The Respiratory System Flashcards
Functions of the respiratory system
- Extensive SA for gas exchange
- Moving air
- Protecting surfaces
- Producing sounds
- Detecting odours
Upper respiratory system
Nose, nasal cavity, paranasal sinuses, pharynx
Lower respiratory system
Larynx, trachea, bronchi, bronchioles and alveoli
Respiratory tract
The passageways that carry air to and from the lung exchange surfaces
Conducting portion
Begins at the entrance to the nasal cavity and extends through the pharynx, larynx, trachea, bronchi and larger bronchioles
Respiratory portion
Smallest, thinnest bronchioles and alveoli
Respiratory mucosa
Lines the conducting portion of the respiratory system
Mucosa
Mucous membrane
Function of respiratory mucosa
To provide a series of filtration mechanisms that make up the respiratory defence system
What does the respiratory defence system protect surfaces from?
Debris or pathogens inhaled in air that could damage the surfaces
Structure of respiratory mucosa
Epithelium and underlying areolar layer lamina propria
Which upper respiratory components contain mucous glands in the lamina propria?
Trachea and bronchi
Respiratory mucosa of the trachea
Mucosa
Submucosa
Hyaline cartilage
Adventitial layer
What is in the lamina propria of the conducting portions of the lower respiratory system?
Bundles of smooth muscle cells
What do the smooth muscles do in the bronchioles?
Form thick bands that encircle the lumen
Cells lining nasal cavity and superior portion of pharynx
Pseudostratified ciliated columnar epithelium
Cells lining inferior portion of the pharynx and oral cavity
Stratified squamous epithelium
Why are the cells lining inferior portion of the pharynx stratified squamous epithelium?
This portion conducts air to the larynx and carries food to oesophagus so it needs protection from abrasion and chemicals
Superior portion of the lower respiratory system and nasal cavity
Pseudostratified ciliated columnar epithelium
Smaller bronchioles
Cuboidal epithelium with scattered cilia
Exchange surface of the alveoli
Simple squamous epithelium
Alveolar epithelium
The alveolar simple squamous epithelium and specialised cells scattered among the squamous cells
What do mucous glands produce?
Sticky mucus that bathes exposed surfaced
Mucociliary escalator
In the nasal cavity, cilia sweep mucus toward the pharynx where it is swallowed and exposed to stomach acids and enzymes
In the lower respiratory system, the cilia beat toward the pharynx, moving a carpet of mucus in that direction and cleaning the respiratory surfaces
Tuberculosis (TB)
Results from an infection of the lungs by a bacteria which may colonise respiratory passageways, interstitial spaces, the alveoli or a combination
Cystic fibrosis (CF)
Respiratory mucosa produces dense, viscous mucus that can’t be transported by the respiratory defence system
Mucociliary escalator stops working - frequent infections
Mucus blocks smaller respiratory passageways so breathing is difficult
Nasal vestibule
The space contained within the flexible tissues of the nose
Nasal septum
Formed by the fusion of the perpendicular plate of the ethmoid and vomer
Anterior portion is formed of hyaline cartilage
Dorsum of nose
Bridge
Apex of nose
Tip
Lateral and superior walls of the nasal cavity
Maxillae, nasal bone, frontal bone, ethmoid and sphenoid
Paranasal sinuses
Sinuses of the frontal bone, sphenoid, ethmoid, and paired maxillae and palatine bones
Olfactory region
Superior portion of the nasal cavity
- Interior surface of the cribiform plate
- Superior portion of nasal septum
- Superior nasal conchae
What gives us our sense of smell?
Receptors in olfactory epithelium
Choanae
Openings of the nasal cavity
Superior, middle and inferior nasal conchae
Air flows between adjacent conchae to pass from vestibule to the choanae
Superior, middle and inferior nasal meatuses
Narrow grooves between chonchae
Purposes of nasal turbulence
- Small airborne particles are likely to come into contact with mucus
- Extra time for warming and humidifying air
- Creates circular air currents that bring olfactory stimuli to olfactory receptors
Hard palate (bony)
Made up of portions of the paired maxillae and palatine bones
What separates nasal cavity from oral cavity?
