Chapter 21 - Respiratory System Flashcards
Rising CO2 levels are the most powerful respiratory stimulant.
As CO2 is hydrated in the brain tissue, liberated H+ acts directly on the central chemoreceptors causing a reflexive increase in breathing rate and depth. Low PCO2 levels depress respiration.
______ involves the intermittent realse of expired air as the glottis opens and closes.
Speech
As the length and tension of the voval folds change, the pitch of the sound varies. Generally, the tenser the vocal folds the farster they vibrate and the higher the pitch.
Under normal resting conditions (PO2 = 100 mm Hg), arterial blood is _____ % saturated, and 100 ml of systemic arterial blood contains about _____ ml of O2.
98; 20
The oxygen content is written as 20% (volume percent).
At sea level, the atmosphic pressure is
760 mm Hg (the pressure exerted by a column of mercury 760 mm high)
760 mm Hg = 1 atm
The lungs are perfused by two circulations:
The pulmonary circulation
The bronchial circulation
Differ in size, origin and function.
Submucosa
Connective tissue layer dep tot he mucosa.
Contains seromucus glands that help rooudce mucus “sheets” within the trachea.
Supported by 16-20 C-shaped rings of hyaline cartilage encaded by the adverntitia, the outermost later of connective tissue.
Internal and External Respiration are driven by ______ diffusion. They are also driven by partial pressure gradients of O2 and CO2 that exist on the opposite sides of the exchange membranes.
Simple
During forced or deep inspiration, accessory muscles further increase the thoracic volume. Several muscles, including the ______ and ______ muscles of the neck and the _______ ________ of the chest, rasie the ribs even more than during quiet inspirations.
The back extends as the the _____ ______ muscles straighten the throacic curvature.
Scalenes; Sternocleidomastoid
Pectoralis Minor
Erector Spinae
Dorsal Respiratory Group (DRG)
Integrates input from peripheral stretch and chemoreceptors and communicates this information to the VRG.
The tissue composition of the walls of th main bronci mimics that of the trachea, however, the conducting tubes become smaller, the following structural chagnes occur:
1. Support structures change - Irrecgular patches of cartilage replace the cartilage ringes, and by the time the broncioles are reached, the tube walls no longer contain supportive cartialge.
The tube walls throughout the broncial tree contain elastic fibers.
2. Epithelium changes - Tthe mucosal epithelium thins as it changes from pseudostratified columnar to simple columnar and then to simple cuboidinal in the terminal bronchioles. Most airborne debris found at or below the level of the broncioles must be removed by macrophages in the alveoli.
3. Amount of smooth muscle increases - A complete layer of circular smooth muscle in the bronchioles and the lack of supporting catilage allows the bronchioles to provide substantial resistnace to air passage under certin conditions.
Chronic inflammation, or infections such as tuberculosis, can cause _____ _____ tissue to replace normal lung tissue.
Nonelastic Scar
Decreased produciton of surfactant can also decrease lung compliance, the more energy is needed to breath.
Increased ventilation in response to metabolic needs is called ______.
Hyperpnea
The lungs are innervated by ________ and ________ motero fibers and visceral sensory fibers.
Nerve fibers enter each lung through the _____ _____ on the lung root and run along the broncial tubes and blood vessesl in the lungs.
Parasympathetic fibers cause the air tubes to ______, whereas sympathetic fibers _____ them.
Parasympathetic; Sympathetic
Pulmonary Plexus
Constrict; Dilate
Once inside the lungs, each main broncus subdivides into _____ (secondary) bronchi - _____ on the right and ____ on the left - each supplying one lung lobe.
Lobar
Three; Two
Spirometer
A cumbersome instrument utilizing a hollow bell inverted over water, now patients blow into a small electronic measuring device.
Declining blood pH (acidosis) and increasing PCO2 weaken the Hb-O2 bond, a phenomenom called the ______ ______.
Bohr Effect
This enhances oxygen unloading where it is needed the most.
When you move on a long-term basis from sea level to the mountains your body makes respiratory hematopoietic adjustments via an adaptive response called _________.
Acclimatization
Vital Capacity (VC)
The total amount of exchangeable air.
VC = TV + IRV + ERV
The trachea’s _____ ______ make it flexible enough to stretch and move inferiorly during inspiration and recoil during expiration, but the cartilage rings prevent it from collapsing and keep the airway patent despite the pressure changes that occur during breathing.
Elastic Elements
Distinguised by permanent enlargement of the alveoli, acccompanied by destruction of the alveolar walls.
Invariably the lungs lose their elasticity.
Emphysema
The respiratory changes in ________ do not alter blood O2 and CO2 levels significantly.
Hyperventilation is excessive ventilation, and is characterized by low ____ and alkalosis.
hyperpnea
PCO2
Cellular Respiration
The actual use of oxygen and production of carbon dioxide by tissue cells and the cornerstone of all energy-producing chemical reactions in the body.
Quiet expiration depends more on lung ______ than on muscle _______.
Elasticity; Contraction
Reduced Hemoglobin or Deoxyhemoglobin (HHb)
Hemoglobin that has released oxygen.
Henry’s Law
States that when a gas is in contact with a liquid, the gas will dissolve in the liquid in proportion its partial pressure.
The greater the concentation of a particular gas in the gas phase, the more and the faster that gas will go into solution in the liquid.
Example - When PCO2 in the pulmonary capillaries is higher than in the lungs, CO2 diffuses out of the blood and enters the air in the alveoli.
Irreversible decrease in thea bility ro force air out of the lungs.
Chronic Obstructive Pulmonary Diseases (COPD)
The nearly complete saturation of Hb in arterial blood explains why breathing deeply _____ both the alveolar and arterial blood PO2 but causes very little ______ in the O2 saturation of hemoglobin.
Increase; Increase
Smoking inhibits and ultimately destroys _____.
Ciliia.
Ciliary activity, coughing is the only way to prevent mucus from accumulating in the lungs.
When someone stops stmoking, cilary funcitonusually recovers within a few weks, and the morning “smoker’s cough” subsides.
Because of the strong adhesive force between the parietal and visceral pleurae…
…pleural fluid secures the pleuae together the same way a drop of water holds two glasses slides together.
Pleural fluid in the pleural cavity must remain minimal to maintain a negative Pip. The pleural fluid is actively pumped out of the pleual cavity into the lymphatics continously.
Pneumothorax
The presence of air in the pleural cavity.
Reversed by drawing air out of the intrapleural space with chest tubes
Allows the pleurae to heal and the lung to reinflate and resume normal function.
Changes in Intrapulmonary and Intrapleural Pressures During Inspiration and Expiration
Inspiration
The period when air flows into the lungs.
The most common kind of sleep apnea and is caused by collapse of the upper airway.
Obstructive sleep apnea
The two lungs differ in size and shape beacsue the apex of the hart is slightly to the left of the median plane. The left lung is smaller than the right, and the ____ _____ - a concavity in its medial aspecit - is molded to and accomodates the heart.
Cardiac Notch
An increase in the rate and depth of breahting that exceeds the body’s need tor remove CO2.
Hyperventilation
Low CO2 levels in the blood (hypocapnia) constrict cerebral blood vessels.This reduces brain perfusion, producing cerebral ischemia that causes dizziness and involuntary muscle spasms (tetany) int he hands and face caused by blood Ca2+ levels falling as pH rises.
Three major types of cells are found in the alveoli:
- Type 1 Alveolar Cells - squamous epithelial cells that form the major part of the alveolar walls.
- Type II Alveolar Cells - cubodial epithelial cells that are scattered among the type 1 cells.
Secrete a fluid containing a detergent-like substance called surfactant that coats the gas-exposed alveolar surfaces. Secrete a number of antimicrobial proteins that are important elements of innate immunity.
- Alveolar macrophages - crawl freely along the interanl alveolar surfaces consuming bacteria, dust and other debris.
Inhaled irritants lead to chonic prdocution of excessive mucus.
The mucosae of the lower respiratory passageways become inflamed and fibrosed.
Chronic Bronchitis
Defintied by the presence of thin-walled air sacs called alveloi, the respiratory zone beings as the termial broncioles feed into _____ ______ within the lung.
