CH. 20: Respiratory System Flashcards
What is the function of the respiratory system?
The air passageway moves air between the external environment and the alveoli of the lungs
The site of gas exchange enables oxygen and carbon dioxide to diffuse across the barrier between alveoli and pulmonary capillaries
Detects odor by olfactory receptors in the nasal cavity
Sound production is where vocal cords of the larynx vibrate as air is passed between them
What is the structural organization of the respiratory system?
Upper Respiratory Tract
-Nose
-Nasal Cavity
-Pharynx
Lower Respiratory Tract
-Larynx
-Trachea
-Bronchi
-Bronchioles
-Alveoli
What is the functional organization of the respiratory system?
Conducting Zone - nose to terminal bronchioles
Respiratory Zone - respiratory bronchioles, alveolar ducts, alveoli
What is the mucosal lining?
The lining of the respiratory tract is layered by:
-epithelium
-basement membrane
-lamina propria
Gets progressively thinner the deeper the structure
(pseudostratified ciliated columnar -> simple columnar -> simple cuboidal -> simple squamous) EXCEPT in the pharynx and larynx
What are the mucus and its components?
The secretion produced by and covering the mucosa produced by goblet cells and lamina propia (mucous and serous glands)
Composition:
-Mucin (sticky mucus protein)
-Lysozyme (antibacterial enzyme)
-Defensins (antimicrobial proteins)
-IgA (antibodies)
What are the nose and nostrils?
Nose
-Main conducting passageway for inhaled air formed by the bone, hyaline cartilage, dense irregular CT, and converted with skin externally
Nostrils (Nares)
-Open into the inferior surface of the nose leading into the nasal cavity
What is the nasal cavity anatomy?
It is the internal space formed by the nose (anterior) and skull (superior & posterior)
Composition:
-Floor (hard palate)
-Roof (composed of bones of the skull and nose cartilage)
-Nasal Septum
-Nasal Conchae
-Nasal Meatus
What is the nasal septum?
It divides the nose into two chambers and is formed by nasal septal cartilage and bone (vomer and ethmoid)
What is the nasal conchae?
These are the lateral walls where it is three paired projections (superior, middle, and inferior) referred to as the turbinate bones
It produce turbulence in the inhaled air
What is the nasal meatus?
Partitions formed by conchae and is immediately inferior to their corresponding conchae
What is the nasal cavity function?
-Warms the air to body temperature
-Cleanses the air
-Humidifies
It is enhanced by conchae due to turbulence
What is the pharynx and the components?
It is the throat that is posterior to the nasal cavity, oral cavity, and larynx
It conducts air and food along its entire length
Lateral walls are composed of skeletal muscle that aids in swallowing and propelling food down the esophagus
3 Regions:
-Nasopharynx
-Oropharynx
-Laryngopharynx
What is the nasopharynx?
The superior-most region of the pharynx is lined with pseudostratified ciliated columnar epithelium
Posterior to the nasal cavity
Lateral walls house the openings to the auditory tubes to equalize pressure in the middle ear
The posterior wall houses the pharyngeal tonsil (adenoids)
What is the oropharynx?
It is the middle region of the pharynx and is lined with non-keratinized stratified squamous epithelium
Posterior to the oral cavity
Lateral walls house the palatine tonsils
Lingual tonsils located at the base of the tongue
What is the laryngopharynx?
It is the inferior region of the pharynx and is lined with non-keratinized stratified squamous epithelium
Posterior to the larynx
Serves as common passageway for food and air with oropharynx
What is the larynx and its components?
It is the voice box that is continuous with the laryngopharynx (superior) and trachea (inferior)
Composed of cartilage and supported by muscle and ligaments
What is the function of the larynx?
Passageway for air
Prevents ingested materials from entering the respiratory tract by the EPIGLOTTIS closing over the laryngeal inlet (opening) and glottis closes during swallowing
Produces sound for speech via the glottis where the vibration of the vocal folds is caused by air passing between them through the RIMA GLOTTIDIS
Assists in increasing pressure in abdominal cavity by sneezing and cough reflex
What are the trachea and its components?
The windpipe that extends through the mediastinum from the larynx to the main bronchi
Lateral and anterior walls consist of C-shaped rings of TRACHEAL CARTILAGE and ANULAR LIGAMENTS
The posterior wall consists of TRACHEALIS MUSCLE allowing for distention during food swallowing and contraction during coughing
What are the components of the wall of trachea?
It is mucosa consists of pseudostratified ciliated columnar epithelium with goblet cells & lamina propria
Acts as a MUCOCILIARY ESCALATOR that traps particles to sweep them to the pharynx to be swallowed
What are the components of the bronchial tree?
