Ch 22: Respiratory Part 1 Flashcards
What is the major function of respiration?
Supply body with O2 for cellular respiration; dispose of CO2, a waste product of cellular respiration
What are the 4 respiration processes?
- Pulmonary ventilation
- External respiration
- Transport
- Internal respiration
What is pulmonary ventilation?
Movement of air into and out of lungs
What is external respiration?
O2 and CO2 exchange between lungs and blood
What is the transport process of respiration?
O2 and CO2 in blood
What is internal respiration?
O2 and CO2 exchange between systemic blood vessels and tissues
What are the major organs of respiratory system?
Nose, nasal cavity, and paranasal sinuses
Pharynx
Larynx
Trachea
Bronchi and their branches
Lungs and alveoli
What is the respiratory zone?
Site of gas exchange
What are the structures of the respiratory zone?
- Respiratory bronchioles
- Areolar ducts
- Alveoli
What is the conducting zone?
Conducts to gas exchange sites, cleanses, warms, humidifies air
What is the purpose of the diaphragm?
Promote ventilation
Describe the pathway from air passages to respiratory zone
Air passages undergo 23 orders of branching → bronchial tree → tips of bronchial tree → conducting zone structures → respiratory zone structures
Where does the trachea enter into?
Right and left main bronchi to hilium
What is the difference between lobar and segmental bronchi?
Lobar: supply one lobe
Segmental: divide repeatedly
What structures do the bronchus branches become?
Bronchioles
Describe the passage of air from terminal bronchioles to alveolar sacs
Terminal bronchioles → respiratory bronchioles → alveolar ducts → alveolar sacs
What is the alveoli?
Cluster of alveolar sacs that is the site of gas exchange
How many alveoli are in the lungs?
300 million
What is the purpose of alveolar and capillary walls in fused basement membranes?
Gas exchange across membrane by simple diffusion
What is Type 1 alveolar cells?
Single layer of squamous epithelium
What is the purpose of type 2 alveolar cell?
Secrete surfactant and antimicrobial proteins
What connects to adjacent alveoli?
Alveolar pores
What is the purpose of alveolar macrophages?
Keep alveolar surfaces sterile
What is the purpose of alveolar pores?
Equalize air pressure throughout lung
What are components of the lungs?
- Apex
- Base
- Hilium
Which lung is the smallest?
Left
What are lobules?
Smallest subdivisions visible to the naked eye served by the bronchioles and branches
How many lobules are in each lung?
Right: 3
Left: 2
What is pulmonary circulation?
Low pressure, high volume
What is the purpose of pulmonary arteries?
Deliver systemic venous blood to lungs for oxygenation
What is the purpose for pulmonary veins?
Carry oxygenated blood from respiratory zones to heart
What enzyme is carried in the lungs to activate blood pressure hormone?
Angiotensin-converting enzyme
What is the purpose of bronchial arteries?
Provides oxygenated blood to lung tissues
Are bronchial arteries pulmonary or systemic?
Systemic
What is the purpose of bronchial veins?
Anastomose with pulmonary veins that carry venous blood back to heart
What is the pleurae?
Thin, doubled-layers serosa that divides the thoracic cavity into 2 pleural compartments
What is the parietal pleura?
On the thoracic wall superior face of diaphragm, around heart, between lungs
What is visceral pleura?
External lung surface
What is pleural fluid?
Fills pleural cavity providing lubrication and surface tension used to assist expansion and recoil
What is the difference between inspiration and expiration?
In: gases flow into lungs
Ex: gases exit lungs
What is atmospheric pressure?
Pressure exerted by air surrounding body
What is the average atmospheric pressure?
760mmHg = 1atm
What is negative respiratory pressure?
Less than Patm
What is positive respiratory pressure?
Greater than Patm
What is zero respiratory pressure?
equal to Patm
What is intrapulmonary pressure?
- Pressure in alveoli
- Fluctuates with breathing
- Always eventually equalizes with Patm
What is intrapleural pressure?
- Pressure in pleural cavity
- Fluctuates with breathing
- Always negative
- Fluid level must be minimal
What are the opposing forces caused by promoting lung collapse?
- Elastic recoil of lungs decreases lung size
- Surface tension of alveolar fluid reduces alveolar size
What is the opposing force that cause enlarged lungs?
Elasticity of chest wall pulls thorax outward
What is purpose of transpulmonary pressure?
Keeps airways open, the greater the pressure the larger the lungs
What is atelectasis?
Lung collapse due to plugged bronchioles causing of alveoli
What is pneumothorax?
Air in pleural cavity
How is pneumothorax treated?
Treated by removing air with chest tubes → lung reinflates
What are the mechanical processes that depend on volume changes?
Volume change → Pressure changes
Pressure changes → gasses flow to equalize pressure
What is Boyle’s Law?
Relationship between pressure and volume of gas, Proportional
What occurs during the active process of inspiration?
- Inspiratory muscles contract
- Thoracic volume increases → Intrapulmonary pressure drops
- Intrapulmonary volume increases
- Air flow into lungs by a pressure gradient
What is forced inspiration?
Vigorous exercise, COPD → accessory muscles → further increase in thoracic cage size
What is the passive process of inspiration?
