Respiratory System Flashcards
Functions of the Respiratory System
- Bring in oxygen to fuel cells & remove
carbon dioxide
- At rest we take in 5-6 liters of air/minute
- Brain damage & death after 5 to 10 min. w/o air - Sound production →air through vocal
folds - Smell →air past receptor cells in nasal
cavity - Protection via coughing & sneezing to keep
airways clear
What is Respiration?
- Ventilation
- Breathing = inhalation & exhalation - Gas Exchange
- External respiration
- Internal respiration - Oxygen utilization by cells
External and Internal Respiration
External respiration
- Gas exchange between air & red
blood cells in the lungs
Internal respiration
- Gas exchange between red blood
cells & body tissues outside of the
lungs
Organs of the Respiratory System
Divided into
* Conducting zone
- Respiratory passageways that transport air
- Filter out dust, humidify and warm
incoming air
* Respiratory zone
- Site of gas exchange in the lungs
What are the structures of the conducting zone?
Structures of the conducting zone (in order of passage with inhalation):
* Nasal cavity
* Pharynx
* Larynx
* Trachea
* Main bronchi
* Lobar bronchi
* Segmental bronchi
* Bronchioles
* Terminal bronchioles
What are the structures of the respiratory zone?
Respiratory zone: site of gas exchange; includes:
* Respiratory bronchioles
* Alveolar ducts
* Alveoli
- Cluster of alveoli = alveolar sac
What is pleura
Lungs are lined with pleural membranes
* Visceral pleura →serous membrane surrounding lungs
* Parietal pleura →serous membrane lining cavity
- Thoracic wall
- Mediastinum
* Pleural fluid between the visceral and parietal pleura causes the lungs to inflate with breathing
- Vacuum is created
What is Pneumothorax and Pleural Effusion?
- If the negative pressure is broken between the two pleurae, lung can collapse
- Results in a pneumothorax
- Pleural effusion
- Accumulation of fluid in
pleural cavity
What is external nose?
Support structures of external nose
* Nasal bones
* Hyaline cartilage
* Dense CT
Functions of the nose & nasal cavity:
* Filter, warm, humidify air
* Smell →epithelium in roof of cavity has special receptor cells
* Speech →resonating chamber
What kinds of mucos membranes line the nasal cavity?
- Olfactory mucosa
- Respiratory mucosa
What is Olfactory mucosa?
Olfactory mucosa
* Near roof of nasal cavity
* Houses the receptors for smell
(more in Special Senses lecture)
What is Respiratory mucosa?
Respiratory mucosa
* Lines most of the respiratory
passageway (nasal cavities to lungs)
What is Respiratory mucosa made of?
- Pseudostratified ciliated columnar epithelium
- With scattered goblet cells (mucus)
- Underlying lamina propria (CT)
- Has mucous cells
– Secrete mucus - And serous cells
– Secrete watery fluid containing digestive enzyme (lysozyme—destroys bacteria) - Very vascular
– Warms air
– Why nosebleeds so easily occur - Pseudostratified ciliated columnar epithelium + lamina propria = mucous membrane
- Sticky mucus helps trap pathogens and debris
What is the make up of mucus?
- Goblet cells and glands produce ~ 1 quart per day
- Covers epithelium and traps debris
- Mucociliary escalator:
- Cilia constantly moving sheets of mucus to posterior region of nasal cavity
- Cold air slows cilia down →runny nose in winter
What are the components of the nasal cavity?
External nares and vestibule
* Opening to nasal cavity
* Lined with protective hairs = vibrissae (not seen in image)
Nasal conchae
* Bony ridges that create air turbulence
* Flings pathogens onto mucus-lined epithelium
* Warms air
What are Olfactory receptor cells?
- Olfactory receptor cells pass through the cribriform plate into olfactory mucosa
- Odorants bind to receptors (smell)
- found in nasal cavity
Where does nasal cavity end?
- Nasal cavity ends at posterior nasal
aperture
What are Paranasal Sinuses?
- Air-filled cavities in bone
- Functions
- Lighten the skull
- Warm and moisten the air
- Have single opening into nasal cavity
- Lined with pseudostratified ciliated columnar epithelium
- Named for the bone found in
- Frontal
- Ethmoid
- Sphenoid
- Maxillary
What is the nasal meatus?
Nasal meatus: opening for sinus into nasal cavity
* Superior, middle, inferior
Sinus infection
* Inflammation of epithelium caused by virus or bacterial →over-secretion of mucus
* Meatus becomes blocked
* Pressure within sinus very painful
What is a deviated septum?
Nasal septum
* Bone and cartilage that separates nasal cavity in half
Deviated septum
* Typically the cartilage becomes misaligned
* Disrupts air flow into cavity
What are the components of the Pharynx?
