Patho exam 3

upper respiratory system

nose, pharynx, associated structures

lower respiratory system

larynx, trachea, bronchi, lungs

2 respiratory zones

conducting zone and respiratory zone

conducting zone

carries air from the outside to the lungs (nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles)

respiratory zone

where O2 and CO2 are exchanged between the air and blood (respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli)

alveoli

air sacs found in the lungs where O2 and CO2 are exchanged between the air and the blood

surrounded by network of pulmonary capillaries

two types of alveolar cells

type I and type II

type I alveolar cells

allow gas exchange

type II alveolar cells

secrete surfactant

ventilation

mechanical movement of gas or air into and out of the lungs

alveolar ventilation

volume of air that enters the alveoli each minute

portion of total ventilation, that participates in the exchange of O2 and CO2

respiratory membrane

formed by shared alveolar and capillary walls, composed of:

• a layer of type I and type II alveolar cells

• epithelial basement membrane underlying the alveolar wall

• capillary basement membrane

• capillary endothelium

lung compliance

ability of lungs to expand in response to changes in pressure

describes how easily the lungs inflate

lung compliance affected by:

1. elastic recoil of lung tissue

2. surface tension within alveoli

elastic recoil of lung tissue

tendency of lungs to return to their original size

lungs naturally tend to recoil inward; chest wall tend to spring outward

these opposing forces help maintain normal lung expansion

surface tension within alveoli

surfactant reduces surface tension

prevents alveolar collapse during expiration

increases lung compliance and reduces work of breathing

respiratory volumes

represent amount of air present in the lungs during different phases of breathing

measured using pulmonary function tests (PFTs)

tidal volume

amount of air moved into and out of lung with each breath (~500ml)

vital capacity

maximum volume of air a person can forcefully expel from their lungs after a maximum inhalation

residual volume

amount of air that always remains in lungs - needed to keep alveoli open

total lung capacity

maximum volume of air the lungs can hold

TLC = VC + RV (~6000ml)

central chemoreceptors

located in medulla oblongata

reflect CO2

stimulated by H+ in cerebrospinal fluid (pH)

increases respiratory depth and rate

peripheral chemoreceptors

located in aorta and carotid bodies

stimulated by hypoxemia

responsible for increases in ventilation that occurs in response to arterial hypoxemia

hypercapnia - what, why, how

CO2 levels in the blood increased

CO2 easily diffuses into CSF

lowers pH and stimulates central chemoreceptors

increased rate and depth of respirations (hyperventilation)

hypoxemia

marked decrease in blood O2 level

peripheral chemoreceptors respond

important control mechanism in individuals with chronic lung disease (move to hypoxic drive)

hypoxic drive

mechanism where the body relies on low arterial O2 levels to stimulate breathing rather than the primary stimulus (high arterial CO2 levels - PCO2)

COPD primary control of respiration

cystic fibrosis hypoxic drive

hypoxic drive due to: (2 things)

hypercapnic desensitization: chronic hypercapnia makes central chemoreceptors become less sensitive to high carbon dioxide levels.

shift to peripheral chemoreceptors: breathing control shifts entirely to peripheral chemoreceptors located in the carotid bodies and aortic arch. These receptors respond to decreased arterial oxygen (PaO2 < 60 mmHg)

manifestations of mild hypoxemia + cause

cause: stimulation of CNS

➢ Increase in heart rate

➢ Peripheral vasoconstriction

➢ Diaphoresis – sweating

➢ Increase in blood pressure

manifestations of chronic hypoxemia

➢ Increased ventilation

➢ Increased production of red blood cells: hypoxia stimulates erythropoietin secretion

➢ Cyanosis – decreased oxygenation of RBCs

eupnea

normal breathing pattern 14-20bpm

tachypnea

abnormally fast breathing

bradypnea

abnormally slow breathing

apnea

cessation of breathing

kussmaul respirations (hyperpnea)

slightly increased ventilatory rate, very large tidal volume, and no expiratory pause (commonly in diabetic ketoacidosis)

cheyne stokes respiration

alternates between deeper and faster breathing and shallower breathing, culminating in a period of apnea before the cycle repeats.

associated with HF and other neurological conditions

dyspnea

subjective sensation of uncomfortable breathing described as shortness of breath

severe dyspnea

flaring of nostrils, use of accessory muscles of respiration

dyspnea on exertion

shortness of breath with activity1

orthopnea

dyspnea when lying down

wheezing

high-pitched whistling sound during breathing caused by narrowed airways.

hemoptysis

coughing up blood or bloody secretions

cough

protective reflex that helps clear the airways by an explosive expiration

productive cough (wet)

brings up sputum

non productive cough (dry)

does not bring up mucus or sputum, characterized as “hacking”

abnormal sputum

changes in amount, consistency, color, and odor provide information about the progression of disease and the effectiveness of therapy.

