A&P Chapter 23 :)

Two characteristics of deoxyhemoglobin give rise to the Haldane effect

(1) Deoxyhemoglobin binds to and thus transports more CO2 than does Hb-O2 (2) Deoxyhemoglobin also buffers more H+ than does Hb-O2, thereby removing H+ from solution and promoting conversion of CO2 to HCO3− via the reaction catalyzed by carbonic anhydrase

What two inwardly directed forces contribute to elastic recoil?

(1) the recoil of elastic fibers that were stretched during inhalation (2) the inward pull of surface tension due to the film of alveolar fluid

The interior structures of the external nose have what three functions?

(1) warming, moistening, and filtering incoming air (2) detecting olfactory stimuli (3) modifying speech vibrations as they pass through the large, hollow resonating chambers

Cancer of the larynx

- found almost exclusively in individuals who smoke - condition is characterized by hoarseness, pain on swallowing, or pain radiating to an ear - treatment consists of radiation therapy and/or surgery

Tracheotomy

- if the obstruction is above the level of the larynx, a tracheotomy may be performed - in this procedure, also called a tracheostomy, a skin incision is followed by a short longitudinal incision into the trachea below the cricoid cartilage - a tracheal tube is then inserted to create an emergency air passageway

Laryngitis

- inflammation of the larynx that is most caused by respiratory infection or irritants such as cigarette smoke - inflammation of the vocal folds causes hoarseness or loss of voice by interfering with the contraction of the folds or by causing them to swell to the point where they cannot vibrate freely - many long-term smokers acquire a permanent hoarseness from the damage done by chronic inflammation

Fact

- the 16-20 incomplete, horizontal rings of hyaline cartilage resemble the letter C, are stacked one above another, and are connected by dense connective tissue --> they may be felt through the skin inferior to the larynx - the open part of each C-shaped cartilage ring faces posteriorly toward the esophagus and is spanned by a fibromuscular membrane --> within this membrane are transverse smooth muscle fibers, called the trachealis muscle, and elastic connective tissue that allow the diameter of the trachea to change subtly during inhalation and exhalation, which is important in maintaining efficient airflow - the solid C-shaped cartilage rings provide a semirigid support to maintain patency so that the tracheal wall does not collapse inward (especially during inhalation) and obstruct the air passageway - the adventitia of the trachea consists of areolar connective tissue that joins the trachea to surrounding tissues

Intubation

- the second method is intubation, in which a tube is inserted into the mouth or nose and passed inferiorly through the larynx and trachea - the firm wall of the tube pushes aside any flexible obstruction, and the lumen of the tube provides a passageway for air; any mucus clogging the trachea can be suctioned out through the tube

Rhinoplasty

-"nose job" -surgical procedure in which the shape of the external nose is altered -in the procedure, both local and general anesthetics are given. Instruments are then inserted through the nostrils, the nasal cartilage is reshaped, and the nasal bones are fractured and repositioned to achieve the desired shape. An internal packing and splint are inserted to keep the nose in the desired position as it heals

BPG (2,3-biphosphoglycerate)

-A substance found in red blood cells called 2,3-bisphosphoglycerate (BPG) decreases the affinity of hemoglobin for O2 and thus helps unload O2 from hemoglobin -BPG is formed in red blood cells when they break down glucose to produce ATP in a process called glycolysis -When BPG combines with hemoglobin by binding to the terminal amino groups of the two beta globin chains, the hemoglobin binds O2 less tightly at the heme group sites -Certain hormones, such as thyroxine, human growth hormone, epinephrine, norepinephrine, and testosterone, increase the formation of BPG. The level of BPG also is higher in people living at higher altitudes

Daltons law

-According to Dalton's law, each gas in a mixture of gases exerts its own pressure as if no other gases were present -The pressure of a specific gas in a mixture is called its partial pressure (Px); the subscript is the chemical formula of the gas -The total pressure of the mixture is calculated simply by adding all of the partial pressures

Partial pressure difference of the gases

-Alveolar PO2 has to be higher than blood PO2 for oxygen to diffuse from alveolar air into the blood --> the rate of diffusion is faster when the diff btw PO2 is larger -The diff btw PO2 and PCO2 in alveolar air vs pulmonary blood increases during exercise -The partial pressures of O2 and CO2 in alveolar air also depend on the rate of airflow into and out of the lungs --> certain drugs like morphine slow ventilation, thereby decreasing the amount of O2 and CO2 that can be exchanged btw the alveolar air and the pulmonary blood -The PO2 of inhaled air decreases with increasing altitude --> alveolar PO2 decreases correspondingly and O2 diffuses into the blood more slowly

Internal nares (choanae)

-Anteriorly, the nasal cavity merges with the external nose, and posteriorly it communicates with the pharynx through two openings called the internal nares or choanae -Ducts from the paranasal sinuses (which drain mucus) and the nasolacrimal ducts (which drain tears) also open into the nasal cavity

Alveolus

-Around the circumference of the alveolar ducts are numerous alveoli and alveolar sacs -An alveolus is a cup-shaped outpouching lined by simple squamous epithelium and supported by a thin elastic basement membrane -The walls of alveoli consist of two types of alveolar epithelial cells

Acidity (pH)

-As acidity increases (pH decreases), the affinity of hemoglobin for O2 decreases, and O2 dissociates more readily from hemoglobin -The main acids produced by metabolically active tissues are lactic acid and carbonic acid

Fact

-As inhaled air whirls around the conchae and meatuses, it is warmed by blood in the capillaries -Mucus secreted by the goblet cells moistens the air and traps dust particles -Drainage from the nasolacrimal ducts also helps moisten the air, and is sometimes assisted by secretions from the paranasal sinuses -The cilia move the mucus and trapped dust particles toward the pharynx, at which point they can be swallowed or spit out, thus removing the particles from the respiratory tract

Partial pressure of carbon dioxide

-As rises, hemoglobin releases O2 more readily -low blood pH (acidity) results from high -As CO2 enters the blood, much of it is temporarily converted to carbonic acid (H2CO3), a reaction catalyzed by an enzyme in red blood cells called carbonic anhydrase (CA) --> the carbonic acid thus formed in red blood cells dissociates into hydrogen ions and bicarbonate ions --> As the H+ concentration increases, pH decreases --> an increased PCO2 produces a more acidic environment, which helps release O2 from hemoglobin. During exercise, lactic acid—a by-product of anaerobic metabolism within muscles—also decreases blood pH

Nitrogen narcosis

-As the total air pressure increases, the partial pressure of all of its gases increase -When a scuba diver breathes air under high pressure, the nitrogen in the mixture can have serious negative effects --> since the partial pressure of nitrogen is higher in compressed air than air at sea level, a considerable amount of N2 dissolves in blood plasma and interstitial fluid --> excessive amounts of dissolved N2 can may produce giddiness and other symptoms related to alcohol intoxication --> this condition is called nitrogen narcosis (rapture of the deep)

Alveolar pressure

-As the volume of the lungs increases, the pressure inside the lungs, called the alveolar (intrapulmonic) pressure, drops from 760 to 758 mmHg --> a pressure difference is thus established between the atmosphere and the alveoli. Because air always flows from a region of higher pressure to a region of lower pressure, inhalation takes place -During deep, forceful inhalations, accessory muscles of inspiration also participate in increasing the size of the thoracic cavity -->the accessory muscles of inhalation include the sternocleidomastoid muscles, which elevate the sternum; the scalene muscles, which elevate the first two ribs; and the pectoralis minor muscles, which elevate the third through fifth ribs -Because both normal quiet inhalation and inhalation during exercise or forced ventilation involve muscular contraction, the process of inhalation is said to be active

Alveolar macrophages

-Associated with the alveolar wall are alveolar macrophages (dust cells), phagocytes that remove fine dust particles and other debris from the alveolar spaces. -Also present are fibroblasts that produce reticular and elastic fibers. Underlying the layer of type I alveolar cells is an elastic basement membrane. On the outer surface of the alveoli, the lobule's arteriole and venule disperse into a network of blood capillaries that consist of a single layer of endothelial cells and basement membrane

Carina

-At the point where the trachea divides into right and left main bronchi an internal ridge called the carina is formed by a posterior and somewhat inferior projection of the last tracheal cartilage -The mucous membrane of the carina is one of the most sensitive areas of the entire larynx and trachea for triggering a cough reflex -Widening and distortion of the carina is a serious sign because it usually indicates a carcinoma of the lymph nodes around the region where the trachea divides

Fact

-Atmospheric air is a mixture of gases—nitrogen (N2), oxygen (O2), argon (Ar), carbon dioxide (CO2), variable amounts of water vapor (H2O), plus other gases present in small quantities -Atmospheric pressure is the sum of the pressures of all of these gases

