C3, C4, C5

  • Motor & Sensory

• Other Cervical Nerves (C5-C8)

• Thoracic Spinal Nerves (T2-T12)

• Lumbar Spinal Nerves (L1)

Breathing Mechanics:

• Quiet breathing

• Forced breathing

• Speech breathing

Quiet Breathing:

• Goal → Gas exchange – CO2 for O2

• Baseline: Alveolar pressure = Atmospheric pressure

Active Inspiration during Quiet Breathing:

• Diaphragm contracts & flattens

• Intercostals elevate & twist ribs

• Thorax expands

  • Intra-pleural pressure (pressure in the lungs) decreases

• Abdomen compresses

  • Abdominal pressure increases

• Further thoracic expansions

  • Intra-pleural pressure decreases some more

  • Alveolar pressure decreases

• Lungs pulled by chest wall – alveoli expand

• Alveoli expansion is passive

• Decreased alveoli pressure → lung pressure is now less than atmospheric pressure, & air enters the system

• Air continues to enter until baseline pressure (alveolar = atmospheric)

Expiration (Exhalation) during Quiet Breathing:

• Work together to reverse actions of inspiration

• Intrapleural & Alveolar pressures now greater than atmospheric

• Passive expiratory forces = Relaxation pressures

• Gravity

• Torque

• Elastic Recoil

Gas Exchange Process:

• Gas exchange –CO2 for O2

• Exchange is via the alveolar capillaries

  • “dead space” – structures of no gas exchange

    • Walls too thick so not O2 permeable

  • O2 carried in blood via Hemoglobin (Hb)

  • Process of gas exchange at alveoli is “Respiration”

  • Process of gas exchange in/out of lungs is “Ventilation”

What is the normal adult respiratory rate?

• 12-20 breaths per minute (bpm) → how often we ventilate

Gas Exchange Terms:

• Oxygen Saturation

• Perfusion

• Hypoxemia

• Hypoxia

• Hypercapnia

(Gas Exchange Terms) Oxygen Saturation:

• Amount of oxygen in blood

  • SpO2 = measured peripherally with a sensory (“pulse oximetry”) → oxygen measured in capillaries on the finger

  • SaO2 = measured internally in the lab blood

(Gas Exchange Terms) Perfusion:

• Amount of blood (& therefore oxygen) reaching the tissue → if ur not getting enough blood ur likely not getting enough oxygen either

(Gas Exchange Terms) Hypoxemia:

• Not enough oxygen (O2) in the blood

(Gas Exchange Terms) Hypoxia:

• Not enough oxygen (O2) in the tissue

(Gas Exchange Terms) Hypercapnia:

• excessive CO2 (carbon dioxide in the blood)