ZOOL-3303 Exam 2

What is pulmonary ventilation?

- It is the physical movement of air into and out of the lungs, or respiratory tract.

How is pulmonary ventilation all about the pressure?

Primary Function:
-Maintain adequate alveolar ventilation.
-To do this, it is important to understand the interactions between gases, liquid, and pressure

What are the primary differences between gases and liquids?

-Primary difference between gases and liquids is the interaction between individual molecules

-Water (liquid) molecules bonds (usually H) have a close associated.
I.e.: Dense.

-Air (gas), the molecules are independent entities.
--Therefore, farther part, so they are less dense.
--Not many forces working on gas because they are farther apart, so pressure can be applied to push them together. Greater collisions = Higher pressure

What is atmospheric pressure?

-The weight of air
-Has several important physiological effects

What is Boyle's Law?

-Defines the relationship between gas pressure and volume: P=1/V

-In a container gas...
--External pressure forces molecules closer together
--Movement of gas molecules exerts pressure on container

What are the mechanics of breathing?

-Alveolar surface tension and ventilation
--Function of surfactant

-Elastic properties of the lung and chest wall:
--Elastic recoil
--Compliance

-Airway resistance

-Work of breathing

What is quiet breathing (Eupnea)?

-Involves active inhalation and passive exhalation

-Diaphragmatic breathing or deep breathing
--Is dominated by diaphragm
--Men dominate

-Costal breathing or shallow breathing
--Is dominated by rib cage movement
--Women dominate

What is dyspnea?

-Subjective sensation of uncomfortable breathing

-Orthopnea
--Dyspnea when a person is lying down

-Paroxysmal Nocturnal Dyspnea (PND)

What is hypercapnia?

-An increase in arterial Pco2

-Stimulates chemoreceptors in the medulla oblongata
--To restore homeostasis

Causes of hypercapnia?

-Hypoventilation is a common cause of hypercapnia

-Abnormally low respiration rate:
--Allows CO2 build up in blood

Causes of hypocapnia?

-Excessive ventilation, hyperventilation, results in abnormally low Pco2 (hypocapnia)

-Stimulates chemoreceptors to decrease respiratory rate

What is apnea?

-A period of suspended respiration

-Normally followed by explosive exhalation to clear airways
--Sneezing or coughing

What is laryngeal spasm?

-Temporarily closes airway
--To prevent foreign substances from entering

What types of coughs are there?

-Acute cough

-Chronic cough

What is abnormal sputum?

Can include:
-Blood
-Pus
-Microorganism

What is hemoptysis?

Blood in sputum

What are abnormal breathing patterns?

Kussmaul respirations:
-Hyperpnea

Cheyne-Stokes respirations:
-Abnormal breathing pattern characterized by progressively deeper (sometimes faster) breathing followed by a gradual decrease that results in a temporary stop in breathing

What are signs and symptoms of pulmonary disease?

-Hypoventilation
--Hypercapnia
-Hyperventilation
--Hypocapnia
-Cyanosis
-Clubbing
-Pain

What is the chest wall?

-Skin, ribs, and intercostal muscles
-Thoracic cavity

What is the pleura?

-Serous membrane
-Parietal and visceral layers
-Pleural space (cavity)
-Pleural fluid

What are some chest wall disorders?

Chest wall restriction:
-Compromised chest wall
--Deformation, immobilization, and/or obesity

Flail chest:
-Instability of a portion of the chest wall
-No break in the lungs, just no stability

What are some pleura abnormalities?

Pneumothorax:
-Open pneumothorax
-Tension pneumothorax
-... (primary) pneumothorax
-Secondary pneumothorax

Pleural effusion:
-Transudative effusion
--Watery
-Exudative effusion
--WBC and plasma proteins
-Hemothorax
--Blood
-Empyema
--Infected pleural effusion; pus
-Chylothorax
Chyle (fluid containing lymph and fat) milky color

What is tidal volume?

-Amount of air moved in and out of lungs in a single respiratory cycle

What does an injury to the chest wall do?

-Pneumothorax allows air into pleural cavity
-Atelectasis (also called a collapsed lung) is a result of pneumothorax

What are the measurements of gas pressure?

