Respiratory System Study Guide
identify the location of the central and peripheral chemoreceptors.
Central chemoreceptors are located throughout the brain stem, including the ventrolateral medulla. Peripheral chemoreceptors are found in the aortic arch and carotid arteries.
Explain the law of partial pressures of gases (daltons law).
total pressure exerted by a mixture of gases equals the sum of the pressures exerted by each individual gas in the mixture the pressure exerted by a specific gas in a mixture is partial pressure
name and identify the location of the main respiratory control centers in the brainstem.
ventral respiratory group (VRG), a network of neurons that extends in the ventral brain stem from the spinal cord to the pons-medulla junction dorsal respiratory group (DRG), located dorsally near the root of cranial nerve IX pontine respiratory centers in the pons phrenic nerve
Name and describe the location of the three levels of the pharynx. How does the epithelial lining change from one level of the pharynx to another? How does the change in epithelium support the functions of the pharynx?
Nasopharynx: posterior to the nasal cavity, inferior to the sphenoid bone, superior to the level of the soft palate, contains pseudo-stratified columnar ciliated epithelium which traps and destroys pathogens entering through the nasopharynx Oropharynx: posterior to the oral cavity, extends from the soft palate to the epiglottis, contains stratified squamous epithelium which accommodates increased friction and chemical trauma accompanying foods Laryngopharynx: lies directly posterior to the larynx, and extends inferiorly to the edge of the circuit cartilage, contains stratified squamous epithelium which serves as passageway for food and air
Identify the structures comprising the upper tracts.
Nose, paranasal sinuses, pharynx
What is the function of type II alveolar cells? of alveolar macrophage?
Type II alveolar cells secrete surfactant that coats the gas-covered alveolar surfaces. Alveolar macrophages consume debris, dust and bacteria along the internal alveolar surfaces.
Define the terms ventilation, external respiration, internal respiration and cellular respiration.
Ventilation: breathing, consists of inspiration and expiration External Respiration: when O2 is taken up and CO2 is released in pulmonary capillaries Internal Respiration: When CO2 is taken up and O2 is released into body tissues Cellular respiration: conversion of O2 to energy and the production of CO2 waste within body cells
Define the following: anatomical dead space; alveolar dead space; total dead space
anatomical dead space is the volume of these conducting zone conduits alveolar dead space is the sum of the volumes of those alveoli which have little or no blood flowing through their adjacent pulmonary capillaries total dead space the sum of the nonuseful volumes
In what form is most CO2 transported?
as a bicarbonate ion in plasma
How is O2 transported in the blood?
bound to hemoglobin within red blood cells and dissolved in plasma
what chemical factors influence respiration?
changing levels of CO2, O2, and H+ in arterial blood.
what are the muscles of quiet inspiration?
diaphragm and external intercostals
what are the three forms of CO2 transport in the blood?
dissolved in plasma (7-10%) chemically bound to hemoglobin (just over 20%) as bicarbonate ions in plasma (about 70%)
Explain why only the peripheral chemoreceptors (and not the central chemoreceptors) are sensitive to changes in arterial pH.
hydrogen ions cannot pass the blood-brain barrier
Under what circumstances might you see a decrease in pH of arterial blood while arterial pCO2 and pO2 are normal?
if it resulted from metabolic factors
What direction does the oxygen hemoglobin dissociation curve shift when the affinity between Hb and O2 increases? when the affinity decreases?
increase in affinity causes leftward shift decrease in affinity causes rightward shift
What is the effect of changes in lung compliance on pulmonary ventilation?
increase in lung compliance, increase in ventilation
What effect do changes in thoracic volume have on intrapulmonary pressure?
increase in thoracic volume > decrease in intrapulmonary pressure and vice versa
What effect does each of the following have on O2-Hb affinity? Temperature, pCO2, pH, 2-3-BPG
increased in any of these factors decrease affinity
what is the general function of the pontine respiratory centers?
influence and modify the activity of medullary neurons modifies and fine-tunes the breathing rhythms generated by the VRG during certain activities such as vocalization, sleep, and exercise
What happens to the HCO3- formed in red blood cells through the dissociation of H2CO3?
moves quickly from the RBCs into the plasma, where it is carried to the lungs
Is carbonic anhydrase present in the plasma? inside red blood cells?
only present in RBCs
specifically, what changes are monitored by each of the central and peripheral receptors?
peripheral chemoreceptors are the ones sensitive to changes in pO2 central regulates pCO2 and pH
What reversible reaction is catalyzed by carbonic anhydrase?
reactions that convert carbon dioxide to bicarbonate ions (HCO3−)
What is the function of surfactant?
reduces the surface tension of alveolar fluid
what is the role of the ventral respiratory group in breathing control?
rhythm-generating and integrative center excites the phrenic nerve which triggers the diaphragm and intercostal muscles
Describe the oxygen-hemoglobin dissociation curve.
shows how local PO2 controls oxygen loading and unloading from hemoglobin up to 40 mmHg, an increase in PO2 will increase saturation, but then it will level off
Explain the chain of reactions that occur as pCO2 (i.e., the amount of CO2) increases inside red blood cells.
