Respiratory System Chapter 24. The main function of the respiratory system is to supply oxygen to, & eliminate carbon dioxide from the body In order to.

Respiratory SystemRespiratory SystemChapter 24Chapter 24

Respiratory SystemRespiratory SystemChapter 24Chapter 24

The main function of the respiratory system is to supply oxygen to, & eliminate carbon dioxide from the body

In order to accomplish this task, the respiratory system must work in conjunction with the cardiovascular system

“Respiration” refers to the overall exchange of gases between the atmosphere, blood & cells

Respiration involves 3 processes

Pulmonary ventilation

External respiration

Internal respiration

Anatomy OverviewNasal cavity

Pharynx

Larynx

Trachea

Bronchi

RightLung

Left Lung

Bronchioles

Respiratory bronchioles

Alveolar duct

Alveoli

The respiratory tract includes: Nose (nasal cavity) Pharynx (nasopharynx, oropharynx, laryngopharynx) Larynx Trachea Bronchi (primary, secondary (lobar), tertiary (segmental) Bronchioles Terminal bronchioles Respiratory bronchioles Alveolar ducts Alveoli

Histology

Respiratory Epithelium = Pseudostratified Ciliated Columnar (PSCC)

Nose (nasal cavity)Air normally enters through external nares through nasal vestibule into nasal cavity.

Nasal cavity divided by nasal septum and has a respiratory area with 3 nasal conchae (superior, middle & inferior) projecting into the midline from each lateral wall creating nasal meatuses between; and an olfactory area

Functions of nasal cavity include: warming, moistening & filtering air; olfaction

Nasal cavity communicates with the paranasal sinuses in frontal, maxillary, ethmoid & sphenoid bones

PharynxAir passes from nasal cavity, across internal nares into nasopharynx, past oropharynx & through laryngopharynx to larynx

Nasopharynx lined with PSCC epithelium, but oro & laryngopharynx lined with stratified squamous epithelium because they are also part of digestive system

Eustachian (auditory) tube – connects nasopharynx & middle ear cavity

Pharyngeal tonsil – lymphatic tissue embedded in wall of nasopharynx

Palatine tonsils - lymphatic tissue embedded in wall of oropharynx

Uvula – posterior tissue from soft palate; protects nasopharynx when swallowing

LarynxAir passageway made of 9 pieces of cartilage – (1) Thyroid cartilage, (1) Epiglottis, (1) Cricoid cartilage, (2) Arytenoid, (2) Corniculate, (2) Cuneiform

A.K.A your “voicebox” because it contains the vocal cords

LarynxThyroid cartilage – protects anterior & lateral walls of airway Epiglottis – leaf-shaped cartilage that protects opening (“glottis”) of airway when swallowing Cricoid cartilage – complete ring of cartilage; protects posterior wall of airway; attaches to trachea

Arytenoid, corniculate & cuneiform cartilages – attach to upper (vestibular) vocal folds & lower (true) vocal cords

Larynx

Trachea

Tough but flexible “windpipe”, anterior to esophagus

attached to cricoid cartilage (at about C6 vertebral level) & ends within mediastinum by branching into left & right primary bronchi (at T5 vertebral level)

End of trachea known as Carina

Carina

Trachea Lined with respiratory epithelium

“C”-shaped pieces of hyaline cartilage protecting airway while allowing for swallowing

Trachealis muscle (smooth muscle) runs across posterior wall of trachea connecting ends of tracheal cartilage

Trachea

Low power

Medium powerHigh power

Bronchi

Carina

Trachea splits into a left & right primary bronchus which enters into the hilus of each lung

Within the lung, the primary bronchi branch into secondary (lobar) bronchi (3 in right lung/2 in left lung)

Secondary bronchi then branch into 10 tertiary (segmental) bronchi

Tertiary bronchi then continue to branch into smaller & smaller bronchi & then into very narrow bronchiolesThis branching patterns

creates the “bronchial tree”

Changes In AirwayAs you go further down into the bronchial tree of each lung, changes in the airway occur:

increased number of airways (1 primary; 2 or 3 secondary; 10 tertiary bronchi; 6000 terminal bronchioles; millions of alveolar ducts)

decreased diameter of each airway

decreased amount of cartilage in the airways (no cartilage at all by terminal bronchioles)

increased amount of smooth muscle (relative to diameter)

lining epithelium changes from PSCC simple squamous epithelium (in alveoli)

LungsLocated within the thoracic cavity, surrounded by the double-layered pleural membrane –

parietal pleura – lines cavity wall

visceral pleura – covers the lungs

Lungs- Anatomical Features

Apex – extends 1” above clavicle

Base – rests on diaphragm

Right lung Left

lung

Superior lobe

Middle lobe

Inferior lobe

Horizontal fissure

Oblique fissure

Superior lobe

Inferior lobe

Oblique fissure

Cardiac notch

Hilum – at medial surface; where primary bronchus, pulmonary artery & veins enter/exit lung

Hilum

Cardiac notch of Lt. lung

Lung – medial surface

Groove for aorta

Each lung has a primary bronchus entering at the hilus Each lobe of a lung has a secondary (a.k.a. lobar) bronchus Lobes are functionally divided into bronchopulmonary segments & each segment has a tertiary (segmental) bronchus Segments are functionally divided into many lobules & each lobule receives a terminal bronchiole

Airways within Lungs

Relationship of Airways & Pulmonary Vessels

As airways branch within lungs, they are accompanied by branches of the pulmonary artery (carrying de-oxygenated blood into the lungs), & branches of the pulmonary veins (carrying oxygenated blood out of the lungs)

As the alveolar ducts expand to form alveoli, pulmonary arterioles will branch to form a network of pulmonary capillaries, surrounding the alveoli

Alveoli

Alveoli are expanded chambers of epithelial tissue that are the exchange surfaces of the lungs

There are about 150 million alveoli in each lung

Multiple alveoli usually share a common alveolar duct, creating “alveolar sacs”

Alveoli There are three types of cells found within alveoli:

Alveolar Squamous epithelial (aka “type I”) cells – primary cells making up the wall of the alveoli

Septal (aka “type II”) cells – sectrete “surfactant” to reduce surface tension which prevents alveoli from sticking together & allows for easier gas exchange

Alveolar macrophages (aka “dust cells”) – phagocytic cells that remove dust, debris & pathogens

Gas “exchange” occurs across the Respiratory membrane – the fused membranes of the alveolar epithelium & the pulmonary capillary endothelium