A&P Unit 3

Air from the environment is inhaled directly into the lungs. The partial pressures of the gases within the alveoli are different from the respective atmospheric partial pressures measured for several reasons:

(1) Air from the environment mixes with the air remaining in the anatomic dead space in the respiratory tract; (2) oxygen diffuses out of the alveoli into the blood, and ____________ diffuses from the blood into the alveoli; and (3) more water vapor is present within the alveoli because of the higher humidity there. Consequently, the percentage of oxygen in the alveoli is lower and the percentage of carbon dioxide in the alveoli is higher than in the atmosphere.

Using the graph provided, determine the correct oxygen partial pressure associated with the classification of "high altitude."

112 mm Hg

If intrapulmonary pressure was 760 mm Hg, what would you expect the intrapleural pressure to be? Contraction of the diaphragm and external intercostal muscles results in ____________ in the thoracic volume which results in _______________ of the intrapulmonary pressure.

756 mm Hg an increase; a decrease

The altitude of Kabul, Afghanistan is approximately 6000 feet. What is the approximate alveolar oxygen partial pressure found here?

85 mm Hg

Put the processes of gas exchange into the correct order, beginning with inhalation.

Air is drawn into the lungs. Oxygen is transported to body cells by blood. Cells use oxygen and generate carbon dioxide as a waste product. Blood transports carbon dioxide from the cells to the lungs. The lungs exhale carbon dioxide into the atmosphere.

The pleural cavity is located between the visceral and parietal serous membrane layers. When the lungs are fully inflated, this cavity is considered a potential space because the visceral and parietal pleurae are almost in contact with each other.

An oily, serous fluid is produced by the membranes and covers their surface within the pleural cavity. This oily substance is drained continuously by lymph vessels within the visceral pleura.

Check the events that occur during internal respiration.

Blood transports oxygen from the lungs to the body cells. Blood transports carbon dioxide produced by the body cells to the lungs.

The pulmonary circulation conducts blood to and from the gas exchange surfaces of the lungs. Pulmonary arteries carry deoxygenated blood to pulmonary capillaries within the lungs. The deoxygenated blood that enters these capillaries is reoxygenated here before it returns to the left atrium. The bronchial circulation is a component of the systemic circulation and transports oxygenated blood to the tissues of the lungs.

Bronchial veins collect blood from capillary beds that supply structures in the bronchial tree. Some of this deoxygenated blood drains into the pulmonary veins. Consequently, blood exiting the lungs via the pulmonary veins is slightly less oxygenated than the blood that leaves the pulmonary capillaries.

During alveolar gas exchange, blood P(CO₂) decreases from 45 to 40 mm Hg; during systemic gas exchange, blood P(CO₂) increases from 40 to 45 mm Hg. Blood P(O₂) increases from 40 to 104 mm Hg during alveolar gas exchange, and blood P(O₂) decreases from 95 to 40 mm Hg during systemic gas exchange.

Bronchial veins dump small amounts of deoxygenated blood into the pulmonary veins and the blood P(O₂) decreases from 104 to 95 mm Hg.

The paired lungs are located within the thoracic cavity on either side of the mediastinum, the region that houses the heart and other structures. Each lung also has a(n) apex that is slightly superior and posterior to the clavicle. Each lung has a wide, concave base that rests inferiorly upon the muscular diaphragm.

Each lung has a conical shape with an indented region on its mediastinal surface called the hilum. Collectively, the structures that extend from this indented region are termed the root of the lung.

Check the functions that can be carried out by the respiratory system.

Exchange of oxygen and carbon dioxide Passageway for air between the external environment and the alveoli of the lungs Detection of odors Production of sound

The primary inspiratory neurons that innervate the diaphragm arise from the dorsal respiratory group. The pontine respiratory group, also known as the pneumotaxic center, plays a role in regulating the length of each breath and switching between inspiration and expiration. Over inflation of the lungs is prevented by the Hering-Breuer reflex.

Monitoring CO₂ levels by detecting pH of the CSF is the function of central chemoreceptors, which provide the primary sensory input leading to the regulation of the rate and depth of breathing. Forced breathing and heavy breathing are controlled by the ventral respiratory group, which also give rise to both inspiratory and expiratory neurons.

Check the components of the conducting zone of the respiratory system.

Nose Nasal cavity Bronchioles Larynx Trachea (not Alveoli)

Henry's law pointed out that the solubility coefficient of oxygen is very low. This means that only small amounts of oxygen are dissolved in the plasma. Consequently, about 98% of the oxygen in the blood must be transported within erythrocytes where it attaches to the iron within hemoglobin molecules.