Cortical influences on breathing

-Because the cerebral cortex has connections with the respiratory center, we can voluntarily alter our pattern of breathing -The ability to not breathe, however, is limited by the buildup of CO2 and H+ in the body. When PCO2 and H+ concentrations increase to a certain level, the DRG neurons of the medullary respiratory center are strongly stimulated, nerve impulses are sent along the phrenic and intercostal nerves to inspiratory muscles, and breathing resumes, whether the person wants it to or not -Nerve impulses from the hypothalamus and limbic system also stimulate the respiratory center, allowing emotional stimuli to alter breathing as, for example, in laughing and crying

Carbaminohemoglobin (Hb-CO2)

-Because the most prevalent protein in blood is hemoglobin (inside red blood cells), most of the CO2 transported in this manner is bound to hemoglobin. The main CO2 binding sites are the terminal amino acids in the two alpha and two beta globin chains. Hemoglobin that has bound CO2 is termed carbaminohemoglobin (Hb-CO2) -The formation of carbaminohemoglobin is greatly influenced by . For example, in tissue capillaries is relatively high, which promotes formation of carbaminohemoglobin. But in pulmonary capillaries, is relatively low, and the CO2 readily splits apart from globin and enters the alveoli by diffusion

Pleural cavity

-Between the visceral and parietal pleurae is a small space, the pleural cavity, which contains a small amount of lubricating fluid secreted by the membranes - This pleural fluid reduces friction between the membranes, allowing them to slide easily over one another during breathing. Pleural fluid also causes the two membranes to adhere to one another just as a film of water causes two glass microscope slides to stick together, a phenomenon called surface tension. Separate pleural cavities surround the left and right lungs

Exhalation

-Breathing out, called exhalation (expiration), is also due to a pressure gradient: pressure in the lungs is greater than the pressure of the atmosphere -Normal exhalation during quiet breathing, unlike inhalation, is a passive process because no muscular contractions are involved -exhalation results from elastic recoil of the chest wall and lungs, both of which have a natural tendency to spring back after they have been stretched -Exhalation starts when the inspiratory muscles relax. As the diaphragm relaxes, its dome moves superiorly owing to its elasticity. As the external intercostals relax, the ribs are depressed. These movements decrease the vertical, lateral, and anteroposterior diameters of the thoracic cavity, which decreases lung volume -->alveolar pressure increases to about 762 mmHg --> air then flows from the area of higher pressure in the alveoli to the area of lower pressure in the atmosphere -exhalation becomes active only during forceful breathing (like during exercise) --> During these times, muscles of exhalation—the abdominal and internal intercostals—contract, which increases pressure in the abdominal region and thorax / contraction of the abdominal muscles moves the inferior ribs downward and compresses the abdominal viscera, thereby forcing the diaphragm superiorly /contraction of the internal intercostals, which extend inferiorly and posteriorly between adjacent ribs, pulls the ribs inferiorly -Although intrapleural pressure is always less than alveolar pressure, it may briefly exceed atmospheric pressure during a forceful exhalation

Terminal bronchioles

-Bronchioles in turn branch repeatedly, and the smallest ones branch into even smaller tubes called terminal bronchioles -These bronchioles contain club (Clara) cells, columnar, nonciliated cells interspersed among the epithelial cells. Club cells may protect against harmful effects of inhaled toxins and carcinogens, produce surfactant (discussed shortly), and function as stem cells (reserve cells), which give rise to various cells of the epithelium. The terminal bronchioles represent the end of the conducting zone of the respiratory system

Inspiratory reserve volume

-By taking a very deep breath, you can inhale a good deal more than 500 mL --> this additional inhaled air, called the inspiratory reserve volume, is about 3100 mL in an average adult male and 1900 mL in an average adult female -Even more air can be inhaled if inhalation follows forced exhalation

Carbon monoxide poisoning

-Carbon monoxide (CO) is a colorless and odorless gas found in exhaust fumes from automobiles, gas furnaces and space heaters, and in tobacco smoke -It is a by-product of the combustion of carbon-containing materials such as coal, gas, and wood -CO binds to the heme group of hemoglobin, just as O2 does, except that the binding of carbon monoxide to hemoglobin is over 200 times as strong as the binding of O2 to hemoglobin -at a concentration as small as 0.1% (PCO = 0.5 mmHg), CO will combine with half the available hemoglobin molecules and reduce the oxygen-carrying capacity of the blood by 50% -Elevated blood levels of CO cause carbon monoxide poisoning, which can cause the lips and oral mucosa to appear bright, cherry-red (the color of hemoglobin with carbon monoxide bound to it) -Without prompt treatment, carbon monoxide poisoning is fatal -It is possible to rescue a victim of CO poisoning by administering pure oxygen, which speeds up the separation of carbon monoxide from hemoglobin

chemoreceptors

-Chemoreceptors are sensory neurons that are responsive to chemicals -Chemoreceptors in 2 locations of the respiratory system monitor levels of CO2, H+, and O2, and provide input to the respiratory center --> central chemoreceptors and peripheral chemoreceptors

Anatomic dead space

-Collectively, the conducting airways with air that does not undergo respiratory exchange are known as the anatomic (respiratory) dead space -Not all of the minute ventilation can be used in gas exchange because some of it remains in the anatomic dead space

Compliance

-Compliance refers to how much effort is required to stretch the lungs and chest wall --> high compliance means that the lungs and chest wall expand easily / low compliance means that they resist expansion -In the lungs, compliance is related to two principal factors: elasticity and surface tension --> the lungs normally have high compliance and expand easily because elastic fibers in lung tissue are easily stretched and surfactant in alveolar fluid reduces surface tension

Intrapleural pressure

-During quiet inhalations, the pressure between the two pleural layers in the pleural cavity, called intrapleural (intrathoracic) pressure, is always subatmospheric (lower than atmospheric pressure) -Just before inhalation, it is about 4 mmHg less than the atmospheric pressure, or about 756 mmHg at an atmospheric pressure of 760 mmHg -As the diaphragm and external intercostals contract and the overall size of the thoracic cavity increases, the volume of the pleural cavity also increases, which causes intrapleural pressure to decrease to about 754 mmHg. During expansion of the thorax, the parietal and visceral pleurae normally adhere tightly because of the subatmospheric pressure between them and because of the surface tension created by their moist adjoining surfaces. As the thoracic cavity expands, the parietal pleura lining the cavity is pulled outward in all directions, and the visceral pleura and lungs are pulled along with it

External respiration

-External respiration (pulmonary gas exchange) is the diffusion of O2 from the air in the alveoli to blood in pulmonary capillaries and the diffusion of CO2 in the opposite direction --> as blood flows thru pulmonary capillaries, it picks up O2 from alveolar air and unloads CO2 into alveolar air --> each gas diffuses independently from the area where its partial pressure is higher to the area where its partial pressure is lower -Converts deoxygenated blood coming from the right side of the heart into oxygenated blood that returns to the left side of the heart

Fetal hemoglobin (Hb-F)

-Fetal hemoglobin (Hb-F) differs from adult hemoglobin (Hb-A) in structure and in its affinity for O2 -Hb-F has a higher affinity for O2 because it binds BPG less strongly -Thus, when is low, Hb-F can carry up to 30% more O2 than maternal Hb-A -As the maternal blood enters the placenta, O2 is readily transferred to fetal blood. This is very important because the O2 saturation in maternal blood in the placenta is quite low, and the fetus might suffer hypoxia were it not for the greater affinity of fetal hemoglobin for O2

Henrys law

-Henrys law states that the quantity of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility -The higher the partial pressure of a gas over a liquid and the higher the solubility, the more gas will stay in solution -Much more CO2 is dissolved in blood plasma than O2 because the solubility of CO2 is 24 times greater than that of O2 -Even though the air we breath is mostly N2, this gas has no known effects on bodily functions and very little of it dissolves in blood plasma at sea level because its solubility is very low

Hyperbaric oxygenation

-Hyperbaric oxygenation is the use of pressure to cause more O2 to dissolve in the blood -> effective technique in treating patients infected by anaerobic bacteria (cuz anaerobic bacteria cant live in the presence of free O2) -A person undergoing hyperbaric oxygenation is placed in a hyperbaric chamber that contains O2 at a pressure greater than 1 atm, and as body tissues pick up the O2, the bacteria are killed

Decompression sickness

-If a diver comes to the surface slowly, the dissolved nitrogen can be eliminated by exhaling it. But if the ascent is too rapid, nitrogen comes out of solution too quickly and forms gas bubbles in the tissues, resulting in decompression sickness (the bends) -The effects of decompression sickness usually result from bubbles in nervous tissue and can be mild or severe depending on the number of bubble formed -Symptoms include joint pain (esp in arms nd legs), dizziness, SOB, extreme fatigue, paralysis, and unconsciousness