-Barometric pressure
--Partial pressure

-Partial pressure of water vapor

What is compliance?

-An indicator of ex
-Low compliance requires greater force
-High compliance requires less force

What are factors that affect compliance?

-Connective tissue structure of the lungs
-Level of surfactant production
-Mobility of the thoracic cage

What Are some restrictive lung diseases?

-Aspiration
-Atelectasis
-Bronchiectasis
-Bronchiolitis
-Pulmonary fibrosis
-Inhalation disorders
-Pulmonary edema
-Acute lung injury (ALI)/Acute respiratory distress syndrome (ARDS)

What is an aspiration?

-Passage of fluid and solid particles into the lungs

What is atelectasis?

-Collapsed lung

-Compression atelectasis
--External pressure

-Absorption atelectasis
--Removal of air from obstructed or hypoventilated alveoli

-Surfactant impairment

What is bronchiectasis?

Persistent abnormal dilation of the bronchi

What is bronchiolitis?

-Inflammatory obstruction of the small airways

-Most common in children

-Occurs in adults with
--Chronic bronchitis
--In association with a viral infection
--With inhalation of toxic gases

What is pulmonary fibrosis?

-Scarring of the lungs

-More common in men
-- >60 y/o

-Idiopathic

What are some inhalation disorders?

-Toxic gases

-Pneumoconiosis:
--Silica
--Asbestos
--Coal

-Allergic Alveolitis:
--Extrinsic allergic alveolitis (hypersensitivity pneumonitis)
--Allergic reaction from inhaled particles or fumes

What is pulmonary edema?

Excess fluid in the lungs

What is acute lung injury (ALI)/Acute respiratory distress syndrome (ARDS)?

-Characterized by acute lung inflammation and diffuse alveolocapillary injury
--Injury and inflammation to the alveolocapillary membrane
---Pulmonary edema

Three Phases:
-Exudative
--W/i 72 hours
-Proliferative
--4 days to 21 days
-Fibrotic
--14 days to 21 days

Manifestations:
-Dyspnea and hypoxemia
-Hyperventilation and respiratory alkalosis
-Decreased tissue perfusion, metabolic acidosis, organ dysfunction
-Increase work of breathing, decreased tidal volume, and hypoventilation
-Hypercapnia, respiratory acidosis
-Respiratory failure, decreased cardiac output, hypotension, and death

Diagnosis is based on:
-A History of the lung injury
-Physical examination
-Analysis of blood gases
-Radiologic examination

-Supportive therapy

-All disorders causing ALI cause acute injury to the respiratory membrane (Alveolocapillary)
1. Induce massive inflammation
2. Increased capillary permeability
3. Severe pulmonary edema
4. Shunting
5. Perfusion rate mismatch
6. Hypoxemia
--Abnormally low O2 concentration in blood

What is respiratory distress?

-Difficult respiration
--Due to alveolar collapse
--Caused when pneumocytes type II do not produce enough surfactant

What is the respiratory membrane?

-The thin membrane of alveoli where gas exchange takes place

What is the respiratory epithelium?

-For gases to exchange efficiently
--Alveoli walls must be very thin (

What are the three layers of the respiratory membrane?

1. Squamous epithelial lining of alveolus

2. Endothelial cells lining an adjacent capillary

3. Fused basal laminae between alveolar and endothelial cells

Why is diffusion across respiratory membrane very rapid?

-Because distance is short
-Gases (O2 and CO2) are lipid soluble

What is inflammation to the lung lobules?

-Also called pneumonia
--Causes fluid to leak into alveoli
--Compromises function of respiratory membrane

Explain blood supply to respiratory surfaces

-Each lobule receives an arteriole and a venule
--Low oxygenated blood goes through arterioles
--High oxygenated blood goes through venules

-Respiratory exchange surfaces receive blood:
--From arteries of pulmonary circuit

-A capillary network surrounds each alveolus
--As part of the respiratory membrane

-Blood from alveolar capillaries
--Passes through pulmonary venules and veins
--Returns to left atrium

What are pulmonary vessels easily blocked by?

-Blood clots
-Fat
-Air Bubbles

What does a blockage of a pulmonary vessel cause?