Nasopharynx
* Posterior nares to soft palate
Oropharynx
* Soft palate to epiglottis
Laryngopharynx
* Epiglottis to superior esophagus
What are the epithelium of the pharynx?
Nasopharynx
* Pseudostratified ciliated columnar epithelium
* Primarily air passes through
Oropharynx
* Stratified squamous epithelium; protection
* Food and air
Laryngopharynx
* Stratified squamous epithelium; protection
* Food and air
What is the Nasopharynx?
- Pharyngeal tonsils (= adenoids)
- Lymphoid tissue (immunity)
- Pharyngotympanic tube
- Connects to middle ear
- During swallowing, uvula closes off nasopharynx
(preventing food from moving into nasal cavity
What is the Oropharynx?
- Palatine and lingual tonsils
- Lymphoid tissue; immunity - Tonsillitis
- Inflammation of palatine tonsils
- Can be painful and interfere with swallowing
What is the Laryngopharynx?
- Connects pharynx with openings to larynx (air) and esophagus (food)
What are the Cartilage Structures of the Larynx?
- Epiglottis: elastic cartilage, covers larynx when swallowing food
- Thyroid cartilage: hyaline, attachment site for vocal folds
- Larger in males
- Cricoid cartilage: hyaline
- Arytenoid cartilage: hyaline, anchors vocal folds posteriorly
What is the Larynx Anatomy?
Vocal folds = true vocal cords
* Elastic fibers covered with mucosa & suspended between thyroid and arytenoid cartilages
* Vibrate when air passes over
* Longer in males; slower vibrations, deeper voice
* Shorter in females; faster vibrations, higher voice
Vestibular folds = false vocal cords
* Folds of mucosa that support vocal folds
What is the anatomy of the vocal folds?
- Vocal folds move apart
- Rima glottidis = space between open vocal folds
- Glottis = vocal folds + rima glottidis
What is the Movement of Vocal Cords?
Sound is due to vibrations of vocal folds as air moves pass them
* Longer and thinner the vocal fold→higher the pitch
* The whole pharynx, nasal cavity, oral cavity, and sinuses contribute to sound
* Vocal folds move apart as breathe in air, close as air moves through them (making sound)
What is Laryngitis?
- Laryngitis: excess mucus and inflammation prevent proper vibration of vocal folds (note the color of the inflamed folds)
What is the Trachea?
- Flexible but strong connection to lungs
- Pseudostratified ciliated columnar epithelium
- With goblet cells
- 16-20 hyaline cartilage rings joined by fibroelastic CT
- Rings are C-shaped
- Keep tracheal lumen open
- Allows large boluses of food to go through esophagus
What are the mucus structures in the trachea?
Specialized mucus-secreting
structures
* Goblet cells (in epithelium)
* Seromucous glands (in
submucosa)
What are the effects of smoking on cillia?
Cilia can be paralyzed or destroyed by toxins in cigarette smoke
* The buildup of mucus causes “smokers cough”
What are the Cross Section of the Trachea?
- Mucous membrane
- Submucosa with
seromucous glands - Hyaline cartilage
- Adventitia covering
- Trachealis muscle
- Smooth muscle that completes posterior of
trachea
- Smooth muscle that completes posterior of
What is the Carina?
Carina
* Last ring of tracheal cartilage; where
trachea branches into left and right main bronchi
* Epithelial cells very sensitive to irritants and excess mucus
* Initiates the cough reflex
What is the anatomy of the Bronchial Tree?
Branching of bronchial tree
* Main (primary) bronchi (1 per lung)
* Lobar (secondary) bronchi (1 per lobe)
* Segmental (tertiary) bronchi (1 per bronchopulmonary segment)
* Bronchioles = branches of tertiary,
lack cartilage, <1mm diameter
What is the anatomy of Main (Primary) Bronchi?
- Cartilage rings replaced by irregular cartilage
plates - Still lined with pseudostratified ciliated
columnar epithelium - Right bronchus is wider, shorter, and more
vertical than left - Inhaled substances often enter right primary
bronchus
What are the Lobes and Lobar Bronchi of Lungs?
- Right lung has 3 lobes
- Right lung has 3 lobar bronchi
- Branches of right main bronchus
- 1 lobar bronchus serves 1 lobe
- Left lung has 2 lobes
- Left lung has 2 lobar bronchi
- Branches of left main bronchus
- Each lobar bronchus serves 1 lobe
What is the Segmental (Tertiary) Bronchi?
Each segmental bronchus serves a bronchopulmonary segment
* Lobes are divided into segments
- The segments can function independently of other segments
* If one segment is diseased it won’t move to other segments
What are the transitions of the pulmonary airway tree?