-Main bronchi (primary bronchi)
-Lobar bronchi (secondary bronchi)
-Segmental bronchi (tertiary bronchi)
-6 to 9 more levels
-Terminal bronchioles
-Respiratory bronchioles
What is the main bronchi?
Trachea splits into two branches at the level of the manubrium and body of the sternum
Right bronchus is shorter
What are the lobar bronchi?
Extend to teach lobe of the lung from the main bronchi
Right lung has 3 lobes, so it has 3 bronchi
Left lung has 2 lobes, so it has 2 bronchi
What are the segmental bronchi?
Extend from the lobar bronchi serving the bronchopulmonary segment
Right lung has 10 segmental bronchi
Left lung has 9-10 segmental bronchi
What is the difference between the terminal and respiratory bronchioles?
Terminal bronchioles are the last segment of the conducting zone
Respiratory bronchioles are the first segment of the respiratory zone
What are bronchi?
They are incomplete rings (hyaline cartilage) that ensure that bronchi remain open
The extent of cartilage decreases in size and number as the bronchi branch increases
What are bronchioles?
They lack cartilage, are small in diameter, and have a proportionally thicker layer of smooth muscle to regulate the flow of air
What are the components of the respiratory zone?
-Respiratory bronchioles
-Alveolar ducts
-Alveolar sacs
-Alveoli
What are alveolar ducts?
It leads in alveolar sacs
What are alveolar sacs?
A cluster of interconnected alveoli
What are alveoli?
Small sac-like structures for gas exchange
1 to 4 sacs * 106 per lung
Interconnected with other alveoli by alveolar pores to provide collateral ventilation
Capillaries surround each alveolus
The interalveolar septum contains elastic fibers
What is the difference between type I and type II alveolar cells?
Type I:
-Most abundant (95%) and flattened cells that forms the thin barrier through which gas exchange occurs
Type II:
-Secrete pulmonary surfactant that opposes alveolar collapse
What are alveolar macrophages?
Engulf pathogens and dust and reside within the alveolus
What are the components of the respiratory membrane?
It is a thin barrier where gases diffuse between the alveoli and the capillaries providing a vast amount of surface area
Consists of:
-alveolar epithelium and basement membrane
-capillary endothelium and basement membrane
What is a pulmonary surfactant?
Secreted by type II alveolar cells
Composed of like-charged lipids & proteins
Lowers alveolar surface tension by:
-Increasing pulmonary compliance
-Reduces lung recoil ability
-Decreases surface tension to a greater degree in smaller alveoli
-Equilibirates pressure between alveoli of varying size
What is the structure of the lungs?
Paired structures where:
-Costal surface lies adjacent to the ribs
-Mediastinal surface lies against the mediastinum
-Diaphragmatic surface is the base that rests on the diaphragm muscle
Lobes are organized with bronchopulmonary segments:
-Is an autonomous unit with a CT capsule
-Possess own segmental bronchus, pulmonary artery & vein, and lymph vessels
Segments are organized into lobules and are supplied by:
-Terminal bronchiole
-Arteriole
-Venule
-Lymph vessel
What is the structural difference between the right and left lungs?
Right Lung:
-Slightly larger and has 3 lobes
Left Lung:
-Accommodates the heart and has 2 lobes
What is the pleura?
Outer lung surfaces and adjacent internal thoracic wall are lined with a double-walled serous membrane:
-Visceral pleura = lung surface
-Parietal pleura = thoracic wall, diaphragm, & mediastinum
Composed of simple squamous epithelium
What is the pleural cavity?
Located between visceral and parietal membranes filled with serous fluid to minimalize friction
What components is respiration consists of?
It is the exchange of respiratory gases between the ATM and tissues of the body consisting of:
-Pulmonary Ventilation
-Alveolar Gas Exchange
-Gas Transport
-Systemic Gas Exchange
What is pulmonary ventilation?
Movement of oxygen and carbon dioxide between ATM and alveoli
-ATM air with more oxygen inhaled during inspiration
-alveolar air with more carbon dioxide during expiration
What is alveolar gas exchange?
Exchange of oxygen and carbon dioxide between alveoli and blood
-oxygen diffuses from alveoli to blood down pressure gradient
-carbon dioxide diffuses from blood to alveoli down pressure gradient
What is gas transport?
Transport of oxygen and carbon dioxide between lungs and system cells
-oxygen and carbon dioxide are transported through blood
What is the systemic gas exchange?
Exchange of oxygen and carbon dioxide between systemic cells & blood
-oxygen diffuses from blood to cells down pressure gradient
-carbon dioxide diffuses from cells to blood down pressure gradient
What is lung inflation dependent on?
