Flashcards in Respiratory System Deck (59):
4 functions of nasal cavity
1. Warms, cleans and humidifies inspired air
2. Serve as resonating chambers for speech
3. Sense of smell
4. Open airway for ventilation
Structure of nasal cavity
- soft cartilages (hold nose open, prevent from breaking; lateral, alar and septal)
- septal cartilage (midline)
Nasal cavity & Paranasal sinuses:
- Lined w/ respiratory mucosa
- blood vessels and seromucous glands beneath respiratory mucosa (warm and humidify air)
- divided in midline by nasal septum
- 3 mucosa-covered projections (superior, middle, & inferior terminate)
2 functions of the pharynx
1. Nasal cavity to the oral cavity
2. Larynx and the esophagus
3 regions of the pharynx, their position & their function
- posterior to nasal cavity
- air passage
- posterior to oral cavity
- passage for food and air
- inferior to the epiglottis
- guides where food and air go to
3 functions of the larynx
1. Provides open airway (prevents from collapse)
2. conducts air
3. Sound/voice production
4. Diverts air and food in proper directions
Compare the epithelium of regions where air AND food pass through w/ those where only air passes through
Air and food = stratified, squamous epithelium
Air only = respiratory mucosa
Describe respiratory mucosa
pseudo-stratified, ciliated, columnar epithelium containing goblet cells.
What is the respiratory system and its main function?
A system of connected organs and structures that function to conduct warm, moist, clean air into close proximity with blood for gas exchange.
Which epithelium type lines most of the URT?
Respiratory mucosa: pseudo-stratified, ciliated, columnar epithelium containing goblet cells
What is the main function of the epiglottis?
Protect the airway
Structures of the LRT?
3 functions of the trachea
1. Maintain open airway for conduction of air
2. Clean, warm and humidify inhaled air
3. Cilia form the mucociliary escalator remove debris to the pharynx & redirects to the stomach
Structure of trachea
- Anterior to esophagus
- Rigid tubular structure from larynx to primary bronchus
- Lined w/ respiratory mucosa and seromucous glands in the submucosa
- C-shaped rings of cartilage; smooth muscle posteriorly
Describe the bronchial tree and it's levels.
Include pulmonary & bronchial circulation.
- tubular structures w/ rings of cartilage to prevent collapse
1. Trachea (Lined w/ respiratory mucosa and seromucous glands)
2. Primary bronchi (Lined w/ respiratory mucosa and seromucous glands)
3. Secondary bronchi (Lined w/ respiratory mucosa and seromucous glands)
4. Tertiary bronchi (Lined w/ respiratory mucosa and seromucous glands)
5. Bronchioles (lack cartilage and submucosal glands; goblet cells start to disappear) - branch to form alveolar ducts and terminate in alveolar sacs
6. Alveoli (flattened pneumocystis)
Pulmonary circulation supplies deoxygenated blood
Bronchial circulation perfuses the lung tissue w/ oxygenated blood from the systemic circulation.
How many lobes and fissures do each of the right and left lung have?
3 lobes, 2 fissures
2 lobes, 1 fissure
What are the surface cells of alveoli? What are their structure?
- Type I pneumocytes: squamous
- Type II pneumocytes: cuboidal (surfactant-secreting)
What 2 features of alveoli make them efficient at exchanging gases w/ blood?
- Thin membrane
- Close proximity to blood
What are the structures w/in the thoracic cavity?
What are the two types of joints in the thoracic cavity and where are they found?
- (Most) sternocostal joints (b/w hyaline cartilage and sternum)
- Interchondral joint (b/w hyaline cartilage of false ribs)
- Costotransverse and costovertebral joints (b/w thoracic vertebrae and ribs; bi-lateral articulations)
- 1 sternocostal joint (first one - attached to clavicle)
- Costochondral (b/w ribs and hyaline cartilage)
What are the muscles of respiration? How do they function to assist in breathing?
