A&P chapter 22 – Flashcards
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Respiration
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ventilation of the lungs (breathing) or the use of oxygen in cellular metabolism
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Squamous (type I) alveolar cells
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thin, broad cells covering about 95% of the alveolar surface area; their thinness allows for rapid gas diffusion between the air and blood
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Great (type II) alveolar cells
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cover about 5% of the alveolar surface area; repair alveolar epithelium when squamous cells are damaged and secrete pulmonary surfactant
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Pulmonary surfactant
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a mixture of phospholipids and protein that coats the alveoli and smallest bronchioles and prevents the bronchioles from collapsing when one exhales
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Alveolar macrophages (dust cells)
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wander the lumens of the alveoli and the connective tissue between them and keep the alveoli free of debris by phagocytizing dust particles that escape entrapment by mucus in the higher parts of the respiratory tract
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Respiratory membrane
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barrier between the alveolar air and blood
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Respiratory cycle
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one complete breath, in and out
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Quiet respiration
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relaxed, unconscious, automatic breathing
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Forced breathing
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unusually deep or rapid breathing, as in a state of exercise or when singing, etc.
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Valsalva maneuver
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consists of taking a deep breath, holding it by closing the glottis, and then contracting the abdominal pressure and push the contents out
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Ventral respiratory group (VRG)
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primary generator of the respiratory rhythm; an elongated nucleus in the medulla with 2 commingled webs of neurons (inspiratory-I and expiratory-E)
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Dorsal respiratory group (DRG)
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web of neurons that extends for much of the length of the medulla between the VRG and the central canal of the brainstem; an integrating center that receives input from several sources and issues output to the VRG that modifies the respiratory rhythm to adapt to varying conditions
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Pontine respiratory group (PRG)
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modifies the rhythm of the VRG; adapts breathing to special circumstances such as sleep, exercise, vocalization, and emotional responses
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Central chemoreceptors
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brainstem neurons that respond especially to changes in the pH of the CSF
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Peripheral chemoreceptors
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located in the carotid and aortic bodies of the large arteries above the heart; respond to the O2 and CO2 content of the blood and the pH
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Stretch receptors
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found in the smooth muscle of the bronchi and bronchioles and in the visceral pleura; respond to inflation of the lungs and signal to the DRG by way of vagus nerves
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Inflation reflex
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triggered by excessive inflation; a protective somatic reflex that strong inhibits the I neurons and stops inspiration
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Irritant receptors
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nerve endings amid the epithelial cells of the airway; respond to smoke, dust, pollen, chemical fumes, cold air, and excess mucus
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Atmospheric (barometric) pressure
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the weight of the air above us; averages about 760 mm Hg at sea level
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Boyle's law
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at a constant temperature, the pressure of a given quantity of gas is inversely proportional to its volume
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Intrapulmonary pressure
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pressure within the alveoli
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Charle's law
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the volume of a given quantity of gas is directly proportional to its absolute temperature
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Pneumothorax
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the presence of air in the pleural cavity
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Atelectasis
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the collapse of part or all of a lung
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Bronchodilation
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increase in the diameter of a bronchus or bronchiole stimulated by sympathetic nerves
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Bronchoconstriction
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reduction in the diameter of a bronchus or bronchiole stimulated by parasympathetic nerves, cold air, and chemical irritants
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Pulmonary compliance
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the ease with which the lungs expand- the change in lung volume relative to a given pressure change
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Anatomical dead space
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the conducting division- air cannot exchange gases with the blood
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Physiological dead space
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the sum of anatomical dead space and any pathological alveolar dead space that may exist
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Spirometry
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the process of measuring a patient's pulmonary ventilation in order to assess the severity of a respiratory disease or monitor the patient's improvement or deterioration
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Tidal volume (TV)
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the amount of air inhaled and exhaled in one cycle in one cycle
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Inspiratory reserve volume (IRV)
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amount of air in excess of TV that can be inhaled with maximum effort
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Expiratory reserve volume (ERV)
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amount of air in excess of TV that can be exhaled with maximum effort
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Residual volume (RV)
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amount of air remaining in the lungs after maximum expiration
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Restrictive disorders
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those that reduce pulmonary compliance, thus limiting the amount to which the lungs can be inflated (black lung disease and tuberculosis)
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Obstructive disorders