Oxygen bound to hemoglobin is referred to as oxyhemoglobin. Hemoglobin without bound oxygen is called deoxyhemoglobin.

___________________ is used to sustain metabolic activities within the cells, and ________________ is produced as a result of these activities. Under normal conditions, the partial pressure of carbon dioxide within the tissues is _____________ than the partial pressure of carbon dioxide within the systemic capillaries. The unloading of oxygen at the tissues results in the formation of ______________________ . This configuration of hemoglobin _____________________ carbon dioxide.

Oxygen; carbon dioxide higher deoxyhemoglobin; more readily binds to

Pulmonary ventilation is known as breathing, which is the movement of air between the atmosphere and the lungs. It consists of two cyclic phases: inspiration, which brings air into the lungs and expiration, which forces air out of the lungs.

Pulmonary ventilation that occurs at rest is called quiet breathing, whereas forced breathing, accompanies exercise or hard exertion. The principles of this involve autonomic nuclei in the brainstem that stimulate skeletal muscle to cyclically contract and relax. This contraction and relaxation causes dimensional changes within the thoracic cavity and results in establishing a changing pressure gradient between the lungs and the atmosphere.

The P(O₂) in the tissue cells is 40 mm Hg. The blood as it enters the surrounding systemic capillaries has a P(O₂) of 95 mm Hg. Therefore, oxygen diffuses out of the systemic capillaries down its partial pressure gradient into the cells.

Simultaneously, carbon dioxide is diffusing in the opposite direction. The P(CO₂) in tissue cells is 45mm Hg, and the blood entering the systemic capillaries is 40 mm Hg. Carbon dioxide diffuses downits partial pressure gradient from the cells into the blood until blood P(CO₂) is 45 mm Hg.

The P(O₂) in the alveoli is 104 mm Hg, and the blood entering the pulmonary capillaries has a P(O₂) of 40 mm Hg. This allows oxygen to diffuse from the alveoli into the capillaries because of the P(O₂) partial pressure gradient. The P(O₂) in the alveoli remains constant because oxygen is continuously entering the alveoli through the respiratory passageways.

The P(CO₂) in the alveoli is 40 mm Hg and that of the blood entering the pulmonary capillaries is 45 mm Hg. This causes carbon dioxide to diffuse down its partial pressure gradient from the blood into the alveoli.

The atmospheric partial pressure of oxygen P(O₂) at sea level is 159 mm Hg. The atmospheric partial pressure of carbon dioxide P(CO₂) at sea level is .3 mm Hg. The alveolar partial pressure of oxygen P(O₂) at sea level is 104 mm Hg.

The alveolar partial pressure of carbon dioxide P(CO₂) at sea level is 40 mm Hg. The systemic partial pressure of oxygen P(O₂) at sea level is 40 mm Hg. The systemic partial pressure of carbon dioxide P(CO₂) at sea level is 45 mm Hg.

The majority of CO₂ in the blood is carried as bicarbonate ions. The ability of CO₂ to bind to deoxygenated hemoglobin more readily than it binds oxyhemoglobin is referred to as the Haldane effect. The chloride shift is an anion exchange that takes place in red blood cells as a mechanism to transport bicarbonate ions out of the cell.

The combination of carbon dioxide and protein known as carbaminohemoglobin is abbreviated HbCO₂. The decrease in the ability of oxygen to bind to hemoglobin when the pH decreases is known as the Bohr effect. The reaction between CO2 and H2O to form H2CO3 is catalyzed by carbonic anhydrase.

Fill in the blanks using the terms provided. Not all terms will be used

The law of partial pressure, also known as Dalton's law, states that the individual gases in the air contribute to the total atmospheric pressure as a function of the percentage each gas contributes to the total volume. If two gases have the same partial pressure, but gas A has a higher water solubility coefficient than gas B, then gas A will diffuse at a faster rate. Henry's law states that the amount of a gas that dissolves in water is a function of its partial pressure and its solubility coefficient. If the alveolar partial pressure of gas A is 110 mm Hg and the partial pressure of gas B is 135, then gas B will diffuse into the blood at a faster rate. If the P(CO2) in the tissues increases, then the P(CO2) in the systemic venous blood will increase.

Fill in the blanks of the paragraph with the correct terms.

The nasal cavity extends from the nostrils to paired openings called choanae or posterior nasal apertures. These paired openings lead into the pharynx. The floor of the nasal cavity is formed by the hard and soft palate. The roof of the nasal cavity is composed of the nasal, frontal, ethmoid, and sphenoid bones. The nasal septum divides the nasal cavity into left and right portions. The bony part of this divider is formed by the perpendicular plate of the ethmoid and the vomer. Three paired, bony projections called nasal conchae are located along the lateral walls of the nasal cavity. These projections partition the nasal cavity into separate air passages, each called a nasal meatus.