Respiratory bronchioles
Protruding from these smalles bronciles are scattered alveoli.
Anatomical Dead Space
Does not contribute to the gas exchange in the alveoli.
Typically about 150 ml out of the TV of 500 ml; only 350ml of TV is used in alveolar ventilation.
Our voluntary hold of our breath is limited, however, because the brain stem respiratory centers automatically reinitiate breathng when the blood concentration of ____ reaches critical levels.
CO2
COPD is treated with:
Inhaled bronchodilators and corticosteroids.
Severe dyspnea and hypoxia mandate oxgen use, but oxygen must be administered with care. Oxgen can elevated the PCO2 (lower pH) to life-threenting levels.
Pharynx
Expiration
The period when gases exit the lungs.
Respiratory Zone
Actual site of gas exahnce is composed of the respiratory broncioles, avelolar ducts, and alveoli, all microscopic events.
Mucosa
Has the asame goblet cell-containg pseduostratified epithelium that occurs through most of the respiratory track.
Cilia continioually propel debris-laden mucus thoward the pahrynx.
Epithelium rest on a fairly thick lamina propria that has a rich supply of elastic fibers.
Indicated by reduced arterial PO2. Possible causes include disordered or abnormal ventilation-perfusion coupling, pulmonary diesease that impair ventilatio, and breathing air containing scant amounts of O2.
Hypoxemic Hypoxia
Oxygen Toxicity
Develops rapidly when PO2 concentrations are greater than 2.5-3 atm. Excessively high O2 concentrations generate huge amounts of harmful free radicals, resulting in profound CNS disturbances, coma and death.
Pharyngeal Tonsil
Traps and destroys pathogens entering the nasopharynx in air.
Haldane Effect
The lower the PO2 and the lower the Hb saturation with oxygen, the more CO2 that the blood can carry.
This reflects the greater ability of HHb to form carbaminohemoglobin and to buffer H<span>+</span> by combining with it.
Encourages CO2 exchange in both the tissues and the lungs. In the pulmonary circulation, this is reversed - uptake of O2 facilitates the release of CO2.
The pharynx is divided into three regions:
The nasopharynx, the oropharynx and the laryngopharynx.
When inspiratory neurons fire, a burst of impuses travel along the _____ and _______ _______ to excite the diaphragm and external intercostal muscles.
As a result, the thorax expands and air rushes into the lungs.
As the expiratory neruons fire, the output stops, and expiration occur as the inspiratory muscles relax and the lungs recoil.
Phrenic; Intercostal Nerves
At the tips of the bronchial tree, ________ zone structures give way to ________ zone structures.
Conducting; Respiratory
Two significant features of Alveoli:
- Surrounded by fine elsastic fibers of the same type that surround the elastic fibers of the same type that surround the entire broncial tree.
- Open alveolar pores connecting adjacent alveoli allow airpressure throughout the lung to be equalized and provide alternate air routes to any alveoli whose bronci have collapsed due to disease.
REVIEW TABLE 21.2 on Page 729.
The rate at which Hb reversibly bind or releases O2 is regulated by:
PO2
Temperature
Blood pH
PCO2
Blood concentration of organic chemical called BPG.
On the mediastinal surface of each lung is an identation, the _____, through which pulmonary and systemic blood vessels, bronci, lympathic vessels, and nerves enter and leave the lungs.
Hilum
Respiratory Capacities (4)
Inspiratory
Functonal Residual
Vital
Total Lung
Always consist of (2) or more lung volumes.
The inflation reflex in the _____ _____ and conducting passages in the lungs contain numerous stretch receptors that are vigorously stimulated when the lungs are inflated.
These receptors signal the _____ _____ _____ via afferent fibers of the vagus nerves sending inhibitory impules that end inspiration and allow expiration to occur.
Visceral Pleurae
Medullary Respiratory Centers
Loudness of the voice depends on the force with which the airstream rushes across the vocal folds.
The greater the force, the stronger the virabation and the louder the sound.
The vocal folds do not move at all when we whisper, but they vibrate vigorously when we yell.
The muscles of the chcest, abomen and back provide the power for the airstream.
Inspiratory Reserve Volume
The amount of air that can be inspired forcibly beyond the tidal volume (2100 to 3200 ml).
Atelectasis
Lung collapse
Occurs when a brionchiole becomes plugged and the associated alveoli then absorb all of the air and collapse.
Can also occur in a chest wound or a rupture of the visceral pleura, which allows air from the respiratory tract to enter the pleural cavity.
Henry’s Law
C = KPgas
C = Solubility of a gas at fixed temperature in a particular solvent (M, mL gas/L)
K = Henry’s law constant (M/atm)
Pgas = Partial pressure of gas (atm)
When a liquid’s temperature rises, gas solubility decreases.
All of these factors influence Hb saturation by modifying hemoglobin’s 3-D structure, thereby changing the affinity of O2.
Increase in:
Temperature, PO2, H+, or BPG
Levels in the blood lower’s Hb’s affinity for O2, enhancing oxygen unloading from the blood.
Alveolar Ventilation (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.
AVR = Frequency x (TV - Dead Space)
= 12 Breaths Per Minute x (500ml - 150 ml)
= 4200 ml/minute
Because deads space is constant, increasing the volume of each inspiration (breathing depth) enhances AVR and gas exhange mor ethan raise the respiratory rate).
AVR drops dramatically during rapid shallow breathing because mos to fthe inspired air never reaches the exchange sites.
The normal respiratory rate and rhythm is called….
Eupnea.
Dalton’s law of partial pressures
The total pressure exered by a mixture of gases is the sum of the pressures exerted by each gas.
Partial Pressure - is directly proportional to the percentage of that gas in the gas mixture.
At high altitudes, partial pressures decline in direct proportion to the decrease in atmospheric pressure. The same occurs below sea level - eveything stays proportional.
The nasal cavity is lined with two types of mucous membrane (2):
- Olfactory mucosa - lines the slitlike superior region of the nasal cavity and contains smell receptors in its olfactory epithelium
- Respiratory mucosa - lines most of the nasal cavity. It is a psuedostratified ciliated columnar epithelium, containng scattered goblet cells that ress on the lamina propria richly supplied with seromucous nasal glands.
Exerrnatl Respiration
O2 diffueses from the lungs to the blood.
CO2 diffueses from the blood to the lungs.
Systemic venous blood that is to be oxygenated in the lungs is delivered by the ______ ______, which lie anterior to the main bronchi.
Branch profusely along with the bronchi and finally feed the ______ ______ ______ surroding the alveoli.
The _______ _______ convery the freshly oxygenated blood from the respiratory zone of the lungs to the heart.
Pulmonary Arteries
Pulmonary Capillary Networks
Pulmonary Veins
*Tributaries course back to the hilum both with the corresponding bonci and in the connectvie tussue septa seprating the bronchopulmonary segments.
Vocal Ligaments
Attach the arytenoid cartilages to the thyroid cartilages.
Composed of elastic fibers.
Form the core of mucosal folds called the vocal chords, which appear pearly white because they lack blood vessels.
Vibrate producing sounds as air ruses up from the lungs.
The most common cases of lung cancer:
- Adenocarcinoma (20%)
- Squamous cell carcinoma (40%)
- Small cell carcinoma (15%)
As arterial blood flows through systemic capillaries, it releases about 5 ml of O2 per 100 ml of blood, yielding an Hb saturation of ____ % and an O2 content of _____ % volume in venous blood.
This means that substantial amounts of O2 are normally still available in venous blood (the venous reserve), which can be used if needed
75; 15
15/20 = 75%
Inhibit cell growth and division, so the inactivation of these genes is a factor in uncontrolled cell growth.
Tumor suppressor genes
The reclamation process minimizes:
The amount of moisture and heat lost from the body though breathing, helping us to survivve in dry and cold climates.
The Larynx (3) Functions:
- Provdie a patent (open) airway.
- Actas a switching mechanism to route air and food into the proper channels.
- Voice production (because it houses the vocal folds (vocal cords).
Intrapleural Pressure (Pip)
The pressure in the pleural cavity.
Fluctuates with breathing phases, but is always about 4 mm Hg lesss than Ppul.