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How many O2 molecules are bound to Hb that is fully saturated? Define the term percent saturation of Hb.
4 the fraction of oxygen-saturated hemoglobin relative to total hemoglobin
Describe the structure and function of the respiratory membrane.
A blood-air barrier that has blood on one side and air on the other; gas exchange occurs via simple diffusion. O2 passes from the alveolus into the blood, CO2 passes in the opposite direction.
How does the partial pressure of a gas influence its diffusion?
Each gas diffuses down its own partial pressure gradient
Distinguish between the following levels of lung organization: lobe, bronchopulmonary segment, and lobule
Each lung is separated into multiple lobes, subdivided by fissures (the left lung is divided into superior and inferior lobes by the oblique fissure; the right lung is divided into superior, middle, and inferior lobes by the oblique and horizontal fissures). Each lobe contains a number of pyramid-shaped bronchopulmonary segments, separated from one another by connective tissue septa. A lobule is the smallest subdivision of the lung visible to the naked eye.
Name the branches of the bronchial tree, beginning with the tubes formed by the branching of the trachea.
Right and left primary bronchi, lobar (secondary) bronchi, segmental (tertiary) bronchi, fourth order, fifth order, bronchioles, terminal bronchioles
Define minute respiratory volume (MRV) and alveolar ventilation rate (AVR)
MRV - the total amount of gas that flows into or out of the respiratory tract in 1 minute AVR - takes into account the volume of air wasted in the dead space and measures the flow of fresh gases in and out of the alveoli during a particular time interval
Identify the three main physical factors that influence pulmonary ventilation.
Airway resistance Alveolar surface tension Lung compliance
Describe the fluctuations in intrapleural pressure during inspiration and expiration.
Always about 4 mm Hg less than pulmonary pressure. Intrapleural pressure is always negative relative to pulmonary pressure. During inspiration, the volume of the thoracic cavity increases which makes the intrapleural pressure more negative. During expiration, the volume of the thoracic cavity decreases, which makes the intrapleural pressure less negative.
Which provides the best assessment of effective ventilation?
AVR because it takes into account the volume of air wasted in the dead espace
Why is oxygen-hemoglobin binding called cooperative binding?
After the first O2 molecule binds to iron, the Hb molecule changes shape. As a result, it more readily takes up two more O2 molecules, and uptake of the fourth is even more facilitated.
What is the effect of bronchodilation on airway resistance and gas flow?
Bronchodilation decreases airway resistance and therefore increases gas flow
what chemical factor exerts the most powerful influence on respiration?
CO2
Which the respiratory system structures are considered part of the conducting zone? of the respiratory zone?
Conducting zone: consists of all respiratory passageways from the nose to the respiratory bronchioles Respiratory zone: respiratory bronchioles, alveolar ducts, and alveoli, all microscopic structures
Is alveolar (intrapulmonary) pressure higher or lower than atmospheric pressure during inspiration? during expiration?
During inspiration, alveolar pressure is lower than atmospheric pressure. During expiration, alveolar pressure is higher than atmospheric pressure.
what is the role of the dorsal respiratory group in regulating breathing?
DRG integrates input from peripheral stretch and chemoreceptors and communicates this information to the VRG
Which phase of quiet breathing is a passive process?
Expiration
Identify the main factors that influence the rate of pulmonary and systemic gas exchange.
External respiration (pulmonary gas exchange) is influenced by partial pressure gradients and gas solubilities, thickness are surface area of the respiratory membrane, and ventilation perfusion coupling. Internal respiration (systemic gas exchange) the factors promoting gas exchanges between systemic capillaries and tissue cells are essentially identical to those acting in the lungs.
Define FEV and tell its clinical significance.
FEV = forced expiratory volume Those with COPD have a much lower FEV than healthy people. This is tested.
Describe the phenomenon of ventilation-perfusion coupling. How does ventilation-perfusion coupling enhance respiratory efficiency?
For optimal gas exchange, there must be a close match between ventilation (the amount of gas reaching the alveoli) and perfusion (the blood flow in the capillaries). Low ventilation and/or high perfusion of alveoli causes a local increase in PCO2 and decrease in PO2; pulmonary arterioles serving this area constrict; low ventilation, low perfusion. High ventilation and/or low perfusion of alveoli causes a local decrease in PCO2 and increase in PO2; pulmonary arterioles serving the area dilate; increase in perfusion, increase in ventilation
What are the functions of the larynx? What structural features support these functions?