pneumothorax

air accumulation in the pleural cavity causing the lung to partially or

completely collapse

manifestations of pneumothorax

➢ Chest pain

➢ Dyspnea and tachypnea

➢ Reduced breath sounds

closed pneumothorax

air can enter pleural cavity from internal airways - no opening from chest wall (erosion from internal side)

secondary pneumothorax

associated with underlying respiratory disease

rupture of emphysematous bleb or erosion by a tumor

open pneumothorax

traumatic pneumothorax

Atmospheric air enters the pleural cavity though an opening in the chest wall - “sucking” wound on chest

tension pneumothorax

occurs when an opening in the chest wall or lung tissue allows air to enter the pleural cavity during inhalation but prevents it from escaping during exhalation

trapped air accumulates, causing increasing pressure in pleural space

most serious form

pleural effusion

presence of excessive fluid in the pleural cavity

cause increased pressure in pleural cavity

two types of pleural effusion

exudative effusions and transudative effusions

exudative effusions

response to inflammation

purulent drainage

empyema

blood exudative effusion name

hemothorax

transudative effusions

result of increased hydrostatic pressure or decreased osmotic pressure in blood vessels

water effusions

hydrothora

common manifestations of pleural effusions

➢ Chest pain: unilateral, localized to lower and lateral part of the chest

• Usually becomes worse with chest movements

➢ Dullness to percussion and absence of breath sounds over the affected area

➢ Dry cough – persistent cough without producing mucus.

management of pleural effusions

thoracocentesis - chest drainage is performed to remove fluid and relieve pressure

atelectatsis

incomplete expansion of a lung or portion of a lung

Collapse of the lung or part of the lung leads to decreased gas exchange and hypoxia

Alveoli become airless – inflammation or atrophy occur.

Interferes with blood flow through the lung.

➢ When alveoli receive little or no oxygen, the nearby pulmonary blood vessels constrict

Both ventilation and perfusion are altered - diminished or absent gas exchange

3 main types of atelectasis

obstructive, compression, postoperative

obstructive atelectasis

caused by total obstruction of airway

compression atelectasis

external mass or tumor exerts pressure on part of the lung.

postop atelectasis

can occur after surgery

COPD

group of chronic respiratory disorders that cause irreversible and progressive damage to lungs

Characterized by long-term breathing difficulties and airflow limitation.

May lead to the development of respiratory failure and cor pulmonale (right sided HF)

causes and risk factors of COPD

➢ Tobacco smoke as well as second-hand smoke exposure

➢ Environmental exposures: prolonged exposure to air pollution, chemical fumes, dust.

➢ Genetic factors: α_1-antitrypsin deficiency a genetic disorder that leads to early-onset emphysema even in non-smokers.

bronchial smooth muscle

found in walls of bronchi and bronchioles

controls diameter of airways, regulating how much air enters and leaves the lungs

innervated by autonomic NS

presence/absence of airway secretions can also influence airway patency

parasympathetic vagal control

bronchoconstrictor

sympathetic B2-adrenergic receptor control

bronchodilator

asthma

bronchial obstruction occurs in persons with hypersensitive or hyperresponsive airways

Most common chronic disease in children

➢ 18.9 million in US, estimated 7.1 million are children

two categories of asthma

extrinsic and intrinsic

extrinsic asthma

acute episodes triggered by type I hypersensitivity reactions - common in children (allergy)

intrinsic asthma

triggered by cold, respiratory infections, stress (onset during adulthood)

pathologic changes of asthma

changes in bronchioles

➢ Inflammation of the mucosa with edema

➢ Bronchoconstriction caused by contraction of smooth muscle

➢ Increased secretion of thick mucus

pathogenesis of asthma

allergen → mast cells with IgEs (release histamine, leukotrienes, interleukins, and prostaglandins) → infiltration of inflammatory cells (release cytokines, interleukins, and other inflammatory mediators) → airway inflammation → edema/epithelial injury/impaired mucociliary function

early phase of asthma

5-60min; exposure to allergen, IgEs bind to mast cells, sensitized mast cells release histamine

➢ Inflammation of the mucosa with edema

➢ Bronchoconstriction caused by contraction of smooth muscle

➢ Increased secretion of thick mucus

late phase of asthma

4 – 24 hours: recruitment of eosinophils and sustained inflammation

➢ Repeated inflammatory episodes and injury

manifestations of asthma

 On inhalation narrowed bronchial lumen expands slightly

 Exhalation becomes prolonged due to obstruction.

➢ Accessory muscles of expiration are used

 Forced expiratory volume decreased, residual volume increase

➢ Dyspnea: difficult to exhale air from lungs, trapping it in the smaller airway

➢ Wheezing: air is forced through narrowed airways, creating a high-pitched whistling sound on exhalation

asthma pH changes

 Initially mild respiratory alkalosis caused by hyperventilation

 Prolonged severe asthma attack causes respiratory acidosis due to airway obstruction and air trapping

• Status asthmaticus

status asthmaticus

persistent severe attack of asthmas (life threatening episode)

➢ Does not respond to usual therapy fatal because of severe hypoxia and acidosis

management of asthma

 Pulmonary function studies to assess and monitor asthma

 Peak expiratory flow rate –- measure the speed of exhalation

treatment of asthma

➢ Short and long-acting B2 agonists (albuterol). (bind like a normal neurotransmitter)

➢ Corticosteroids. (anti-inflammatory)

emphysema

abnormal permanent enlargement of air spaces distal to terminal bronchioles

Destruction of alveolar walls and septae leads to large, permanently inflated alveolar air spaces

➢ Hypercapnia becomes marked.