Pip is alwyas negative relative to Ppul
Infant Respiratory Distress Syndrome (IRDS)
Alveoli must be completely reinflated during each inspiration, an effor tthat uses tremendous amounts of energy.
This is a a problemt faced by newborns.
A condition common in premature babies. Since fetal lugns do not produce adqueate amounts of surfactant until the last two months of development, babies born prematurely often are unable to keep their alveoli inflated between breaths.
Treated by sparing natural or syntheic surfactant into the newborn’s respiratory passageways.
Devices to keep alveoli open between breaths can be used.
Many survivors suffer from bronchopulmonary dysplasia, a chronic lung disease during childhood and beyond.
Forced Vital Capacity (FVC)
Measures the amount of gas expelled when a subject takes a deep breathand then forcefully exhales maximally and as rapidly as possible.
Unique type of hypoxemic hypoxia and a leading cause of death from fire.
Carbon Monoxide Poisioning
Hb’s affinity for CO is more than 200x greater than its affinity for O2, CO outcompetes O2 for heme binding sites.
Nasopharynx
Posterior to the nasal cavity; Inferior to the sphenoid bone; Superior to the level of the soft palate.
Only serves as an air passageway.
During swallowing, the soft palate anduvula move supeiorly to close off the nasopharynx and prevents food from entering the nasal cavity.
Pseudostratified ciliated epithelium takes over the jobof propelling mucus where the nasal mucosa leaves off.
- Pharyngotympanic (auditory) tubes*, which drain the middle ear caviities and allow middle ear pressure to rqualize with atmospheric pressure, openinto the lateral walls of the nasopharynx.
- Tubal tonsil* helps protect the middle ear against infections likely to spread from the nasopharynx.
Blood transports CO2 from the tissue cells to the lungs in three forms:
1. Dissolved in Plasma - 7-10% - The smallest amount of CO2 is transported simply dissolved in plasma.
2. Chemically bound to hemoglobin - just over 20% - Dissolved CO2 is bound and carried in the RBC’s as carbaminohemoglobin.
CO2 + Hb ⇔ HbCO2
Carbon dioxide transport in RBCs does not compete with HbO2 transport because CO2 binds directly to the amin.o acids of globin (not the heme).
Carbon dioxide rapidly dissociates from the hemoglobin in the lungs where the PCO2 of alveolar air is lower than that in blood (CO2 leaves the pulmonary capillaries and enters into the alveoli through the respiratory membrane).
CO2 readily binds with Hb in the tissues, where the PCO2 is higher than that in blood.
HHb combines more readliy with CO2 than HbO2.
3. As bicarbonate ions in plasma - About 70% - The reactions that convert bicarbonate (HCO3-) for transport mostly occur inside RBCs.
When dissolved CO2 diffuses into RBCs, it combines with H2O, forming carbonic acid (H2CO3).
CO2 + H2O ⇔ H2CO3 ⇔ H+ + HCO3-
This reaction occurs in plasma, but due to carbonic anhydrase, it occurs 1000x faster in RBCs.
H+ and CO2 bind to Hb, triggering the Bohr Effect (releasing O2).
HCO3- moves quickly from the RBCS into the plasma, where it is carried to the lungs. Cl- moves from the plasma in the RBCs (chloride shift) which occurs via facilitated diffusion through an RBC membrane protein.
In the lungs, the process is reversed.
The nasal cavity is continuous posteriorly with the nasal portion of the pharynx through the _____ ______ _____, also called the choanae.
Posterior nasal apertures
The lower respiratory system consists of:
Larynx
Trachea
Bronchi and branches
Lungs and alveoli
A positive respiratory pressure is ______ than atmospheric pressure.
Higher
- Chemically bound to hemoglobin
Just over 20% - Dissolved CO2 is bound and carried in the RBC’s as carbaminohemoglobin.
CO2 + Hb ⇔ HbCO2
Carbon dioxide transport in RBCs does not compete with HbO2 transport because CO2 binds directly to the amin.o acids of globin (not the heme).
Carbon dioxide rapidly dissociates from the hemoglobin in the lungs where the PCO2 of alveolar air is lower than that in blood (CO2 leaves the pulmonary capillaries and enters into the alveoli through the respiratory membrane).
CO2 readily binds with Hb in the tissues, where the PCO2 is higher than that in blood.
HHb combines more readliy with CO2 than HbO2.
Episodes of coughing, dyspnea, wheezing, and chest tightness - alone or in combinations.
Obstructive disorder that is marked by acute episodes followed by symptom-free periods - that is, the obstruction is reversible.
Active inflammation of the airways comes first. The inflammation is an immune response controlled by a subset of T lymphocytes that stimulate the production of IgE antibodies and recruit inflammatroy cells to the site.
Bronchodilators and inhaled corticosteriods.
Asthma
Lung Compliance
Measure of the change in lung volume that occurs with agiven cahgne in transpulmonary pressure.
C1 = (VL2 - VL1) / (PPul-Pip)2-PPul-Pip)1
The more the lung expands for a given rise in transpulmonary pressure, the greater the compliance.
The higher the lung compliance the easier it is to expand the lungs at any given transpulmonary pressure.
Many people mistake alveoli, site of gas exchange, with alveolar sacs, but they are not the same thing.
The alvelor sac is analogous to a bunch of grapes, and the alveloi ar the individual graps.
Total Lung Capacity (TLC)
The sum of all lung volumes.
TLC = TV + IRV + ERV + RV
Respiratory Volumes (4):
Tidal Volume
Inspiratory Volume
Reserve Volume
Residual Volume
Bicarbonate Buffer System
If the H+ concentration in blood begins to rise, excess H+ is removed by combining with HCO3- (alkaline reserve - weak base) to from H2CO3 (weak acid).
If H+ concentration in the blood drops below desirable levels, H2CO3 dissociates, releasing H+ and lowering pH again.
The result from lactic acid levels in the blood during exercise results from the _____ ______.
Anaerobic respiration
Lesions made in the superior region of the pontine respiratory center cause inspirations to become very prolonged.
Apneustic breathing
Carina
The last tracheal cartilage is expanded, and a cartilage projects posteriorly from its inner face, marking th epoint whe the trachea branches into two main bronchi.
Highly sensitive, and violent coughin is triggered whena foreing object makes contact with it.
By the time incoming air reaches the end of the trachea, it is warm, cleased of most impuritis and saturaded with water vapor.
Under normal conditions, declining PO2 has only a slight effect on ventilation, mostly limited to enhancing the sensitivity of peripheral receptors (aortic and carotid) to increased PCO2.
Arterial PO2 must _____ substantially before O2 levels become a major stimulus for increased ventilation.
Drop
There is a huge reservoir of O2 bound to Hb, and Hb remains almost entirely saturated unless or until the PO2 of alveolar gas and arterial blood falls below 60 mm Hg.
The brain stem centers then begin to suffer from O2 starvation, and their activity is depressed at the same time, the peripheral chemoreceptors become excited and stimulate the respiratory centers to increase ventilation, even if PCO2 is normal.
The peripheral chemoreceptor can maintain ventilation even though the brain stem centers are depressed by hypoxia.
The high _____ content of mucus film humidifies incoming air.
water
Three factors influence external respiration:
1. Partial pressure gradients and gas solubilities. PO2 of deoxygenated blood int he pulmonary arteries is only 40 mm HG as opposed to PO2 in the alveoli of 104 mm Hg. Equilibrium, which is 104 mm Hg on each side of the respiratory membrane, occurs in 0.25 seconds.
CO2 can diffuse in the opposite direction (pulmonary capillaries to the alveoli) much gentler partial pressure gradient of 5 mm Hg. This is the pulmonary capillary of 45 mm Hg to the alveoli of 40 mm Hg, until 40 mm Hg is on both sides of the respiratory membrane.
Equal amounts are exchanged becuase CO2 is 20x more soluble in plasma and alveolar fluid than O2.
2. Thickness and surface area of the respiratory membrane. The respiratory membrane is only 0.5 to 1 µm thick and gas exchange is very efficient. The greater the surface area of the respiratory membrane the more gas that can diffuse across it in a given time period.
