Lecture 2 (Test 2) Flashcards
What is the pressure in the thorax?
-4 mmHg or -5cmH2O
What happens when half the diaphragm is paralyzed?
The lung on the paralyzed side may sink, while the other lung may rise
Which lung is larger, the right or left lung?
Right lung
What are the two types of pleura surrounding the lungs?
- Visceral pleura
- Parietal pleura
What is the function of pleura?
Allows tissues to slide around easily inside the chest
What is eupnea?
Normal breathing
Define dyspnea.
Respiratory distress
What does apnea refer to?
Not breathing
What is the term for abnormal sounds coming from the lungs?
Stridor
What is bradypnea?
Slow breathing
What is tachypnea?
Rapid breathing
Define orthopnea.
Change in breathing when changing body position
What is hyperventilation?
Ventilation well in excess of metabolic demands
What is hypoventilation?
Insufficient ventilation for metabolic demands
What does hypercapnia refer to?
Excessive CO2 in blood
What is hypocapnia?
Lower than normal CO2 in blood
What is the definition of cyanosis?
Presence of deoxyhemoglobin, leading to a blue appearance
What is the threshold for cyanosis in blood?
5 g or greater deoxyhemoglobin per deciliter of blood
What is atelectasis?
Collapsed portion or region of a lung
What is the diameter of a typical adult trachea?
About 2 cm
What are bronchioles primarily responsible for?
Conducting air, with no real gas exchange
What is the main muscle of ventilation?
Diaphragm
What does the term ‘accessory muscles’ refer to in respiration?
Additional muscles involved in ventilation when needed
What are the two main openings in the diaphragm?
- Inferior vena cava
- Esophagus
What is the central tendon of the diaphragm?
A large connective tissue structure where the heart sits
What is the role of the phrenic nerve?
Innervates the diaphragm
What are the two main zones of the respiratory system?
- Conducting zone
- Respiratory zone
Fill in the blank: The pressure inside the chest is _______.
Sub atmospheric
What unit is often used to measure thoracic pressures?
Centimeters of water (cm H2O)
What happens during inspiration?
Diaphragm pulls down on thoracic cavity, creating negative pressure
Why is using centimeters of water beneficial for measuring pressure?
It gives greater resolution at very low pressures
Using less dense fluids like water allows for better differentiation of small pressure changes compared to denser fluids like mercury.
What does the term ‘content’ refer to in the context of blood gases?
It refers to the total gas content, specifically the O2 content in arterial blood
O2 content is the sum of oxygen attached to hemoglobin and dissolved in solution.
What is the abbreviation for arterial pressure?
Pa (capital P)
This is a standard notation for pressures in pulmonary contexts.
What does PaO2 signify?
The pressure of dissolved oxygen in an arterial sample
It is expected to be about 100 mmHg.
What is the abbreviation for ventilation?
V (uppercase V)
This represents the amount of air going in and out.
What is Tidal Volume abbreviated as?
Vt
Tidal Volume is typically 0.5 L in a healthy adult.
What does VO2 stand for?
Volume of Oxygen Absorbed Each Minute
It indicates the amount of oxygen utilized by the body per minute.
Define compliance in respiratory physiology.
The ability of the lungs to stretch; high compliance means easy stretch
Low compliance indicates difficulty in ventilation.
What is elastance?
The inverse of compliance; high elastance means low compliance
It refers to the tendency of the lungs to return to their original shape after being stretched.
What is the Total Lung Capacity (TLC) in a healthy adult?
6 L
This is the maximum amount of air the lungs can hold.
What is the Functional Residual Capacity (FRC) for a normal person?
3 L
This is the amount of air remaining in the lungs after a normal expiration.
What does an Expiratory Reserve Volume (ERV) of 1.5 L indicate?
The volume of air that can be forcibly exhaled after normal expiration
This is the additional air that can be expelled beyond the tidal volume.
What is the Inspiratory Reserve Volume (IRV) in a healthy adult?
2.5 L
This is the amount of air that can be inhaled beyond a normal tidal volume.
How is Vital Capacity calculated?
IRV + Tidal Volume + ERV = 4.5 L
Vital Capacity is the maximum amount of air that can be exhaled after a maximum inhalation.
What does Inspiratory Capacity consist of?
IRV + Tidal Volume = 3 L
It is the total amount of air that can be inhaled starting from the functional residual capacity.
What is the normal respiratory rate for adults?
12 breaths per minute
This is derived from a 5-second respiratory cycle.