- Increases thoracic cavity length (lowers thoracic floor) which increases vol. --> increases size
- Main muscle involved in inspiration
- Skeletal muscle; contracts during inspiration
- Phrenic nerve innervation
2. Intercostal muscles
- Increases tc diameter & thus vol. --> size
- Backup/used when necessary
- Two layers of muscle:
a) External intercostals; inspiration; drctn of muscle fibres down and medial
b) Internal intercostals; forced expiration; drctn of muscle fibres down and lateral
3. Accessory muscles
- Used during forced breathing
- e.g. abdominal muscles
What is pleura?
Where are the two pleurae found? How does one of them aid in respiration?
What is the function of pleural/serous fluid?
- Serous membranes lining the thoracic cavity which secrete serous/pleural fluid
- Visceral pleura covers the lungs
- Parietal pleura lines the thoracic wall & mediastinum; since it is fixed there, thoracic expansion allows the lungs to expand further
- Allows low-friction movement of the lungs, decreases surface tension and adhesion
Is inspiration and/or expiration passive and/or active? Why?
- Inspiration is active; uses muscles to expand thoracic cavity
- Expiration is passive; cartilage and elastin tissue recoil after inspiration
8 functions of the respiratory system?
1. Provide O2
2. Eliminate CO2
3. Filter, warm and humidify inspired air
5. Sense of smell
6. Regulates the pH of the blood
7. Microbial defence
What is Dalton's law (partial pressure)?
What is total pressure for atmospheric air?
Partial pressure (gas) = Fraction of individual gas x total gas pressure
~760mmHg (= barometric pressure)
What is needed for air flow into/out of the lungs?
Pressure gradient (caused by change in vol.); air moves from high to low
What is the intrapleural space? Function?
- Lung has tendency to recoil inwards, chest wall tends to expand outwards --> gap formed
- Helps lungs stay larger/expanded
What pressure is what prevents the lungs from collapsing?
Function of nasal sinuses?
1. Sound resonance
2. Lighten skull
3. Warm air
4. Fill with mucous when sick
How is air warmed in the nasal cavity?
Large venous beds under nasal epithelium
(venodilate when cold, bc blood is warm)
What happens to the structure of bronchi as they decrease in diameter? (i.e. move down the bronchial tree)
- Decrease in amount of cartilage
- Increase in amount of smooth muscle (until alveoli)
- Decrease in cilia
- Walls become thinner
What is the work of breathing?
1. Expanding chest/lungs
- need to overcome stiffness/elasticity of lung/chest wall and the effects of surface tension
2. Move air
- airways resistance (mainly) in the upper airway; bronchoconstriction/bronchodilation
How does a pulmonary function test (spirometry) measure the vol. and speed of air inhaled/exhaled?
- Divides air in lungs into 4 volumes:
1. Tidal vol. (TV): vol. of air moved in/out during normal breathing
2. Inspiratory reserve vol. (IRV): extra vol. that can be inspired w/ max. inhalation
3. Expiratory reserve vol. (ERV): extra vol. that can be exhaled w/ max. effort
4. Residual vol. (RV): vol. remaining in lungs after max. exhalation.
What are the lung capacities?
1. Vital capacity (approx. 5L)
- Total volume of air that can be shifted into/out of the lungs (max. breath in to max. breath out)
2. Total lung capacity (approx. 6L)
- Total vol. in lungs when full (VC + RV)
3. Inspiratory capacity
- Total vol. of air that can be held in the lungs (TV + IRL)
4. Functional residual capacity (approx. 2.5L)
- Vol. at end of normal breath out
5. Residual vol. (RV)
- vol. remaining in lungs after max. exhalation.
What 3 factors can be used to predict someone's forced vital capacity (FVC)?
What factors indicate restrictive lung disease and chronic obstructive lung disease? What is an example of both?
- decreased lung vol/capacity (reduced lung compliance)
- e.g. fibrosis
- increased resistance to airflow
- e.g. asthma
What is pulmonary ventilation and how do you calculate it?
How much air flows through the mouth:
V = f x TV
total ventilation (ml/min) = frequency (breaths/min) x tidal vol. (ml/breath)
What is dead space? Approximate quantity per breath?
Inhaled air that never gets to the alveoli and thus cannot gas exchange; approx. 150mL per breath
What is alveolar ventilation and how do you calculate it?