3. Ventilation-perfusion coupling (matching alveolar ventiation with pulmonary blood perfusion). Ventilation is the amoutn of gas reaching the alveoli and perfusion is the blood flow in pulmonary capillaries.
PO2 controls perfusion by changing arteriolar diameter.
PCO2 controls ventilation by changing bronchiolar diameter.
A _____ in body temperature raises the respiratory rate, while a drop in body temperature produces the opposite effects.
Rise
Sudden chilling (a dip in the North Atlantic Ocean in late October) can stop your breathing (apnea) - or at the very least, leave you gasping.
In restrictive diseases, VC, TLC, FRC and RV ______ because lung expansion is limited.
Decline
The nasal conchae and mucosa funtion during exhalaiton to:
Reclaim heat and moisture.
Exhalation the cooled conchae precipitate moisture and extract heat from the humid air flowing over them.
Cancer-causing genes and inactivate tumor suppressing genes.
Oncogenes
Boyle’s Law
P1V1 = P2V2
At a constant temperature, the pressure of a gas varies inversely with its volume.
Gases always fill their container.
High-altitude conditions result in _____ than normal Hb saturation levels because less O2 is available to be loaded.
Lower
Common disorder that is characterized by the temporary cessation of breathing during sleep.
Sleep Apnea
The nasal concahe and nasal mucosa function during inhalation to:
Filter, heat and moisten the air.
Inspired air cools the conchae.
While rising blood CO2 levels act as the initial stimulus, it is rising levels of ____ generated within the brain that prod the central chemoreceptors into increased activity.
H+
Effect of PCO2, H+, or BPG on the Oxygen Dissociation Curve
Smoking paralyzes _____ that clear mucus from the airways, allowing irritants and pathogens to accumulate. The “cocktail” of free radicals and other carcinogens in tobacco smoke eventually translates into lung cancer.
Cilia
Control of breathing during rest is aimed primarily at regulating the ____ concentration in the bran.
H+
Changes in Thoracic Volume and Sequence of Events During Inspiration
The gases in inhaled air swirl through the twists and turns deflecting heavier, nongaseous particles onto the mucus-coated surfaces, were they become trapped.
As a result, few partickesl larger tha. 6 µm make it pas the nasal cavity.
The epithelial cells of the respiratory mucosa also secrete ______, natual antibiotics that help kill invading microbes.
Defensins
Intrapulmonary Pressure (Ppul)
The pressure in the alveoli.
Rises and falls with the phases of breathing, but it is always equalizes with the atomospheric pressure eventually.
Two forces act to pull the lungs (visceral pleura) away from the thorax wall (parietal pleura) and cause the lungs to collapes:
- The lungs natural tendency to recoil.
- The surface tension of the alveolar fluid.
*These forces are opposed by the natural elasticity of the chest wall.
The external surfaces of alveoli are densely covered with a “cobweb” of pulmonary capillaries. Together the capillary and alvelolar walls and their fused basement membranes form the _______ _______, a 0.5 µm-thick-blood air barrier that has blood flowing pass on one side and gas on the other.
Respiratory membrane
Gas exchanges occur readily by simple diffusiona cross the respiratory membrane - O2 passes from the alveolus into the blood, and CO2 leveas the blood to enter the gas-filled alveolus.
Ventilation-Perfusion Coupling
More than 80% of patients have a history of smoking.
Dyspnea
Coughing and frequent pulmonary infections.
Most COPD patientds develop respiratoy failure manifested as hypoventilation.
COPD
In contrast to the Pulmoonary Circulation, _____ ______ provide oxygenated systemic blood to lung tissue.
The bronchiole arteries arise from the aorta, enter the lugns at the hikum, and hen run along the branching bronchi. They provide a _____ pressure, _____ volume supply of oxygenated blood to all lung tissues except ______.
Bronchial Arteries
High, Low
Alveoli
The lobar bronci branch into third-order _____ (tertiary) bronchi, which divide repeatedly into smaller and smaller bronci (4th, 5th-order, etc…)
Segmental
Occurs when the body cells are unable to use O2 even though adequate amoutns are delivered. Metabolic poisions, such as cyanide, can cause _______ ________.
Histotoxic Hypoxia
Clustered neurons in two areas of the medulla oblongata appear to be critically important in respiration:
- Ventral respiratory group (VRG)
- Dorsal respiratory group (DRG)
Chemoreceptors are found in two major body locations:
1. Central Chemoreceptors - located throughout the brain stem, including the ventrolateral medulla.
2. Peripheral Chemoreceptors - located in the aortic arch and carotid arteries.
Anaerobic respiration is not a lack of respiratory function because alveolar ventilation and pulmonary perfusion are as well matched ruing exericse as during rest (hemoglobin remains fully saturated).
It refletcs ____ ____ limitations or inability of the skeletal musclces in further to further increase their oxygen consumption.
Cardiac Output
Nasal Vestibule
the part of the nasal cavity just supeiror toeach nostril and is liined with skin containing sebaceous and sweat glands and numours hair follicles.
Features of the external nose:
Root (Area between the eyebrows) Bridge Dorsum Nasi (Anterior margin) Apex (Tip of the nose) Nostrils (External openings of the nose) bound laterally by the flared alae.
Transport of Respiratiory Gases
The cardiovascular system transports gaes using blood as the transporting fluid.
O2 is transported from the lugns to the tissue cells of the body.
CO2 is transported from the tissues cells to the lungs.
The upper respiratory system consists of all the structures from the ____ to the ____.
Nose and nasal cavity
Paranasal sinuses
Pharynx
A zero respiratory pressure is ______ to atomospheric pressure.
Zero
Leading cause of cancer death for both men and women in North America.
90% of cases result from smoking.
Cure rate is notoriously low, with most people dying within one year of diagnosis. The five year survival rate is 16%
Metasized quickly and rapidly; not diagnosed until advanced.
Activated oncogenes.
Ordinarily nasal hairs, sticky mucus and cilia do a fine job of protecting the lungs from chemical and biological irritants, but when a perosn smokes, these defesnes are overwhelmed and eventually stop functioning.
Lung Cancer
Ventral Respiratory Center (VRG)
- Rhythm-generating integrative center
- Contains groups of neurons that fire during inspiration and others that fire during expiration in a dance of mutual inhibition.
Laryngitis
Inflammation of the vocal folds to swell, interfering with their vibration.
Changes in vocal tone, causing hoarsness, or in sever cases limiting us to a whisper.
Often caused by viral infections, but may also be due to overusing th voice, very dry air, bacterial infections, tumors on the vocal folds, or inhalation of irritating chemicals.
During voluntary control, the ______ _____ ______ sends signals to the motor neurons that stimulate the respiratory muscles bypassing the medullary centers.
Cerebral Motor Cortex
The pleurae also help divide the thoractic cavity into three chambers:
The central mediastinum and the two lateral pleural comparntments (each containing a lung).
Helps from ograns interferring with one another.
Also, limits the spread of local infections.
Noses vary a great deal is size and shape, largely because of the differences in ______ ______.
Nasal Cartilages
- Dissolved in Plasma
About 7-10% - The smallest amount of CO2 is transported simply dissolved in plasma.
Influence of PO2 on Hemoglobin Saturation
The oxygen-hemoglobin dissociation curve shows how local PO2 controls
oxygen loading and unloading from hemoglobin.
The infectious disease caused by bacterium by coughing and primarily enters the body in inhaled air.
Mostly affects the lungs but can be spread through the lymphatics to other organs.
1/3 of the world’s population is infected.
Most people never develop active TB because a massive inflammatory response usually contains the primary infection in fibrous, or calcified, nodules (tubercles) in the lungs.
The bacteria may survive in a person’s lungs and when the immune system is weakened it may break out and become active.
Symptoms include fever, night sweats, weigth loss, racking cough, and coughing up blood.
Treatment needs to be complete.
Tuberculosis (TB)
The walls of the alveoli are composed primarily of single layer of squamous epithelial cells, called ____ ____ ____ ____, surronded by a flimsy basement membrane.
Type 1 Alveolar Cells
A sheet of tissue paper is 15x thicker!
