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163 Cards in this Set
- Front
- Back
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What is the primary function of the respiratory system?
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to obtain oxygen for cellular use and to remove carbon dioxide
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What are the two types of respiration?
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Internal and external
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What is internal respiration?
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cellular mitochondrial respiration
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What is external respiration?
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exchange of gas between cells and the environment
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What are the four steps of external respiration?
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1) gas exchange between the atmosphere and the alveoli
2) exchange of oxygen and carbon dioxide between air in alveoli and blood 3) transport of oxygen and carbon dioxide between lungs and tissues 4)exchange of oxygen and carbon dioxide between the blood and the tissues |
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What are the nonrespiratory functions of the respiratory system?
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1)water loss and heat elimination
2) enhance venous return 3) maintenance of normal acid base balance 4) enable vocalizations 5) defend against foreign matter 6) modify, activate, and inactivate materials passing through circulatory system 7) nose = organ for smell |
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What are the sites for gas exchange?
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alveoli
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What is the main respiratory organ?
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The lungs
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Name the connecting air passages.
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nasal passage/oral cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveolar ducts, and alveolar sacs
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What helps keep the trachea open?
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Cartilaginous rings
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What branch of the nervous system innervates the smooth muscle in the respiratory tract?
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The autonomic nervous system
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What are the Pores of Kohn?
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pores in the alveoli that allow for collateral ventilation
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What encircles the alveoli?
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pulmonary capillaries
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What secretes pulmonary surfactant?
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Type II cells in the alveolar epithelium
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What is the immune defense of the alveoli?
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Alveolar macrophages
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What is the importance of the elastic connective tissue in the lung?
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Allows for expansion during inhalation
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Tru or fals, the lungs ocupy most of the volume of the thoracic cavity?
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True
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What is the diaphragm?
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skeletal muscle for breathing that seperates the thoracic and abdominal cavities
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What seperates each lung from the thoracic wall?
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The pleurl sac, which forms the pleural cavity into which fluid from the pleural surface is secreted
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What is the atmospheric (barometric) pressure?
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pressure produced by weight of air on objects on earth's surface, 760 mm Hg at sea level, decreases with increasing altitude
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What is the intra-alveolar/intra-pulmonary pressure?
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The pressure in the alveoli
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What is the intrapleural/intrathoracic pressure?
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The pressure in pleural sac
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What is the average intrapleural pressure at rest?
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756 mm Hg (or -4 below 760 mm Hg) a slight vaccume compared to normal atmospheric pressure
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What happens during a pneumothorax?
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The intrapleural pressure is lost
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What is transmural pressure?
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Pressure accross the cavity wall
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What is the transmural pressure gradient accross the lung wall?
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net outward P diference b/n intra-alveolar and intrapleural pressure
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What happens to the lungs when the intra-alveolar pressure is greater than the intrapleural pressure?
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lungs are pushed out
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What is the transmural pressure gradient accross the thoracic wall?
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The net inward pressure difference b/n the atmospheric and intrapleural pressure
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Why does the transmural pressure on the lung wall have a greater effect?
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Because the lungs contain highly condensible soft tissue
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What produces air flow in and out of lungs?
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changes in the intra-alveolar pressure
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What happens when intr-alveolar pressure < atmospheric pressure?
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air flows into lung
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What happens when intra-alveolar pressure is > atmospheric pressure?
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air leaves the lungs
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What is Boyle's law?
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P1V1=P2V2
there is an inverse relationship between pressure and volume |
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What is the major muscle of inspiration?
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diaphragm
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What are the muscles of active respiration?
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internal intercostal muscles and abdominal muscles
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Is expiration and active or passive process?
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passive
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Dos inspiration require work?
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Yes, it is an active process
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What nerves innervate the diaghram?
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phrenic nerves
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What innervates the external intercostal muscles?
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intercostal nerves
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What is most of the enlargement of the thoracic cavity during quiet respiration due to?