- Inspiratory muscles relax
- Thoracic cavity volume decreases–
- Elastic lungs recoil and intrapulmonary volume decreases → pressure increases (Ppul rises to +1 mm Hg)
- Air flows out of lungs
What is forced expiration?
Active process uses abdominal and internal intercostal muscles
What are the 3 physical factors that influence the ease of air passage and the amount of energy required for ventilation?
- Airway resistance
- Alveolar surface tension
- Lung compliance
What is friction?
Major-non elastic source of resistance to gas flow occurring in the airways
Why is airway resistance considered insignificant?
Large airway diameters in first part of conducting zone
Progressive branching of airways as get smaller, increasing total cross-sectional area
Resistance greatest in medium-sized bronchi
Why does resistance disappear are terminal bronchioles?
Diffusion drives gas movement
What occurs when there is sever constriction to obstruction of bronchioles?
Prevent life sustaining ventilation
Acute asthma attacks, stops ventilation
What is purpose for epinephrine in regards to bronchioles?
Dilates bronchioles reducing air resistance
What is the purpose for surface tension in the lungs?
Attracts liquid molecules to one another at gas liquid interface
How does water provide surface tension?
Coats alveolar walls → reduces them to smallest size
What is surfactant?
Reduces surface tension of alveolar fluid and discourages alveolar collapse
What is surfactant compared of?
Detergent-like lipid and protein complex produced by type II alveolar cells
What is infant respiratory distress syndrome?
Alveoli collapse after each breath
What is lung compliance?
Measure of change in lung volume that occurs with given change in trans pulmonary pressure
What causes lung compliance?
- Distensibility of lung tissue
- Surfactant that decreases alveolar surface tension
What diminishes lung compliance?
- Nonelastic scar tissue replacing lung tissue
- Reduced production of surfactant
- Decreased flexibility of thoracic cage
What factors decrease total compliance of the lungs?
- Deformities of thorax
- Ossification of costal cartilage
- Paralysis of intercostal muscles
What is tidal volume?
Amount of air inhaled or exhaled with each breath under resting conditions
What is inspiratory reserve volume?
Amount of air that can be forcefully inhaled after a normal tidal volume of inspiration
What is expiratory reserve volume?
Amount of air that can be forcefully exhaled after a normal tidal volume expiration
What is residual volume?
Amount of air remaining in lungs after a forced expiration
What is anatomical dead space?
No contribution to gas exchange
Air remaining in passageways
What is alveolar dead space?
Non-fucntional alveoli due to collapse or obstruction
What is total dead space?
Sum of anatomical and alveolar dead space
What is minute ventilation?
Total amount of gas flow into or out of respiratory tract in one minute
What is alveolar ventilation rate?
Flow of gases into and out of alveoli during a particular time
What are non respiratory movements?
Voluntary, modifies normal respiratory rhythm
What are examples of non respiratory air movements?
- Cough
- Sneeze
- Crying
- Laughing
- Hiccups
- Yawns
What is the difference between external and internal respiration?
E: Diffusion of gases in lungs
I: Diffusion of gases at body tissues
What is involved during external and internal respiration?
- Physical properties of gases
- Composition of alveolar gases
What is Dalton’s Law?
Total pressure exerted by mixture of gases = sum of pressures exerted by each gas
What is partial pressure?
Pressure exerted by each gas in mixture
Directly proportional to its percentage in mixture
What is Henry’s Law?
When gas mixtures con into contact with liquid:
- Each gas dissolves in proportion to its partial pressure
What are the 2 phases that are equal to partial pressure?
- Solubility
- Temperature
Where does the gas in alveoli come from?
- Gas exchanges in lungs
- Humidification of air
- Mixing of alveolar gas with each breath
What is external respiration?
Exchange of O2 and CO2 across respiratory membrane
What influences external respiration?
- Thickness and surface area of respiratory membrane
- Partial pressure gradients and gas solubilities
- Ventilation-perfusion coupling
How does thickness assist external respiration?
Thicken if lungs become waterlogged and edematous → gas exchange inadequate
What is the purpose for large surface area of the lungs?
Increase gas exchange
What are factors that reduce surface area?
Emphysema, tumors, infammation, mucus
What is the Po2 of venous blood?
40 mmHg
What is the alveolar Po2?
104 mmHg
Drives oxygen flow to blood
What is the partial pressure gradient for CO2 in lungs less steep?
- Venous blood: 45mmHg
- Alveolar: 40 mmHg
What occurs when the partial pressure gradient is not steep?
CO2 diffuses in qual amounts with oxygen, 20x more soluble in plasma than O2
What is perfusion?
Blood flow reaching alveoli
What is ventilation?
Amount of gas reaching alveoli
What is the relationship between ventilation and perfusion?
Never balanced for all alveoli due to regional variations due to gravity and some alveolar ducts are plugged with mucus
When would Po2 in alveoli change diameter of arterioles?
- Where alveolar O2 is high, arterioles dilate
- Where alveolar O2 is low, arteriole constrict
- Directs most blood where alveolar oxygen is high
When would Pco2 in alveoli cause changes in diameters of bronchioles?
- Where alveolar CO2 is high, bronchioles dilate
- Where alveolar CO2 is low, bronchioles constrict
- Allows elimination of CO2 more rapidly
