CV 8 Flashcards
Respiratory Anatomy and Physiology
Please study the Airway Diagram, Larynx and Vocal Cords, and the Table 27-1 The Nine Cartilages of Larynx
Nerve supply to the larynx
- Superior and inferior laryngeal nerves (branches of the cranial nerve X)
- The superior laryngeal nerve arises from the ganglion of the _______(1) and divides into 2 branches, the external and the internal.
- ______(a) segment gives a branch to the inferior constrictor muscle of the pharynx & the cricothyroid muscle. It lengthens or increases tension of vocal cords. Damage results in _______(2).
- ______(b) segment enters the larynx, provides sensation from the laryngeal side of the epiglottis down to the true vocal cords. Damage = difficulty _______(3).
Nerve supply
- The inferior or recurrent laryngeal nerves – arise from the _______(4) nerve at 2 different levels.
- ______(c) nerve descends with the vagus and loops around the arch of the aorta to the neck.
- ______(d) nerve travels with the vagus to the subclavian artery, loops around the subclavian up to the neck.
- Damage to the ______(e) during surgery can lead to unilateral or bilateral vocal cord paralysis with hoarseness or _______(5).
- Blood supply to the larynx is from the _______(6) (branch of the external carotid artery) and also the ______(f) (branch of the thyrocervical trunk).
Trachea
- Lined with ______(g) epithelium and extends from the inferior larynx to the carina.
- Distance from your incisors to the carina is 26 cm (or roughly 10.4 inches)
- Very tall patients may need longer _______(7)
- Diameter is _______(8)
- Not a fixed structure
- Bifurcates into 2 main bronchi
- Blood supply is from the _______(9)
Answers:
1. vagus
a. External
2. hoarseness
b. Internal
3. phonating
4. vagus
c. Left
d. Right
e. recurrent laryngeal nerve
5. dyspnea
6. superior thyroid artery
f. inferior thyroid artery
g. pseudo stratified ciliated columnar
7. ETT (endotracheal tube)
8. 2.5 cm
9. inferior thyroid artery
Bronchi
- Cellular structure begins to change at this level
- From columnar to _______(1) epithelium
- From the carina, the bronchi branches off slightly at different angles.
Right Bronchus
- Takes off at _______(2) degrees from trachea
- Mainstem is ______(a) (2cm) than the left.
- Nearly vertical as compared to the left
- Which side is Likely to be intubated: _______(3)
- Divides into _______(4) lobar bronchi
- Mainstem bronchus ends 2 - 2.5 cm from the carina and gives rise to the _______(5) bronchus
- After the RUL takeoff, main bronchus continues into 3 cm as the bronchus intermedius then divides into the middle and lower lobes
Left Bronchus
- Takes off at _______(6) degrees
- Left mainstem is _______(7) cm
- Divides into _______(8) lobar bronchi
- The left main bronchus is ______(b) cm long and terminates by bifurcation into the:
- _______(9) lobe bronchus
- _______(10) lobe bronchus
- The left upper lobe bronchus divides into halves, and upper half and a lower half (______(c) branch)
- Each division is referred to as a ______(d). Mainstem bronchi is the ______(e) generation.
- Third generation is called the segmental bronchi.
- Delivery of ventilation to the various bronchopulmonary segments of the lung.
- Bronchopulmonary segments create distinct units.
- ______(f) generations before the alveoli
- Terminal bronchioles are the last structure perfused by the bronchial circulation and are at the end of the conducting airways.
- ______(g) lead to respiratory bronchioles that are perfused by pulmonary circulation .
Please study Lung lobes and segments
Answers:
- cuboidal
- 25
a. wider and shorter - Right Mainstem
- 3
- RUL (right upper lobe)
- 45
- 4
- 2
b. 4 - left upper
- left lower
c. lingular
d. generation
e. first
f. 20-25
g. Terminal
Conducting Zone
- All parts of the airway from the nose to the terminal bronchioles conduct gas without exchanging gas with the blood (i.e. “gas exchange”) and are referred to as the _______(1).
- It is imperative to exceed _______(2) to ensure gas exchange occurs.
- _______(2) is typically 2 ml per kg of body weight.
Transitional airways
- The _______(3) bronchiole follows the terminal bronchiole and is the first site where gas exchange occurs.
- In adults, _______(4) generations of respiratory bronchioles lead to alveolar ducts, of which 4 - 5 generations, each with multiple openings into alveolar sacs.
- The final divisions of alveolar ducts terminate in alveolar sacs that open into alveolar clusters.
- Section of lung showing many alveoli and a small bronchiole. The pulmonary capillaries run in the walls of the alveoli.
- The holes in the alveolar walls are the pores of _______(5).
- They function as a means of collateral ventilation; that is, if the lung is partially deflated, ventilation can occur to some extent through these pores.
