Respiratory System Flashcards
Point at which the bronchus enters the lung
Hilum
Bronchodilation
When sympathetic stimulation relaxes the smooth muscle, dilating or enlarging the bronchioles
How does the respiratory mucosa change as it moves towards the terminal respiratory bronchioles?
From pseudostratified columnar to simple columnar then to simple cuboidal
Surfactant
The inside surfaces of the alveoli are coated with a very small amount of fluid. Has a detergent action that reduces surface tension (the tendency for fluid to reduce its surface area by forming droplets). This facilitates inspiration and prevents total collapse of alveoli during expiration
Parietal pleura
Lines the inside of the thoracic cavity, adhering to the chest wall and diaphragm.
Pleural cavity
Small space, slightly negative pressure (less than atmospheric pressure) assists in holding the pleura in close approximation and promoting lung expansion. Provides lubrication during respiratory movements and a force that provides cohesion (high surface tension)
True ribs and false ribs
Upper seven pairs of ribs articulate with the vertebrae and are attached to the sternum by costal (hyaline) cartilage. . The next three are connected to the costal cartilage of the seventh rib, not directly to the sternum. Last two (11th and 12th) are attached only to vertebrae (floating)
How does airflow on inspiration and exhalation work?
Depends on a pressure gradient, air always moves from high pressure to low pressure area. If atmospheric pressure is higher than air pressure inside the lungs, air will move from the atmosphere into the lungs.
Boyle’s law
As the size of the cavity decreases, the pressure inside the cavity increases.
Process of normal quiet inhalation
Contraction of diaphragm and external intercostal muscles
Eternal intercostals raise the ribs and sternum up and out
Increased size of thoracic cavity results in decreased pressure in the pleural cavity
As ribs and diaphragm move, the attached parietal pleura pulls the adhering visceral pleura and lungs along with it
As visceral pleura moves outward, elastic lungs expand with it, resulting in a decrease in air pressure inside the lungs
Air flows from atmosphere down airways into the alveoli.
Inhalation is active and requires energy, exhalation is passive
What muscles are involved in forced inspiration or expiration?
Sternocleiodmastoid, scalene, pectoralis minor, serratus muscles during inhalation
Abdominal muscles contract during forceful expiration and intercostals
Compliance
Refers to ability of the lungs to expand, depends on elasticity of the tissues, alveolar surface tension and shape, size, flexibility of thorax
Why do we measure pulmonary volumes?
They can change with disease processes and are helpful in monitoring a patient’s progress or response to treatment.
Residual volume
The volume of air remaining in the lungs after maximum expiration. This air continues to provide gas exchange and maintains partial inflation of the lungs
Vital capacity
Maximal amount of air that can be moved in and out of the lungs - can be altered by disease, size of thorax, amount of blood in lungs, body position
Dead space
Passageways or areas where gas exchange cannot take place. Bronchi and bronchioles
Tidal volume
500 mL - amount of air entering lungs with each normal breath
Residual volume
1200 mL - amount of air in lungs after forced expiration
Inspiratory reserve (IRV)
3000 mL - Max amount of air that can be inhaled in excess of normal quiet inspiration
Expiratory reserve (ERV)
1100 mL - Max volume of air expired following a passive expiration
Vital Capacity (VC)
Max amount of air expired following max inspiration
Total Lung Capacity
Total volume of air in lungs after max inspiration
Primary control centers for breathing
Medulla and pons - inspiratory center controls the basic rhythm by stimulating the phrenic nerves to the diaphragm and the intercostal nerves to the external intercostal muscles.
The expiratory center in the medulla appears to function primarily when forced expiration is required
Additional centers in the pons play a role in coordinating inspiration, expiration and intervals for each
Factors that can depress central nervous system activity
Drugs like morphine
Activity of hypothalamus - perhaps in response to emotions
Stretch receptors in the lungs
Hering-Breuer reflex - prevents excessive lung expansion
Voluntary control - singing
Voluntary control is limited by levels of carbon dioxide in the blood. When the concentration or partial pressure of carbon dioxide in the blood rises, breathing resumes automatically.
Central chemoreceptors
In medulla - respond quickly to slight elevations in CO2 (40-43mmHg) or a decrease in pH (increased H+) of cerebrospinal fluid.
Peripheral chemoreceptors
Located in the carotid bodies at the bifurcation of the common carotid arteries and in the aortic body in the aortic arch, sensitive to decreased oxygen levels in arterial blood as well as to low pH.