Hard palate
Soft palate (fleshy)
Marks the boundary between superior nasopharynx and the rest of the pharynx
Where does the nasal cavity open into the nasopharynx?
At the choanae
Functions of the nasal mucosa
- Traps particles
- Warms and humidifies incoming air
- Dehumidifies and absorbs heat of outgoing air
Why do patients breathing on a respirator need to receive air that has been externally filtered and humidified?
Since they are not breathing through their nasal cavity and thus they do not receive warmed and humidified air (dangerous)
Epistaxis
Nose bleed
Where does the pharynx extend?
Between the choanae and entrances to the larynx and oesophagus
Wall of the pharynx
Superior and posterior: closely bound to axial skeleton
Lateral walls: flexible and muscular
3 parts of the pharynx
- Nasopharynx
- Oropharynx
- Laryngopharynx
Nasopharynx
- Superior portion
- Ciliated columnar epithelium
- Pharyngeal tonsil on posterior wall
- Pharyngeal opening of auditory tube on each side of pharyngeal tonsil
Oropharynx
- Between soft palate and base of the tongue
- Continuous with the oral cavity
- Stratified squamous epithelium
Laryngopharynx
- Inferior portion
- Between the hyoid bone and entrance to the larynx and oesophagus
- Stratified squamous epithelium
Glottis
Slit like opening between the vocal cords
Larynx
- Cartilaginous tube that surrounds and protects the glottis
- C4 or 5 to C6
3 unpaired cartilages of larynx
- Thyroid cartilage
- Cricoid cartilage
- Epiglottis
Thyroid cartilage
- Hyaline cartilage
- Largest
- U shaped
- Adam’s apple
Cricoid cartilage
- Hyaline cartilage
- Most inferior
- Expanded to provide support where there’s no thyroid cartilage
Functions of thyroid and cricoid cartilages
- Protect the glottis and entrance to trachea
- Broad surfaces provide sites for attachment for ligament and muscles
Epiglottis
- Elastic cartilage
- Forms a lid over glottis
- Prevents liquids and solids from entering respiratory tract
3 pairs of smaller hyaline cartilages of larynx
- Arytenoid
- Corniculate
- Cuneiform
What binds the laryngeal cartilages?
Ligaments
What surrounds the glottis?
Vestibular folds
What makes up the glottis?
Vocal folds = vocal cords
Space between vocal folds
Rima glottidis
Function of vestibular folds
Help prevent foreign objects from entering the open glottis and protect more inferior, delicate vocal folds of glottis
Muscles of the larynx
- Muscles of the neck and pharynx - stabilise larynx
2. Smaller intrinsic muscles - control tension in glottal vocal folds
Bolus
Pasty mass of food before swallowed
Phonation
Sound production at the larynx
Articulation
Modification of those sounds by voluntary movements of structures like tongue teeth and lips to form words
How do we produce sounds?
Air passing through our open glottis vibrates its vocal folds and produces sound waves
What controls the pitch of the sound?
Diameter, length and tension in the vocal cords
Tension is controlled by voluntary muscles
Laryngitis
Infection or inflammation of larynx
Epiglottitis
Swelling caused by bacterial or viral infections
Dangerous - could cause suffocation
Where does the trachea extend?
Begins anterior to vetebra c6
Ends mediastinum, vetebra t5
What is the epithelium of the trachea continuous with?
The epithelium of the larynx
Submucosa
A thick layer of connective tissue surrounds the mucosa
Tracheal glands
- Contained within submucosa
- Secretes mucous that reach tracheal lumen through short ducts
Functions of tracheal cartilages
- Stiffen tracheal walls
- Protect the airway
- Prevent it from collapsing or over-expanding
Tracheal cartilages
- C shaped
- Discontinuous with tracheal wall so can easily distort when swallowing, allowing large masses to pass through
Annular ligament and trachealis
Connect the ends of each tracheal cartilage
Trachealis
Band of smooth muscle
What reduces the diameter of the trachea?