PO2 are a good index of lung function and when arteriol PO2 is signifcantly _____ than aveolar PO2 some degree of respiratory impairment exists.
Less
The pulmonary circuit is a ____ pressure, ____ volume circulation.
All the body’s blood passes through the lungs about ____ each minute, the lung capillary endothelium i an ideal locaiton for enzymes that cat on materisl in the blood.
Examples include ______ ______ ______, which activates an important blood pressure hormone, and enzymes that inactive ertani prostaglandins
Low; High
Once
Angiotension Converting Enzyme
The alveolar ducts lead into terminal clusters of alveoli called _____ _____.
Alveolar sacs
Respiratory Volumes and Capacities
Glottis
The medial opening between the vocal chords through which air passes.
Inhaled irritants activate a reflex of the parasympathetic divison of the nervous system that causes constriction of the bronchioles and dramatically reduces air passage.
During an asthma attack, histamine and other inflammatory chemicals can cause such strong broncoconstriction that pulmonary ventailation almost ocmpleelty stops, regardless of the pressure gradient.
Conversly, epinephrine relesed during sympathetic nevous system activation or adminsitered as a drug dilates bronchioles and reduces airway resistance.
Local accumulation of mucus, infectious materials, or solid tumors in the passageways are important sources of airway resistnace in those with respiratory disease.
When bronchioles are severly constricted or obstructed, even the most extreme respiratory efforts cannot restore ventialation to life-sustaning levels.
Each lobe contains a number of pyramind - shaped _______ _______ seperated from one another by connective tissue septa.
Bronchopulmonary Segments
The right lung has 10 segments and the left lung has 8-10 segments.
Each segemnt is served by its own artery and vein and recieves air from an indiviual segmental (tertiary) bronchus.
Under normal conditions, blood PO2 affects breathing only indirectly.
It influences peripheral chemoreceptor sensitivity to changes in PCO2. Low PO2 augments PCO2 effects and high PO2 levels diminish the effectiveness of CO2 stimulation.
Larynx
Voice box.
Superiorly attaches to thehyoid bone and opens into the laryngopharynx. It is inferiorly continuous with the trachea.
The respiratory bronchioles lead into winding _____ ______, whose walls consist of diffusely arranged rings of smoth muscle cells, connective tissue fibers, and outpocketing alveoli.
Alveolar ducts
The skeletal framework is fashioned by the ____ l and ____ bones superiorly, the _______ bones laterally, and flexible plates of ______ cartilage inferiorly.
Nasal; Frontal, Maxillary, Hyaline
Three neural factors for the abrupt increase in ventilation during exercise:
- Psychological stimuli (conscious anticipation of exercise)
- Simultaneous cortical motor activities of skeletabl muscles and respiration centers.
- Excitatory input reaching respiratory centers from proprioceptors in moving mucles, tendons and joints.
Each broncs runs ______ in the ______ before plunging into the medial depression (hilium) of its lung.
Obliquely, Mediastinum
Spirometry
Cannot provide a specific diagnoses, but it can distinguish between obstructive pulmonary disease involving increased airway resistance and restrictive diseases involving involving reduced total lung capacity.
Thought to be more of a protective response than a normal regulatory mechanism.
Inflation (Hering-Breuer) Reflex
Paranasal Sinues
Surround the nasal cavity in a ring.
Located in the frontal, sphenoid, ehtmoid and maxillary bones.
Lightens the skull.
Help warm and moisten the air.
The mucus they produce ulitamtely flows into the nasal cavity, and the suctioning effect created by blowing the nose helps drain the sinuses.
Terminal bronchioles
Less than 0.5 mm in diameter.
The ciliated cells of the respiratory mucosa create a gentle current that moves the sheet of contaminated mucus posteriorly toward the throat, where it is ______ and ______.
Swallowed; digested.
Surface Tension (2)
- Draws the liquid molecules closer together and reduces their contact iwth the dissmilar gas molecules.
- Resists any force that tends to increase the surface area of the liquid.
Transpulmonary Pressure
The difference between the intrapulmonary pressure and the intrapleural pressure.
Pip - Ppul
This pressure keeps the air spaces of the lungs open, or keeps the lungs from collapsing.
The size of the transpulmonary pressure determines thesize of the lungs at any time (directly proportional).
Any condition where Pip = Ppul causes immediate lung collapse.
An inadequate blood supply to an organ or part of the body, especially the heart muscles.
Ischemia
Nonrespiratory air movements
Occur whenever you sneee, cough, cry, laugh, hiccup or yawn.
The peripheral chemoreceptors - found in the aortic arch and carotid arteries - contain cells sensitive to aerterial O2.
The main oxygen sensors are in the _____ _____.
Carotid Bodies
The most important factors in influence breathing rate and depth are:
Changing levels of CO2, O2, and H+ in arterial blood.
Effect of Temperature on the Oxygen Dissociation Curve
Air Resistance is insignificant for two reasons:
- Airway diameters in the first part of the conducting zone are huge, relative to the low viscosity of iar.
- As the airways get smaller, there are progressively more branches. As a result, the cross sectional area is huge.
Greatest resitance to gas flow is in the medium-sized bronci.
Laryngopharynx
Serves as a passageway for food and inhaled air.
Lined with stratified squamous epithelium.
Lies directly posterior to the larynx, where respiratory and digestive pathways diverege, and extends into the inferior edge of the cricoid cartilage.
Continuous with the esophogus.
Esphogus conducts food and fluids ot the stomahcl air enters thelarynx anteriorly.
During swallowing, food has the “right of way” and air passage temporarily stops.
Oropharynx
Lies posterior to the oral cavity and is continuous with it through an archway called isthmus of the fauces.
Both swallowe food and inhaled air pass through it.
Epithelium changes from pseudostratified columnar to a more protective stratified squamous epithelium to accomade increased friction and chemical trauma accompanying food passage.
The palantine tonsil lie embedded int he lateral walls of the oropharyngela mucosa just posterior to the oral cavity.
The lingual tonsil covers the psoterior surface of the tongue.
The smallest subdivision of the lung visible with the naked eye are the ______.
Lobules
Appear at the lung surace as hexagons ranging rom the size of a pencil eraser to the size of a penny.
A larger bronchiole and its brancehs serve each lobule.
In most city dwellersand in smokers, the connective tissue that seperates the individual lobules is blackened with carbon.
The lungs consist of largely of air spaces.
The balalance of lung tissue, or its ______, is mostly elastic connective tissue.
Stroma
As a result the lungs are elastic organs togherer weigh just over 1kg.
The air passageways in the lungs branch about ___ times.
23
Layers of the Trachea
The mucosa, the submucosa, the adventitia - plus the layrer of hyaline cartilage.
Hypoxia
Inadequate oxygen delivery to the body tissues.
Tissue Composition of the Tracheal Wall
Oxyhemoglobin (HbO2)
Hemoglobin-oxygen combination
Each cone shaped lung is surrounded by _____ and connected to the _____ by vascular and broncial attachments collectively called the lung _____.
Pleurae; Mediastinum
Root
Bronchioles
Passages smaller tham 1mm in diameter.
The unsupported posterior portion is the muscular _____ _____.
Soft Palate
Internal Respiration
Involves capillary gas exchange in the body tissues (systemic circulation).
O2 diffuses from the blood into the tissue cells and CO2 diffuses from the CO2 into the blood.
Venous blood draining the tissue capillary beds and returning to the heart has a PO2 of 40 mm Hg and a PCo2 of 45 mm Hg
During breathing, air enters the nasal cavity by passing through the _____ or ______.
Nostrils, nares
The groove inferior to each concha is a _____ _____.
Nasal meatus.
Respiratory Volumes and Capacities
The skin covering the nose anterior and lateral aspects is ____ and contains many _____ glands.
Thin, sebaceous
Expiratory Reserve Volume (ERV)
The amount of air - normally 1000 to 1200 ml - that can be expelled form the lugns after a normal tidal volume expiration.
The framework of the larynx is an intricate arrangelment of nine cartilages connected by membranes and ligaments. Except for the ______, all laryngeal cartilages are hyaline cartilage.