➢ Hypoxia becomes driving force of respiration (hypoxic drive)

contributing factors - genetic deficiency, smoking

pathogenesis of emphysema

smoking → attraction of inflammatory cells → release of elastase (produced by neutrophils - breaks down elastic fibers) (action inhibited by alpha-1 antitrypsin) → decreased alpha1-antitrypsin activity or inherited alpha1-antitrypsin deficiency → destruction of elastic fibers in lungs → emphysema

alpha -1 antitrypsin

 Alpha-1 antitrypsin (AAT) is a protein produced mainly by the liver.

➢ Main function is to protect the lungs from damage caused by an enzyme called neutrophil elastase

process of alpha-1 antitrypsin + deficiency effects

➢ Genetic deficiency: abnormal genes produce insufficient alpha-1 antitrypsin

➢ Inflammation attract neutrophils

➢ Neutrophils release elastase to breakdown harmful bacteria and potentially damaging elastic fibers in the lungs

• Normally alpha -1antitrypsin inhibits elastase and coats lungs protecting them from neutrophil elastase

➢ Alpha -1antitrypsin deficiency – uninhibited elastase cause destruction of elastic fibers in the lungs

pathologic changes in emphysema

 Breakdown of alveolar wall results in

➢ Loss of surface area for gas exchange.

➢ Loss of pulmonary capillaries.

➢ Altered ventilation-perfusion ratio: mismatch between air reaching alveoli and blood flow in pulmonary capillaries

 Fibrosis cause weakening of walls and narrowing in airways

➢ Interference with passive expiratory airflow - difficult to remove air from lungs

manifestations of emphysema

progressive difficulty with expiration causes air trapping and increased residual volume

➢ Overinflation of the lungs

➢ Barrel chest: fixation of ribs in respiratory position, increased anterior-posterior diameter of thorax

➢ Flattened diaphragm (on radiographs)

➢ “Pink Puffer” – shortness of breath and pink color of the skin: no cyanosis until late stage of the disease.

➢ Pursed-lip breathing - prolonged expiration using accessory muscles

management of emphysema

 Injections of donor alpha-1 antitrypsin

 Anti-inflammatory drugs

 Bronchodilators – medications relax bronchial smooth muscles, widen the airways, and improve airflow.

 Oxygen therapy as condition advances

 In late stages, lung reduction surgery and lung transplant

chronic bronchitis

an inflammation, obstruction, and repeated infection in bronchi with excessive mucus production, resulting in persistent coughing and difficulty breathing.

clinical def of chronic bronchitis

productive cough lasting at least 3 months per year for 2 consecutive years, after excluding other possible causes.

causes and risk factors of chronic bronchitis

➢ Increased risk with history of cigarette smoking or living in urban or industrial area

➢ Chronic irritation from smoke cause inflammation and swelling in mucosa in large and small bronchi and overproduction of mucus

pathogenesis of chronic bronchitis (large bronchi and small bronchi)

 Chronic inflammation cause obstructive narrowing of airways

➢ In large bronchi: increase in goblet cells and squamous metaplasia of ciliary epithelial cells

• Impaired ciliary function: build-up of mucus plugs in airways.

➢ In small bronchi: smooth muscle hyperplasia and fibrosis: thickening walls and narrowing of bronchial lumen = increased airway resistance

manifestations of chronic bronchitis

 Manifestations develop gradually – chronic productive cough in early stages.

 In advanced stages dyspnea and wheezing

 Pulmonary hypertension due to fibrosis in pulmonary capillaries cause cor pulmonale – right-sided heart failure

➢ Peripheral edema – back up effects of R sided HF

➢ “Blue Bloater” – cyanosis and fluid retention due to right-sided heart failure

blue bloater vs pink puffer

blue bloater = chronic bronchitis (cough, cyanosis, crackles/wheezes, cor pulmonale)

pink puffer = emphysema (minimal cough, dyspnea, pink skin, pursed lip breathing, barrel chest)

bronchiectasis

abnormal irreversible dilation of the medium-sized bronchi

➢ Result of weakening of muscle and elastic fibers in bronchial walls, causing permanent damage and abnormal dilation

 Bronchiectasis develops when repeated inflammation or infection damages the bronchial walls.

 Impaired bronchial drainage causes recurrent infections by streptococci, staphylococci, pneumococci, H. influenzae

manifestation of bronchiectasis

➢ Chronic productive cough with large amounts of sputum

➢ Rales and rhonchi in the lungs –- light and harsh sounds

➢ Foul breath – due to persistent bacterial infection

➢ Dyspnea

➢ Hemoptysis (coughing up blood) – due to damaged bronchial blood vessels

cystic fibrosis

inherited genetic disorder that affects the lungs, pancreas, digestive system, and other organs.

It causes the body to produce thick, sticky mucus

➢ Tenacious thick mucus from exocrine glands obstructs airways, pancreatic, bile ducts