Hypoxemia
A marked decrease in oxygen (105 to 60 mmHg) is necessary before chemoreceptors respond to hypoxemia.
Hypoxic drive
Individuals with chronic lung disease adapt to sustained elevation in PCO2 and move to hypoxic drive, such individuals are dependent on low oxygen levels rather than the normal slight elevation in carbon dioxide to stimulate inspiration. The medullary chemoreceptors become insensitive to high PCO2. Therefore it is important for these patients always to remain slightly hypoxic and not be given excessive amounts of oxygen.
Hypercapnia
When carbon dioxide levels in the blood increase, gas diffuses into the cerebrospinal fluid. lowers pH and stimulates the respiratory center, results in increased rate and depth of respirations (hyperventilation)
Causes respiratory acidosis which depresses the nervous system.
Hypocapnia
Low PCO2 may be caused by hyperventilation after excessive amounts of CO2 have been expired. Causes respiratory alkalosis.
Dalton’s law
Each gas in a mixture moves or diffuses according to its own partial pressure gradient and independent of other gases
What does atmospheric air contain?
Oxygen, carbon dioxide, nitrogen and water
Factors effecting diffusion
Thickness of the respiratory membrane. When fluid accumulates in the alveoli or interstitial tissue, diffusion is greatly impaired. Presence of extra fluid may also impede blood flow through the pulmonary capillaries and increase surface tension in the alveoli, restricting expansion of the lung.
Total surface area available for diffusion and the thickness of the alveolar membranes.
Ventilation perfusion ration (Va / Q)
An autoregulatory mechanism in the lungs can adjust ventilation and blood flow in an attempt to produce a good match.
E.g. if PO2 is low because of poor ventilation in an area, vasoconstriction occurs in the pulmonary arterioles, shunting the blood to other areas of the lungs where ventilation may be better.
How much total oxygen is dissolved in plasma?
1% because oxygen is relatively insoluble in water, which also limits the ease that oxygen can diffuse.
Where is the dissolved form of oxygen found?
That which diffuses from the alveolar air into the blood in the pulmonary capillaries, diffuses into the interstitial fluid and the cells during internal respiration.
Fully saturated hemoglobin
When all four heme molecules have taken up oxygen
What effects the rate that hemoglobin binds or releases oxygen?
Partial pressure of dissolved oxygen Partial pressure of carbon dioxide Temperature Plasma pH Normally approx 25% of the bound oxygen is released to the cells for metabolism during the erythrocyte's trip through the systemic circulation, leaving 75% of the hemoglobin in the venous blood still saturated with oxygen.
How is carbon dioxide transported?
7% dissolved in plasma
20% loosely and reversibly bound to hemoglobin (attached to an amino group on the globin portion - carboaminoglobin)
Majority resulting from cell metabolism diffuses into the RBCs where under the influence of the enzyme carbonic anhydrase transitions briefly as carbonic acid, then is immediately converted into bicarbonate ions, which can then diffuse back into the plasma to function in the buffer pair.
Co2 + H2O reversibily H2Co3 reversibly H+ + HCO3-
What maintains the blood pH
A ratio of 20 parts bicarbonate ion to 1 part carbonic acid maintains pH at 7.35
Spirometry- pulmonary function testing
Tests pulmonary volumes and airflow times
Arterial blood gas determinations
Oxygen, carbon dioxide, bicarbonate levels, serum pH
Oximeters
Measure O2 saturation
Exercise tolerance testing
Useful for patients with chronic pulmonary disease for diagnosis and monitoring of patients progress.
Radiography - helpful in evaluating tumors or infections
Bronchoscopy - - biopsy, checking lesions
Culture and sensitivity tests on exudates from upper respiratory tract can identify pathogens
Coughing
May result from irritation caused by a nasal discharge dripping into the oropharynx, or inflammation or foreign material in the lower respiratory tract or from inhaled irritants.
Cough reflex
Controlled by a center in the medulla, consists of coordinated actions that inspire air and then close the glottis and vocal cords, followed by forceful expiration in which the glottis is opened, unwanted material is blown upward and out of the mouth.
Sputum - yellowish-green
Indication of bacterial infection
Sputum - rusty or dark-colored
Pnumococcal pneumonia
Very large amounts of sputum containing pus with foul odor
Bronchiectasis
Hemoptysis
Blood-tinged frothy sputum usually associated with pulmonary edema
Eupnea
Breathing rhythm is smooth and even, expiration longer than inspiration
Tachypnea
Rapid superficial breathing, regular or irregular pattern
Bradypnea
Slow rate, deeper than usual depth, regular rhythm
Apnea
Cessation of breathing
Hyperpnea
Increased depth of respiration with a normal to increased rate and regular rhythm.