Hypocapnia

-If arterial PCO2 is lower than 40 mmHg—a condition called hypocapnia or hypocarbia—the central and peripheral chemoreceptors are not stimulated, and stimulatory impulses are not sent to the DRG -As a result, DRG neurons set their own moderate pace until CO2 accumulates and the PCO2 rises to 40 mmHg -DRG neurons are more strongly stimulated when PCO2 is rising above normal than when PO2 is falling below normal. As a result, people who hyperventilate voluntarily and cause hypocapnia can hold their breath for an unusually long period -Swimmers were once encouraged to hyperventilate just before diving in to compete. However, this practice is risky because the O2 level may fall dangerously low and cause fainting before the PCO2 rises high enough to stimulate inhalation

Minimal volume

-If the thoracic cavity is opened, the intrapleural pressure rises to equal the atmospheric pressure and forces out some of the residual volume. The air remaining is called the minimal volume -Minimal volume provides a medical and legal tool for determining whether a baby is born dead (stillborn) or died after birth. The presence of minimal volume can be demonstrated by placing a piece of lung in water and observing if it floats. Fetal lungs contain no air, so the lung of a stillborn baby will not float in water

Pneumothorax and Hemothorax

-In certain conditions, the pleural cavities may fill with air (pneumo- = air or breath), blood (hemothorax), or pus. Air in the pleural cavities, most commonly introduced in a surgical opening of the chest or as a result of a stab or gunshot wound, may cause the lungs to collapse -The goal of treatment is the evacuation of air (or blood) from the pleural space, which allows the lung to reinflate. A small pneumothorax may resolve on its own, but it is often necessary to insert a chest tube to assist in evacuation

Fact

-In pulmonary ventilation, air flows between the atmosphere and the alveoli of the lungs because of alternating pressure differences created by contraction and relaxation of respiratory muscles -The rate of airflow and the amount of effort needed for breathing are also influenced by alveolar surface tension, compliance of the lungs, and airway resistance

pre-Bötzinger complex

-Located in the VRG is a cluster of neurons called the pre-Bötzinger complex that is believed to be important in the generation of the rhythm of breathing -This rhythm generator, analogous to the one in the heart, is composed of pacemaker cells that set the basic rhythm of breathing. The exact mechanism of these pacemaker cells is unknown -However, it is thought that the pacemaker cells provide input to the DRG, driving the rate at which DRG neurons fire action potentials

hypercapnia

-Normally, the PCO2 in arterial blood is 40 mmHg --> if even a slight increase in PCO2 occurs (condition called hypercapnia), the central chemoreceptors are stimulated and respond vigorously to the resulting increase in H+ level / the peripheral chemoreceptors are also stimulated by the high PCO2 and H+, and they also respond to a deficiency of O2

Oxyhemoglobin

-Oxygen and hemoglobin bind in an easily reversible reaction to form oxyhemoglobin

Fact

-Oxygen doesn't dissolve easily in water, so only about 1.5% of inhaled O2 is dissolved in blood plasma (cuz its mostly water) / About 98.5% of blood O2 is bound to hemoglobin in red blood cells -Each 100 mL of oxygenated blood contains the equivalent of 20 mL of gaseous O2 --> so the amount dissolved in plasma is 0.3 mL and the amount bound to hemoglobin is 19.7 mL

Peripheral chemoreceptors

-Peripheral chemoreceptors are located in carotid bodies and aortic bodies -These chemoreceptors are part of the peripheral nervous system and are sensitive to changes in PO2, H+, and PCO2 in the blood

Proprioreceptors

-Proprioreceptors monitor movement of joints and muscles -->As soon as you start exercising, your rate and depth of breathing increase, even before changes in PCO2, PO2, or H+ level occur. The main stimulus for these quick changes in respiratory effort is input from proprioceptors -Nerve impulses from the proprioceptors stimulate the DRG of the medulla. At the same time, axon collaterals (branches) of upper motor neurons that originate in the primary motor cortex (precentral gyrus) also feed excitatory impulses into the DRG

Alveolar ducts

-Respiratory bronchioles in turn subdivide into several (2-11) alveolar ducts, which consist of simple squamous epithelium -The respiratory passages from the trachea to the alveolar ducts contain about 25 orders of branching; branching from the trachea into primary bronchi is called first-order branching, that from main bronchi into lobar bronchi is called second-order branching, and so on down to the alveolar ducts

Respiratory distress syndrome (RDS)

-Respiratory distress syndrome (RDS) is a breathing disorder of premature newborns in which the alveoli do not remain open due to a lack of surfactant. (surfactant reduces surface tension and is necessary to prevent the collapse of alveoli during exhalation) -Symptoms of RDS include labored and irregular breathing, flaring of the nostrils during inhalation, grunting during exhalation, and perhaps a blue skin color --> besides the symptoms, RDS is diagnosed on the basis of chest radiographs and a blood test -A newborn with mild RDS may require only supplemental oxygen administered through an oxygen hood or through a tube placed in the nose. In severe cases oxygen may be delivered by continuous positive airway pressure (CPAP) through tubes in the nostrils or a mask on the face. In such cases surfactant may be administered directly into the lungs.

Baroreceptors or stretch receptors

-Similar to those in the blood vessels, stretch-sensitive receptors called baroreceptors or stretch receptors are located in the walls of bronchi and bronchioles. When these receptors become stretched during overinflation of the lungs, nerve impulses are sent along the vagus (X) nerves to the dorsal respiratory group (DRG) --> in response, the DRG is inhibited and the diaphragm and external intercostals relax. As a result, further inhalation is stopped and exhalation begins -As air leaves the lungs during exhalation, the lungs deflate and the stretch receptors are no longer stimulated. Thus, the DRG is no longer inhibited, and a new inhalation begins. This reflex is referred to as the inflation reflex

Molecular weight and solubility of the gases

-Since O2 has a lower molecular weight than CO2, it could be expected to diffuse across the respiratory membrane about 1.2 times faster BUT the solubility of CO2 in blood plasma is 24 times greater than that of O2 SO net outward diffusion of CO2 occurs 20 times faster than net inward diffusion of O2 -Therefore, if diffusion is slower than normal like in emphysema or pulmonary edema, O2 insufficiency (hypoxia) occurs before significant retention of CO2 (hypercapnia)

Respiratory bronchioles

-Terminal bronchioles subdivide into microscopic branches called respiratory bronchioles -They also have alveoli budding from their walls. Alveoli participate in gas exchange, and thus respiratory bronchioles begin the respiratory zone of the respiratory system -As the respiratory bronchioles penetrate more deeply into the lungs, the epithelial lining changes from simple cuboidal to simple squamous

Ventral respiratory group (VRG)

-The VRG becomes activated when forceful breathing is required, such as during exercise, when playing a wind instrument, or at high altitudes -During forceful inhalation, nerve impulses from the DRG not only stimulate the diaphragm and external intercostal muscles to contract, they also activate neurons of the VRG involved in forceful inhalation to send impulses to the accessory muscles of inhalation (sternocleidomastoid, scalenes, and pectoralis minor). Contraction of these muscles results in forceful inhalation -During forceful exhalation, the DRG is inactive along with the neurons of the VRG that result in forceful inhalation, but neurons of the VRG involved in forceful exhalation send nerve impulses to the accessory muscles of exhalation (internal intercostals, external oblique, internal oblique, transversus abdominis, and rectus abdominis). Contraction of these muscles results in forceful exhalation

Spirometer

-The apparatus commonly used to measure the volume of air exchanged during breathing and the respiratory rate is a spirometer or respirometer -The record is called a spirogram -Inhalation is recorded as an upward deflection, and exhalation is recorded as a downward deflection

Superior, middle, and inferior nasal meatuses

-The conchae, almost reaching the nasal septum, subdivide each side of the nasal cavity into a series of groovelike air passageways—the superior, middle, and inferior nasal meatuses -The arrangement of conchae and meatuses increases surface area in the internal nose and prevents dehydration by trapping water droplets during exhalation

Forced expiratory volume in 1 second

-The forced expiratory volume in 1 second, (FEV1.0) is the volume of air that can be exhaled from the lungs in 1 second with maximal effort following a maximal inhalation -Typically, chronic obstructive pulmonary disease (COPD) greatly reduces FEV1.0 because COPD increases airway resistance

Bicarbonate ions

-The greatest percentage of CO2—about 70%—is transported in blood plasma as bicarbonate ions -As CO2 diffuses into systemic capillaries and enters red blood cells, it reacts with water in the presence of the enzyme carbonic anhydrase (CA) to form carbonic acid, which dissociates into H+ and HCO3− -Thus, as blood picks up CO2, HCO3− accumulates inside RBCs. Some HCO3− moves out into the blood plasma, down its concentration gradient. In exchange, chloride ions (Cl−) move from plasma into the RBCs. This exchange of negative ions, which maintains the electrical balance between blood plasma and RBC cytosol, is known as the chloride shift. The net effect of these reactions is that CO2 is removed from tissue cells and transported in blood plasma as HCO3−. As blood passes through pulmonary capillaries in the lungs, all of these reactions reverse and CO2 is exhaled