Epiglottis
Inspiratory Muscle Activation
1. Action of the diapraghm - When the dome-shaped diapraghm contracts, it moves inferiorly and flattens out. The superior-inferior dimension (height) of the thoracic cavity increases.
2. Action of the intercostal muscles - when they contract, they lift the rib cage and pull the sternum superiorly.
This is enough to increase the thoracic volume by 500ml - the usual volume that enters the lungs during a normal quiet inspiration. The diaphragm is far more imporatnt in producing these volume changes that lead to normal quiet inspiration.
As thoracic dimensions increase during inspiration, the lungs are stretched and the intrapulmonary volume increases.
Ppul drops about 1 mm Hg relative to Patm. Anytime Ppul < Patm, air rushes into the lugns along the pressure gradient.
Inspiration ends when Ppul = Patm. During this period, Pip declines to about -6 mm Hg relative to Patm.
In obstructive diseases, TLC, FRC and RV may _______ because the lungs hyperinflate.
Increase
Total Dead Space
Anatomical Dead Space + Alveolar Dead Space
The nose (5):
- Provides an airway for respiration. 2. Moistens and warms entering air. 3. Filters and cleans inspired air. 4. Serves as a resonating chamber for speech. 5. Houses the olfactory (smell) receptors.
At high altitudes, Hb’s affinity for O2 is reduces because ____ concentrations increase. This releases more O2 to the tissues during each circulatory round.
BPG
Internal Respiration
Oxygen leaves the blood and enters tissue cells, carbon dioxide leaves the tissue cells and enters the blood.
The respiratory system includes:
The nose
The paranasal sinuses
The pharynx
The larynx
The trachea
The bronchi and their smaller branches
The lungs and tiny air sacs called the alveoli
Inspiratory Capacity (IC):
The toal amount of air that can be inspired after a normal tidal volume expiration.
IC = TV + IRV
Pleurisy
Inflammation of the Pleurae
Often from Pneumonia
Become rough, rsulting in frcitona nd stabbing pain with each breath.
With progression, more fluid accumulates, which relieves pain, but exerts pressure on the lungs and makes breathing movement hard.
Other fluids may include blood, blood filtrate - pleural effusion.
PO2 measurements indicate only the amount of O2 dissolved in _____, not the amount bound to ______. PO2 are a good index of lung function.
Plasma; Hemoglobin.
Conducting Zone
Consists of all the respiratory passageways from the nose to the respiratory bronchioles.
Provide fairly rigid conduits for air to treach the gas exchange sites.
Cleanse, humidfy and warm incoming air.
As a result, air reaching the lungs has fewer irritants (dust, bacteria, etc) than when it entered the body, and it is warm and damp, like the air of the tropics.
Sensors responding to chemical fluctuations
Chemoreceptors
Pharynx
Commonly referred to as the throat.
Tunnel-shaped.
Connects the nasal cavity and mouth superiorly to the larynx and esophagus inferiorly.
Extends from the base of the skull to the level of the sixth cervical vertebra (C6).
Composed of skeletal muscle throughout its length.
Cellular composition changes from one pharygneal region to another.
The structures of the nose is divided into the ______ nose and the ______ ______ ______.
External; Internal nasal cavity.
Located dorsally near the root of cranial nerve IX.
Dorsal Respiratory Group (DRG)
Integrates Peripheral sensory input and modifies the rhythms generated by the VRG.
The left lung is subdivided into superior and inferior lobes by the ______ fissure, where as the right lung is partioned into superior, middel and inferior lobes by the _____ and _____ fissure.
Oblique
Oblique; Horizontal
Nonelastic sources of resistance
Friction or drag encountered in the respiratory passages.
Vibrissae
The hairs that filter corase partcles (dust, pollen) from inspired air.
The pleura produce ____ _____, which fills the slitlike pleural cavity between them.
Pleural Fluid
The lubricating secretion allos the lungs to glide easily over the thorax wall during our breathing movements.
Lungs cling tightly to the thorax wall and expand and recoil passively as the volume of the thoracacic cavity alternatively increases and decreases during breathing.
Lung Compliance depends on (2):
- Distensibility of Lung Tissue
- Alveolar Surface Tension
Healthy lungs usually have a high compliance.
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.
When 1, 2, or 3 oxygen molecules are bound, a hemoglobin moelcule is partially saturated. When all 4 of its heme groups are bound to O2, the hemoglobin is fully saturated.
Unloading of one oxygen molecule enhances the unlaoding of the next, and so on. The affinity of hemoglobin for oxygen changes with the extent of oxygen saturation, and both loading and unloading of oxygen are very efficient.
During hypercapnia, CO2 accumulates in the brain. As CO2 accumulates, it is hydrate to form _____ _____. The acid dissociates, H+, and the pH drops. This is the same reaction that occurs when CO2 enters RBCs.
Carbonic Acid
The major function of _______ is to supply the body with oxygen and dispose of carbon dioxide
Respiratory System
Working muscles consume tremndous amounts of ____ and produce large amoutns of _____, so ventilation can increase 10-20x during vigorous exercise.
O2; CO2
The respiratory system as a whole consists of two zones:
- Respiratory Zone
- Conducting Zone
Reflects poor O2 delivery resulting from too few RBS or from RBCs that contain abnormal or too little Hb.
Anemic Hypoxia
During hypoxia, VRG networks generate gasping.
Respiration stops when a certain cluster of VRG neurons is completely surpessed, as by an overdose of ______ or ______.
Morphine; Alcohol
When blood O2 levels decline, the kidney’s produce more erythropoietin, which stimulates bone marrow production of RBCs. This provides long-term compensation for living at ____ altitudes.
High
Influence of Arterial pH
Changes in arterial pH can modify the respiratory rate and rhythm even when CO2 and O2 levels are normal.
H+ does not cross the blood brain barrier, the increased ventilation that occurs in response tofall arterial pH is mediated throgh the peripheral chemoreceptors.
Changes in CO2 and H+ are distinct stimuli.
A drop in blood pH may be a result from retention of CO2, but it may also result from metabolic causes, such as accumulation of lactic acid during exercise or of fatty acid metabolites (ketone bodies) in patients with poorly controlled diabetes mellitus.
The respiratory system tries to control decreases in pH by increasing the respiratory rate and depth to eliminate CO2 (and carbonic acid) from the blood.
External Respiration
Oxygen enters the blood and carbon dioxide leave the blood by diffusion.
The ______ from a thin, dobule-latered serosa.
The layer called the _____ ______ voers the thoracic wall and superior face of the diaphragm.
It continues around the heart and between the lungs, forming the lateral walls of the mediastinal enclosure and snugly enclosing the lung root.
The pleura extens as the layer called the ______ ______ to cover the external lung surface, dipping into the lining its fissures.
Pleura
Parietal Pleura
Visceral Pleura
Insufficent ventilation in relation to metabolic needs, causing them to retain CO2.
Hypoventilation
Changes in Thoracic Volume and Sequence of Events During Inspiration and Expiration
The entire length of the _____ acts as aresonating chamber, to amplify and enhacne the sound quality.
Pharynx
The nasal cavity is divided by a midline _____ _____ formed anteriorly by the septal cartilage and posterior by the vomer bone and perpendicular plate of ethmoid bone.
Nasal septum
Surfactant
A detergent-like complex of lipids and proteins produced by the type II alveolar cells.
Decreases the cohesiveness of water molecules, much the way laundry deteregent reduces the attraction of water for water, allowing water to interact with and pass through fabric.
As a result, the surface tension of alveolar fluid is reduced, and less energy is needed to overcome those forces to expand the lungs and discourage alvelolar collapse.
Deeper than normal breaths, stimulate surfactant production by Type II Alveolar Cells.
As the rib cage decends and the lungs recoil, the thoracic and intrapulmonary volumes ______. The volume _______ compresses the alveoli, and Ppul rises to about 1 mm Hg above atmospheric pressure.
Decreases; Decreases
Caused by a reduced drive from the respiratory centers of the brain stem during sleep rather than by an obstruction of the airway.
Central sleep apnea
Anteriorly, where the palate is supported by the palatine bones and processes of the maxillary bones, it is called the ______ ______.