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Contraction and flattening of the diaphragm
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What effect does expansion of the thoracic cavity have n intrapleural pressure?
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It decreases it
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What happens when the lungs are drawn into an area of lower pressure?
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they expand
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What happens to intra-alveolar pressure when lung volume increases?
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intra-alveolar pressure lowers below atmospheric pressure
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What happens when the inspiratory muscles relax?
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chest cavity siz decreases (due to relaxation of diaphragm, chest wall muscles, and elastic recoil of alveoli)
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What happens when the intrapleural pressure increases?
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the lungs are compressed
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What happens to the intr-alveolar pressure with decreased lung volume?
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it increases above atmospheric pressure and forces the air out
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What is forced expiration?
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An active process where contraction of expiratory muscles further increses teh pressure gradient between alveoli and atmosphere, forcing the air out
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What influences the rate of airflow?
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airway resistance
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What happens when the difference between atmospheric and intra-aveolar presures are increased?
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air flow increases, flow rate and change in presure are directly proportional
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What happens when airway resistance is increased?
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airflow decreases, flow rate and resistance are inversely proportional
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What is the major determinant of resistance?
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the radius of conducting airways, R=1/r^4
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What portion of the nervous system controls contraction of smooth muscles in the bronchioles?
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autonomic nervous system
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What can change the conducting airway radii?
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the ANS
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What causes bronchdialation?
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sympathetic stimulation and epinephrine
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What causes bronchoconstriction?
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parasympathetic stimulation (at rest) - demand for airflow is low
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What two properties allow lungs to behave like balloons?
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stretching and recoiling
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What is elastic recoil?
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how readily lungs rebound if stretched - allows lungs to return to preinspiratory volume when inspiratory muscles relax
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What is compliance?
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The effort required to stretch lungs
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What decreases lung compliance?
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fibrotic lungs
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What two factors effect pulmonary elastic behavior?
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-pulmonary elastic connective tissue
-alveolar surface tension |
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What does alveolar surface tension depend on?
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it is determined by a thin liquid film lining each alveolus
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What does the film lining each alveolus do?
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-allows alveolus to resist expansion
- squeezes alveolus producing recoil |
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What prevents the alveolus from collapsing from surface tension?
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pulmonary surfactant
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What is pulmonary surfactant?
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mixture of proteins and lipids secreted by Type II alveolar cells
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Where is pulmonary surfactant found?
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b/n water molecules in fluid lining of alveolus
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What are two important benefits of pulmonary surfactant reducing alveolar surface tension?
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-increases pulmonary compliance, reducing work needed to inflate lung
-reduces lungs tendency to recoil so they do not readily collapse |
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What percentage of total energy expenditure is normally required for breathing?
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3%
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What 4 situations increase the work needed for breathing?
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- decreased pulmonary compliance
- increased airway resistance (COPD) -decreased elastic recoil (emphysema) -need for increased ventilation (excercise) |
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How is tidal volume measured?
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a spirometer
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What is tidal volume (TV)?
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air entering or leaving the lungs in a single breath
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What is pulmonary (minute) ventilation?
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volume of air breathed in and out in 1 minute
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What is the respiratory rate?
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# of breaths/minute
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How is pulmonary ventilation calculated?
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tidal volum X respiratory rate
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What is the average pulmonary ventilation?
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6 liters
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What is anatomic dead space?
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not all inspired air reaches the alveoli where gas exchange can occur, some remains in conducting airways
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Why is alveolar ventilation less than pulmonary ventilation?
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because of dead space
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How is the alveolar ventilation calculated?
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(tidal volume - dead space volume) / breath X respiratory rate
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What is the average alveolar ventilation?
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4200 ml/min
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What can effect alveolar ventilation?
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breathing patterns - deep slow breaths increase alveolar ventilation
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True or flase - resistance of individual alveoli can be adjusted independently?
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true
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What do local controls on resistance act on?
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smooth muscle of the airways
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What decreases airway resistance by causing airway supplying alveoli to relax?