Only the air reaching the alveoli is available for gas exchange. When air is moved from the atmosphere into the respiratory tract, a portion of it remains in the conducting zone. This collective space, where there is no exchange of respiratory gases, is referred to as the anatomic dead space, and it has an average volume of approximately 150 mL.

The normal anatomic dead space plus any loss of alveoli is the physiologic dead space. The usual loss of alveoli is minimal in a healthy individual, so the anatomic dead space is equivalent to the physiologic dead space.

The most important stimulus affecting breathing rate and depth is blood P(CO₂). Central chemoreceptors monitor CSF and peripheral chemoreceptors monitor blood.

The peripheral chemoreceptors differ from central chemoreceptors because they are stimulated by changes in H⁺ produced independently of P(CO₂). In general, decreased P(O₂), increased P(CO₂), and production of H⁺, will cause greater stimulation of the respiratory center.

Fill in the blanks with the correct terms.

The respiratory membrane consists of an alveolar epithelium and its basement membrane, and a(n) capillary endothelium and its basement membrane. The gas that diffuses from the alveolus, across the respiratory membrane, and into the pulmonary capillary is oxygen. This gas is then transported by the blood to tissue cells. Conversely, carbon dioxide gas diffuses from the blood in the capillary through the respiratory membrane. This gas then enters the alveoli and is eventually expired into the external environment.

Fill in the blanks with the appropriate terms regarding the general functions of the respiratory system.

The respiratory tract is a passageway for air between the external environment and the alveoli (air sacs) of the lungs. There are two gases that are exchanged during respiration. Carbon dioxide diffuses from the blood into the alveoli while the other gas, oxygen, diffuses from the alveoli into the blood. Receptors located in the superior regions of the nasal cavity called olfactoryreceptors detect odors as air moves across them. The vocal cords of the larynx (voice box) vibrate as air moves across them to produce sound. Sounds then resonate in upper respiratory structures.

The residual volume is the amount of air remaining in the lungs after a forced expiration. The volume of air exchanged during normal breathing is called the tidal volume. After a normal inspiration, the amount of air that can then be inspired forcefully is called the inspiratory reserve volume.

The total lung capacity minus the residual volume equals the vital capacity. The vital capacity minus the expiratory reserve volume equals the inspiratory capacity. The effects of obstructive diseases such as asthma or emphysema may be determined by measuring the forced expiratory volume.

The solubility coefficient of carbon dioxide is 0.57. Due to both this value and the small partial pressure gradient for CO₂, approximately 7% of carbon dioxide is transported to the alveoli as a dissolved gaswithin the plasma of blood. Hemoglobin is capable of transporting about 23% of the CO₂ as a carbaminohemoglobin compound. The remaining 70% of the CO₂ diffuses into erythrocytes and combines with water to form bicarbonate and H⁺.

Thus, the largest percentage is carried from the tissue cells to the lungs in plasma as dissolved bicarbonate.

Surfactant is produced by __________________ Increased production of surfactant would __________________ Insufficient surfactant production would result in __________________

Type II pneumocytes. result in an increase in the thickness of the respiratory membrane, which would decrease diffusion of respiratory gases. a tendency for the lungs to collapse.

Under normal conditions, the alveolar oxygen partial pressure is ______________________ than the atmospheric oxygen partial pressure.

always lower

Hyperpnea would result in ___________________________ within the blood.

an increase in Pressure (oxygen) and a decrease in Pressure (carbon dioxide)

Under normal conditions, the region expected to have the lowest PCO2 is the__________? atmosphere. systemic capillaries. pulmonary capillaries. lungs.

atmosphere

An internal ridge of mucosal covered cartilage called the _______ is located at the bifurcation (split) of the main bronchi.

carina

Which of the following are bicarbonate ions exchanged for when they diffuse from plasma back into red blood cells? At the respiratory membrane, the partial pressure of carbon dioxide in the plasma is higher than in the alveoli of the lungs.

chloride ions higher; alveoli

During quiet breathing, about two-thirds of the thoracic cavity volume change comes from contraction/movement of the _______, and one-third comes from external intercostal movement.

diaphragm

Negative pressure ventilation, demonstrated by iron lungs, allows a person to breathe by producing an intermittent negative pressure that moves across the chest and diaphragm. This specific action would artificially induce the intrapulmonary pressure to _____________ atmospheric pressure thus resulting in ______________ When this negative pressure stops being applied, the lungs __________________and the intrapulmonary pressure __________________ When using positive pressure ventilators, what triggers the elastic recoil of the lung, and what does this action cause?