Trachealis
Controlled by sympathetic nervous system
Bronchial tree
Left and right main bronchus > lobar bronchi
Carina of trachea
Ridge that separates the openings of the right and left main bronchi
Which main bronchus is larger in diameter?
The right
Which lung is slightly larger?
The right
Lobes of lungs
Right: Superior, middle and inferior (3 lobar bronchi)
Left: Superior and inferior (2 lobar bronchi)
Segmental bronchi
- Branch from lobar bronchi
- Supply air to bronchopulmonary segment
Bronchopulmonary segment
Specific region of one lung
Number of bronchopulmonary segment
Right: 10
Left: 10 during development and then 8 or 9
Cartilage and smooth muscle in bronchi
Main, lobar and segmental bronchi contain progressively less cartilage
As cartilage decreases, smooth muscle increases
Bronchitis
During an infection, bronchi and bronchioles become inflamed and constricted
Bronchioles
Form from segmental bronchus
Bronchiole walls
Lack cartilage
Dominated by smooth muscle tissue
How does the ANS control the luminal diameter of the bronchioles?
By regulating smooth muscle layer
Sympathetic: bronchodilation
Parasympathetic: bronchoconstriction
Asthma
Excessive stimulation of smooth muscles in bronchioles cause mucosa to form a series of folds
Pulmonary lobule
Each terminal bronchiole delivers air to a single pulmonary lobule
Respiratory bronchiole
Deliver air to gas exchange surfaces of the lungs
Within the lobule, the terminal bronchiole branches to form several respiratory bronchiole
What lines the terminal bronchioles and respiratory bronchioles?
Cuboidal epithelium
Only scattered cilia and no mucous cells or underlying mucous glands
Alveolar ducts
Connect respiratory bronchioles and individual alveoli
Alveolar sacs
Alveolar ducts end at alveolar sacs
Common chambers connected to individual alveoli
What surrounds capillaries associated with alveoli?
Elastic fibres which help maintain relative positions of the alveoli and respiratory bronchioles
What reduces the size of the alveoli during exhalation?
Elastic fibres surrounding capillaries
Alveolar cell layer
Simple squamous epithelial cells called pneumocytes type I
Alveolar macrophages
Patrol the epithelial surfaces and engulf any particles that have eluded other defences
Pneumocytes type II
Scattered among the squamous cells
Produce surfactant
Surfactant
Oily secretion containing phospholipids and proteins
Helps keep alveoli open by reducing surface tension in thin layer of water coating alveolar surface
Respiratory distress syndrome
When pneumocytes type II don’t produce enough surfactant and the alveoli collapse after each exhalation, making it difficult to breathe
Blood air barrier
Where gas exchange occurs
3 layers of blood air barrier
- The alveolar cell layer
- The capillary endothelial layer
- The fused basement membrane between them
Why can gas exchange take place quickly at the blood air barrier?
- Only a very short distance separates alveolar air from blood
- Oxygen and CO2 are small lipid-soluble molecules
- SA of the blood air barrier is large
Pneumonia
Develops from an infection or inflammation-causing particle
Inflammation occurs, fluid leaks into alveoli, respiratory bronchioles swell, narrowing passageways
Breathing is difficult
What makes pneumonia more likely?
- Epithelial damage from smoking
- Breakdown of immune system in AIDS
Lobes and fissuresof the lungs
Right: superior, middle and inferior (separated by horizontal and oblique fissures)
Left: superior and inferior (separated by oblique fissure)
Why is the right lung broader than the left?
Because most of the heart and great vessels project into the left thoracic cavity
Which lung is longer?
