Pulmonary Ventilation Flashcards
Components of conductive zone
Bronchi, bronchioles, and terminal bronchioles
Components of respiratory zone
Respiratory bronchioles, alveolar ducts, alveoli
Role of conductive zone
Bulk movements of air, No respiratory function but does play a defensive role
Role of respiratory zone
Site for gas exchange, functional unit is acinus: terminal bronchiole, respiratory bronchioles, alveolar duct, and alveoli (alveolar sac) and their circulation
What is equal at all points in the respiratory system? (because it is a closed system)
air velocity * total airway area / time
What makes up the respiratory membrane?
capillary endothelium, basement membrane of capillary endothelium, (extracellular fluid with connective tissue fibers), basement membrane of alveolar epithelium, alveolar epithelium
Distance from alveolus to capillary lumen
less than or equal to .5 micrometers
Defensive functions of the respiratory system
Conditioning of inspired air (nose to pharynx)
(Humidification and warming, prevents dessiccation of respiratory surface/infection)
Filtration (Particles greater than 10 micrometers removed by hairs in the nose, 2-5 micrometer particles settle out in bronchioles due to slow air velocity and gravity. Particles less than one micrometer settle out in alveoli (industrial pollutants and cigarette smoke))
Removal of debris (Mucous (only as far as terminal bronchioles), cilia, alveolar macrophages, sneezing and cough)
Intrapleural space
Liquid-filled area between visceral pleura and parietal pleura that provides fluid coupling between the two surfaces. Allows application of force from the chest wall and diaphragm to the lungs and vice versa. (Like two wet pieces of glass that slide easily against each other but resist being pulled apart)
Muscles responsible for inspiration
75% from diaphragm
Remaining from intercostals (lift and expand rib cage)
Stenocleidomastoids and scalenes used in forced respiration to elevate ribs on rear pivot
How does inspiration work?
Expansion of the chest lowers intrapleural pressure, which makes intrapulmonary pressure subatmospheric. The pressure differential between alveoli and upper respiratory tract causes air to flow towards the alveoli.
Expiration
Passive
recoil of elastic elements in lungs. Lungs recoil until their force is balanced by outward force of chest wall. Active expiration uses abdominal muscles
Respiratory resistance
Rtotal = Rairway + Rtissue + Rthoracic
Airway and pulmonary tissue resistance are also known as pulmonary resistance.
What increases pulmonary resistance?
diseases such as pulmonary fibrosis, increased blood in the lungs (higher when lying down)
What increases thoracic resistance?
increased intraabdominal pressure, higher when lying down, diseases of the rib cage
Alveolar surface tension
Mutual attraction of water molecules at an air-water interface that tends to minimize the area of the interface.
Compliance
Change in volume divided by change in pressure
What decreases compliance?
Surface tension
What increases compliance?
A saline-filled lung has greater compliance than a air-filled lung because the saline abolishes surface tension
Pulmonary surfactant also lowers surface tension, as well as detergent. (Surfactant also has an area-dependent effect on tension due to area-dependent changes in the packing of surfactant molecules)
Composition of pulmonary surfactant
Phospholipid consisting mainly of dipalmitoyl phosphatidylcholine and 4 proteins
Purpose of surfactant
Lowers surface tension of the ECM coating the lumenal alveolar surface. Makes tension decrease with decreasing area. They reduce the amount of work required to expand the lung and prevent the collapse of smaller alveoli
Causes decreased tension to compensate for increased pressure due to smaller radius
Surfactant production begins at ___ weeks according to Rosen’s notes. (Note: This number was different for Walker in Anatomy)
It occurs under the control of ____.
32
(23 for anatomy)
cortisol
Tidal volume
volume of normal breath - .5 L
Inspiratory capacity
Maximum volume inhaled after normal exhale (3L) (Tidal Volume + Inspiratory reserve volume)
Expiratory reserve volume
Maximum volume of forced exhale after normal exhale (1.5 L)
Vital Capacity
Maximum volume inhaled and exhaled (tidal volume + inspiratory reserve volume + expiratory reserve volume) (4.5 L) Measures muscle effectiveness
Residual volume
Volume of air in lungs after maximal exhale (1.5L) (25% total lung capacity)
Functional residual capacity
Volume of air in lungs after normal exhale (expiratory reserve volume + residual volume) (3L) (50% of total lung capacity)
Balance of force between lung collapse and chest wall recoil
FRC Equilibration technique
C1V1 = C2 (V1 + FRC) (C1 is known concentration of insoluble gas, V1 is volume of that gas, C2 is the concentration of insoluble gas after the gas comes to a constant concentration in the spirometer after equilibrating with the lungs.
Residual volume = Functional residual capacity - expiratory reserve volume
Total Lung Capacity
Maximum volume of air lungs can hold
Obstructive conditions, such as _____ have decreased FEV/FVC as a result of the increased airway resistance combined in some cases with loss of lung elasticity/recoil action.
asthma, COPD/emphysema
Restrictive lung diseases
Characterized by a loss in total lung capacity
FEV/FVC increases
Atelectasis - collapse of part or entire lung
Consolidation - Filling of alveolar spaces with inflammatory exudates
Pleural effusion - heart failure, hypoproteinemia, infection, neoplasm
Pneumothorax
Respiratory Distress Syndrome - (infants - idiopathic (premature births), adults - acute (12-24 hours after trauma, near-drowning, acid respiration, etc.)) Reduced Functional residual capacity
Anatomic dead space
The volume of conductive, non-respiratory passages
Alveolar ventilation equation
Alveolar ventilation = alveolar air * number of breaths per minute
Alveolar air = TV(Total volume) - dead space volume
Why is deeper, slower breathing more efficient than rapid, shallow breathing?
There is a constant contribution of dead space in rapid shallow breathing
Arterial oxygen concentration is related to?
alveolar volume
Arterial carbon dioxide concentration is related to?
1/(alveolar volume)
How do you treat a pneumothorax?
Insert a chest tube connected to a water trap and vacuum line to pull out air for ~2 days. Once stable, remove tube by placing continuous suture around entry and remove tube at same time as pulling “purse strings” clamps