drop below; inspiration. recoil; increases. airway pressure reaching zero; expiration

Within the Tibetan highlander population, genetic variation has been found to determine relative oxygen-hemoglobin saturation levels. Individuals within this population may be homozygous for either the low oxygen saturation gene or the high oxygen saturation gene. Individuals may also be heterozygous, carrying one low and one high oxygen saturation gene. Based on this information, individuals within the population carrying __________________________ alleles are expected to demonstrated a physiological advantage for survival.

homozygous high oxygen saturation population

No genetic differences were found among the Andean population in either oxygen-hemoglobin saturation levels, nor hemoglobin concentrations. However, this group as a whole displayed higher hemoglobin concentration levels than their lower altitude neighbors. The most accurate explanation for this finding is that individuals constantly exposed to lower atmospheric partial pressures for oxygen would have a physiologic response which would _______________________.

increase the cumulative number of red blood cells

If the atmospheric Pressure(CO2) exceeded the alveolar Pressure(CO2) the pulmonary capillary Pressure(CO2) would ________________________ drop well below normal range. increase well above normal range. likely remain in normal range

increase well above normal range.

A person suffering from hypercapnia compensates by ____________________ ventilation. increasing decreasing

increasing

Decreased Pressure (carbon dioxide) results in an increase in blood pH levels. Both of these conditions result in a shift of the oxygen-hemoglobin dissociation curve to the ______________________. This shift _______________ hemoglobin's affinity for oxygen.

left; increases

Carbonic anhydrase is found in the _______________ where it directly catalyzes the formation of ____________________ Blood pH decreases in response to ________________________ Renal retention of bicarbonate _______________ blood pH acting as a compensatory mechanism for the condition of respiratory ____________________________ Hypoventilation results in a(n) _________________ in the arterial partial pressure of carbon dioxide, which may result in respiratory ___________________________

red blood cells; carbon dioxide gas into carbonic acid. the dissociation of carbonic acid into bicarbonate and hydrogen ions. increases; acidosis. increase; acidosis.

The inspiratory muscles ____________ during normal exhalation resulting in a(n) __________________ in the thoracic volume. The intrapulmonary pressure is _______________ than the atmospheric pressure during exhalation.

relax; decrease higher

The thin barrier that oxygen and carbon dioxide diffuse across during gas exchange between the alveoli and the blood in the pulmonary capillaries is the _______ membrane.

respiratory

Increased levels of 2,3 BPG occur in response to decreased blood pH levels. With all other variables unchanged, an increased concentration of 2,3 BPG in the blood would _____________________.

result in a shift of the oxygen-hemoglobin dissociation curve to the right enhancing unloading of oxygen at the tissues.

The binding of CO to hemoglobin causes the oxygen-hemoglobin dissociation curve to ___________________ Acute carbon monoxide poisoning would result in ____________________ of the tissues because oxygen ____________________

shift to the left, indicating that the carboxyhemoglobin is less likely to release bound oxygen. hypoxia; is not released from hemoglobin in sufficient amounts at the tissues.

Respiratory gases cross the respiratory membrane by ___________________ Which environment separated by the respiratory membrane would display the highest oxygen partial pressure?

simple diffusion Alveolar air

Oxygen molecules bind ___________________ of the hemoglobin. A single hemoglobin displaying a saturation level of 75% would be bound to ___________________________

specifically to the heme region three oxygen molecules.

Carbon dioxide enters the blood at the _____________________ capillaries. Here, some of the carbon dioxide binds to the _____________ region of hemoglobin. The empirical formula for bicarbonate is ________________. Carbon dioxide goes through a series of reactions resulting in the formation of bicarbonate. Where does this reaction occur?

systemic; globin HCO3- Systemic capillaries

The reason tetrodotoxin causes death so quickly is directly related to __________________________ If four new drugs were discovered and each of them esulted in the unique physiologic responses indicated below, which drug do you think would hold the most promise as a cure for tetrodotoxin poisoning? Drug 1: Stimulated an increase in the amount of neurotransmitters released from motor neurons Drug 2: Inhibited action potentials of motor neurons Drug 3: Caused hyper-exitability of nervous and muscle tissue Drug 4: Dilated the alveoli within the lungs

the loss of respiratory muscle function, which disables a person's ability to appropriately adjust thoracic volumes and associated intrapulmonary. pressures Drug 3

Oxygen unloading occurs at the _________________________ This process causes a(n) _________________ in the oxygen partial pressure of the blood leaving this region.

tissues; decrease