Functions: to provide an open airway, act as a switching mechanism to route air/food into proper passageways (epiglottis), voice production (vocal folds)
identify each of the molecules in the reaction that converts CO2 to bicarbonate H2O+CO2 <->H2CO3 <->HCO3- +H+
H2O= water CO2= carbon dioxide H2CO3= carbonic acid HCO3=bicarbonate ion H= hydrogen
What are the general functions of the nostrils and nasal cavity? What structural features support these functions?
Hair follicles (vibrissae) filter coarse particles from the inspired air. Sticky mucus traps inspired dust, bacteria and other debris. High water content of mucus humidifies incoming air.
Determine what your respiratory assessment findings would be in a health person, in a patient with pneumothorax, a patient with atelectasis, and in a patient who is choking.
Healthy - full inhale/exhale with chest rise and fall; tactile fremitus, auscultate breath sounds, percuss Pneumothorax - decreased or absent breath sounds; decreased or absent tactile fremitus; tympanic percussion Atelectasis - difficulty taking deep breaths; absent tactile fremitus, dull percussion, no breath sounds Choking - they cannot breathe; probably choking; there must be something obstructing the airway
Rank the pCO2 of the following sites: air in the alveoli; arterial blood; venous blood; interstitial fluid; intracellular fluid. (HINT: remember that gasses diffuse down their partial pressure gradients)
Highes pCO2 intracellular fluid interstitial fluid venous blood air of alveoli arterial blood
Rank the pO2 of the following sites: air in the alveoli; arterial blood; venous blood; interstitial fluid; intracellular fluid. (HINT: remember that gasses diffuse down their partial pressure gradients)
Highest in the air in the alveoli, then the arterial blood, venous blood, then the interstitial fluid, then the intracellular fluids
explain the chemical reaction s that occur during gas exchange in both the pulmonary and systemic capillaries.
In pulmonary capillaries - O2 diffuses from the alveolus into the RBC where it combines to form HbO2; this causes the release of an H+ ion which is taken up in RBC by a free bicarbonate ion to form carbonic acid; carbonic acid is quickly catalyzed by carbonic anhydrase for form CO2 and water In systemic capillaries - CO2 is taken up by RBCs; CO2 combines with H2O to form carbonic acid; carbonic acid is dissociated to H+ and a bicarbonate ion; bicarbonate ion is shuttled into the plasma and Cl- is taken up to compensate; HbO2 dissociates and O2 is taken up by the tissues
How does an increase in O2-Hb affinity effect O2 unloading in the tissues? a decrease in affinity?
Increase in affinity decreases unloading in the tissues. Decrease in affinity increases unloading in the tissues.
Explain the indirect effect that increased arterial pCO2 exerts on the central chemoreceptors.
Increased PCO2 decreases the pH in the extracellular fluid; central chemoreceptors in the brain stem respond to the increase in H+ in the brain ECF
Describe the mechanics of inspiration and expiration (how do we move air into and out of our lungs?).
Inspiration - the diaphragm contracts, flattening out and increasing the height of the lungs; the intercostal muscles contract, lifting the ribcage and increasing the diameter of the ribs; increase in volume, decrease in pressure in the lungs; if lung pressure is less than atmospheric pressure, we will inhale Expiration - passive, the lungs recoil; decrease in lung size/volume, increase in lung pressure; if lung pressure is greater than atmospheric pressure, we will exhale
What is intrapleural pressure? How is intrapleural pressure created?
Intrapleural pressure in the pressure in the pleural cavity. Created by the lungs natural tendency to recoil and assume the smallest size possible; the surface tension of alveolar fluid constantly acts to reduce the alveoli to the smallest possible size; the chest wall also has an elastic component.
How does the structure of the bronchial tubes change as they branch and become smaller?
Irregular patches or plates of cartilage replace cartilage rings; epithelium changes from pseudo-stratified columnar to simple columnar to cuboidal; increase in the amount of smooth muscle
Identify and describe the three layers of the tracheal wall.
Mucosa: pseudostratified epithelium, contains goblet cells, ciliated, most internal layer Submucosa: connective tissue layer deep to the mucosa, contains glands that help produce sheets of mucus Adventitia: outermost sheet of connective tissue, encases the hyaline cartilage
Describe the differences between obstructive and restrictive lung disease.
Obstructive lung disease - lung compliance is normal or increased, which is true of people with emphysema; main problem is increased resistance, especially during expiration Restrictive lung disease - decreased compliance of the lungs, chest wall or both; shallow rapid breathing
What is Boyle's Law? How does this law relate to the mechanics of pulmonary ventilation?
P1V1=P2V2 When volume increases, pressure decreases. Controls how inhale/exhale works.