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accumulation of carbon dioxide in alveoli
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What does decreased carbon dioxide do to airflow?
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reduces airflow by increasing the contraction of airways supplying the alveoli
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True or false, ventilation and perfusion should match?
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true
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What are the stages of gas transfer?
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-breathing movements
-diffusion of oxygen and carbon dioxide across the respiratory epithelium -transport of gases -diffusion of oxygen and carbon dioxide across capillary walls between blood and tissue cells |
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How does oxygen and carbon dioxide exchange occur at pulmonary and tissue capillaries?
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simple diffusion
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What does the partial pressure of each gas in the air depend on?
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the % of that gas in the total atmospheric pressure
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What is a partial pressure gradient?
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2 partial pressures for a gas in different regions of the body
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Where is the partial pressure of oxygen higher, the alveoli or the blood of pulmonary capillaries?
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the alveoli, thus oxygen diffuses from alveoli to capillaries
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Where is the partial pressure of carbon dioxide greater?
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greater in the blood if the pulmonary capillaries, thus carbon dioxide diffuses into the alveoli from the capillaries
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Which direction does oxygen move between the alveoli and capillaries?
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It flows from the alveoli into the capillaries
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Which direction does carbon dioxide flow between the capillaries and alveoli?
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it diffuse into the alveoli from the capillaries
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which direction does oxygen flow between blood and tissue cells?
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it diffuses from blood into tissue cells
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Which direction does carbon dioxide flow between tissue cells and blood?
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it diffuses from tissue cells into the blood
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How does surface area effect the rate of gas transfer?
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increases the rate of gas exchange, alveoli collectively have a tremendous surface area, increased pulmonary blood pressure = increased cardiac ourput = increased surface area
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How does distance affect the rate of gas transfer?
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thin walls lead to rapid gas exchange
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What disease states decrease gas exchange by thickening areas for gas exchange?
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pulmonary edema, pulmonary fibrosis, penumonia
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How does the gas diffusion coeffecient affect gas transfer?
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gas exchange is directly proportional to diffusion coefficient for a gas
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How is oxygen and carbon dioxide transported?
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in blood between alveoli and tissues
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What percentage of oxygen is bound to hemoglobin?
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98.5%
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What % of carbon dioxide is physically dissolved?
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10%
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What percentage of carbon dioxide is bound to hemoglobin?
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30%
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What percentage of carbon dioxide is in the form of bicarbonate ion?
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60%
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Does the oxygen bound to hemoglobin contribute to its partial pressure?
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no
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Where is oxyhemoglobin formation favored ?
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the lungs
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When does Hb bind with oxygen?
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when oxygen diffuses from alveoli into the pulmonary capillaries
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Where does dissociation of oxyhemoglobin occur?
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tissue cells
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What portion of oxygen contributes to its partial pressure?
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The 1.5% dissolved in plasma
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What is the main determinant of the percent hemoglobin saturation?
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the partial pressure of oxygen
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What promotes the net transfer of oxygen at the alveolar and tissue levels?
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hemoglobin
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When does the net diffusion of oxygen from the alveoli to the blood stop?
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when the hemoglobin is saturated
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What does increased carbon dioxide from tissues cells into systemic capillaries do to Hb dissociation from oxygen?
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increses Hb dissociation from oxygen
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What is the Bohr (Haldane) effect?
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the shift of the dissociation curve to the right, increasing oxygen unloading
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How does increased acidity affect Hb-oxygen dissociation?
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it increases dissociation (shifts curve to right)
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How does increased temp affect oxygen dissociation?
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increases
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how does BPG production effect oxygen unloading?
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increases it
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How is most carbon dioxzide transported?
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as bicarbonate ion
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What is formed when carbon dioxide combines with water?
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carbonic acid
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What enzyme facilitates the production of carbonic acid in red blood cells?
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carbonic anhydrase
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What ions does carbonic acid disociate into?
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hydrogen ions and bicarbonate ions
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Where is carbonic acid dissociation favored?