- They also allow air to pass through, this provides collateral ventilation and even distribution of air to the _______(6) despite the pressure in adjacent alveoli thus allowing the preservation of lung collapse.
- The holes in the alveolar walls are the pores of _______(5).
Answers:
1. conducting zone
2. Dead Space
3. respiratory
4. 2 - 3
5. Kohn
6. alveoli
Respiratory airways and alveolar-capillary membrane
- Two primary functions:
1. Transport of respiratory gases (oxygen & carbon dioxide).
2. Production of a wide variety of local and humoral substances.
Respiratory Zone
- The respiratory zone is comprised of the:
- Respiratory bronchioles
- Alveolar ducts
- Sacs
- Alveoli
- The respiratory zone is where _______(1) occurs.
Answers:
1. gas exchange
Respiratory airways
- Gas transport is facilitated by the _______(1).
- These are the densest capillary networks in the body.
- There are 3 types of alveolar cells – Type I, II, and III.
- ______(a) – flattened, squamous cells, which covers ~80% of the alveolar surface
- Most likely to be _______(2)
- ______(b) – polygonal cells have vast metabolic and enzymatic activity and _______(3).
- ______(c) – alveolar macrophages, which are important to immunologic lung defense. Permit ingestion of foreign materials within alveolar spaces.
- ______(a) – flattened, squamous cells, which covers ~80% of the alveolar surface
Pulmonary vascular system Two major circulatory systems supply blood to the lungs:
1. Pulmonary vascular networks
2. Bronchial vascular networks
- Delivers mixed venous blood from the right ventricle to the pulmonary capillary bed via two _______(4).
- After gas exchange occurs, oxygenated blood returns to the left atrium via four _______(5).
- Pulmonary veins run independently along the intra-lobar connective tissue planes, _______(6) the pulmonary capillary system adequately provides the metabolic and oxygen needs of the pulmonary parenchyma.
Answers:
1. pulmonary capillary beds
a. Type I
2. injured
b. Type II
3. manufacture surfactant
c. Type III
4. pulmonary arteries
5. pulmonary veins
6. ensuring
Bronchial Vascular System
- Provides oxygen to the conductive airways and pulmonary vessels.
- Anatomic connections between the bronchial and pulmonary venous circulations create an absolute shunt of ~2 – 5% of the total cardiac output, and represents a “normal” shunt.
M E D I A S T I N U M
Subdivision | Location | Contents
Superior | Above level of the sternal angle, extending superior to the thoracic inlet | Thymus, esophagus, trachea, great vessels
Anterior | Between sternum and pericardium | Thymus
Posterior | Between vertebral column & posterior pericardium | Esophagus, thoracic aorta, thoracic duct
Middle | Between anterior and posterior divisions, bounded laterally by the parietal pleura | Heart, distal trachea, mainstem bronchi, and great vessels
Pleura
- Serous membrane lines the thoracic wall and lungs.
- The parietal pleura attaches to the chest wall, diaphragm and mediastinum.
- Reflected back to cover the lungs and thereafter referred to as the _______(1).
- Closely opposed with a thin layer of pleural fluid in between them, a potential space, known as the _______(2).
Pleura
- An accumulation of air in the pleural space is referred to as a _______(3).
- Tension pneumothorax – inspired air accumulates in the pleural space and is not expelled.
- The elastic recoil of the lung tends to favor lung collapse once the negative pressure of the pleural space is disrupted by the breach.
Study the Conditions that affect the Pleural Space Table 27-2
Answers:
1. visceral pleura
2. pleural space
3. pneumothorax
Lung Mechanics
- The diaphragm and external intercostals are the muscles that contract during normal breathing (eupnea).
- Contraction of the muscles of inspiration ↓ intrathoracic pressure → the volume of thoracic cavity to ↑
- Boyle’s law: ↑ volume creates ↓ pressure.
- This causes air to enter the atmosphere.
- Spontaneous respiration is passive movement of gas.
- Pressure of -20 is a good indicator that patient is moving their _______(1) and is ready to _______(2).
Mechanics of Breathing
- Each half of the diaphragm is innervated by a branch of the phrenic nerve arising from C 3, 4 and 5 (“keeps me alive!”)
- Deep Cervical Plexus block in a patient with a respiratory condition could _______(3) their diaphragm strength
- Eupneic expiration results from passive recoil of the chest wall. Internal intercostal muscles may be used to augment exhalation. (Signs of respiratory distress)
- During forced exhalation (coughing), the abdominal muscles may be used.
- Sternocleidomastoid and scalene muscles contract in conjunction with the diaphragm and intercostal muscles for forceful exhalation. (Alternatively, they can be used for forceful inhalation, per your textbook!)
Answers:
1. diaphragm
2. extubate
3. obliterate
Answers:
1. diaphragm
2. extubate
3. obliterate
Lung mechanics
- Lung movement occurs secondary to external forces.