Left
Cardiac notch
Indents the medial margin of the left lung
Hilum
Groove on the mediastinal surface of each lung where each main bronchus travels along
Also provides entry to pulmonary vessels, nerves and lymphatics
Root of the lung
Complex of dense connective tissue
Attaches to the mediastinum and fixes the position of the major nerves, blood vessels and lymphatic vessels
Parenchyma
Functional cells
Trabeculae
Connective tissues of the root of each lung
Branch to form small partitions
Interlobular septa
Divide the lung into pulmonary lobules
What is the is the interlobular septa continuous with?
Visceral pleura, serous membrane covering the lungs
Where do the respiratory exchange surfaces receive blood from?
Arteries of the pulmonary circuit
Where does the conducting portion of the the respiratory tract receive blood from?
Bronchial arteries
Venous blood from bronchial capillaries
Dilutes oxygenated alveolar blood within the pulmonary veins
Pulmonary embolism
When a branch of a pulmonary artery stops blood flow to a group of lobules or alveoli
After a few hours the alveoli will collapse
What separates the two pleural cavities?
Mediastinum
Pleura
Serous membrane lining pleural cavity
Layers of the pleura
Visceral and parietal
Pleural fluid
Moist, slippery coating the lubricates the pleurae
Thoracentesis
Sampling procedure where a long needle obtains pleural fluid to check for bacteria, blood cells, etc.
Pleurisy
Condition when pleural fluid doesn’t prevent friction between pleural surfaces
External respiration
All processes involved in the exchange of oxygen and carbon dioxide between the body’s interstitial fluids and external environment
Function of external respiration
To meet respiratory demands of cells
Internal respiration
Absorption of oxygen and the release of carbon dioxide by those cells
Integrated steps of external respiration
- Pulmonary ventilation - physical breathing
- Gas diffusion - across blood air barrier
- Transport of oxygen and carbon dioxide - between alveolar capillaries and capillary beds in other tissues
Hypoxia
Low tissue oxygen level
Anoxia
Oxygen supply cut off completely
Pulmonary ventilation
Physical movement of air into and out of the respiratory tract
Alveolar ventilation
Movement of air into and out of the alveoli
Function of pulmonary ventilation
Maintain adequate alveolar ventilation
Function of alveolar ventilation
Prevents the buildup of carbon dioxide in the alveoli
Ensures a continuous supply of oxygen that keeps pace with absorption by the blood stream
Boyle’s law
Inverse relationship whereby decreasing volume of gas increases its pressure. Increasing volume of gas decreases its pressure
P = 1/V
What holds the two pleural membranes together?
A fluid film
Diaphragm contracts
It tenses and moves inferiorly, increasing the volume of the thoracic cavity, decreasing the pressure within it
Diaphragm relaxes
It returns to its original position and the volume of the thoracic cavity decreases
What are the pressures inside and outside of the thoracic cavity just prior to inhalation?
Identical
What happens when the thoracic cavity enlarges?
Lungs expand to fill the additional space
Increase in volume decreases the pressure inside the lungs
Air then enters the respiratory passageways because P inside is lower than P outside
What happens when the thoracic cavity decreases in volume?
Pressures increase inside the lungs, forcing air out of the respiratory tract
Primary respiratory muscles
Diaphragm and external intercostals
Active during normal breathing at rest
Accessory respiratory muscles
Active when the depth and frequency and breathing must be greatly increased
Muscles used in inhalation
- Contraction of diaphragm
- Contraction of external intercostal muscles raises ribs
- Contraction of accessory muscles help raise ribs
Muscles used in exhalation
- Internal intercostal muscle and transverus thoracis depress the ribs
- Abdominal muscles can assist by compressing abdomen, forcing the diaphragm upward
Quiet breathing, eupnea
Inhalation involves muscular contractions but exhalation is a passive process
Elastic rebound
Diaphragmatic breathing, deep breathing
Contraction of the diaphragm provides necessary change in thoracic volume
Costal breathing, shallow breathing
Thoracic volume changes because rib cage alters shape
External intercostal muscles raise ribs
Forced breathing, hyperpnea
Active inspiratory and expiratory movements
Accessory muscles assist with inhalation
Exhalation involves contraction of internal intercostal muscles
What happens in absolute maximum levels of forced breathing?