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those that interfere with airflow by narrowing or blocking the airway (asthma and chronic bronchitis)
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Forced expiratory volume (FEV)
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the volume of air or the percentage of the vital capacity that can be exhaled in a given time interval
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Peak flow
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maximum speed of expiration
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Minute respiratory volume (MRV)
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amount of air inhaled per minute; largely determine alveolar ventilation rate
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Eupnea
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relaxed, quiet breathing
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Dyspnea
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labored, gasping breathing; shortness of breath
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Respiratory arrest
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permanent cessation of breathing (unless there is medical intervention)
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Hyperventilation
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increased pulmonary ventilation in excess of metabolic demand, frequently associated with anxiety; expels CO2 faster than it is produced, thus lowering blood CO2 concentration and raising blood pH
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Hypoventilation
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reduced pulmonary ventilation; leads to an increase in blood CO2 concentration if ventilation is insufficient to expel CO2 as fast as it is produced
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Dalton's law
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the total atmospheric pressure is a sum of the contributions of these individual gases
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Alveolar gas exchange
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the back-and-forth transport of O2 and CO2 across the respiratory membrane
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Henry's law
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at the air-water interface, for a given temperature, the amount of gas that dissolves in the water is determined by its solubility in water and its partial pressure in the air
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Gas transport
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the process of carrying gases from the alveoli to the systemic tissues and vice versa
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Oxyhemoglobin (HbO2)
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one or more molecules of O2 bound to hemoglobin
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Deoxyhemoglobin (HHb)
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hemoglobin with no oxygen bound to it
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Oxyhemoglobin dissociation curve
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at low Po2, the curve rises slowly; then there is a rapid increase in oxygen loading as Po2 rises further
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Carbonic acid
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90% of CO2 is hydrated to form H2CO3
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Carbamino compounds
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5% of CO2 binds to the amino groups of plasma proteins and hemoglobin
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Chloride shift
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the chloride-bicarbonate exchanger pumps most of the bicarbonate (HCO3-) out of the RBC in exchange for Cl- from the blood plasma
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Venous reserve
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the oxygen remaining in the blood after it passes through the capillary bed; can sustain life for 4-5 minutes even in the event of respiratory arrest
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Bohr effect
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hydrogen ions weaken the bond between hemoglobin and oxygen and thereby promote oxygen unloading
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Biphosphoglycerate (BPG)
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metabolic intermediate of RBCs that binds to hemoglobin and promotes oxygen unloading
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Haldane effect
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a low level of oxyhemoglobin enables the blood to transport more CO2
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Acidosis
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blood pH < 7.35
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Alkalosis
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blood pH > 7.45
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Hypocapnia
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Pco2 < 37 mm Hg
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Hypercapnia
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Pco2 > 43 mm Hg
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Hypoxic drive
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respiration is driven more by the low Po2 than by CO2 or pH; caused by long-term hypoxia
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Hypoxemic hypoxia
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a state of low arterial Po2, usually due to inadequate pulmonary gas exchange
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Ischemic hypoxia
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results from inadequate circulation of the blood, as in congestive heart failure
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Anemic hypoxia
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due to anemia and the resulting inability of the blood to carry adequate oxygen
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Histotoxic hypoxia
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occurs when a metabolic poison such as cyanide prevents the tissues from using the oxygen delivered to them
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Cyanosis
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blueness of the skin, often indicating hypoxia
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Oxygen toxicity
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develops when pure oxygen is breathed at 2.5 atm or greater
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Chronic obstructive pulmonary diseases (COPDs)
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long-term obstruction of airflow and substantial reduction of pulmonary ventilation
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Chronic bronchitis
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severe, persistent inflammation of the lower respiratory tract
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Emphysema
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alveolar walls break down and alveoli converge into fewer and larger spaces --> much less respiratory membrane available for gas exchange
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Cor pulmonale
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hypertrophy and potential failure of the right heart due to obstruction of the pulmonary circulation
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Squamous cell carcinoma
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most common form of lung cancer
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Adenocarcinoma
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lung cancer that originates in the mucous glands of the lamina propria
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Small-cell carcinoma
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least common but most dangerous form of lung cancer; originates in the main bronchi but invades the mediastinum and metastasizes quickly to other organs
