THE RESPIRATORY SYSTEM
Notes By: D. K. Mangusan Jr., PTRP
Two systems that supply oxygen and remove carbon dioxide are:
Respiratory System
Cardiovascular System
Respiration: refers to the following processes
1. Ventilation - movement of air in and out of the lungs
2. Gas exchange between the air in the lungs and blood
3. Transport of oxygen and carbon dioxide in the blood
4. Gas exchange between the lungs and tissues
5. Cellular metabolism
Respiration is composed of three basic steps:
1. Pulmonary Ventilation - mechanical flow of air in and out of the lungs.
2. External Respiration - exchange of gases between the air spaces of the lungs and the blood in the pulmonary capillaries.
3. Internal Respiration - exchange of gases between blood and the systemic capillaries and tissue cells
ANATOMY
Structurally divided into 2 portions:
a. Upper Respiratory Tract: Nose, Pharynx, Larynx
b. Lower Respiratory Tract: Trachea, Bronchi, Lungs
Functionally, has two portions:
a. Conducting Portion: series of interconnecting tubes and cavities both outside and within the lungs.
b. Respiratory Portion: consists of tissues within the lungs where gas exchange takes place.
1. NOSE AND NASAL CAVITY
- divided into external and internal parts
A. EXTERNAL: Consists of a supporting framework of:
Bones: Cartilage:
Frontal Bones Lateral Nasal Cartilages
Nasal Bones Septal Cartilage
Maxillae Alar Cartilages
External Nares or Nostrils: two openings of the external nose; located on the undersurface
Functions: Warm, moisten and filter incoming air
Detects olfactory stimuli
Modifies Speech vibration
B. INTERNAL: located on the anterior aspect of the skull
- Lies inferior to the nasal bone and superior to the mouth
Anteriorly: merges with the external nose
Posteriorly: Communicates with the pharynx through two small openings called the INTERNAL NARES or CHOANAE.
Lateral Walls: formed by the ethmoid, maxillae, palatine, lacrimal and nasal conchae
Roof: fromed by the ethmoid
Floor: Hard palate
- Nasolacrimal duct and paranasal sinuses drain to the internal nose
NASAL CAVITY: space inside the nose
NASAL SEPTUM: divides the nose into left and right
VESTIBULE: anterior portion of the nose
- lined by coarse hair which filters passing air
3 Projections extending from the lateral walls of each cavity: Superior, Middle and Inferior
Nasal Conchae.
OLFACTORY EPITHELIUM: contains the olfactory receptors
Has: Goblet Cells - moisten air and traps dust
Capillaries - warms air
Cilia - moves mucus and dust towards pharynx
PARANASAL SINUSES
Functions: a. Reduces the weight of the skull
b. Produces mucus
c. Influences quality of voice by acting as resonating chambers.
SINUSITIS -
SINUS HEADACHE -
2. PHARYNX - aka THROAT
- funnel shaped tube, about 13 cm long
- starts at the internal nares and extends up to the level of the cricoid cartilage
- Location: Anterior to the cervical vertebrae
Posterior to the oral and nasal cavities
Superior to the larynx
- Functions: Passageway for air and food
Resonating chamber for speech sounds
Houses the tonsils
Has 3 Regions: a. Nasopharynx
b. Oropharynx
c. Laryngopharynx
a. NASOPHARYNX - superior portion of the pharynx
- Extends from the internal nasal cavity to the level of the uvula
- SOFT PALATE - forms the floor of the nasopharynx
- Lined with mucous membranes similar to that of the nasal cavity.
- 5 openings: openings of the eustachian tubes, opening of the internal nares, opening to the oropharynx
- Posterior portion contains the PHARYNGEAL TONSILS
b. OROPHARYNX - extends from the soft palate to the level of the hyoid bone.
- Lined with strat. Squamous epithelium
- FUNCTION: Passageway of food and air
- Has only one opening, the FAUCES (opening from the mouth)
- Two sets of tonsils, the PALATINE and LINGUAL TONSILS are located near the opening between the mouth and the oropharynx.
c. LARYNGOPHARYNX/ HYPOPHARYNX
- Extends from the level of the hyoid bone to the lower margin of the larynx
- Lined with strat. Squamous epithelium
- Respiratory and digestive pathway.
2. LARYNX
- Consists of outer casings of nine cartilages that are connected to each other by muscles and ligaments.
- Consists of 3 paired and 3 unpaired cartilages
3 Unpaired Cartilages:
a. THYROID CARTILAGE - aka ADAM'S APPLE; shield shape
b. CRICOID CARTILAGE - forms base of larynx on which the other cartilages rest.
c. EPIGLOTTIS - different: consists of elastic cartilage rather than hyaline cartilage
- inferior margin is attached to the anterior rim of the thyroid cart.