Pulmonary embolism

What is Obstructive Lung Disease?

-Airway obstruction that is worse with expiration

Common signs and symptoms:
-Dyspnea
-Wheezing

What are some common obstructive lung disorders?

-Asthma
-Chronic Bronchitis
-COPD
-Emphysema

What is bronchitis?

-Inflammation of bronchial walls
--Causes constriction and breathing difficulty

What is asthma?

-Chronic inflammatory disorder of the airways

-Inflammation results from hyperresponsiveness of the airways

-Can lead to obstruction
--Later can cause status asthmaticus

Symptoms include:
-Expiratory wheezing
-Dyspnea
-Tachypnea

Treatments:
-Peak flow meters
-Corticoidsteroids
-Beta agonists
-Anti-inflammatories

What is chronic bronchitis?

-Hypersecretion of mucus and chronic productive cough that lasts for at least 3 months of the year and for at least 2 consecutive years

-Inspired irritants increase mucus production and the size and number of mucous glands

-The mucus is thicker than normal

Treatments:
-Bronchodilators
-Expectorants
-Chest physical therapy

What is Chronic Obstructive Pulmonary Disease (COPD)?

-Characterized by persistent airflow limitation

-Usually progressive
--Will get worse with age

-Most common chronic lung disease in world

Risk factors:
-Smoking
-Occupational dusts and chemicals
-Air pollution
-Any factor affecting lung growth during gestation and childhood

What is emphysema?

-Abnormal permanent enlargement of the gas-exchange airways accompanied by:
--Destruction of alveolar walls without obvious fibrosis

-Inherited deficit of 𝛼1-antitrypsin
--Loss of elastic recoil

What are the three effects of compliance?

-Elastic tissues deteriorate
--Altering lung compliance
--Lowering vital capacity

-Arthritic Changes: Aging
--Restrict chest movements
--Limit respiratory minute volume

-Emphysema
--Affects individuals over age 50
-Depending on exposure to respiratory irritants
--Cigarette smoke

What is acute bronchitis?

-Acute infection or inflammation of the airways or bronchi

-Commonly follows a viral illness

-Acute bronchitis symptoms similar to those of pneumonia
--However, does not demonstrate pulmonary consolidation and chest infiltrates

What is pneumonia?

-Lower respiratory tract infection

Caused by:
-Bacteria
-Viruses
-Fungus
-Protozoa
-Parasites

-Healthcare acquired (HCAP) or community acquired (CAP)

-Pneumococcal
--Most common and most lethal
--Intense inflammatory response

-Viral
--Seasonal and usually self-limiting

-Usually preceded by viral URI

What is tuberculosis?

Caused by:
-Mycobacterium tuberculosis

-Acid-fast bacillus

-Airborne transmission

-Tubercle formation

-Caseous necrosis

-Positive tuberculin skin test
--PPD

What is pulmonary embolus?

-Occlusion of a portion of the pulmonary vascular bed by a
--Thrombus
--Embolus
--Tissue fragment
--Lipids
--Air bubble

-Pulmonary emboli commonly arise from the deep veins in the lower leg

-Virchow triad
--Venous stasis
--Hypercoagulability
--Injuries to the endothelial cells that line the vessels

What are some abscess formations and cavitations?

-Abscess
-Consolidation
-Cavitation

What is pulmonary artery hypertension?

-Mean pulmonary artery pressure 5 to 10 mm Hg above normal or above 20 mm Hg

-Primary pulmonary hypertension
--Idiopathic

-Diseases of the respiratory system and hypoxemia are more common causes

Classifications:
-Pulmonary arterial hypertension
-Pulmonary venous hypertension
-Pulmonary hypertension due to a respiratory disease or hypoxemia
-Pulmonary hypertension due to thrombotic or embolic disease
-Pulmonary hypertension due to diseases of the pulmonary vasculature

What is cor pulmonale?

-Pulmonary heart disease
--Right ventricular enlargement
--Secondary to pulmonary hypertension
--Pulmonary hypertension creates chronic pressure overload in the right ventricle

What are O2 delivery in tissues and pickup at the lungs regulated by?