Fact about the internal nose

-The lateral walls of the internal nose are formed by the ethmoid, maxillae, lacrimal, palatine, and inferior nasal conchae bones -the ethmoid bone also forms the roof -The palatine bones and palatine processes of the maxillae, which together constitute the hard palate, form the floor of the internal nose

Lungs

-The lungs (= lightweights, because they float) are paired cone-shaped organs in the thoracic cavity -They are separated from each other by the heart and other structures of the mediastinum, which divides the thoracic cavity into two anatomically distinct chambers -As a result, if trauma causes one lung to collapse, the other may remain expanded -The lungs extend from the diaphragm to just slightly superior to the clavicles and lie against the ribs anteriorly and posteriorly -The lungs almost fill the thorax

Type I alveolar cells

-The more numerous type I alveolar (squamous pulmonary epithelial) cells are simple squamous epithelial cells that form a nearly continuous lining of the alveolar wall -The thin type I alveolar cells are the main sites of gas exchange

Diaphragm

-The most important muscle of inhalation is the diaphragm, the dome-shaped skeletal muscle that forms the floor of the thoracic cavity -It is innervated by fibers of the phrenic nerves, which emerge from the spinal cord at cervical levels 3, 4, and 5 -Contraction of the diaphragm causes it to flatten, lowering its dome. This increases the vertical diameter of the thoracic cavity -During normal quiet inhalation, the diaphragm descends about 1 cm (0.4 in.), producing a pressure difference of 1-3 mmHg and the inhalation of about 500 mL of air -In strenuous breathing, the diaphragm may descend 10 cm (4 in.), which produces a pressure difference of 100 mmHg and the inhalation of 2-3 liters of air -Contraction of the diaphragm is responsible for about 75% of the air that enters the lungs during quiet breathing -Advanced pregnancy, excessive obesity, or confining abdominal clothing can prevent complete descent of the diaphragm

Pharynx

-The pharynx, or throat, is a funnel-shaped tube about 5 in (13 cm) long that starts at the internal nares and extends to the level of the cricoid cartilage, the most inferior cartilage of the larynx (voice box) -The pharynx lies just posterior to the nasal and oral cavities, superior to the larynx, and just anterior to the cervical vertebrae -Its wall is composed of skeletal muscles and is lined with a mucous membrane -->relaxed skeletal muscles help keep the pharynx patent / contraction of the skeletal muscles assists in deglutition (swallowing) -The muscles of the entire pharynx are arranged in two layers, an outer circular layer and an inner longitudinal layer -The pharynx functions as a passageway for air and food, provides a resonating chamber for speech sounds, and houses the tonsils, which participate in immunological reactions against foreign invaders

pontine respiratory group (PRG)

-The pontine respiratory group (PRG), formerly called the pneumotaxic area, is a collection of neurons in the pons -The neurons in the PRG are active during inhalation and exhalation -The PRG transmits nerve impulses to the DRG in the medulla -The PRG may play a role in both inhalation and exhalation by modifying the basic rhythm of breathing generated by the VRG, as when exercising, speaking, or sleeping

Boyle's law

-The pressure of a gas in a closed container is inversely proportional to the volume of the container -This inverse relationship between volume and pressure is called boyle's law -Differences in pressure caused by changes in lung volume force air into our lungs when we inhale and out when we exhale. For inhalation to occur, the lungs must expand, which increases lung volume and thus decreases the pressure in the lungs to below atmospheric pressure. The first step in expanding the lungs during normal quiet inhalation involves contraction of the main muscle of inhalation, the diaphragm, with resistance from external intercostals

Diffusion distance

-The respiratory membrane is very thin, so diffusion occurs quickly + the capillaries are so narrow that the red blood cells must pass through them in single file, which minimizes the diffusion distance from an alveolar air space to hemoglobin inside red blood cells -Buildup of interstitial fluid btw alveoli, like in pulmonary edema, slows the rate of gas exchange because it increases diffusion distance

The Respiratory System

-The respiratory system consists of the nose, pharynx (throat), larynx (voice box), trachea (windpipe), bronchi, and lungs -Structurally, the respiratory system consists of two parts: the upper respiratory system and the lower respiratory system -Functionally, the respiratory system also consists of two parts: the conducting zone and the respiratory zone

Respiratory center

-The size of the thorax is altered by the action of the breathing muscles, which contract as a result of nerve impulses transmitted from centers in the brain and relax in the absence of nerve impulses -These nerve impulses are sent from clusters of neurons located bilaterally in the brain stem -This widely dispersed group of neurons, collectively called the respiratory center, can be divided into two principal areas on the basis of location and function: (1) the medullary respiratory center in the medulla oblongata (2) the pontine respiratory group in the pons

Dissolved CO2

-The smallest percentage—about 7%—is dissolved in blood plasma -On reaching the lungs, it diffuses into alveolar air and is exhaled

Surface area available for gas exchange

-The surface area of the alveoli is huge + many capillaries surround each alveolus --> 900 mL of blood is able to participate in gas exchange at any instant -Any pulmonary disorder that decreases the functional surface area of the respiratory membranes decreases the rate of external respiration (in emphysema, the alveolar walls disintegrate, so surface area is smaller than normal and pulmonary gas exchange is slowed)

Superior, middle, and inferior nasal conchae

-Three shelves formed by projections of the superior, middle, and inferior nasal conchae extend out of each lateral wall of the nasal cavity

Type II alveolar cells

-Type II alveolar cells, also called septal cells, are fewer in number and are found between type I alveolar cells -Type II alveolar cells, rounded or cuboidal epithelial cells with free surfaces containing microvilli, secrete alveolar fluid, which keeps the surface between the cells and the air moist

Relationship btw the percent saturation of Hb and PO2

-When PO2 is high, Hb binds with large amounts of O2 and is almost 100% saturated / when PO2 is low, Hb is only partially saturated --> so the greater the PO2, the more O2 will bind to Hb, until all available Hb molecules are saturated --> so in pulmonary capillaries where PO2 is high, a lot of O2 bind to Hb, and in systemic capillaries where PO2 is lower the Hb does not hold as much O2 and the dissolved O2 is unloaded via diffusion into tissue cells

External intercostals

-When these muscles contract, they elevate the ribs. As a result, there is an increase in the anteroposterior and lateral diameters of the chest cavity -Contraction of the external intercostals is responsible for about 25% of the air that enters the lungs during normal quiet breathing

Tidal volume

-While at rest, a healthy adult averages 12 breaths a minute, with each inhalation and exhalation moving about 500 mL of air into and out of the lungs. The volume of one breath is called the tidal volume (VT) -Tidal volume varies considerably from one person to another and in the same person at different times. In a typical adult, about 70% of the tidal volume (350 mL) actually reaches the respiratory zone of the respiratory system—the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli—and participates in external respiration. The other 30% (150 mL) remains in the conducting airways of the nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles

Bronchopulmonary segment

-Within the lung, the lobar bronchi give rise to the segmental bronchi, which are constant in both origin and distribution—there are 10 segmental bronchi in each lung -The segment of lung tissue that each segmental bronchus supplies is called a bronchopulmonary segment -Bronchial and pulmonary disorders (such as tumors or abscesses) that are localized in a bronchopulmonary segment may be surgically removed without seriously disrupting the surrounding lung tissue

Cricoid cartilage

-a ring of hyaline cartilage that forms the inferior wall of the larynx -cricoid cartilage is the landmark for making an emergency airway called a tracheotomy

Surface tension

-a thin layer of alveolar fluid coats the luminal surface of alveoli and exerts a force known as surface tension -surface tension arises at all air-water interfaces because the polar water molecules are more strongly attracted to each other than they are to gas molecules in the air -when liquid surrounds a sphere of air, as in an alveolus or a soap bubble, surface tension produces an inwardly directed force -in the lungs, surface tension causes the alveoli to assume the smallest possible diameter -during breathing, surface tension must be overcome to to expand the lungs during each inhalation -surface tension also accounts for 2/3 of lung elastic recoil, which decreases the size of the alveoli during exhalation -surfactant (a mixture of phospholipids and lipoproteins) present in alveolar fluid reduces its surface tension below the surface tension of pure water --> a deficiency of surfactant in premature infants causes respiratory distress syndrome, where the surface tension of alveolar fluid is greatly increased so tht many alveoli collapse at the end of each exhalation, and great effort is then needed at the next inhalation to reopen the collapsed alveoli

Nasal septum

-a vertical partition, the nasal septum, divides the nasal cavity into right and left sides -anterior portion of the nasal septum consists primarily of hyaline cartilage / remainder is formed by the vomer, perpendicular plate of the ethmoid, maxillae, and palatine bones

Carbamino compounds

-about 23%, combines with the amino groups of amino acids and proteins in blood to form carbamino compounds -Because the most prevalent protein in blood is hemoglobin (inside red blood cells), most of the CO2 transported in this manner is bound to hemoglobin. The main CO2 binding sites are the terminal amino acids in the two alpha and two beta globin chains. Hemoglobin that has bound CO2 is termed carbaminohemoglobin (Hb-CO2)