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at the tissue cells
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Where does bicarbonae ion form free molecules of carbon dioxide?
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in the lungs
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What occurs during a chloride shift?
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RBC plasma membrane passively facilitates diffusion of bicarbonate and chloride ions
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What is the Haldane effect?
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oxygen removel from hemoglobin at the tissue cells, which increases ability of Hb to bind to carbon dioxide and hydrogen ion
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What is hypoxia?
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insufficient oxygen at the cellular level
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What is hypoxic hypoxia?
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low partial pressure of oxygen in arterial blood
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What is circulatory hypoxia?
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too little oxygenated blood deleivered to tissues (normal partial pressure of oxygen blood just isn't getting to tissues)
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What is anemia hypoxia?
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reduced oxygen carrying capacity in the blood, decreased RBCs, CO poisoning
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What is histotoxic hypoxia?
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oxygen delivery to tissues is normal but cells can't use it
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What is hyperoxia?
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above normal arterial partial pressure of oxygen
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What is hypercapnia?
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excess carbon dioxide in arterial blood caused byhypoventilation
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What is hypocapnea?
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below normal carbon dioxide in arterial blood caused by hyperventilation
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What is hyperpnea?
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increased need for oxygen delivery and carbon dioxide removal - during times of increased metabolic need
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What do the respiratory centers in the brain stem due?
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establish rythmic breathing pattern which can be modified via voluntary activity
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What is the medullary respiratory center?
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an aggregation of neuronal cell bodies in medulla that provide output to respiratory muscles
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Name the parts of the medullary respiratory centers.
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Pre-Botzinger complex, dorsal respiratory group, ventral respiratory group
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What are the two respiratory centers in the pons?
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the pneumotaxic center and the apneustic center
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What do the respiratory center in the pons do?
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infuence output from medullary respiratory center
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What are the two types of inspiratory muscles?
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phrenic and intercostal
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What do the inspiratory neurons do?
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signal inspiratory muscles, the diaphragm and external intercostals
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Where do impulses from the medullary center terminate?
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the phrenic and intercostal motor neurons
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Where are cell bodies for the inspiratory neurons located?
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in the spinal cord
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Where are signals from the inspiratory neurons sent?
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to inspiratory muscles
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What happens when there is no signal from inspiratory neurons?
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expiration
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What is the dorsal respiratory group responsible for?
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inspiration
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When is the ventral respiratory group utilized?
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during increased demand for ventilation, particlarly during active expiration
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What is responsible for the basic respiratory rythym?
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the pre-botzinger complex
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What sends the impulses that switch off inspiratory neurons?
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pneumotaxic center, it limits the duration of inspiration
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What prevents inspiratory neurons from being switched off?
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the apneustic center
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What is the Hering-Breuer reflex?
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stretch receptors in lungs activated with large tidal volumes during inspiration
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What are the 3 chemical factors that adjust the magnitude of ventilation?
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partial pressure of oxygen
partial pressure of carbon dioxide hydrogen ion |
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What is reflective of carbon dioxide?
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hydrogen ion concentration
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What is the primary regulator of magnitude?
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carbon dioxide generated hydrogen ion in the brain
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What is monitored by the peripheral chemoreceptors?
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arterial partial pressure of oxygen
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What are the peripheral chemoreceptors?
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Carotid and aortic bodies
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When are peripheral chemoreceptors stimulated?
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when arterial partial pressure of oxygen is life threateningly low
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Where are the central chemreceptors located?
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in the medulla
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What do the central chemoreceptors monitor?
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increased hydrogen ion concentration in the brain ECF
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What happens when the central chemoreceptors are stimulated?
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ventilation is increased by stimulating the respiratory center
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What does elevated arterial hydrogen ion stimulate?
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ventilation
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What is apnea?
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transient interruption in ventillation
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What is sleep apnea?
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breathing ceases up to 2 minutes up to 500 times a night
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What is dyspnea?
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subjective feeling of "shortness of breath" which often accompanies other conditions.
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