Abdominal muscles take part in exhalation by compressing the abdominal contents and pushing them up against the diaphragm, reducing the volume of the thoracic cavity
Intrapulmonary pressure
Pressure inside respiratory tract, at the alveoli
What happens to pressure gradient when you breathe heavily?
It increases
Intrapleural pressure
Pressure in the pleural cavity between the parietal and visceral pleura
Respiratory pump
Cyclical changes in intrapleural pressure that assist venous return to the heart
Pneumothorax
When air enters the pleural cavity and breaks the fluid bond between the pleurae and allows the elastic fibres to recoil resulting in a collapsed lung
Atelectasis
collapsed lung
Compliance
Measure of their expandability, or how easily the lungs expand in response to applied pressure
Lower the compliance, the greater force required to fill the lungs
Respiratory rate
Number of breaths you take each minute
Tidal volume
Amount of air moved into or out of the lungs during a single respiratory cycle
Respiratory minute volume
Amount of air moved each minute
Respiratory rate X tidal volume
Alveolar ventilation
Amount of air reaching the alveoli each minute
Anatomic dead space
Lagging volume of air in the conducting passages
Expiratory reserve volume (ERV)
Amount of air that you can voluntarily expel after you have completed a normal, quiet respiratory cycle
Residual volume
Amount of air that you can draw into your lungs after you have completed a quiet respiratory cycle
Functional residual capacity (FRC)
Amount of air remaining in your lungs after you have completed a quiet respiratory cycle
Vital capacity
Maximum amount of air that you can move into or out of your lungs in a single respiratory cycle
Total lung capacity
Total volume of your lungs
Dalton’s law
In a mixture of gases, the individual gases exert a pressure proportional to their abundance in the mixture
Partial pressure
Pressure contributed by a single gas
Henry’s law
The amount of gas in solution is directly proportional to the partial pressure of that gas
Hemoglobin saturation
Percentage of heme units containing bound oxygen at any given moment
Oxygen-hemoglobin saturation curve
Graph that relates the hemoglobin saturation to the partial pressure of oxygen
Bohr effect
Effect of pH on the hemoglobin saturation curve
Carbonic anhydrase
An enzyme catalyses the reaction of Co2 with water molecules
2,3-biphosphoglycerate (BPG)
Compound that has a direct effect on oxygen binding and release
Fetal hemoglobin
Contained in the RBCs of a developing fetus
Much higher affinity for oxygen than mature RBCs which allows it to transfer oxygen across the placenta
Chloride shift
Mass movement of chloride ions into the RBCs
Carbaminohemoglobin
Compound whose formation decreases oxygen affinity to hemoglobin
Ventilation-to-perfusion ratio (V/Q ratio)
Lung perfusion (blood flow to alveoli) Alveolar ventilation (airflow)
Respiratory rhythmicity centers
Located in the medulla oblongata
Plays a key role in establishing the respiratory rate and rhythm
Subdivisions of the respiratory rhythmicity centres
Dorsal respiratory group (DRG) - inspiration
Ventral respiratory group (VRG) - expiration
When does the VRG function?
Only during forced breathing
Apneustic centres and pneumotaxic centres of the pons
Regulate the depth and rate of respiration in response to sensory stimuli or input from other centres in the brain
Higher centres
Alter the activity of the pneumotaxic centres
Hypercapnia
An increase in the PCO2 of arterial blood
Inflation reflex
Prevents over expansion of the lungs during forced breathing
Deflation reflex
Stimulates inhalation when lungs are collapsing
Emphysema
Destruction of alveolar surfaces and inadequate surface area for oxygen and carbon dioxide exchange
Apnea
A period in which respiration is suspended