- During spontaneous ventilation, external forces are produced by the ventilatory muscles.
- The response to the lungs to these forces is governed by:
1. ease of elastic recoil of the chest wall
2. resistance to gas flow within the airways
Mechanics of Ventilation: Elastic Resistance
- Chest has a tendency to expand outward.
- Lungs have a tendency to collapse.
- As a result, intrapleural pressure is negative.
- Because the outward force of the thoracic cage exceeds the inward force of the lung, the overall tendency is for the lungs to remain inflated.
Elastic work
- FRC (functional residual capacity) represents the gas volume in the lungs when the outward and inward forces on the lung are equal.
- FRC is defined as the volume of air remaining in the lung at the _______(1).
- Gravitational forces create a more sub-atmospheric pressure in the _______(2) areas of the lung than the dependent areas of the lung.
- A pneumothorax allows lung to collapse and thorax to spring out.
Answers:
1. end of a normal expiration
2. nondependent
Mechanics of Ventilation
- Surface tension forces occur at an air-fluid interface
- Produces forces that reduce the area of the interface
- Favor alveolar collapse
- Gas-fluid interface lining the alveoli behave like bubbles. For a bubble to remain inflated, the gas pressure within a bubble, which is contained by surface tension must be _______(1) than surrounding gas pressure.
Mechanics of Ventilation
- Unlike a bubble, alveolar gas communicates with the atmosphere via airways
- As alveolar radius decreases during exhalation, Law of Laplace’s (P = ______(a)) is satisfied and the alveoli do not collapse.
- Pressure = ______(b)
- Pressure = inside the bubble (alveolus)
- Alveolar collapse
- ______(c) proportional to surface tension
- ______(d) proportional to alveolar size
Answers:
1. higher
a. 2T/r
b. 2 x Surface Tension of the liquid/ Radius of the bubble
c. directly
d. inversely
Mechanics of Ventilation: Elastic Resistance
- Surface tension of the liquid in the lung
- Increases during _______(1)
- Decreases during _______(2)
- Unlike a bubble, pressure within the alveolus decreases as the radius decreases
- Creates gas flow from larger to smaller alveoli
- Maintains structural stability and prevents lung collapse
- ______(a): decreases alveolar surface tension; directly proportional to its concentration within the alveolus
- The smaller the alveolus, the more concentrated the surfactant, and the more effectively surface tension is reduced.
- Over distended alveoli surfactant is less concentrated and surface tension increases
- If you have emphysema- would you expect more production of surfactant or less? Another _______(3)
- Net effect is to stabilize alveoli. Small ones prevented from collapsing and large ones prevented from getting larger.
Physiologic Work of Breathing
- ______(b) work is defined as the work required to overcome the elastic recoil of the pulmonary system. This occurs during inspiration as expiration is passive during normal breathing.
- ______(c) work is defined as work to overcome resistance to gas flow in the airway and includes _______(4)-imposed resistance such as the endotracheal tube (ETT).
Answers:
1. inspiration
2. expiration
a. Pulmonary Surfactant
3. unanswered question
b. Elastic
c. Resistive
4. equipment
Mechanics of Ventilation: Compliance (CL)
- Defined as the change in volume divided by the change in pressure V/P
- ______(a) compliance – is the pressure-volume relationship for a lung when the air is not moving. (e.g., fibrosis, obesity, vascular engorgement, edema, ARDS, external compression, etc.)
- Static compliance can be increased by emphysema which destroys the elasticity of lung tissue (e.g., problem with deflation, not inflation).
- Compliance changes as lung volume changes. It is volume dependent. Less compliant at both very high or very low volumes.
Mechanics of Ventilation: Compliance (CL): Factors
- Sum of the pressure-volume relationships of the thorax and lung (ΔV/ΔP)
- Results in a sigmoidal pressure-volume curve (compliance curve)
- Vertical line at end expiration _______(1).
- Normally breathe on the steepest part of sigmoidal curve
- Where compliance (ΔV/ΔP) or slope is highest
- Restrictive pulmonary disease (↓ compliance)
- curve shifts to the _______(2).
- decreased ______(b),
- or both
- Results in smaller FRC
- ↓ Compliance
- Larger changes in intrapleural pressure needed to create the same TV
- Tend to breathe more rapid and shallow
- CPAP will increase TV and slow RR
Answers:
a. Static
1. FRC (Functional Residual Capacity)
2. right
b. slope
Mechanics of Ventilation: Compliance
- _______(1) compliance
o Increase in fibrous tissue in the lung (pulmonary fibrosis)
o Alveolar edema (prevents inflation of some alveoli)
o Unventilated lung for a long period
o Increased pulmonary venous pressure
- _______(2) compliance
o Pulmonary emphysema
o Normal aging lung
Mechanics of Ventilation: Elastic Resistance - Compliance
- Chest Wall Compliance (~______(a) ml/cm H2O)
- CW = change in chest volume / change in trans-thoracic pressure
- Total compliance of lung and chest wall together ~_______(3) ml/cm H2O
- When the patient lies supine, then chest wall compliance is reduced and the weight of abdominal contents against the diaphragm.