-Rising Pco2 levels:
--Relaxes smooth muscle in arterioles and capillaries
--Increases blood flow

-Coordination of lung perfusion and alveolar ventilation
-Shifting blood flow
--High Po2 in lobules increases blood flow

What is gas transport?

-Distribution of ventilation and perfusion
--Gravity and alveolar pressure
--Ventilation-perfusion ratio
---Normal = .8

What is elastic rebound?

-When inhalation muscles relax
--Elastic components of muscles and lungs recoil
--Returning lungs and alveoli to original position

What is forced breathing?

-Also called hyperpnea

-Involves active inhalation and exhalation

-Assisted by accessory muscles

-Maximum levels occur in exhaustion

How does the respiratory system adapt to changing oxygen demands?

By varying the:
-The number of breaths per minute
--Respiratory rate
-The volume of air moved per breath
--Tidal volume

What is respiratory minute volume?

-Amount of air moved per minute

-Is calculated by:
--Respiratory rate x tidal volume

-Measures pulmonary ventilation

What is the anatomic dead space?

-Only a part of respiratory minute volume reaches alveolar exchange surfaces

-Volume of air remaining in conducting passages

What is alveolar ventilation?

-Amount of air reaching alveoli each minute

-Calculated as:
--(tidal volume - anatomic dead space) x respiratory rate

What is the alveolar gas content?

-Alveoli contain less O2 more CO2 than atmospheric air
--Because air mixes with exhaled air

Explain pulmonary and bronchial circulation

-Pulmonary circulation has a lower pressure than the systemic circulation

-One third of pulmonary vessels are filled with blood at any given time

-Pulmonary artery divides and enters the lung at the hilus

-Each bronchus and bronchiole has an accompanying artery or arteriole

What is the alveolocapillary membrane?

-Formed by the shared alveolar and capillary walls

-Gas exchange occurs across this membrane

What do pulmonary veins drain, where are they dispersed, and where do they leave?

-Each drains several pulmonary capillaries

-Dispersed randomly throughout the lung

-Leave the lung at the hila and enter the left atrium

What controls pulmonary circulation?

-Caliber of pulmonary artery lumina decreases as smooth muscle in the arterial walls contracts

-Contraction (vasoconstriction) and relaxation (vasodilation) primarily occur in response to local humoral conditions
--Most important cause of pulmonary artery constriction is a lower alveolar PO2
--Acidemia also causes pulmonary artery constriction

Why are RBCs apart of gas pickup and delivery?

-Blood plasma cannot transport enough O2 or CO2 to meet physiological needs
--In order to meet physiological needs, red blood cells must be apart of the equation

What are the four steps of ventilation to the lungs?

1. Ventilation of the lungs
2. Diffusion of oxygen from the alveoli into the capillary blood
3. Perfusion of systemic capillaries with oxygenated blood
4. Diffusion of oxygen from systemic capillaries into the cells

-Diffusion of CO2 occurs in reverse order

How do RBC's contribute to gas transport and pickup?

-Transport O2 to, and CO2 from, peripheral tissues

-Remove O2 and CO2 from plasma, allow gases to diffuse into blood

Explain the oxygen transport

-O2 binds to iron ions in hemoglobin (Hb) molecules
--In a reversible reaction

-Each RBC has about 280 million Hb molecules
--Each binds four oxygen molecules

-Diffusion across the alveolocapillary membrane

-Determinants of arterial oxygenation
--Hemoglobin binding
--Oxygen saturation

-Oxyhemoglobin association and dissociation
--Oxyhemoglobin dissociation curve
--Bohr effect

What is the bohr effect?

-Is the effect of pH on hemoglobin-saturation curve

Cause by CO2:
-CO2 diffuses into RBC

-An enzyme, called carbonic anhydrase, catalyses reaction with H2O
--Produces carbonic acid (H2CO3)

-Carbonic acid (H2CO3)
--Dissociates into hydrogen ion (H+) and bicarbonate ion (HCO3-)

-Hydrogen ions diffuse out of RBC, lowering pH

What is hemoglobin saturation?

-The percentage of heme units in a hemoglobin molecule
--That contain bound oxygen

Environmental factors affecting hemoglobin?