Pressure changes during pulmonary ventilation

-air move into the lungs when the air pressure inside the lungs is less than the air pressure in the atmosphere -air moves out of the lungs when the air pressure inside the lungs is greater than the air pressure in the atmosphere

Nasal vestibule

-anterior portion of the nasal cavity just inside the nostrils, called the nasal vestibule, is surrounded by cartilage -when air enters the nostrils, it passes first through the vestibule, which is lined by skin containing coarse hairs that filter out large dust particles

Temperature

-as temperature increases, so does the amount of O2 released from hemoglobin -heat is a by-product of the metabolic reactions of all cells, and the heat released by contracting muscle fibers tends to raise body temperature -metabolically active cells require more O2 and liberate more acids and heat. The acids and heat in turn promote release of O2 from oxyhemoglobin -during hypothermia (lowered body temperature) cellular metabolism slows, the need for O2 is reduced, and more O2 remains bound to hemoglobin (a shift to the left in the saturation curve)

Right main bronchus

-at the superior border of the fifth thoracic vertebra, the trachea divides into a right main (primary) bronchus, which goes into the right lung, and a left main (primary) bronchus, which goes into the left lung -right main bronchus is more vertical, shorter, and wider than the left --> as a result, an aspirated object is more likely to enter and lodge in the right main bronchus than the left

Oblique fissure

-both lungs have an oblique fissure, which extends inferiorly and anteriorly -the oblique fissure in the left lung separates the superior lobe from the inferior lobe -in the right lung, the superior part of the oblique fissure separates the superior lobe from the inferior lobe; the inferior part of the oblique fissure separates the inferior lobe from the middle lobe, which is bordered superiorly by the horizontal fissure

Inhalation

-breathing in is called inhalation (inspiration) -just before each inhalation, the air pressure inside the lungs is equal to the air pressure of the atmosphere, which at sea level is 760 mmHg or 1 atm -for air to flow into the lungs, the pressure inside the alveoli must become lower than the atmospheric pressure --> this condition is achieved by increasing the size of the lungs

aortic bodies

-clusters of chemoreceptors located in the wall of the arch of the aorta -The chemoreceptors of the aortic bodies are located close to the aortic baroreceptors -Axons of sensory neurons from the aortic bodies are part of the vagus (X) nerves

Glottis

-consists of a pair of folds of mucous membrane, the vocal folds (true vocal cords) in the larynx, and the space between them called the rima glottidis -closing of the larynx in this way during swallowing routes liquids and foods into the esophagus and keeps them out of the larynx and airways -->when small particles of dust, smoke, food, or liquids pass into the larynx, a cough reflex occurs, usually expelling the material

Conducting zone

-consists of a series of interconnecting cavities and tubes both outside and within the lungs --> these include the nose, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles -their function is to filter, warm, and moisten air and conduct it into the lungs

Respiratory zone

-consists of tubes and tissues within the lungs where gas exchange occurs --> include the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli --> main sites of gas exchange between air and blood

Thyroid cartilage (Adams apple)

-consists of two fused plates of hyaline cartilage that form the anterior wall of the larynx and give it a triangular shape -present in both males and females but is usually larger in males due to the influence of male sex hormones on its growth during puberty

Soft palate

-forms the posterior portion of the roof of the mouth -an arch-shaped muscular partition between the nasopharynx and oropharynx that is lined by mucous membrane -there are five openings in its wall:two internal nares, two openings that lead into the auditory (pharyngotympanic) tubes (commonly known as the eustachian tubes), and the opening into the oropharynx / the posterior wall also contains the pharyngeal tonsil, or adenoid

Airway resistance

-just like blood flow thru blood vessels, rate of airflow through the airways depends on both the pressure difference and the resistance -airflow equals the pressure difference between the alveoli and the atmosphere divided by the resistance -the walls of the airways, especially the bronchioles, offer some resistance to the normal flow of air into and out of the lungs. As the lungs expand during inhalation, the bronchioles enlarge because their walls are pulled outward in all directions. Larger-diameter airways have decreased resistance (airway resistance then increases during exhalation as the diameter of bronchioles decreases) - Airway diameter is also regulated by the degree of contraction or relaxation of smooth muscle in the walls of the airways. Signals from the sympathetic division of the autonomic nervous system cause relaxation of this smooth muscle, which results in bronchodilation and decreased resistance -Any condition that narrows or obstructs the airways increases resistance, so that more pressure is required to maintain the same airflow. The hallmark of asthma or chronic obstructive pulmonary disease (COPD)—emphysema or chronic bronchitis—is increased airway resistance due to obstruction or collapse of airways

Nasal cavity

-large space in the anterior aspect of the skull that lies inferior to the nasal bone and superior to the oral cavity -it is lined with muscle and mucous membrane -nasal cavity is divided into a larger, inferior respiratory region and a smaller, superior olfactory region --> respiratory region is lined with pseudostratified ciliated columnar epithelium with numerous goblet cells, which is frequently called the respiratory epithelium / superior part of the nasal cavity is surrounded by bone / anterior portion of the nasal cavity just inside the nostrils, called the nasal vestibule, is surrounded by cartilage

Epiglottis

-large, leaf-shaped piece of elastic cartilage that is covered with epithelium -"stem" of the epiglottis is the tapered inferior portion that is attached to the anterior rim of the thyroid cartilage -broad superior "leaf" portion of the epiglottis is unattached and is free to move up and down like a trap door -during swallowing, the pharynx and larynx rise --> elevation of pharynx widens it to receive food or drink; elevation of the larynx causes the epiglottis to move down and form a lid over the glottis, closing it off

Trachea

-or windpipe, is a tubular passageway for air that is about 12 cm (5 in.) long and 2.5 cm (1 in.) in diameter -located anterior to the esophagus and extends from the larynx to the superior border of the fifth thoracic vertebra (T5), where it divides into right and left primary bronchi

Arytenoid cartilages

-paired arytenoid cartilages are triangular pieces of mostly hyaline cartilage located at the posterior, superior border of the cricoid cartilage -they form synovial joints with the cricoid cartilage and have a wide range of mobility

Paranasal sinuses

-paranasal sinuses are cavities in certain cranial and facial bones lined with mucous membrane that are continuous with the lining of the nasal cavity -Skull bone, containing the paranasal sinuses are the frontal, sphenoid, ethmoid, and maxillae -Besides producing mucus, the paranasal sinuses serve as resonating chambers for sound as we speak or sing

External nose

-portion of the nose visible on the face and consists of a supporting framework of bone (the frontal bone, nasal bones, and maxillae form the bony framework) and hyaline cartilage (cartilaginous framework consists of several pieces of hyaline cartilage connected to each other and certain skull bones by fibrous connective tissue) covered with muscle and skin and lined by a mucous membrane -the bony and cartilaginous framework of the nose help to keep the vestibule and nasal cavity patent, that is, open or unobstructed

Nose

-specialized organ at the entrance of the respiratory system that consists of a visible external portion and an internal portion inside the skull called the nasal cavity

Nasopharynx

-superior portion of the pharynx -lies posterior to the nasal cavity and extends to the soft palate -through the internal nares, the nasopharynx receives air from the nasal cavity along with packages of dust-laden mucus -the nasopharynx is lined with pseudostratified ciliated columnar epithelium, and the cilia move the mucus down toward the most inferior part of the pharynx -the nasopharynx also exchanges small amounts of air with the auditory tubes to equalize air pressure between the middle ear and the atmosphere

Tonsillectomy

-surgical removal of the tonsils -procedure is usually performed under general anesthesia on an outpatient basis -performed in individuals who have frequent tonsillitis (inflammation of the tonsils), tonsils that develop an abscess or tumor, or tonsils that obstruct breathing during sleep

What are the components of the cartilaginous framework?