- Superior portion projects as a free flap toward the tongue.
3 Paired Cartilages:
a. CUNEIFORM - most superior paired cartilage; wedge shaped
- lies anterior to the corniculate cartilage
- Supports the vocal cords and lateral aspect of the epiglottis
b. CORNICULATE - Horn shape
- Located at the apex of each arytenoid cartilage
c. ARYTENOID - Ladle shape
- Located at the posterior, superior border of the cricoid cartilage
VOCAL CORDS:
A. VESTIBULAR FOLDS/ FALSE VOCAL CORDS - superior pair
- When they come together, they prevent air from leaving the lungs
B. VOCAL FOLDS/ TRUE VOCAL CORDS - Inferior pair
- Involved in voice production
- Muscles control the length and tension of the true vocal cords
LARYNGITIS
3. TRACHEA/ WINDPIPE
- Tubular passageway of air ~ 12 cm (5 ") long, ~2.5 cm (1") in diameter
- Extends from the larynx to the superior border of the 5th thoracic vertebra
- Membranous tube consisting of CT and smooth muscles reinforced with 15 - 20 C-Shaped cartilages.
- TRACHEALIS MUSCLE: stabilizes the open ends of the cartilage rings.
- Divides into the ® and (L) Primary Bronchi at the level of the 5th thoracic vertebra
4. BRONCHI
CARINA - internal ridge where the trachea divides into ® and (L) Primary Bronchi
- As they enter the lungs, they divide to form smaller bronchi called the
SECONDARY BRONCHI >> TERTIARY BRONCHI >> BRONCHIOLES >> TERMINAL BRONCHIOLES.
BRONCHIAL TREE - formed due to the extensive branching from the trachea which then
Resembles an inverted tree.
5. LUNGS
- Paired coned shaped organs in the thoracic cavity.
- Extends from the diaphragm to just slightly superior to the clavicles.
- Separated from each other by the heart and other structures in the mediastinum.
PLEURAL MEMBRANE - membrane which enclose and protects each lung
a. Parietal Pleura - superficial layer
b. Visceral Pleura - deep layer
PLEURAL CAVITY - lies between the parietal and visceral pleura
- Contains a small amount of fluid
PLEURISY/ PLEURITIS -
PLEURAL EFFUSION -
HILUS - where bronchi, pulmonary blood vessels, lymphatic vessels and nerves exit and enter the lungs.
LOBES, FISSURES, AND LOBULES
- Both lungs have an oblique fissure: extends inferiorly and anteriorly
LEFT LUNG - the oblique fissure separates the superior lobe from the inferior lobe.
RIGHT LUNG - the superior part of the oblique fissure separates the superior lobe from the inferior lobe.
- The inferior part of the oblique fissure separates the inferior lobe from the middle lobe.
- The HORIZONTAL FISSURE subdivides the superior lobe, thus forming a middle lobe.
- Each lobe receives its own secondary bronchus
- Within the lungs, the secondary bronchi gives rise to the TERTIARY BRONCHI.
BRONCHOPULMONARY SEGMENTS - segment of lung tissue supplied by the tertiary bronchi.
- Each segment has many small compartments called lobules
- Each lobule contains a lymphatic vessel, an arteriole, a venule and a branch from a terminal bronchiole.
- TERMINAL BRONCHIOLES divide into microscopic branches called RESPIRATORY BRONCHIOLES >>> ALVEOLAR DUCTS
ALVEOLI/ ALVEOLAR SACS
- Located around the circumference of the alveolar ducts.
ALVEOLUS - cup shaped outpouching lined by simple squamous epith. And supported by a thin elastic membrane.
ALVEOLAR SACS - two or more alveoli that share a common opening.
2 Types of cells on the walls of the alveoli.
a. Type I Alveolar Cells: predominant cells; main site of gas exchange.
b. Type II Alveolar Cells: aka SEPTAL CLLS
- Fewer; found between Type I Alveolar Cells; secretes alveolar fluid which keeps the surface between the cells and air moist.
- SURFACTANT - included in the alveolar fluid.
ALVEOLAR MACROPHAGES (DUST CELLS) - wandering phagocytes
** Gases DIFFUSE through the alveolar wall through the RESPIRATORY MEMBRANE.
4 LAYERS of the ALVEOLAR MEMBRANE:
a. ALVEOLAR WALL
b. EPITHELIAL BASEMENT MEMBRANE
c. CAPILLARY BASEMENT MEMBRANE
d. ENDOTHELIAL CELLS
BLOOD SUPPLY TO THE LUNGS
- Lungs receive 2 sets of arteries: a. Pulmonary Arteries b. Bronchial Arteries
Published: Tue Nov 28 2006