(bronchi) Segmental bronchus –> (bronchioles) Alveolar ducts
Smooth muscle
1. Bands of smooth muscle wrap around bronchi
2. Smooth muscle bands start to thin
3. Smooth muscle absent around alveoli
Cartilage transitions
1. Regular plates
2. irregular plates
3. no cartilage
Epithelium transitions
1. Pseudostratified ciliated columnar
2. Simple columnar
*cilia & mucus secreting cells reduced in number
3. Simple cuboidal
*no cilia or mucus secreting cells
4. Simple squamous
What are the two phases of Bronchial Asthma?
Two phases
* Early phase
* Late phase (after several hours)
What is Early phase Bronchial Asthma?
Early phase
* Allergens, cold air, etc. cause mast cells to release inflammatory chemicals (histamine)
* Cause contraction of bronchial smooth muscle = bronchoconstriction
* Increase in mucus secretion in airways
What is late phase Bronchial Asthma?
Late phase (after several hours)
* Different white blood cells accumulate in bronchi and bronchioles and release inflammatory chemicals →damage mucosa, causing increased release of mucus
* Further increase bronchoconstriction
What are the treatments of Bronchial Asthma?
Treatments
* Bronchodilators (counter bronchoconstriction)
* Anti-inflammatories (counter inflammation)
What is the Respiratory zone?
Respiratory zone
* Location of external gas exchange
* Epithelium transitioning from simple cuboidal to simple squamous
What are the Structures of Respiratory Zone?
Structures
* Respiratory bronchioles
* Alveolar duct
* Alveoli
* Alveolar sac = alveolar duct + alveoli
What are alveoli?
- Alveolar sac = cluster of alveoli on a duct
- Alveoli increase volume of lungs and surface area for gas exchange
Components of Alveoli and the Respiratory
Membrane?
- Gas exchange occurs across the respiratory membrane
- Respiratory membrane = alveolar epithelium + capillary epithelium + fused basement membranes of both epithelia
- Alveolar epithelium is simple squamous
- Capillary epithelium (endothelium) is simple squamous
What are the cell types of Alveoli and the Respiratory Membrane?
Cell types
* Type I cells (simple squamous; extremely thin)
* Type II cells (cuboidal)
- Secrete surfactant which decreases surface tension; allows alveoli to re-inflate more easily
* Macrophages
- Phagocytize inhaled particles
- Move to bronchi where cilia sweep them up and out
What are Alveolar pores?
Alveolar pores
* Equalize pressure between alveoli
What are Lobules?
A lobule is made of 1 larger bronchiole
and all its branches
* Hexagonal shape
* Size of pencil eraser to a penny
Stroma = elastic CT that surrounds lobules
* In most city dwellers and smokers, the
stroma is blackened with smoke
What are the Mechanics of Breathing?
Inspiration
* Diaphragm moves inferiorly with contraction
* Ribs elevates and sternum flares as external intercostals contract
* Thoracic volume increases
Expiration
* Diaphragm moves superiorly as it relaxes
* Ribs and sternum depress as external intercostals relax
* Thoracic volume decreases
What is Respiratory Distress Syndrome?
- Type II cells are not fully functional until ~35 weeks of development
- Premature infants have difficulty inflating collapsed alveoli due to insufficient production of
surfactant - Treatment includes supplying surfactant and oxygen
What are the Primary Cause of Lung Cancer is Smoking?
- Damage due to smoking isn’t just in the lungs
- Strokes, cataracts, heart disease, cancers throughout the body (cervix, stomach, kidney, etc.)
- Smoking
- causes damage to cilia and
- increases mucus production
- Depresses lung’s macrophages
- Lung cancer
- Most effective treatment is removal of diseased tissue
– Usually by diagnosis, though, the cancer has metastasized
What is Chronic Obstructive Pulmonary Disease (COPD)?
Category of disorders where flow of air into and out of lungs is difficult or obstructed
* Two types:
- Chronic bronchitis
– Increased mucus secretion, inflammation, formation of scar tissue
– “blue bloaters”—cyanotic
- Emphysema (see next slide)
- Both often occur together
* Patients have a history of smoking
* Have labored/difficult breathing = dyspnea
What is Emphysema?
- Emphysema = “to inflate”
- Most often related to smoking-related inflammation
- Permanent enlargement of alveoli
- Alveolar walls are destroyed by lysosomal enzymes produced by macrophages
- Fibrosis (scarring) occurs, lungs become less elastic
- This causes difficulty with expiration
– Also, bronchioles are open during inhalation but collapse during exhalation→trapping huge volumes of air in alveoli
— This enlarges the lung →“barrel-chested”
— Also referred to as “pink puffers” - Patients are unable to fully exhale