-Po2 of blood
--Higher the less likely for oxygen to bind

-Blood pH
--Higher the alkalinity the greater the binding

-Temperature
--Lower temps are more responsive with what is happening to blood pressure

-Metabolic activity within RBCs

What is the oxygen-hemoglobin saturation curve?

-Is a graph relating the saturation of hemoglobin to partial pressure of oxygen
--Higher Po2 results in greater Hb saturation

-Is a curve rather than a straight line
--Because Hb changes shape each time a molecule of O2 is bound

-Each O2 bound makes next O2 binding easier

-Allows Hb to bind O2 when O2 levels are low

-Is standardized for normal normal blood
--pH 7.4 and 37 C

-When pH drops or temperature rises
--More oxygen is released
--Curve shifts to the right

-When pH rises or temperature drops
--Less oxygen is released
--Curve shifts to the left

How is carbon dioxide transported?

-Dissolved in plasma

-Bicarbonate

-Carbamino compounds

-Haldane effect

What is carbon monoxide?

-CO from burning fuels
--Binds strongly to hemoglobin
--Takes the place of O2
--Can result in carbon monoxide poisoning

What comes with aging and the pulmonary system?

-Decreased chest wall compliance and elastic recoil of the lungs
--Reduces ventilatory reserve

-Decreased surface area for gas exchange as well as capillary perfusion decreasing exercise capacity

What is croup?

-Acute laryngotracheobronchitis

-Different from adults - Primarily in children
--Same as adults

-Common in children from 6 months to 5 years

-Commonly caused by a virus
--Parainfluenza
--Causes subglottic edema

-Spasmodic croup
--Older children
--Sudden night onset without prior illness

Usually occurs after an episode of:
-Rhinorrhea
-Sore throat
-Low-grade fever
-Inspiratory stridor
-Hoarse voice

-Causes seal-like cough
--Self-limiting condition

-Most resolve within 24-48 hours

-Severe cases are treated with nebulized epinephrine

What is acute epiglottitis?

-Severe, rapidly progressive, life-threatening infection of the epiglottis and surrounding area
--Same as adults

-Historically caused by Haemophilus influenzae type B
--Overall incidence of acute epiglottitis has been reduced due to Hib vaccination

Manifestations:
-High fever
-Irritability
-Sore throat
-Inspiratory stridor
-Muffled voice
-Severe respiratory distress

Treatment:
-No throat exams
--Due to inflammation
-Emergency airway and antibiotics

What are tonsillar infections?

-Same as adults

-Incidence to tonsillitis secondary to GABHS (group A strep) and MRSA has risen in the past 15 years

-Complication of infectious mononucleosis

-Can lead to upper airway obstruction

What is bacterial tracheitis?

-Most common, life-threatening upper airway infection in children
--Different from adults
--Primarily in children

Often caused by:
-S. aureus
-H. influenzae
-Group A β-hemolytic strep

Treatment:
-Antibiotics
-Endotracheal intubation

What is an aspiration of foreign bodies?

-Foreign body aspiration in children occurs frequently between the ages 1 and 4
--Can occur at any age
--Most common in children

Manifestations:
-Coughing
-Choking
-Gagging
-Wheezing
-Symptoms depend on foreign body size

-Aspirated foreign bodies can be removed by bronchoscopy

What is Obstructive Sleep Apnea Syndrome? (in children)

-Same as adults
--Primarily in children

-Partial or intermittent complete upper airway obstruction during sleep
--Obstructive sleep apnea disrupts normal ventilation and sleep patterns
--One of the most common causes for childhood obstructive sleep apnea is adenotonsillar hypertrophy
--Likely in children who have had a clinically significant episode of RSV bronchiolitis in infancy

Manifestations:
-Snoring and labored breathing during sleep
-Daytime sleepiness
-Chronic mouth breathing

Treatment:
-Tonsillectomy and adenoidectomy or CPAP

What is respiratory distress syndrome (RSD) of newborns?

