Respiratory System Flashcards
Upper respiratory tract
Sphenoidal sinus, frontal sinus, nasal cavity, and pharynx
Lower respiratory tract
Larynx, trachea, bronchi, and lungs
Respiration
Exchange of O2 and CO2 to and from the blood
Only occurs at the lowest portion of the respiratory tract
Conducting portion
Cleans and humidifies air and provides a conduit for
air movement to and from the alveoli. A combination of cartilage, collagen and elastic fibers, and smooth muscle provides structural support and the necessary flexibility and extensibility. Mostly pseudostratified ciliated columnar epithelium.
Nasal cavities
Pharynx
Larynx
Trachea
Bronchi
Bronchioles
Terminal bronchioles
Respiratory portion
Provides the sites for the exchange of O2 and CO2
between air and blood.
Respiratory bronchioles
Alveolar ducts
Alveoli are small, air-filled, saclike structures that make up most of the lung
structure.
Nasal cavities
The two nasal cavities (separated by the nasal septum) have pseudostratified columnar epithelium (= respiratory epithelium).
The conchae, or turbinate bones, are three bony shelflike projections extending from each lateral wall of the nasal cavity.
Mucosa (or mucous membrane)
One or more layers of epithelial cells that secrete
mucus, and an underlying layer of loose connective tissue (lamina propria).
Mucosa covering the conchae functions
Releases heat to warm that air.
The air is humidified
Remove particulate and gaseous air impurities.
Contain immunoglobulin A (IgA) from plasma cells.
Respiratory epithelium
The classic example of
pseudostratified ciliated
columnar epithelium.
Two most important cell types:
Ciliated columnar cells
Mucus-secreting goblet cells
Olfactory Epithelium
The olfactory mucosa covers the superior conchae bilaterally and sends axons from throughout its entire 10 cm2 area to the brain via small openings in the cribriform plate of the ethmoid bone. The olfactory cells are bipolar
olfactory neurons; Their dendrites are at the luminal end and have cilia specialized with many membrane receptors for odor molecules.
Anosmia
The loss or reduction of the ability to smell caused by traumatic damage to the ethmoid bone (e.g., severe broken nose) that severs olfactory nerve axons
Hyposmia
The loss or reduction of the ability to smell caused by damage to the olfactory epithelium caused by intranasal drug use.
Pheromones
Secreted substances that alter social behavior;
e.g., alarm pheromones, food trail pheromones, sex
pheromones.
Vomeronasal organ
A second “smell” organ, in the nasal passageway of many animals.
It is a pheromone receptor in most other primates and other mammals. However, in humans and chimps the organ does not appear to
be functional
Paranasal Sinuses
Bilateral cavities in the frontal, maxillary, ethmoid,
and sphenoid bones.
They are lined with a thinner respiratory epithelium having fewer goblet cells producing mucus.
Pharynx from nose to throat
Nasopharynx, oropharynx, and laryngopharynx
Larynx
The larynx is a short (4 cm × 4 cm) passage for air between the pharynx and the trachea. Its rigid wall
is reinforced by hyaline cartilage (in the thyroid, cricoid, and the inferior arytenoid cartilages) and
smaller elastic cartilages (in the epiglottis, cuneiform, corniculate, and the superior arytenoid cartilages), all of which are connected by ligaments. In addition to maintaining an open airway, movements of these cartilages by skeletal muscles participate in sound production during
phonation.
Epiglottis
A flattened structure projecting from the upper rim of the larynx, prevents swallowed food or fluid from entering that passage.
Vocal cords
Vocal ligament (fold) + conus elasticus + vocalis muscle + thyroarytenoid muscle
Laryngitis
Typically due to viral
infection and is usually accompanied by edema of the lamina propria. This changes the shape of the vocal folds or other parts
of the larynx, producing hoarseness or complete loss of voice.
Trachea
Lined with respiratory
mucosa which contains
seromucous glands producing watery mucus.
A series with about a dozen C-shaped rings of hyaline cartilage reinforces the wall and keeps the tracheal lumen open.
Bronchial Tree
The trachea divides into two primary bronchi that
enter each lung at the hilum
After entering the lungs,
the primary bronchi give rise to three secondary
(lobar) bronchi in the right lung and two in the left lung, each of which supplies a pulmonary lobe.
These lobar bronchi again divide, forming tertiary
(segmental) bronchi.
The tertiary bronchi give rise to smaller bronchi, whose branches are called bronchioles. These are
important in bronchoconstriction and bronchodilation.
Each bronchiole branches to form five to seven
Bronchioles
The smallest branches of the bronchial
They lack both mucosal glands and cartilage.