Resistance to Gas Flow
- Patterns of gas flow in the respiratory tract
o _______(4) (distal to small bronchioles)
o _______(5) (large airways)
o Mixed
- Resistance
o Increases in proportion to gas flow
o Directly proportional to gas density
o Inversely proportional to the _______(6)
- If radius is ______(b), resistance ↑ 16-fold
- _______(7) the length only doubles the resistance
Answers:
1. Reduced
2. Increased
a. 200
3. 100
4. Laminar
5. Turbulent
6. radius
b. halved
7. Doubling
Turbulent Gas Flow
- Laminar flow:
o occurs when low flow rates move through a straight tube resulting in a series of concentric cylinders of gas flowing at different velocities. - _______(1) flow:
o They are parallel to the sides of the tube and have a velocity of zero at the cylinder wall. The maximum velocity at the center of the advancing “cone.”
o Viscosity is relevant under laminar flow. - _______(2) flow:
o Occurs when resistance to gas flow is significant.
o Random movement of gas molecules down air passages. It is very loud and audible. - Four conditions that will change laminar flow to _______(3) flow:
o _______(4) gas flows
o sharp angles within the tube
o branching in the tube
o decrease in the tube’s diameter
At low flow rates, stream lines are )_____(a) to the sides of the tube.
As the flow rate ______(b), unsteadiness develops, especially at branches and separation of stream lines occurs with formation of local eddies.
At ______(c) flow rates, there is complete disorganization of the stream lines.
Answers:
1. Laminar
2. Turbulent
3. turbulent
4. high
a. parallel
b. increases
c. Higher
Volume-Related Airway Collapse
- Low lung volumes and loss of radial traction ______(a) contribution of small airways to total resistance.
- Airway resistance becomes ______(b) proportional to lung volume.
- Increasing lung volume up to normal with PEEP can reduce airway resistance.
Flow-Related Airway Collapse
- Forced exhalation causes a ______(c) of normal transmural pressure and can cause dynamic airway compression, which limits air flow during a forced expiration. This results in a large pressure drop across intrathoracic airways.
- Equal Pressure Point is defined as the point along the airways where dynamic compression occurs.
- ______(d): destroys elastic tissues that support smaller airways
- ______(e): bronchoconstriction and edema intensify airway collapse
- Pursed-lip breathing or premature termination of exhalation helps to prevent reversal of transmural pressure gradients and trapping of air.
Ventilation
- ______(f) are the gases in non-respiratory airways.
- ______(g) involves alveoli that are not perfused.
- Physiologic dead space = the sum of the two .
- ______(h) refers to areas of the lung that are ventilated but poorly perfused.
- Dead space
o normally about 2 ml/Kg
o nearly all _______(1)
Answers:
a. increases
b. inversely
c. reversal
d. Emphysema
e. Asthma
f. Anatomic Dead Space
g. Alveolar dead space
h. Physiologic dead space
1. anatomic
Distribution of Ventilation
- Alveolar ventilation is unevenly distributed
o Right receives more than left
- Dependent areas tend to be better ventilated
o Alveoli in upper lung areas are nearly maximally inflated and relatively noncompliant
o Smaller alveoli in dependent areas are more compliant and undergo greater expansion
Pulmonary Perfusion
- Blood flow 5 L/min (Cardiac Output)
o ~ _______(1) ml at any one time in pulmonary capillaries undergoing gas exchange
- Supine to erect position _______(2) pulmonary blood volume up to 27%.
o Trendelenburg has the opposite effect.
- Pulmonary vascular tone → _______(3)
o ______(a) is the most powerful stimulus.
o Pulmonary arterial and alveolar hypoxia reduces pulmonary blood flow from non-dependent areas to dependent areas and prevents hypoxemia.
Hypoxic Pulmonary Vasoconstriction
- ______(b) allow the lungs:
o To maintain optimal V/Q matching
o Stimulated by alveolar hypoxia
o Severely decreases blood flow
o Decreased regional pulmonary blood flow results in bronchoconstriction and diminishes the degree of dead space ventilation.
- ______(b) protect the lungs, particularly during one-lung ventilation.
o When either a shunt or dead space occurs, the unit of the lung effectively becomes a “silent” unit in which little ventilation or perfusion occurs.
Answers:
1. 70 to 100
2. decreases
3. vasoconstriction
a. Hypoxia
b. HPV and Bronchoconstriction