Cheyne-Stokes respiration
Periodic breathing with periods of apnea, alternating regularly with a series of respiratory cycles; the respiratory cycle gradually increases, then decreased in rate and depth
Ataxic breathing
Apnea alternating irregulary with a series of shallow breaths of equal depth.
Kussmaul’s respiration
Deep regular sighing respirations with an increase in rate. Deep rapid. “air hunger” Typical of acidosis or strenuous exercise.
Apneusis
Long gasping inspiratory phase followed by a short, inadequate expiratory phase
Obstructed breathing
Long, ineffective expiratory phase with shallow, increased respirations.
Wheezing or whistling sounds
Obstruction in small airways
Stridor
High-pitched crowing noise, possible upper airway obstruction
Rales and rhonchi
Abnormal sounds resulting from air mixing with excessive secretions in the lungs.
Rales - light bubbly or crackling associated with serous secretions
Rhonchi - deeper and harsher resulting from thicker mucus
Atelectasis
Absence of breath sounds - nonaeration, collapse
Dyspnea
Subjective feeling of discomfort that occurs when a person feels unable to inhale enough air - breathlessness or shortness of breath
Signs of dyspnea
Flaring of nostrils, sue of accessory respiratory muscles, retraction (pulling in) of muscles between or above ribs
Orthopnea
Dyspnea that occurs when a person is lying down - pulmonary congestion develops as more blood pools in the lungs and as abdominal contents push upward - raising pillows helps
Paroxysmal nocturnal dyspnea
Sudden acute type of dyspnea common in patients with leftsided congestive heart failure. Causes pulmonary edema - individual wakes gasping for air and coughing
Cyanosis
Bluish coloring of skin and mucous membranes resulting from large amounts of unoxygenated hemoglobin in blood.
Pleural pain
Inflammation or infection of the parietal pleura - cyclic, increases as the inflamed membrane is stretched with inspiration or coughing
Friction rub
Soft sound produced as the rough membranes move against each other. May be caused by pleural inflammation or lobar pneumonia or lung infarction.
Clubbed fingers
Chronic hypoxia associated with respiratory or cardiovascular disease. Painless, firm, fibrotic enlargement at end of digit.
Hypooxemia
Inadequate oxygen in blood
Hypoxia
Inadequate oxygen supply to the cells. Affects cell metabolism reducing cell function and leading to anaerobic metabolism and development of metabolic acidosis. Cerebral hypoxia initially stimulates the sympathetic nervous system - decreased cell function is indicated by fatigue, lethargy or stupor and muscle weakness.
Causes of hypooxemia and hypoxia
Deficit of RBCs or hemoglobin levels are too low for adequate oxygen transport
Circulatory impairment, decreased cardiac output from the heart to the lungs or systemic circulation
Excessive release of oxygen from RBCs if circulation is sluggish or is partially obstructed by vascular disease
Impaired respiratory function - inadequate ventilation, inhalation of oxygen-deficient air, impaired diffusion.
Carbon monoxide poisoning - co2 binds tightly and preferentially to heme, displacing oxygen- bright red skin and mucosa with headache and drowsiness
Compensation mechanisms for hypoxia due to. respiratory impairment
Increased cardiovascular activity such as tachycardia and increased blood pressure. Chronic - erythropoietin secretion is increased, stimulating bone marrow to produce additional red blood cells
Acid-base imbalance
may develop from respiratory disorders - acidosis due to excess carbon dioxide (increased carbonic acid) impaired expiration.
Respiratory Alkalosis - When respiratory rate is increased, usually because of acute anxiety or intake of aspirin.
Common Cold (infectious rhinitis)
Viral infection of upper respiratory tract. Most commonly rhinovirus but can also be adenovirus, parainfluenza
or coronavirus. More than 200 causative organisms, so difficult to develop sufficient immunity. Highly infectious because the virus is shed in large numbers from the infected nasal mucosa during the first few days of infection and can survive several hours outside the body.
Inflammation may spread to cause pharyngitis (strep throat) - strep invades inflamed and necrotic mucus membranes, laryngitis or acute bronchitis.
Can cause secondary bacterial infection such as sinusitis, otitis media or tracheitis
What do decongestants do?