Hard Palate
Good enounciation depends on the muscles in the _____, ______, ______ and the _____ that “shape” sound into recognizable constants and vowels.
Pharynx, tongue, soft palate and the lips
Tissue Composition of the Tracheal Wall
Tidal Volume (TV)
During normal quiet breathing, about 500ml of air moves into and out of the lugns with each breath.
Control of resporation primarily involves neurons in the ______ ______ of the medulla and the pons.
Reticular Formation
High CO2 levels in the blood.
Hypercapnia
Minute Ventilation
The total amount of gas that flows into or out of the respiratory tract in 1 minute.
During normal quiet breathing, the minute ventialtion in healthy people is about 6 L/min (500ml per breath multiplied by 12 breahts per minute).
During vigorous exercise the minute ventailaiton may reach 200 L/min.
Rough yardstick for respiratory efficiency.
The respiratory centers in the medulla and pons are sensitve to both ______ and ______ stimuli.
excitatory; inhibitory
Pontine Respiratory Centers
Influence and modify the activtiy of medullary neurons.
Appear to smooth out the transitions from inspiration to expiration, and vice versa.
Transmit impulses to the VRG of the medulla. This modifies and fine-tunes the breathing rhyrhms generated by the VRG during certain activities such as vocalization, sleep and exercise.
Recieve input from higher brain centers and from various sensory receptors in the periphery (just like the DRG).
Vocal folds an act as a s sphincter that prevents air passage.
During abdominal straining associated with defecation, the glottis closes to prevent exhalation and the abdominal muslce contract, causing the intra-abdominal pressure to rise.
Known as Valsalva maneuver.
Help empty the rexctum and can also splitn (stabilize) the body trunk when lifting a heavy load.
The open posterior parts of the cartilage rigns, wihch like nex tto the esophagus, are connected by smooth muscle fiers of the _______ and by soft connective tissue.
Trachealis
Flexible, the esophogus can expand anterioly as swallowed food passses through it.
When inspired air is cold, the vascular plexus becomes engorged with blood, intensifying the air-heating process.
Because these blood vessels are abundant and located superficially, nosebleleds are common and often profuse.
- As bicarbonate ions in plasma:
About 70% - The reactions that convert bicarbonate (HCO3-) for transport mostly occur inside RBCs.
When dissolved CO2 diffuses into RBCs, it combines with H2O, forming carbonic acid (H2CO3).
CO2 + H2O ⇔ H2CO3 ⇔ H+ + HCO3-
This reaction occurs in plasma, but due to carbonic anhydrase, it occurs 1000x faster in RBCs.
H+ and CO2 bind to Hb, triggering the Bohr Effect (releasing O2).
HCO3- moves quickly from the RBCS into the plasma, where it is carried to the lungs. Cl- moves from the plasma in the RBCs (chloride shift) which occurs via facilitated diffusion through an RBC membrane protein.
In the lungs, the process is reversed.
Alveolar Dead Space
Some alveoli cease to act in gas exchange (due to alveolar collapse or obstrcution by mucus).
Alveolar deadspace is added to anatomical deadspace.
The four processes of the respiratory system are:
Pulmonary Ventilation (Breathing)
External Respiration
Transport of Respiratory Gases
Internal Respiration
Internal Respiration
O2 diffeses from the blood tot the tissue cells
CO2 diffueses from the tissues cells to the blood.
Exercise enhanced ventilation does not appear to be prompted by rise in PCO2 and declining PO2 and pH in the blood for two reasons:
- Ventilation increases abruptly as exercise begins, followed by a gradual increase and then reaches a steady state. When exercise stops, there is a small but abrupt decline in ventilation rate, follwed by a gradual decrease to the pre-exercise value.
- Although venous levels change, arterial PCO2 and PO2 levels remain surprsingly constant during exericse. In fact, PCO2 may fall below normal and PO2 may rise slightly because the respiratory adjustments are so efficient.
Pacemaker neurons
Have intrinsic rhymicity like the pacemaker cells found in the heart. Pacemaker-like activity has been found in the VRG neurons, but supressing their activity does not abolish breathing.
A second hypothesis is that there isn’t one set, but multiple sets of pacemaker neurons that are inhibiting each other and cycle their activity to generate the rhythm.
Forced Expiratory Volume (FEV)
Determines the amount of air expelled during specific time intervals of the FVC test.
Example: the volume exhaled during the first second is FEV1. Those with healthy lungs can exahle about 80% of the FVC within 1 second.
Those with obstructive poulmoanry disease exhale considerably less than 80% of the FVC within 1 second, while those with restrictive disease can exhale 80% or more of FVC in 1 second even though FVC is reduced.
Equation for gas flow (F):
F = (P2-P1)/R
F = Gas Flow
P2-P1 = Change in Pressure; Pressure Gradient between external atmosphere and the Alveoli.
R = Resistance; Mainly determined by the diameter in conducting tubes.
Rhinitis
Inflammation of the nasal mucosa accompanied by excessive mucus production, nasal congestion, and postnasal drip.
Nasal mucosa is continous with the mucosa of the other respiratory passageways, explaining the typical nose to throat to chest progression of colds.
Mucosa extends tenrtacle-like into the nasolacrimal (tear) ducts and paranasal sinues, nasal cavity infections often sprea to these regions, causing sinusitis.
Change in pressure results in a sinus headache.
Breathing cessation
Apnea
Forced Expiration
An active process produced by contacting the abdominal wall muscles, primarly the oblqiue and transversus muscle.
- Increase the intraabdominal prssure, which forces the abdominal organs superiorly against the diaphragm.
- Depresses the rib cage.
Breathing (Pulmonary Ventilation) consists of two phases:
Inspiration
Expiration
Functional Residual Capacity (FRC)
The amount of air remaining in the ungs after a normal tidal volume expiration.
FRC = RV + ERV
Anything other than air entering the larynx initiates the cough reflex to expel the substance.
This protective reflex does not work when we are unconcious, so it is never a good idea to administer liquids when attemptng to revive unconciousl person.
Conducting Zone Passages
Of all chemicals influencing respiration, ____ is the most potent and the most closely controlled.
CO2
The anterior, latreal, and posterior lung surfaces lie in close contact with the ribs and form the continously curving _____ _____.
Costal Surface
Even at high altitudes, the O2 needs by the tissues are met under ______ ______.
Resting conditions.
Thyroid Cartilage
Formed by the fusion of two cartilage plates at the midline.
Resembers an upright open book, with the book’s “spine” lying in the anterior midline of the neck.
The larygneal prominence, which can be seen externally as the Adam’s Apple.
Typically larger in males than in females because male sex hormones stimulate its growth during puberty.
Inferior to the thyroid cartilage is the ring-shaped cricoid cartilage, perched atop and anchored to the arachea inferiorly.
Just deep to the clavicle is the ______, the narrow superior tip of the lung.
The concave, inferior surface that rests on the diaphragm is the ______.
Apex
Base
The cyclic on/off activity of the inspiratory and expiratory neurons repeats continously and produces a respiratory rate of __-__ breaths per minute, with inspiratory phases lasting about ___ seconds followed by expiratory phases lasting about ___ seconds.
12-16
2
3
Increases in H+ excites the central chemoreceptors (brain stem), which make abundant synapses with the respiratory regulatory centers. As a result the depth and rate of breathing ______.
Increase
This enhances avelolar ventilation quickly flushes CO2 out of the blood, raising pH.
Seromucous nasal glands contain mucus-sectreting mucous cells and serous cells that secrete a watery fluid contianing enzymes.
Each day, these glands secrete about a quart (a litrer) of mucus containing ______.
Lysozyme, an antibacterial enzyme.
When Ppul > Patm, the pressure gradient forces gases to flow ____ of the lungs.
Out
The paired _____ occupy all of the thoracic cavity except the ______, which houses the heart, great blood vessels, bronchi, espohagus and other organs.
Lungs; Mediastinum
Contraction of the tachealis ______ the trachea’s diameter, causing expired air to rush upwwrd from the lungs with greater force.
Decreases
Helps expel mucus from the trachea when we cough by accelearting the xhaled air to speeds of 100 mph!