-the components of the cartilaginous framework are the septal nasal cartilage, which forms the anterior portion of the nasal septum; the lateral nasal cartilages inferior to the nasal bones; and the alar cartilages, which form a portion of the walls of the nostrils -because it consists of pliable hyaline cartilage, the cartilaginous framework of the external nose is somewhat flexible

Laryngopharynx

-the inferior portion of the pharynx, the laryngopharynx, or hypopharynx, begins at the level of the hyoid bone -at its inferior end it opens into the esophagus (food tube) posteriorly and the larynx (voice box) anteriorly -like the oropharynx, the laryngopharynx is both a respiratory and a digestive pathway and is lined by nonkeratinized stratified squamous epithelium

Oropharynx

-the intermediate portion of the pharynx, the oropharynx, lies posterior to the oral cavity and and extends from the soft palate inferiorly to the level of the hyoid bone -has only one opening into it, the fauces -this portion of the pharynx has both respiratory and digestive functions, serving as a common passageway for air, food, and drink -because the oropharynx is subject to abrasion by food particles, it is lined with nonkeratinized stratified squamous epithelium -two pairs of tonsils, the palatine and lingual tonsils, are found in the oropharynx

Larynx

-the larynx, or voice box, is a short passageway that connects the laryngopharynx with the trachea -lies in the midline of the neck anterior to the esophagus and the fourth through sixth cervical vertebrae -wall of the larynx is composed of nine pieces of cartilage --> 3 occur singly (thyroid cartilage, epiglottis, and cricoid cartilage), and three occur in pairs (arytenoid, cuneiform, and corniculate cartilages) --> of the paired cartilages, the arytenoid cartilages are the most important because they influence changes in position and tension of the vocal folds (true vocal cords for speech) -extrinsic muscles of the larynx connect the cartilages to other structures in the throat; intrinsic muscles connect the cartilages to one another

Fact

-the lining of the larynx superior to the vocal folds is nonkeratinized stratified squamous epithelium. The lining of the larynx inferior to the vocal folds is pseudostratified ciliated columnar epithelium consisting of ciliated columnar cells, goblet cells, and basal cells -the mucus produced by the goblet cells helps trap dust not removed in the upper passages. The cilia in the upper respiratory tract move mucus and trapped particles down toward the pharynx; the cilia in the lower respiratory tract move them up toward the pharynx

Vocal folds

-the mucous membrane of the larynx forms two pairs of folds: a superior pair called the vestibular folds (false vocal cords) and an inferior pair called the vocal folds (true vocal cords)

Vestibular folds

-the mucous membrane of the larynx forms two pairs of folds: a superior pair called the vestibular folds (false vocal cords) and an inferior pair called the vocal folds (true vocal cords) -vestibular folds do not function in voice production -when the vestibular folds are brought together, they function in holding the breath against pressure in the thoracic cavity, such as might occur when a person strains to lift a heavy object

Olfactory epithelium

-the olfactory receptor cells, supporting cells, and basal cells lie in the respiratory region, which is near the superior nasal conchae and adjacent septum --> these cells make up the olfactory epithelium -contains cilia but no goblet cells

Superior, middle, and inferior lobar bronchi

-the right main bronchus gives rise to three lobar bronchi called the superior, middle, and inferior lobar bronchi -left main bronchus gives rise to superior and inferior lobar bronchi

Eupnea

-the term for the normal pattern of quiet breathing is eupnea -eupnea can consist of shallow, deep, or combined shallow and deep breathing -A pattern of shallow (chest) breathing, called costal breathing, consists of an upward and outward movement of the chest due to contraction of the external intercostal muscles -A pattern of deep (abdominal) breathing, called diaphragmatic breathing, consists of the outward movement of the abdomen due to the contraction and descent of the diaphragm

What four factors affect the affinity of hemoglobin for O2?

1. Acidity (pH) 2. Partial pressure of CO2 3. Temperature 4. BPG

Under normal resting conditions, each 100 mL of deoxygenated blood contains the equivalent of 53 mL of gaseous CO2, which is transported in the blood in three main forms:

1. Dissolved CO2 2. Carbamino compounds 3. Bicarbonate ions

Compared with inhaled air, alveolar air has less O2 and more CO2 for 2 reasons:

1. Gas exchange in the alveoli increases the CO2 content and decreases the O2 content of alveolar air 2. When air is inhaled it becomes humidified as it passes moist mucosal linings --> as water vapor content of the air increases, the relative percentage that is O2 decreases (in contrast, exhaled air contains more O2 than alveolar air and less CO2 because some of the exhaled air was in the anatomic dead space and did not participate in gas exchange --> exhaled air is a mixture of alveolar air and inhaled air that was in the anatomic dead space

The rate of pulmonary and systemic gas exchange depends on what factors?

1. Partial pressure difference of the gases 2. Surface area available for exchange 3. Diffusion distance 4. Molecular weight and solubility of the gases

As the branching becomes more extensive in the bronchial tree, what structural changes can be noted?

1. The mucous membrane in the bronchial tree changes from pseudostratified ciliated columnar epithelium in the main bronchi, lobar bronchi, and segmental bronchi to ciliated simple columnar epithelium with some goblet cells in larger bronchioles, to mostly ciliated simple cuboidal epithelium with no goblet cells in smaller bronchioles, to mostly nonciliated simple cuboidal epithelium in terminal bronchioles. Recall that ciliated epithelium of the respiratory membrane removes inhaled particles in two ways. Mucus produced by goblet cells traps the particles, and the cilia move the mucus and trapped particles toward the pharynx for removal. In regions where nonciliated simple cuboidal epithelium is present, inhaled particles are removed by macrophages 2. Plates of cartilage gradually replace the incomplete rings of cartilage in main bronchi and finally disappear in the distal bronchioles 3. As the amount of cartilage decreases, the amount of smooth muscle increases. Smooth muscle encircles the lumen in spiral bands and helps maintain patency. However, because there is no supporting cartilage, muscle spasms can close off the airways. This is what happens during an asthma attack, which can be a life-threatening situation

The pharynx can be divided into what three anatomical regions?

1. nasopharynx 2. oropharynx 3. laryngopharynx

The process of gas exchange in the body, called respiration, has what three basic steps?

1. pulmonary ventilation, or breathing, is the inhalation (inflow) and exhalation (outflow) of air and involves the exchange of air between the atmosphere and the alveoli of the lungs 2. External (pulmonary) respiration is the exchange of gases between the alveoli of the lungs and the blood in pulmonary capillaries across the respiratory membrane. In this process, pulmonary blood gains oxygen and loses carbon dioxide 3. internal (tissue) respiration is the exchange of gases between blood in systemic capillaries and tissue cells. In this step, blood loses oxygen and gains carbon dioxide. Within cells, the metabolic reactions that consume O2 and give off CO2 during the production of ATP are termed cellular respiration

We know tht airflow during inhalation and exhalation is due to air pressure differences, but 3 other factors affect the rate of airflow and the ease of pulmonary ventilation

1. surface tension of the alveolar fluid 2. compliance of the lungs 3. airway resistance

Extending from the alveolar air space to blood plasma, the respiratory membrane consists of what four layers?

1.A layer of type I and type II alveolar cells and associated alveolar macrophages that constitutes the alveolar wall 2.An epithelial basement membrane underlying the alveolar wall 3.A capillary basement membrane that is often fused to the epithelial basement membrane 4.The capillary endothelium

What are the functions of the respiratory system?

1.gas exchange: intake of O2 for delivery to body cells and removal of CO2 produced by body cells 2.helps regulate blood pH 3.contains receptors for sense of smell, filters inspired air, produces vocal sounds (phonation), and excretes small amounts of water and heat

Diaphragmatic breathing

A pattern of deep (abdominal) breathing, called diaphragmatic breathing, consists of the outward movement of the abdomen due to the contraction and descent of the diaphragm.

Costal breathing

A pattern of shallow (chest) breathing, called costal breathing, consists of an upward and outward movement of the chest due to contraction of the external intercostal muscles

Affinity

Although is the most important factor that determines the percent O2 saturation of hemoglobin, several other factors influence the tightness or affinity with which hemoglobin binds O2

Inflation reflex

As air leaves the lungs during exhalation, the lungs deflate and the stretch receptors are no longer stimulated. Thus, the DRG is no longer inhibited, and a new inhalation begins. This reflex is referred to as the inflation reflex

Fact

At rest, about 200 mL of O2 is used each minute by body cells. During strenuous exercise, however, O2 use typically increases 15- to 20-fold in normal healthy adults, and as much as 30-fold in elite endurance-trained athletes

Left main bronchus

At the superior border of the fifth thoracic vertebra, the trachea divides into a right main (primary) bronchus, which goes into the right lung, and a left main (primary) bronchus, which goes into the left lung

Relationship btw PCO2 and H+ concentration

Because CO2 is lipid-soluble, it easily diffuses into cells where, in the presence of carbonic anhydrase, it combines with water (H2O) to form carbonic acid (H2CO3). Carbonic acid quickly breaks down into H+ and HCO3−. Thus, an increase in CO2 in the blood causes an increase in H+ inside cells, and a decrease in CO2 causes a decrease in H+

Fact

Bronchial arteries, which branch from the aorta, deliver oxygenated blood to the lungs. This blood mainly perfuses the muscular walls of the bronchi and bronchioles. Connections do exist between branches of the bronchial arteries and branches of the pulmonary arteries, however; most blood returns to the heart via pulmonary veins. Some blood drains into bronchial veins, branches of the azygos system, and returns to the heart via the superior vena cava

Central chemoreceptors

Central chemoreceptors are located in or near the medulla oblongata in the central nervous system --> they respond to changes in H+ concentration or PCO2, or both, in cerebrospinal fluid

Atelectasis

Collapse of a part of a lung, or rarely an entire lung, is called atelectasis (ateles- = incomplete; -ectasis = expansion)

Decreased compliance is a common feature in what kind of pulmonary conditions?

