Respiratory pt 2

Respiratory Anatomy Overview

• The trachea is supported by cartilage rings, extending from the cricoid cartilage at C6 down to T2 and T4.

  • The division into right and left primary bronchi occurs at the sternal angle at T4.

Primary Bronchi

• Right Primary Bronchus:

  • Characteristics: shorter, wider, and more vertical.

  • Higher likelihood (90% of the time) that inhaled objects will enter this bronchus due to these traits.

• Left Primary Bronchus:

  • Characteristics: longer, narrower, and more horizontal.

Clinical Relevance: Choking Hazards

• Common choking items for toddlers (e.g., hot dogs, jelly beans) may pass beyond the glottis into the trachea.

  • Majority will enter the right primary bronchus.

  • Emergency procedures may involve forceps to retrieve lodged items from the right bronchus.

Bronchial Structure

• Primary bronchi branch into Secondary Bronchi (also called Lobar Bronchi), which supply each lung lobe.

• Then branch into Tertiary Bronchi, forming Bronchopulmonary Segments.

Cartilage in the Bronchial Tree

• Cartilage begins as larger C-shaped rings in the trachea, transitioning to smaller plates and eventually disappearing in bronchioles.

• This reduction of cartilage as one moves down the bronchial tree leads to Respiratory Bronchioles and Terminal Bronchioles.

Alveoli Structure

• Alveoli are clusters resembling grapes or bubbles; they are the site of gas exchange.

  • Alveolar ducts serve to support and hold the alveoli.

• Macrophages present in alveoli help remove debris from inhaled substances (e.g., dust, smoke).

Gas Exchange Process

• Occurs in the alveoli using the pulmonary capillary system:

  • Deoxygenated blood enters through the Pulmonary Artery, exchanges CO2 for O2, and oxygenated blood exits via the Pulmonary Veins back to the left side of the heart.

Surfactant Function

• Surfactant is a detergent-like substance produced by alveolar cells, reducing surface tension and preventing alveoli from collapsing.

• Surfactant production begins late in gestation, helping to prevent respiratory distress in premature infants.

Lung Anatomy

• Right lung: 3 lobes; Left lung: 2 lobes (due to cardiac notch).

• Base of the lung rests on the diaphragm, which is essential for respiration.

• The Hilum of the lung contains the bronchi and blood vessels entering the lung.

Thoracic Wall and Diaphragm

• Thoracic cavity: enclosed by thoracic vertebrae, ribs, sternum, and diaphragm.

• The Diaphragm is the primary muscle for respiration:

  • Contracts to expand thoracic cavity, allowing for inhalation.

  • Relaxation leads to passive exhalation.

• Intercostal muscles play a supportive role in breathing by elevating the rib cage during inhalation.

Respiratory Muscle Dynamics

• Breathing mechanics:

  • Inhalation: Diaphragm contracts (moves down), intercostals lift ribs.

  • Exhalation: Diaphragm relaxes (moves up), intercostal muscles support rib cage depression.

• Accessory muscles (e.g., pec minor, sternocleidomastoid) assist during deep inhalation or exertion.