-Different from adults
--Only in children

-Previously known as hyaline membrane disease (HMD)

-Poor lung structure and lack of adequate surfactant

-Primarily a disease of preterm infants

-Caused by surfactant deficiency

-Causes widespread atelectasis
--Resulting in hypoxemia

-Pulmonary hypertension causes continued shunting of blood away from the lungs
--Via the ductus arteriosus

Risk Factors for:
-Caucasian or male babies
-Previous birth of baby with HMD
-Perinatal asphyxia
--Lack of air immediately before, during, or after birth
-Cold stress
--A condition that suppresses surfactant production
-Perinatal infection
-Multiple births
--Multiple birth babies are often premature
-Infants of diabetic mothers
--Too much insulin in a baby's system due to maternal diabetes can delay surfactant production
-Babies with patent ductus arteriosus

Symptoms:
-Tachypnea
-Expiratory grunting
-Nasal flaring and retractions
-Cyanosis

What is Bronchopulmonary Dysplasia?

-Different from adults
--Only in children

-Also known as chronic lung disease of prematurity

-Major cause of pulmonary disease in infants

Associated with:
-Premature birth
-Prolonged perinatal supplemental oxygen
-Positive pressure ventilation

-Form of arrested lung development
--Poor formation of the alveolar structure with fewer and larger alveoli and decreased surface area for gas exchange

Manifestations:
-Hypoxemia
-Hypercapnia
-Elevated work of breathing
-Bronchospasm
-Mucus plugging
-Pulmonary hypertension

-Is not as common because of the availability of exogenous surfactant and antenatal glucocorticoids

What are some respiratory infections?

-Bronchiolitis
-Pneumonia
--Bacterial, Viral
-Aspiration Pneumonitis

What is bronchiolitis?

-Different from adults
--Primarily in children

-Fibrotic obstruction of the respiratory bronchioles and alveolar ducts
--Secondary to intense inflammation

-Most common associated pathogen is respiratory syncytial virus (RSV)

-Major reason for hospitalization of infants and young children

-Most often occurs as a sequelae of a severe viral pulmonary infection

-Progression of disease demonstrates:
Increasing tachypnea
Dyspnea
Cough
Sputum production
Crackles
Wheezing
Increased APD
Hypoxemia

Manifestations:
-Rhinorrhea
-Tight cough
-Decreased appetite, lethargy, and fever
-Wheezing, tachypnea

What is bacterial pneumonia?

-Most common streptococci and staphylococci

-Pneumococcal (Streptococcus pneumoniae) Pneumonia is the most common cause of community-acquired bacterial pneumonia

-May follow viral illness or viral pneumonia

What is viral pneumonia?

-Most common viral pneumonia in young children is RSV
--Respiratory syncytial virus
--Also parainfluenza, influenza, and adenovirus

What is pneumonia in children?

-Most common cause of community-acquired pneumonia for school-age and young adults

-Onset is usually gradual, resembling a typical upper respiratory infection
--But with low-grade fever and cough

-Usually not severe and self-limiting

What is aspiration pneumonitis?

-Caused by a foreign substance, such as food, meconium, secretions (saliva or gastric), or environmental compounds, entering the lung and resulting in inflammation of the lung tissue

-Leading cause of death in children who are neurologically compromised

-Lung damage depends on volume and pH of aspirate

What is asthma? (in children)

-Characterized by bronchial hyperreactivity and reversible airflow obstruction
--Usually in response to an allergen (Type I hypersensitivity reaction)

-Most prevalent chronic disease in childhood

-Results from a complex interaction between genetic susceptibility and environmental factors

Allergens including air pollution:
-Dust mites
-Cockroach antigen
-Cat exposure
-Tobacco Smoke

And infections, particularly viral:
-Rhinovirus
-RSV

Manifestations (Same as adults):
-Cough
-Expiratory wheeze
-Shortness of breath, tachypnea
-Nasal flaring
-Use of accessory muscles
-Exercise intolerance

What is acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) in children?

-Life-threatening condition resulting from a direct pulmonary insult (pneumonia, aspiration, near drowning, smoke inhalation) or a systemic insult (sepsis or multiple trauma)

-Inflammatory response activation causes alveolocapillary injury

Manifestations:
-Develops acutely after the initial insult
--Usually within 24 hours
-Progressive respiratory distress, severe hypoxemia, decreased pulmonary compliance
-Hyperventilation

Treatment:
-Mechanical ventilation
-Supportive care