Vasoconstrictors - reduce edema and congestion in the respiratory passages.
Sinusitis
Bacterial infection, secondary to a cold or an allergy that has obstructed the drainage of one or more of the paranasal sinuses into the nasal cavity. As exudate accumulates, pressure builds inside the sinus cavity causing severe pain in facial bone - pain may be confused with headache or toothache. Decongestants, analgesics and antibiotics.
Laryngotracheobronchitis (Croup)
Common viral infection, children 1-2 years. Causative organisms - parainfluenza and adenovirus. Begins as upper respiratory with nasal congestion and cough. Larynx and subglottic area become inflamed with swelling and exudate leading to obstruction and barking cough and inspiratory stridor. Severe at night. Humidifier will relieve obstruction. Self-limited, full recovery in several days. Allergies may require additional treatment.
Epiglottitis
Acute infection, bacterial, common in 3-7year olds, swelling of larynx, supraglottic area, and epiglottis which appears as a round, red ball obstructing the airway. Fever, sore throat, refusal to swallow, drooling, inspiratory stridor, anxiety, pale, sitting position with mouth open, struggling to breathe, oxygen and antimicrobial therapy, intubation or tracheotomy.
Influenza
Viral, may affect both upper and lower respiratory tracts. Three groups of influenza virus - type A (most prevalent), type B and C.
Constant mutation
Prevent effective immune defence for prolonged time periods.
Sudden, acute onset with fever, marked fatigue, aching pains, may also cause a viral pneumonia. Can be complicated by secondary problems such as bacterial pneumonia (causes most deaths).
Treatment is symptomatic and supportive unless there is bacterial infection.
Antiviral drugs can reduce symptoms and duration as well as reduce risk of infecting others.
Incubation 1-4 days - virus can be passed a day before symptoms and 5 days after.
What does humidifying air do?
Moist mucosa resists damage, thins and removes secretions
Decongestants
Vasoconstriction in nasal mucosa, reduce edema - pseudoephedrine
Expectorants
Thin respiratory secretions for easier removal - guaifenesin
Antitussives
Reduce cough reflex - codeine, dextromethorphan
Antihistamines
Block H1 receptors to reduce allergic response - diphenhydramine
Analgesics
Reduce pain - acetaminophen, codeine
Antimicrobials
Prophylaxis and treatment of infection
Antibacterial - penicillin
Antiviral - amantadine, anamivir
Antitubercular
Bronchodilators
Stimulate beta-2 adrenergic receptors to open bronchioles - salbutamol
Glucocorticoids
Anti-inflammatory, antiallergenic - prednisone
Scarlet fever
Upper respiratory infection caused by group A strep
Incubation 1-2 days.
Fever and sore throat, chills, vomiting, abdominal pain, malaise.
““strawberry” tongue, produced by exotoxin produced by bacteria
Fine rash on chest, neck, groin, thighs.
Antibiotics.
Bronchiolitis (respiratory Syncytial Virus Infection)
Common infection in young children 2 to 12 months of age, caused by RSV, a myxovirus.
Transmitted by oral droplet, occurs more frequently in winter months. Familial history of asthma and cigarette smoke.
Virus causes necrosis and inflammation in small bronchi and bronchioles with edema, increased secretions and bronchospasm leading to obstruction of small airways.
Wheezing
dyspnea, rapid, shallow respirations, cough, rales, chest retractions, fever, malaise.
May be areas of hyperinflation with air trapping due to partial obstruction or areas with total obstruction
Supportive and symptomatic, monitoring of blood gases
Pneumonia
May develop as a primary acute infection in the lungs or it may be secondary to another respiratory or systemic condition in which tissue resistance is reduced.
Risk following any aspiration or inflammation in the lung, when fluids pool or defence mechanisms such as cilia are reduced.
In most cases organisms enter lungs directly by inhalation (virus), resident bacteria spreading along the mucosa, or aspiration in secretions.
Classification of Pneumonias.
Categories may be based on the causative agent, anatomic location of the infection, pathophysiologic changes, or epidemiologic data.
Causative agent: virus, bacterium, or fungus - e.g. pneumococcus, Staph aureus, Legionella.
Lobar pneumonia
All of one or two lobes
Inflammation of alveolar wall and leakage of cells, fibrin, and fluid into alveoli causing consolidation. Pleura may be inflamed.
Sudden and acute
High fever and chills, productive cough with rusty sputum, rales progressing to absence of breath sounds in affected lobes.