Bronchi epithelium
Respiratory
Bronchi muscle and skeletal support
Prominent spiral bands of smooth muscle; irregular hyaline cartilage plates
Bronchi major functions
Repeated branching; conduct air deeper into lungs
Bronchioles epithelium
Simple ciliated cuboidal to columnar, with exocrine club cells
Bronchioles muscle and skeletal support
Prominent circular layer of smooth muscle; no cartilage
Bronchioles major functions
Conduct air; important in bronchoconstriction and bronchodilation
Terminal bronchioles epithelium
Simple cuboidal, ciliated cells and club cells
Terminal bronchioles muscle and skeletal support
Thin, incomplete circular layer of smooth muscle; no cartilage
Terminal bronchioles major functions
Conduct air to respiratory portions of lungs; exocrine club cells with several protective and surfactant functions
Respiratory bronchioles epithelium
Simple cuboidal, ciliated cells and club cells, with scattered alveoli
Respiratory bronchioles muscle and skeletal support
Fewer smooth muscle fibers, mostly around alveolar openings
Respiratory bronchioles major functions
Conduct air deeper, with some gas exchange and protective and surfactant functions of club cells
The first truly respiratory parts of the bronchial tree
Alveolar ducts and sacs epithelium
Simple cuboidal between many alveoli
Alveolar ducts and sacs muscle and skeletal support
Bands of smooth muscle around alveolar openings
Alveolar ducts and sacs major features
Conduct air, with much gas exchange
Alveoli epithelium
Types 1 and 2 alveolar cells (pneumocytes)
Alveoli muscle and skeletal support
None (but with network of elastic and reticular fibers)
Alveoli major features
Sites of all gas exchange; surfactant from type 2 pneumocytes; dust cells
Squamous cell carcinoma
Closely correlated with a history of smoking, arises
most often from epithelial cells of segmental
(tertiary) bronchi.
Adenocarcinoma
The most common lung
cancer in nonsmokers, usually arises from
epithelial cells more peripherally, in bronchioles and alveoli.
Asthma
A common condition produced by chronic
inflammation within the bronchial tree of the lungs.
The disorder is characterized by sudden
constrictions of the smooth muscle in bronchioles
called bronchospasms, or bronchial spasms.
Constriction is caused by mast cell degranulation
(release of antimicrobial molecules) triggered by
specific antigens. The difficulty in breathing can be
very mild to severe.
The affect of epinephrine on the respiratory system
Epinephrine and similar drugs relax the muscle and
increase bronchiole diameter (bronchiolar dilation) by stimulating the sympathetic nervous system.
Functions of club cells
- They secrete components of surfactant which reduces surface tension and
prevents collapse of the bronchioles. - They release enzymes that detoxify harmful compounds in air.
- They secrete antimicrobial peptides and
cytokines for local immune defense.
Surfactant
Adding a surfactant reduces surface tension, allowing the liquid to have greater contact with the surface.
Without sufficient surfactant, the alveoli will collapse and gas exchange cannot take place.
Bronchioles –> Alveoli
Terminal bronchioles branch into respiratory bronchioles, which
then branch further into alveolar ducts and individual alveoli.
Pulmonary Blood Vessels
Right and left pulmonary arteries
Right and left pulmonary veins
Alveolar ducts
Distal ends of respiratory bronchioles branch into alveolar ducts that are lined by the openings of alveoli.
Alveolar sacs
Larger clusters of alveoli called alveolar sacs form the ends of alveolar ducts distally. A network of capillaries surrounds each alveolus.
Alveolar cells
Alveolar cells are called pneumocytes.
The alveoli are lined mainly by type I alveolar cells (I), across which gas exchange occurs.
Type II alveolar cells line part of each alveolus
Alveolar macrophages (M) or dust cells phagocytize dust and damaged RBCs.
Type I alveolar cells
The air-blood barrier consists of an alveolar type I cell, a capillary endothelial cell, and their fused basement membranes.
The alveoli are lined mainly by type I alveolar cells (I), across which gas exchange occurs.
Type II alveolar cells
Type II alveolar cells line part of each alveolus and are large rounded cells,
often bulging into the alveolus. These function like club cells (which are in the bronchioles) including production of surfactant.
Alveolar macrophages
Alveolar macrophages or dust cells phagocytize dust and damaged RBCs.
Emphysema
a chronic lung disease (a type of COPD) of the lower respiratory tract, most commonly caused by
cigarette smoking, involves dilation and permanent
enlargement of the respiratory bronchioles with air spaces.
Infant respiratory distress syndrome
The leading cause of death in premature babies, is
due to incomplete differentiation of type II
alveolar cells and a resulting deficit of
surfactant and difficulty in expanding the alveoli in breathing.
Lymphatic vessels
Originate in the connective tissue of bronchioles. They follow the bronchioles, bronchi, and pulmonary vessels and all drain into lymph nodes in the region of the hilum.
Nerves of the respiratory system
Both parasympathetic and sympathetic autonomic fibers innervate the lungs and control reflexes regulating smooth muscle contractions which determine the diameters of the airways.
Pleura
A type of membrane that helps reduce friction
serous membranes
(=serosa) associated with each lung and thoracic cavity.
Pleural fluid
Serous fluid produced by the pleura which allows the two layers of pleura to slide across each other during respiration.
Parietal pleura
Lines the inner surface
of the thoracic cavity
Visceral pleura
Covers the outer
surface of the lung.
Pleural cavity
The narrow space between the parietal pleura and visceral pleura
Pneumothorax
A partially or completely
collapsed lung caused by air trapped in the pleural
cavity, typically resulting from blunt or penetrating
trauma to the chest and producing shortness of
breath and hypoxia.
Pleuritis or pleurisy
Inflammation of the pleura, is most commonly caused by an acute viral infection or pneumonia.