Decreased compliance is a common feature in pulmonary conditions that (1) scar lung tissue (for example, tuberculosis) (2) cause lung tissue to become filled with fluid (pulmonary edema) (3) produce a deficiency in surfactant (4) impede lung expansion in any way (for example, paralysis of the intercostal muscles) Decreased lung compliance occurs in emphysema due to destruction of elastic fibers in alveolar walls

SUMMARY

Deoxygenated blood returning to the pulmonary capillaries in the lungs (Figure 23.22a) contains CO2 dissolved in blood plasma, CO2 combined with globin as carbaminohemoglobin (Hb-CO2), and CO2 incorporated into HCO3− within RBCs. The RBCs have also picked up H+, some of which binds to and therefore is buffered by hemoglobin (Hb-H). As blood passes through the pulmonary capillaries, molecules of CO2 dissolved in blood plasma and CO2 that dissociates from the globin portion of hemoglobin diffuse into alveolar air and are exhaled. At the same time, inhaled O2 is diffusing from alveolar air into RBCs and is binding to hemoglobin to form oxyhemoglobin (Hb-O2). Carbon dioxide also is released from HCO3− when H+ combines with HCO3− inside RBCs. The H2CO3 formed from this reaction then splits into CO2, which is exhaled, and H2O. As the concentration of HCO3− declines inside RBCs in pulmonary capillaries, HCO3− diffuses in from the blood plasma, in exchange for Cl−. In sum, oxygenated blood leaving the lungs has increased O2 content and decreased amounts of CO2 and H+. In systemic capillaries, as cells use O2 and produce CO2, the chemical reactions reverse

Fact

Due to the space occupied by the heart, the left lung is about 10% smaller than the right lung. Although the right lung is thicker and broader, it is also somewhat shorter than the left lung because the diaphragm is higher on the right side, accommodating the liver that lies inferior to it

Fact

During exercise, activity in the sympathetic division of the autonomic nervous system (ANS) increases and the adrenal medulla releases the hormones epinephrine and norepinephrine; both of these events cause relaxation of smooth muscle in the bronchioles, which dilates the airways. Because air reaches the alveoli more quickly, lung ventilation improves. The parasympathetic division of the ANS and mediators of allergic reactions such as histamine have the opposite effect, causing contraction of bronchiolar smooth muscle, which results in constriction of distal bronchioles

Dorsal respiratory group (DRG)

During normal quiet breathing, neurons of the DRG generate impulses to the diaphragm via the phrenic nerves and the external intercostal muscles via the intercostal nerves. These impulses are released in bursts, which begin weakly, increase in strength for about two seconds, and then stop altogether. When the nerve impulses reach the diaphragm and external intercostals, the muscles contract and inhalation occurs. When the DRG becomes inactive after two seconds, the diaphragm and external intercostals relax for about three seconds, allowing the passive recoil of the lungs and thoracic wall. Then, the cycle repeats itself

Lobules

Each bronchopulmonary segment of the lungs has many small compartments called lobules; each lobule is wrapped in elastic connective tissue and contains a lymphatic vessel, an arteriole, a venule, and a branch from a terminal bronchiole

Pleural membrane

Each lung is enclosed and protected by a double-layered serous membrane called the pleural membrane

Residual volume

Even after the expiratory reserve volume is exhaled, considerable air remains in the lungs because the subatmospheric intrapleural pressure keeps the alveoli slightly inflated, and some air remains in the noncollapsible airways. This volume, which cannot be measured by spirometry, is called the residual volume and amounts to about 1200 mL in males and 1100 mL in females

Functional residual capacity

Functional residual capacity is the sum of residual volume and expiratory reserve volume

H1N1 influenza (flu)

H1N1 influenza (flu), also known as swine flu, is a type of influenza caused by a new virus called influenza H1N1. The virus is spread in the same way that seasonal flu spreads: from person to person through coughing or sneezing or by touching infected objects and then touching one's mouth or nose. Most individuals infected with the virus have mild disease and recover without medical treatment, but some people have severe disease and have even died. The symptoms of H1N1 flu include fever, cough, runny or stuffy nose, headache, body aches, chills, and fatigue. Some people also have vomiting and diarrhea. Most people who have been hospitalized for H1N1 flu have had one or more preexisting medical conditions such as diabetes, heart disease, asthma, kidney disease, or pregnancy. People infected with the virus can infect others from 1 day before symptoms occur to 5-7 days or more after they occur. Treatment of H1N1 flu involves taking antiviral drugs, such as Tamiflu® and Relenza®. A vaccine is also available, but the H1N1 flu vaccine is not a substitute for seasonal flu vaccines

Common cold

Hundreds of viruses can cause coryza, or the common cold, but a group of viruses called rhinoviruses is responsible for about 40% of all colds in adults. Typical symptoms include sneezing, excessive nasal secretion, dry cough, and congestion. The uncomplicated common cold is not usually accompanied by a fever. Complications include sinusitis, asthma, bronchitis, ear infections, and laryngitis. Recent investigations suggest an association between emotional stress and the common cold

Hypoxia

Hypoxia is the deficiency of O2 at the tissue level

Expiratory reserve volume

If you inhale normally and then exhale as forcibly as possible, you should be able to push out considerably more air in addition to the 500 mL of tidal volume. The extra 1200 mL in males and 700 mL in females is called the expiratory reserve volume

Surfactant

Included in the alveolar fluid is surfactant, a complex mixture of phospholipids and lipoproteins. Surfactant lowers the surface tension of alveolar fluid, which reduces the tendency of alveoli to collapse and thus maintains their patency

Pleurisy

Inflammation of the pleural membrane, called pleurisy or pleuritis, may in its early stages cause pain due to friction between the parietal and visceral layers of the pleura. If the inflammation persists, excess fluid accumulates in the pleural space, a condition known as pleural effusion

Inspiratory capacity

Inspiratory capacity is the sum of tidal volume and inspiratory reserve volume

Fact

Like the trachea, the main bronchi contain incomplete rings of cartilage and are lined by pseudostratified ciliated columnar epithelium

Cardiac notch

Medially, the left lung also contains a concavity, the cardiac notch, in which the apex of the heart lies.

Transport of O2 and CO2

O2: 1.5% dissolved in plasma 98.5% as oxyhemoglobin CO2: 7% dissolved in plasma 23% as Hb-CO2 70% as HCO3-

Lobar bronchi

On entering the lungs, the main bronchi divide to form smaller bronchi—the lobar (secondary) bronchi, one for each lobe of the lung

Fissures

One or two fissures divide each lung into lobes

Fact

PN2: 0.768 O2: 0.209 PAr: 0.0009 PH2O: 0.003 PCO2: 0.0004 Pothergases: 0.0006 Each gas diffuses across a permeable membrane from the area where its partial pressure is greater to the area where its partial pressure is less. The greater the difference in partial pressure, the faster the rate of diffusion

Chloride shift

Some HCO3− moves out into the blood plasma, down its concentration gradient. In exchange, chloride ions (Cl−) move from plasma into the RBCs. This exchange of negative ions, which maintains the electrical balance between blood plasma and RBC cytosol, is known as the chloride shift --> the net effect of these reactions is that CO2 is removed from tissue cells and transported in blood plasma as HCO3−

Alveolar ventilation rate

The alveolar ventilation rate is the volume of air per minute that actually reaches the respiratory zone

Haldane effect

The amount of CO2 that can be transported in the blood is influenced by the percent saturation of hemoglobin with oxygen. The lower the amount of oxyhemoglobin (Hb-O2), the higher the CO2-carrying capacity of the blood, a relationship known as the Haldane effect

Thoracentesis

The apex of the lungs lies superior to the medial third of the clavicles, and this is the only area that can be palpated. The anterior, lateral, and posterior surfaces of the lungs lie against the ribs. The base of the lungs extends from the sixth costal cartilage anteriorly to the spinous process of the tenth thoracic vertebra posteriorly. The pleura extends about 5 cm (2 in.) below the base from the sixth costal cartilage anteriorly to the twelfth rib posteriorly. Thus, the lungs do not completely fill the pleural cavity in this area. Removal of excessive fluid in the pleural cavity can be accomplished without injuring lung tissue by inserting a needle anteriorly through the seventh intercostal space, a procedure called thoracentesis (centesis = puncture). The needle is passed along the superior border of the lower rib to avoid damage to the intercostal nerves and blood vessels. Inferior to the seventh intercostal space there is danger of penetrating the diaphragm

Otorhinolaryngology

The branch of medicine that deals with the diagnosis and treatment of diseases of the ears, nose, and throat (ENT) is called otorhinolaryngology

Base

The broad inferior portion of the lung, the base, is concave and fits over the convex area of the diaphragm

Hyperventilation

The chemoreceptors participate in a negative feedback system that regulates the levels of CO2, O2, and H+ in the blood. As a result of increased PCO2, decreased pH (increased H+), or decreased PO2, input from the central and peripheral chemoreceptors causes the DRG to become highly active, and the rate and depth of breathing increase. Rapid and deep breathing, called hyperventilation, allows the inhalation of more O2 and exhalation of more CO2 until PCO2 and H+ are lowered to normal