The curved conchae greatly _____ the mucosal _____ _____ exposed to air and enhance air turbulence in the cavity.
Increase; Surface area
Heimlich Maneuver
A procedure in which air in the victim’s lungs is uded to “pop out” or expel, an obstructing piece of food, has saved many people from becoming victims of “café coronaries”
Tiny ______ _______ drain some systemic venous blood from the lungs, but they are multiple anastomesse between the two circulations, and most venous blood returns to the heart via the pulmonary veins.
Bronchial veins.
A network of neurons that extends in the ventral brain stem from the spinal cord to the pons-medulla junction
Ventral Respiratory Group (VRG)
Contains Rhythm generators whose output drive respiration.
Inspiratory depth is deteremined by how actively the _____ _____ stimulate the motor neurons serving the respiratory muscles.
Respirtory centers
The greater the stimulation, the greater the number of motor units excited and the greater the force of respiratory muscle contractions.
Three pairs of small cartilage form part of the lateral and psoterior walls of the larynx.
Arytenoid
Cuneiform
Corniculate Cartilages
HHb + O2 ⇔ HbO2 + H+
Lungs and Tissues
Epithelium of Larynx
Stratified squamous epithelium line sthe superior portion of the larynx (subject to food contact).
Below the vocal chords, the epithelium is pseudostratified ciliated columnar type that filters dust.
The power stroke of its cilia is directed upward toward the pharynx to continually move mucus away from the lungs.
Residual Volume (RV)
Even after the most strenuous expiration, about 1200 ml of air remains in the lungs, which healps to keep the alveoli open and prevent lung collapse.
Pulmonary irritant relfexes communicate with the respiratory centers via ____ _____ afferents.
Accumulated in the mucus, inhaled debris such as dust or noxious fumes stimulate receptors in the ______ that promote reflex constriction of those air passages.
Vagal nerve
Bronchioles
The ____ main bronchus is wider, shorter and more vertical than the ____.
Right; Left
More commmon for an inhaled foreign object to get stuck there.
Hemoglobin (Hb)
Composed of 4 polypeptide chains, each bound to an iron-containing heme group.
Iron atoms bind to oxygen, each hemoglobin molecule can combine with four molecules of O2, and oxygen loading is rapid and reversible.
During swallowing, the larynx is pulled ______ and the epiglottis tips to cover the ______ inlet. This action keeps food out of the lower respiratory passages, the epiglottis has been called the gaurdian of the airways.
Superiorly; laryngeal
Red Blood Cells produce ______ as they metabolize glucose. ______ bind reversibly with hemoglobin and its levels rise when oxygen levels are chronically low.
BPG (2,3-biphosphoglycerate); BPG
As cells metabolize glucose and use O2, they release ______, which _____ PCO2, and H+ levels in the capillary blood.
CO2; Increases
C6H12O6 (Glucose) + 6 O2 → 6 CO2 + 6 H2O (Cellular Respiration)
When PCO2 is abnormally low, respiraton is inhibited and becomes slow and shallow. Apnea may occur until PCO2 rises and again stimulates respiration.
Sometimes swimmers voluntarily hyperventilate, so they can hold their breath longer during swim meets. This is dangerous.
As PO2 drops, PCO2, rises enough to make breathing unavailable.
Strenuous hyperventilation can lower PCO2 so much that a lag period occurs before PCO2 rebounds enough to stimulate respiration again. The lag may allow oxygen levesl to fall well velow 50 mm Hg, causeing the swimmer to black out and perhaps drown before he or she has the urge to breath.
Breath-holding that occurs when we are angry and increased respiratory rate that occurs when we are excited happens through the _______.
Hypothalamus
The floor of the nasal cavity is formed by the _____, which separates the nasal cavity from the oral cavity below.
Palate
Pulmonary Ventilation
Ventilation consists of inspiration and expiration.
Inspiration moves air into the lungs from the atmosphere.
Expiration moves air out of the lungs into the atmosphere
Hyperbaric Chambers provide a clinical application of Henry’s law.
Chambers contain O2 gas at pressures higher than 1 atm and are used to force greater-than-normal amounts of O2 into the blood of patients suffering from carbon monoxide poisoning.
The trachea divides to form the ____ and ____ main (primary) bronchi.
Right, Left
Normal PCO2 is ____ mm Hg and controlled within +/- ____ mm Hg.
40; 3
A negative respiratory pressure in any respiratory area indicates that the pressure in that regon is ______ than the atmospheric pressure
Lower
- 4 mm Hg = 756 mm Hg
Emphysema three important consequences:
- Accessory muscle s must be enlisted to breathe, and victims are perpetually tired because breathing requires 15-20% of their total body energy supply (as opposed to 5% in healthy individuals).
- The bronchioles open during inspiration but collapse during experiation, trapiing huge volumes of air in the alveoli. This leads to permanent barrel chest and flattens the diaphragm, reducing ventilation efficiency.
- Damage to the pulmonary capillaries as the alveolar walls disintegrate increases resistance in the pulmonary circuit, forcing the right ventricle to overwork and consequently become enlarged.
External Respiration
Dark red blood flowing through the pulmonary circuit is transfomred into the scarlet river that isreturned to the heart for distribution by systemic arteries to all body tissues.
The color change is due to O2 uptake and binding hemoglobin in red blood cells, but CO2 exchange (unloading) is occurng equally as fast.
Difficult or labored breathing often reffered to as “air hunger” gets progressively worse.
Dyspnea
When arterial PO2 falls below 60 mm Hg it become sthe major sitmulus for respiration.
The peripheral chemoreceptors respond reflexively by increasing ventilation.
This may increase O2 loading into the blood, but it also causes hypocapnia (low PCO2 blood levels ) and an increase in blood pH, both of which inhibit respiration.
Results from impaired or blocked blood circulation.
Ischemic (stagnant) hypoxia
Nasal Conchae protrude medially from each lateral wall of the nasal cavity and are three scroll-like mucosa-covered projections, the _______, _______ and ______ _______ ______.
Inferior, middle and inferior nasal conchae.
Respiratory pressures are always described relative to ______, which is the presssure exerted by the air (gases) surrounding the body.
Atmospheric Pressure (Patn)
Intrapulmonary and Intrapleural Pressure Relationships
Changes in arterial pH due to CO2 retention or metabolic factors act through the peripheral chemoreceptors.
Arterial pH does not influence the central chemoreceptors directly.
Two patterns of COPD:
- Pink puffers - work hard to maintain adequate ventilation that they lose weight, becoming thin but still having nearly normal blood gases.
- Blue bloaters - commonly stocky build become sufficiently hypoxic that they are obviously cyanotic. Hypoxia causes constriciton of pulmonary blood vesesl leading to pulmonary hypertension and right-sided heart failure.
Molecular oxygen is carried in the blood in two ways:
- Bound to hemoglobin within red blood cells. 98.5% is carried this way.
- Dissolved in plasma. 1.5% is carried this way.
Trachea
The windpipe, descends from the larynx throught he neck and into the mediastimum.
Divides into two main bronci at midthorax.
Very flexible and moblie.
Epiglottis
The ninth cartilage.
Flexible, spoon-shaped.
Composed of elastic cartilage and is almost entirely covered by a tast bud containg mucosa.
Extends from the posterior aspect of the tongue to its anchoring point on the anterior rimof the thyroid cartilage.
Vestibular folds
Superior to the vocal folds is a similar pair of mucosal folds.
Play no direct part in sound proudciton but help to close the glottis when we swallow.
Composition of Alveolar Gas
The atmosphere is almost entirely O2 and N2.
The alveoli contain more CO2 and water vapor and much less O2.
The differences reflect:
- Gas exchanges occuring in the lungs.
- Humidification of air by conducitn passages.
- The mixing of alveolar gas that occurs with each breath (mixing new inspired gases with remaining gases in the respiratory passaageways).
O2 and CO2 are easily changed by increasing breathing depth and rate. A high AVR brings more O2 into the alveoli, increasing alveloar PO2 and rapidly eliminating CO2 from the lungs.
Sticky mucus traps inspired dust, bacteria and other debris, while lysozyme:
Attacks tand chemically destroys bacteria.