The flow of fresh gases into and out of the alveoli (accounts for dead space)
V = f x (TV - V(dead space))
ventilation (ml/min) = frequency (breaths/min) x (tidal vol. - dead space vol.) (ml/breath)
What causes hyperventilation and hypoventilation?
Hyperventilation = extra alveolar ventilation
Hypoventilation = low alveolar ventilation
What factors/variables contribute to diffusion according to Fick's Law?
What causes emphysema? Pulmonary fibrosis?
- Emphysema = reduced SA of alveolar membrane (and thus reduced partial pressure of O2 in blood)
- Pulmonary fibrosis = increased thickness of alveolar membranes (and thus reduced partial pressure of O2 in blood)
What does alveolar partial pressure of O2 depend on?
1. Partial pressure of oxygen in inspired air
2. Alveolar ventilation
2. Oxygen consumption (VO2)
What does alveolar partial pressure of CO2 depend on?
1. Partial pressure of CO2 in inspired air
2. Alveolar ventilation
3. CO2 production (VCO2)
In what two forms is oxygen carried in blood?
1. Dissolved (very ineffective)
2. Combined with Hb (approx. 97% saturation for arterial blood and 75% in venous blood)
What is the partial pressure of oxygen and its saturation in:
1. Arterial blood
2. Venous blood
Thus, what does binding of O2 depend on?
1. 100mmHg & approx. 97%
2. 40mmHg & approx. 75%
Thus, binding depends on the partial pressure of O2
What does the sigmoidal shape of the oxygen-Hb curve say about O2 saturation?
1. Upper flat part of the curve: moderate changes in PO2 around the normal value (100mmHg) have only SMALL effects on the % saturation
2. Steep part of the curve at lower PO2: small changes in PO2 results in LARGE changes in % saturation; helps w/ loading and unloading
Thus, affinity increases from left to right
What is O2 carrying capacity?
How much O2 can combine with 1 gram of Hb?
- The max. amount of O2 that can be combined with Hb;
i.e. how much Hb x how much O2 per gram of Hb
How do you calculate O2 content?
(O2 capacity x saturation) + dissolved
Why is there an O2 difference b/w arteries and veins?
O2 is extracted by tissues
In what 3 forms is CO2 transported? (Incl. relative percentages)
1. Dissolved in plasma (10%)
2. As bicarbonate (70%)
3. Combined w/ proteins as carbamino compounds (20%)
What is the Bohr effect? What causes a right shift?
~ O2-Hb dissociation curve varies w/ conditions to improve O2 uptake/delivery
~ Increased: PCO2, H+, temp --> high CO2 = unloads O2
What is the Haldane effect?
- Metabolising tissue removes more O2 from blood, which means blood can store more CO2
- I.e. unload O2 = load more CO2
What are the 3 basic elements in the control of breathing? What are there main functions?
1. Central control: brainstem
- Sets rhythm of breathing
- Coordinates sensors and effectors to maintain respiratory homeostasis
2. Sensors: central and peripheral
- Gather chemical/physical info from central/peripheral receptors
3. Effectors: respiratory muscles
- Adjust ventilation
With regards to brainstem respiratory centres, which group is inspiration and which is mainly expiration?
Dorsal respiratory group = inspiration
Ventral respiratory group = expiration
What part of the brain can override/modify the brainstem with regards to control of breathing?
Motor cortex (driven by choice/emotion)
Central chemoreceptors vs. Peripheral chemoreceptors
- Most important for control of breathing
- Sensitive to PCO2
- (slow) response to pH change in ECF/CSF (due to release of H+ ions when bicarbonate dissociates)
- (rapid) response to decreased arterial PO2
Ventilatory response to CO2:
- Main stimulus?
- Main receptors?
- Physical response?
- Decreased by?
1. PaCO2 (tightly controlled +/- 3mmHg)
2. Central chemoreceptors
3. Limits breath-holding
4. Sleep, increased age, genetic factors, training, and drugs
Ventilatory response to hypoxia (low PO2)
- Chemoreceptors involved?
- Conditions for stimulation?
- What increases response?
- When does it become important?
1. Peripheral chemoreceptors
2. Need PO2 < 60mmHg
3. Increased response if hypercapnic (extra CO2)
4. Important at high altitude and in long-term hypoxemia (caused by chronic lung disease)