High altitude sickness

The common signs and symptoms of high altitude sickness- SOB, headache, fatigue, insomnia, nausea, and dizziness- are due to a lower level of oxygen in the blood

Internal respiration

The exchange of O2 and CO2 between systemic capillaries and tissue cells is called internal respiration or systemic gas exchange (Figure 23.16b). As O2 leaves the bloodstream, oxygenated blood is converted into deoxygenated blood. Unlike external respiration, which occurs only in the lungs, internal respiration occurs in tissues throughout the body

Respiratory membrane

The exchange of O2 and CO2 between the air spaces in the lungs and the blood takes place by diffusion across the alveolar and capillary walls, which together form the respiratory membrane

Fact

The exchange of oxygen and carbon dioxide between alveolar air and pulmonary blood occurs via passive diffusion, which is governed by the behavior of gases as described by two gas laws, Dalton's law and Henry's law. Dalton's law is important for understanding how gases move down their pressure gradients by diffusion, and Henry's law helps explain how the solubility of a gas relates to its diffusion

Seasonal influenza (flu)

The higher the stress level, the greater the frequency and duration of colds. Seasonal influenza (flu) is also caused by a virus. Its symptoms include chills, fever (usually higher than ), headache, and muscular aches. Seasonal influenza can become life-threatening and may develop into pneumonia. It is important to recognize that influenza is a respiratory disease, not a gastrointestinal (GI) disease. Many people mistakenly report having seasonal flu when they are suffering from a GI illness

What are the layers of the tracheal wall?

The layers of the tracheal wall, from deep to superficial:(1) mucosa (consists of an epithelial layer of pseudostratified ciliated columnar epithelium and an underlying layer of lamina propria that contains elastic and reticular fibers. It provides the same protection against dust as the membrane lining the nasal cavity and larynx) (2) submucosa (consists of areolar connective tissue that contains seromucous glands and their ducts) (3) hyaline cartilage (4) adventitia

Segmental bronchi

The lobar bronchi continue to branch, forming still smaller bronchi, called segmental (tertiary) bronchi, that supply the specific bronchopulmonary segments within the lobes

Ventilation-perfusion coupling

The lungs receive blood via two sets of arteries: pulmonary arteries and bronchial arteries. Deoxygenated blood passes through the pulmonary trunk, which divides into a left pulmonary artery that enters the left lung and a right pulmonary artery that enters the right lung. (The pulmonary arteries are the only arteries in the body that carry deoxygenated blood.) Return of the oxygenated blood to the heart occurs by way of the four pulmonary veins, which drain into the left atrium. A unique feature of pulmonary blood vessels is their constriction in response to localized hypoxia (low O2 level). In all other body tissues, hypoxia causes dilation of blood vessels to increase blood flow. In the lungs, however, vasoconstriction in response to hypoxia diverts pulmonary blood from poorly ventilated areas of the lungs to well-ventilated regions for more efficient gas exchange. This phenomenon is known as ventilation-perfusion coupling because the perfusion (blood flow) to each area of the lungs matches the extent of ventilation (airflow) to alveoli in that area

Mediastinal surface

The mediastinal (medial) surface of each lung contains a region, the hilum, through which bronchi, pulmonary blood vessels, lymphatic vessels, and nerves enter and exit --> these structures are held together by the pleura and connective tissue and constitute the root of the lung

Medullary respiratory center

The medullary respiratory center is made up of two collections of neurons called the dorsal respiratory group (DRG), formerly called the inspiratory area, and the ventral respiratory group (VRG), formerly called the expiratory area

Minute ventilation

The minute ventilation (MV)—the total volume of air inhaled and exhaled each minute—is respiratory rate multiplied by tidal volume --> so 12 breaths/min x 500 mL per breath = 6 liters/min A lower-than-normal minute ventilation usually is a sign of pulmonary malfunction

Fact

The most imp factor that determines how much O2 binds to hemoglobin is the PO2 --> the higher the PO2, the more O2 combines with Hb

Apex

The narrow superior portion of the lung is the apex

Respiratory epithelium

The nasal cavity is divided into a larger, inferior respiratory region and a smaller, superior olfactory region. The respiratory region is lined with pseudostratified ciliated columnar epithelium with numerous goblet cells, which is frequently called the respiratory epithelium

Percent saturation of hemoglobin

The percent saturation of hemoglobin expresses the average saturation of hemoglobin with oxygen --> for instance, if each hemoglobin molecule has bound two O2 molecules then the hemoglobin is 50% saturated because each Hb can bind a maximum of four O2

Bronchioles

The segmental bronchi then divide into bronchioles

Parietal pleura

The superficial layer, called the parietal pleura, lines the wall of the thoracic cavity

Costal surface

The surface of the lung lying against the ribs, the costal surface, matches the rounded curvature of the ribs

Bronchial tree

This extensive branching from the trachea through the terminal bronchioles resembles an inverted tree and is commonly referred to as the bronchial tree

Total lung capacity

Total lung capacity is the sum of vital capacity and residual volume

Vital capacity

Vital capacity is the sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume

Partially saturated

When Hb consists of a mixture of Hb and Hb-O2, it is partially saturated

Fact

When PO2 in arterial blood falls from a normal level of 100 mmHg but is still above 50 mmHg, the peripheral chemoreceptors are stimulated. Severe deficiency of O2 depresses activity of the central chemoreceptors and DRG, which then do not respond well to any inputs and send fewer impulses to the muscles of inhalation. As the breathing rate decreases or breathing ceases altogether, falls lower and lower, establishing a positive feedback cycle with a possibly fatal result

Bohr effect

When pH decreases, the entire oxygen-hemoglobin dissociation curve shifts to the right; at any given , Hb is less saturated with O2, a change termed the Bohr effect (BŌR). The Bohr effect works both ways: An increase in H+ in blood causes O2 to unload from hemoglobin, and the binding of O2 to hemoglobin causes unloading of H+ from hemoglobin. The explanation for the Bohr effect is that hemoglobin can act as a buffer for hydrogen ions (H+). But when H+ ions bind to amino acids in hemoglobin, they alter its structure slightly, decreasing its oxygen-carrying capacity. Thus, lowered pH drives O2 off hemoglobin, making more O2 available for tissue cells. By contrast, elevated pH increases the affinity of hemoglobin for O2 and shifts the oxygen-hemoglobin dissociation curve to the left

Fully saturated

When reduced Hb is completely converted to oxyhemoglobin, the hemoglobin is said to be fully saturated

Laryngeal ventricle

a lateral expansion of the middle portion of the laryngeal cavity inferior to the vestibular folds and superior to the vocal folds

Pulmonologist

a specialist in the diagnosis and treatment of diseases of the lungs

Alveolar sac

an alveolar sac consists of two or more alveoli that share a common opening

Fact

baroreceptors are sensory receptors that monitor blood pressure

Elastic recoil

exhalation results from elastic recoil of the chest wall and lungs, both of which have a natural tendency to spring back after they have been stretched

Alar cartilages

form a portion of the walls of the nostrils

Septal nasal cartilage

forms the anterior portion of the nasal septum

Lower respiratory system

includes the larynx, trachea, bronchi, and lungs

Upper respiratory system

includes the nose, nasal cavity, pharynx, and associated structures

Lateral nasal cartilages

inferior to the nasal bones

Thyrohyoid membrane

ligament that connects the thyroid cartilage to the hyoid bone

External nares

on the undersurface of the external nose are two openings called the external nares or nostrils

carotid bodies

oval nodules in the wall of the left and right common carotid arteries where they divide into the internal and external carotid arteries (the carotid bodies are located close to the carotid sinus baroreceptors) -axons of sensory neurons from the carotid bodies are part of the right and left glossopharyngeal (IX) nerves

Corniculate cartilages

paired corniculate cartilages, horn-shaped pieces of elastic cartilage, are located at the apex of each arytenoid cartilage

Cuneiform cartilages

paired cuneiform cartilages, club-shaped elastic cartilages anterior to the corniculate cartilages, support the vocal folds and lateral aspects of the epiglottis

Laryngeal vestibule

portion of the cavity of the larynx above the vestibular folds (false vocal cords)

Infraglottic cavity

portion of the cavity of the larynx below the vocal folds

Rima vestibuli

space between the vestibular folds

Cavity of the larynx

space that extends from the entrance into the larynx down to the inferior border of the cricoid cartilage

Cricotracheal ligament

the cricoid cartilage is attached to the first ring of cartilage of the trachea by the cricotracheal ligament

Visceral pleura

the deep layer, the visceral pleura, covers the lungs themselves

Fauces

the opening from the mouth

Horizontal fissure

the right lung also has a horizontal fissure

Cricothyroid ligament

the thyroid cartilage is connected to the cricoid cartilage by the cricothyroid ligament

Palatine and lingual tonsils

two pairs of tonsils, the palatine and lingual tonsils, are found in the oropharynx