What effect do the following neural and chemical factors have on airway resistance? Sympathetic activation Parasympathetic activation Epinephrine Histamine
Parasympathetic nervous system and inflammatory chemicals like histamine cause bronchoconstriction Sympathetic nervous system and epinephrine cause bronchodilation
Distinguish between the conducting zone and the respiratory zone. Anatomically, what is the first structure in the respiratory zone?
The conducting zone directs air from its point of entry, down through the trachea, into the primary bronchi; the respiratory zone is where respiration occurs. The first structure in the respiratory zone is the bronchioles.
What muscles are involves in quiet inspiration? What nerve innervates the diaphragm?
The diaphragm and the intercostal muscles. The diaphragm is innervated by the phrenic nerve.
What is the Haldane effect?
The lower the PO2 and the lower the Hb saturation with oxygen, the more CO2 that blood can carry.
What forces are constantly acting to collapse the lungs? Which of these forces is normally most responsible for quiet exhalation?
The tendency of the elastic lungs to recoil and the descent of the ribcage. The recoil tendency is the most responsible.
Identify the major function of pleural fluid.
The pleural fluid allows the lungs to move easily throughout the thoracic cavity during breathing.
Identify and describe the location of the pleural membranes and pleural cavity.
The pleural membranes are two serous membranes that line the thoracic cavity (parietal pleura) and the exterior surface (visceral pleura) of each lung. The pleural cavity is the space between these two membranes that is filled with pleural fluid.
Describe the structure of an alveolus.
The walls of the alveoli consist of a single layer of squamous epithelial cells resting on a thin basement membrane, which is covered externally by a network of pulmonary capillaries. Together, the capillary walls form a respiratory membrane (blood air barrier)
Describe the general location and function of the thyroid cartilage, cricoid cartilage, epiglottis, glottis, arytenoid cartilage, vestibular folds, vocal folds.
Thyroid cartilage: lies in the anterior midline of the neck, protects the thyroid Cricoid cartilage: inferior to the thyroid cartilage, provides an anchoring point for the muscles involved in speech Epiglottis: extends from the posterior aspect of the tongue to its anchoring point on the anterior rim of the thyroid cartilage, ensures that only air enters the larynx Glottis: opening between the vocal cords, allows air to pass through Arytenoid cartilage: forms the posterior and lateral walls of the larynx, anchors the vocal folds Vestibular folds: superior to the vocal folds, help to close the epiglottis when we swallow Vocal folds: lying under the laryngeal mucosa, helps to produce sound when speaking
Define the following: Tidal volume inspiratory reserve volume expiratory reserve volume residual volume inspiratory capacity functional residual capacity vital capacity total lung capacity
Tidal volume: respiratory volume, the amount of air that moves in and out of the lungs which each breath Inspiratory reserve volume: amount of air that can be inspired forcibly beyond the tidal volume (2100 to 3200 ml) Expiratory reserve volume: is the amount of air—normally 1000 to 1200 ml—that can be expelled from the lungs after a normal tidal volume expiration Residual volume: about 1200 ml of air remains in the lungs even after a forced exhalation, which keeps the lungs from collapsing Inspiratory capacity: the total amount of air that can be inspired after a normal tidal volume expiration, so it is the sum of TV and IRV Functional residual capacity: represents the amount of air remaining in the lungs after a normal tidal volume expiration and is the combined RV and ERV Vital capacity: the total amount of exchangeable air. It is the sum of TV, IRV, and ERV Total lung capacity: the sum of all lung volumes
Distinguish between type I and type II alveolar cells.
Type I alveolar cells are squamous epithelial cells that compose the major part of the alveolar walls. Type II cells are cuboidal cells that are scattered across the Type I cells and secrete surfactant.
What is Henry's law? How does this law relate to the process of respiratory gas?
When a mixture of gases is in contact with a liquid, the concentration of each gas dissolved in the liquid is proportional to the partial pressure of the gas We can use PO2 of blood to describe how much is in the blood
What is the Bohr effect?
a decrease in the amount of oxygen associated with hemoglobin and other respiratory compounds in response to a lowered blood pH resulting from an increased concentration of carbon dioxide in the blood.
Explain the relationship between the following: lung compliance, lung elasticity, alveolar surface tension.
decrease in elasticity, decrease in compliance increase in alveolar surface tension, decrease in compliance
What is grahams law? how does this law relate to the process of respiratory gas exchange?
grahams law states that the diffusion rate is directly proportional to the solubility coefficient of the gas the direction and amount of gas diffused depends on partial pressure and solubility
Rank the solubility in water (or plasma) of the following gases: oxygen, carbon dioxide, nitrogen.
greatest solubility: CO2 O2 least solubility: N
Of what type of cartilage are the thyroid cartilages composed?
hyaline cartilage
In what three ways does the upper respiratory tract "condition" air before it reaches the lungs?
removes debris and other large particles from the air and also humidifies it