Expanding properties of the chest wall due to surface tension caused by the serous fluid
Recoiling properties of the lungs
Anatomic arrangement of the pleural cavity where the thoracic wall pulls out & lungs pull in to create a “suction” due to surface tension (pressure in cavity < pressure in lungs)
What is airflow? What is it dependent on?
The amount of air that moves in & out of the lungs
Dependent on:
-Pressure gradient
-Resistance
What is Boyle’s law?
At constant temperature, the pressure of a gas decreases if the volume of the container increases (and vice versa)
What are pressure gradients?
The difference in pressure between two areas (external environment and alveoli)
Gas flows from an area of high pressure to an area of low pressure (small changes in pressure = movement of large volumes of gas)
What is atmospheric pressure?
Pressure exerted by the atmosphere around us
760 mmHg
What is intrapulmonary pressure?
Pressure in the lungs/alveoli that rise and fall within breathing
Equalizes with atmospheric pressure (760 mmHg)
What is intrapleural pressure?
The pressure inside the pleural cavity that rises and falls with breathing
4 mmHg less than atmospheric pressure = 756 mmHg
What is transpulmonary pressure?
Difference between the intrapulmonary and intrapleural pressure
Recoil pressure
-4 mmHg but changes in response to breathing
What is vertical volume change?
Results from changes in the position of the thoracic floor
Floor dropping = increases volume
Floor returning to original position = decreases volume
What is lateral volume change?
Results from changes in the position of the ribs
Elevation of ribs = widens cage
Depression of ribs = narrow cage
What is anterior-posterior volume change?
Results from movement of the sternum occurring in conjunction with lateral movement
Elevation of ribs and sternum = widens cage
Depression of ribs and sternum = narrows cage
What does pulmonary ventilation consist of?
Breathing (inspiration, expiration, quiet breathing, and forced breathing)
Same physiological processes:
-Autonomic nuclei in brainstem stimulate the skeletal muscle to cycle between contraction and relaxation of the lung
-Thoracic cage changes volume = change in pressure = air moves along the pressure gradients
What is inspiration?
Diaphragm and external intercostal contract
-Ribs are drawn up and outward; the floor is pulled downward
-Thoracic walls and floor pull on pleura
-Pleura pulls on lungs
Air is drawn into the lungs to move until equilibrium is reached (tidal volume)
What are the muscles used in quiet breathing?
Diaphragm and external intercostals
What is expiration?
Diaphragm and external intercostal relax
Ribs & floor move back to the original position (decrease volume in the thoracic cage)
Thoracic walls and floor push on pleura (increased pressure in pleura and plural cavity relaxes)
Pleaura pushes on lungs (lungs recoil and increase pressure within alveoli)
What is forced breathing?
Vigorous breathing involved the same steps as inhalation and exhalation but more air moves in and out
Active process
Requires the contraction of the accessory breathing muscles
What are the muscles used in forced inspiration?
-Sternocleidomastoid
-Scalene
-Pectoralis Minor
-Serratus Posterior Superior
-Erector Spinae
What are the muscles used in forced expiration?
-Internal Intercostals
-Abdominal Muscles
-Transversus Thoracis
-Serratus Posterior Inferior
What is pressure gradient?
Difference in pressure between the external environment and the alveoli (atmospheric pressure - alveoli pressure)
Direct relationship with airflow
Altered by the volume of the thoracic cage
What is resistance?
Determined mostly by the diameters of the conducting tubes
Opposes airflow and has an inverse relationship with it
Altered by:
-Decrease in elasticity of chest wall or lungs (increase R)
-Change in bronchiolar diameter (increase diameter = decrease R)
-Collapse of alveoli (increase surface tension = increase R)
What is the difference between compliance & elastic recoil?
Compliance - how much effort is required to stretch/distend the lung
Elastance (Elastic Recoil) - how readily do the lungs rebound after being stretched
What do compliance and elastic recoil share?
Responsible for lung responsiveness:
-Low compliance = greater resistance = more work to expand lungs = steeper pressure gradient to maintain airflow
-Low elastance = more air remaining in the lung after stretching = increase in intra-alveolar pressure = more work to push out
Affected by the amount of elastin present and alveolar surface tension
What measures oxygen volumes and capacities?
Spirometer
What are the 4 respiratory volumes?
-Tidal volume (TV)
-Inspiratory reserve volume (IRV)
-Expiratory reserve volume (ERV)
-Residual volume (RV)
What is tidal volume?
Volume of air entering/leaving the lung per breath
What is inspiratory reserve volume?