What does a normal thoracic pressure of -4 mmHg correspond to in centimeters of water?
-5 cmH2O
This is the pressure in the thoracic cavity between breaths.
What is the expected thoracic pressure at the end of inspiration?
-7.5 cmH2O
This indicates a drop in pressure as the diaphragm contracts.
What is the normal tidal volume during inspiration?
500 cc’s or ½ liter
This is the amount of air inhaled in a single breath.
How long does it take to inhale the tidal volume?
Two seconds
The airflow rate is affected by the time taken to inhale this volume.
At what point does the inspiratory flow rate peak during inspiration?
At the one second mark
This is when airflow is fastest during the inhalation process.
What is the airflow rate at one second into inspiration?
0.5 liters per second
This indicates the rate at which air is being inspired.
How is expired air flow rate represented on the graph?
As positive airflow
Inspired air is denoted with a negative sign.
What happens to alveolar pressure during normal inspiration?
It becomes negative
Specifically, it drops to -1 cmH2O at peak inspiration.
What is the reference pressure for alveolar pressure when there is no air movement?
0 cmH2O
This is in comparison to atmospheric pressure.
What happens to the alveolar pressure when the diaphragm contracts?
Alveolar pressure decreases
This creates a negative pressure that pulls air into the lungs.
What is the pressure inside the alveolus at the end of normal inspiration?
Zero cmH2O
This indicates equilibrium between the alveolar and environmental pressures.
What is the relationship between delta P and airflow?
Airflow depends on the delta P
Delta P is the pressure difference between alveolar and environmental pressure.
What happens to thoracic pressure during expiration?
It becomes less negative
Specifically, it increases from -7.5 to -5 cmH2O.
What is the mechanism by which air is expelled from the lungs during expiration?
Relaxation of the diaphragm
This allows positive pressure to push air out of the lungs.
What is elastic recoil in the context of expiration?
Tissue tension that helps push air out
It relies on the natural elasticity of lung tissues.
What is COPD associated with regarding expiration?
Problems getting air out
This condition affects the ability to exhale effectively.
What does the peak airflow rate during expiration correspond to?
The highest alveolar pressure
Specifically, it peaks at positive one cmH2O.
What are the abbreviations used for tidal volume and pleural pressure?
Vt for tidal volume and Pip for pleural pressure
PIP stands for intra-pleural pressure.
What is transpulmonary pressure?
The pressure difference across the lung wall
It compares pleural pressure and alveolar pressure.
What is the formula for calculating transpulmonary pressure?
Ptp = PA - PIP
Where PA is alveolar pressure and PIP is pleural pressure.
What is the significance of transpulmonary pressure?
It determines airflow into the lungs
An increase leads to air entering; a decrease leads to air exiting.
What characterizes Zone 2 of lung perfusion?
Intermittent blood flow
Blood flow varies with pulmonary blood pressure.
What is the formula that describes the pressures in Zone 2?
Pa > PA > Pv
Where Pa is arterial pressure, PA is alveolar pressure, and Pv is venous pressure.
What is the relationship between blood flow and gravitational pressure in Zone 3?
Higher blood flow at lower regions of the lung due to increased gravitational pressure
Blood is heavy, leading to higher intravascular pressures in lower lung areas.
What conditions define blood flow in Zone 3?
Continuous blood flow
In Zone 3, arterial pressure is always higher than venous and alveolar pressures.
What is the definition of Zone 1 in lung perfusion?
Areas with no blood flow
Zone 1 occurs when alveolar pressure is higher than both arterial and venous pressures.
In which part of the lung is Zone 1 most likely to occur?
At the top or apical regions
Zone 1 is characterized by lower vascular pressures, making perfusion difficult.
What can cause Zone 1 blood flow?
Positive pressure ventilation
Positive pressure can increase alveolar pressure, leading to compression of blood vessels.
What happens to blood vessels in the lungs during high blood pressure?
They stretch and become wider
Wider blood vessels reduce resistance to perfusion and increase blood flow.
What is the average blood flow through the lungs per minute?
Five liters per minute
Most of this blood flow occurs in the lower parts of the lungs.
What is Zone 4 according to some theories?
A region where blood flow tapers off at the base of the lung
Zone 4 is debated, with some sources like West including it due to compression of blood vessels by gravity.
What happens to blood flow at the very base of the lungs (zone 4)?
Blood flow is slightly less due to gravitational compression of blood vessels
This is referred to as Zone 4, where blood vessels are compressed by the weight of the lung.
