2. oxygen Flashcards
oxygen transport
Oxygen diffuses from the capillary through the capillary wall to the interstitial fluid. At this point, it diffuses through the membrane of the tissue cells, where it is used by the mitochondria for cellular respiration. The movement of carbon dioxide occurs by diffusion in the opposite direction – from cell to blood.
o Diffusion – higher concentration to lower concentration (either side)
respiration
After these tissue capillaries exchange, blood enters the systemic veins and travel to the pulmonary circulation. The oxygen concentration in blood within the capillaries of the lung is lower then in the lung air sacs (alveoli). Because of the concentration gradient, oxygen diffuses from the alveoli to the blood. Carbon dioxide, which has a higher concentration in the blood. Then, in the alveoli, diffuses from the blood into the alveoli. Movement of air in and out of the airways (ventilation) continually replenishes the oxygen and removes the carbon dioxide from the airways and lungs.
o Alveoli – covered in capillary bed with oxygen molecules
ventilation
During inspiration, air flows from the environment into the trachea, bronchi, bronchioles, and alveoli. During expiration, alveolar gas travels the same route in reverse. Physical factors that govern airflow in and out of the lungs are collectively referred to as the mechanics of ventilation and include air pressure variances, resistance to airflow, and lung compliance.
Mechanism of ventilation
pressure changes with inhaling/exhaling (3 components)
3 components of Mechanism of ventilation *
- air pressure variance
- resistance to flow – determined by the diameter of the airway (conditions that can narrow diameter: smoking, collapsed lung)
- compliance – either increased or decreased – how elastic the lungs are, how they recoil and expand
air pressure variance
- air flows from a region of higher pressure to a region of lower pressure. During inspiration, movement of the diaphragm and other muscles of respiration enlarges in the thoracic cavity and thereby lowers the pressure inside the thorax to a level below that of atmospheric pressure. As a result, air is drawn through the trachea and bronchi into the alveoli. During expiration, the diaphragm relaxes in the lungs recoil, resulting in a decrease in the size of thoracic cavity. The alveolar pressure, then exceeds atmospheric pressure, and air flows from the lungs into the atmosphere.
resistance to flow
resistance is determined chiefly by the radius or size of the airway through which the air is flowing. Any process that changes the bronchial diameter or width affect airway resistance and alters the rate of airflow for a given pressure gradient during respiration with increased resistance, greater than normal respiratory effort is required to achieve normal levels of ventilation.
compliance
- or distendability (elasticity), is the elasticity or expandability of the Lungs and thoracic structures. Compliance allows the lung volume to increase when the difference in pressure between the atmosphere and thoracic cavity (pressure gradient) causes air to flow again. Factors that determine lung compliance are the surface tension of the alveoli and the connective tissue of the lungs. Compliance is determined by examining the volume pressure relationship in the lungs in the thorax. Compliance is normal. If the lungs and thorax easily stretch and expand when pressure is applied. High or increase compliance occurs if the lungs have lost their elasticity in the thorax is over distended (emphysema). Low or decrease compliance occurs if the lungs and thorax are “stiff” conditions associated with decreased compliance include morbid obesity, pneumothorax, hemothorax, pleural effusion, pulmonary edema, atelectasis, pulmonary fibrosis, acute respiratory distress syndrome. Measurement of compliance is one method used to assess the progression and improvement in patients with acute respiratory distress syndrome. Lungs with decreased compliance require greater than normal energy expenditure by the patient to achieve normal levels of ventilation. Compliance is usually measured under static conditions.
increase/decrease compliance*
- COPD – lungs injured so increase compliance; can get air in but CO2 can’t get out
- Decreased – lungs stiff; actleticsis, difficult to get oxygen in because lung can’t expand to let in; pulmonary edema, puenothorax, cystic fibrousos
Lung Volumes and Capacities
lung function, which reflects the mechanics of ventilation, as viewed in terms of lung volumes and lung capacities. Lung volumes are categorized as tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume. Lung capacity is evaluated in terms of vital capacity inspiratory capacity, functional residual capacity in total lung capacity.
dyspnea
(decrease lung compliance, increase airway resistance)*; The right ventricle of the heart is affected ultimately by lung disease because it must pump blood through the lungs against greater resistance. Dyspnea may be associated with neurological or neuromuscular disorders that affect respiratory function. Dyspnea can also be after physical exercise in people without disease. It is also common. At the end of life in patients with a variety of disorders. In general, acute diseases of the lung, produce a more severe grade of dyspnea, then do chronic diseases. Sudden dyspnea and a healthy patient may indicate pneumothorax, acute respiratory obstruction, allergic reaction, or myocardial infarction. In immobilized patients, sudden dyspnea may denote pulmonary embolism. Dyspnea and tachypnea, accompanied by progressive hypoxemia in a person who has recently experienced lung trauma, shock, cardiopulmonary bypass, and multiple blood transfusions may signal acute respiratory distress syndrome
orthopnea
inability to breathe easily. Except in the upright position may be found in patients with heart disease, and occasionally in patients were COPD; dyspnea with an expiratory wheeze occurs with COPD. Noisy breathing may result from a narrowing of the airway or localized obstruction of a major bronchus by tumor or foreign body. The high-pitched sound heard usually on inspiration when someone is breathing through a partially blocked upper airways called stridor. The presence of both inspiratory and expiratory wheezing usually signifies asthma, if a person does not have heart failure. Because dyspnea can occur with other disorders. These disorders also need to be considered when obtain the patient’s health history.
cough
cough is a reflex that protects the lungs from the accumulation of secretions or that inhalation of foreign bodies. Its presence or absence can be a diagnostic because some disorders cause coughing and others suppress it. The cough reflex may be impaired by week or paralyzed respiratory muscles, prolonging inactivity, the presence of a nasogastric tube, or depressed function of medullary centers in the brain. Cough results from irritation of the mucous membranes anywhere in the respiratory tract. The stimulus that produces a cough may arise from an infectious process or from an airborne irritants such as smoke, small, dusk, or a gas. A persistent infrequent cough can be exhausting and cause pain. Cough may indicate serious pulmonary diseases or a variety of other problems as well, including cardiac disease, medication reaction, smoking, acid reflux. To help determine the cause of the cough, the nurse describes the cough: dry, hacking, brassy, wheezing, lose, or severe. A dry, irritative cough is characteristic of an upper airway infection of viral origin, or it may be a side effect of ace inhibitor medication. And irritative, high pitched cough can be caused by laryngitis. A brassy cough is a result of tracheal lesion, while a severe or changing cough may indicate bronchial genic carcinoma. Pleuritic chest pain that accompanies coughing may indicate plural or chest wall involvement.
sputum
patient who coughs long enough almost invariably produces sputum. Sputum production is a reaction to the lungs to and constant reoccurring irritant. It also may be associated with the nasal drainage. The nature of the sputum is often indicative of its cause. A profuse amount of purulent sputum (thick yellow, green, or rust colored) or a change in color of the sputum is a common sign of bacterial infection. Thin, mucoid sputum frequently results from viral bronchitis. A gradual increases sputum over time may occur with chronic bronchitis. Pink tinge, mucoid sputum suggests a lung tumor. Profuse frothy pink material, often wells up into the throat may indicate pulmonary edema*. Foul-smelling sputum in bad breath points to the presence of lung abscess.
wheezing
is a high-pitched, musical sound heard mainly on expiration (asthma) or inspiration (bronchitis). It is often the major finding in a patient with bronchial constriction or airway narrowing. Rhonchi are low pitch continuous sounds heard over the lungs in partial airway obstruction. Depending on their location and severity, the sounds may be heard with or without the stethoscope.