Volume of air maximally inspired over tidal volume
What is expiratory reserve volume?
Volume of air maximally expired over tidal volume
What is residual volume?
Minimum volume of air remaining in lungs after maximal expiration (cannot be directly measured)
What are the 4 respiratory capacities?
-Inspirational capacity (IC)
-Functional residual capacity (FRC)
-Vital capacity (VC)
-Total lung capacity (TLC)
What is inspirational capacity?
Maximal volume of air that can be inspired after quiet expiration
IC = TV + IRV
What is functional residual capacity?
Volume in lungs at the end of passive expiration
FRC = ERV + RV
What is vital capacity?
Maximal volume of air that can be moved out after maximal inspiration
VC = IRV + TV + ERV
What is total lung capacity?
Maximal volume of air lungs can hold
TLC = ERV + IRV + RV + VT
What are the various lung capacities?
Max capacity = 4300ml to 5800ml
During quiet breathing = 2700ml inspired & 2200ml expired
During forced expiration = 1200ml
What is forced expiratory volume?
Percentage of the vital capacity that can be expelled in a specific time period
FEV1 in healthy person = 75-85% of VC
What is maximum voluntary ventilation?
The greatest amount of air that can be inhaled then exhaled in 1 minute by breathing quickly and deeply as possible
What is pulmonary ventilation?
Volume of air breathed in/out in 1 minute
PV = TV * RR
Increases if tidal volume and respiratory rate both increase (but the tidal volume increases more because it elevates alveolar ventilation)
What is anatomic dead space?
The volume of air that doesn’t enter the alveoli nor exit the airways during inspiration or expiration
Volume of air unavailable for gas exchange
Result = alveolar ventilation (AV) < pulmonary ventilation (PV)
AV = (TV - anatomic dead space) * RR
What is Dalton’s Law?
The total pressure of a gas in a mixture is equal to the sum of the individual partial pressures
What is a partial pressure gradient?
Difference between partial pressure in capillary & the surrounding tissue
Gases move down partial pressure gradients by simple diffusion (passive)
When gas is dissolved in liquid, it still exerts a partial pressure
Is alveolar air equal to inspired air?
No, partial pressure in alveoli is different than partial pressure in the atmosphere because:
-Atmospheric air mixes with air in anatomic dead space
-Oxygen is always diffusing into the blood, carbon dioxide is always diffusing out of the blood
-More water vapor in lungs than atmosphere
Results in a lower percentage of oxygen & higher percentage of carbon dioxide in alveoli and modified partial pressures
Alveolar partial pressure stay more/less constant due to rhythmic exchange as we breathe
What is partial pressure like in systemic cells?
Oxygen is used during cellular respiration and carbon dioxide is produced
-Oxygen partial pressure decreases due to the movement of oxygen from the blood to the cells to fuel cellular respiration
-Carbon dioxide partial pressure increases the movement of carbon dioxide out of the cells into the blood as a waste product of cellular respiration
Systemic partial pressure stay more/less constant due to the continuous production of carbon dioxide and consumption of oxygen
What are the factors that influence gas transfers (other than partial pressure)?
Surface area is increased by opening more capillaries and increased alveolar space due to increase tidal volume
Thickness increases causing less diffusion
The diffusion coefficient of the gas is a constant value for each gas and is related to solubility in lung tissues & MW (carbon dioxide difusses more rapidly than oxygen)
What is Henry’s Law?
The solubility of a gas in a liquid is dependent on:
-Partial pressure in the air (the more partial pressure in the air, the greater the driving force into the liquid, and vice versa)
-The solubility coefficient of the gas in liquid (carbon dioxide solubility > oxygen solubility by 20x)
What is the net diffusion of oxygen & carbon dioxide?
Oxygen:
-First occurs between alveoli & blood then between blood * tissues due to continuous replenishment of alveolar oxygen
Carbon Dioxide:
-First occurs between the tissues & blood then between blood & alveoli due to the continuous production of carbon dioxide
What happens in alveolar gas exchange?
What is ventilation-perfusion coupling?
Serve to match blood flow with airflow to maximize gas exchange
Ventilation:
-Bronchioles dilate due to increased partial pressure of carbon dioxide in alveoli (vice versa)
Perfusion:
-Arterioles dilate due to increased partial pressure of oxygen or decreased partial pressure of carbon dioxide
What happens when perfusion is greater than ventilation and vice versa?
Perfusion > Ventilation:
-Bronchioles dilate and arterioles constrict
Perfusion < Ventilation:
-Bronchioles constrict and arterioles dilate
What happens in systemic gas exchange?
What happens in oxygen transport?
What happens in carbon dioxide transport?
