3 - Pulmonary Ventilation and Flow Flashcards
What is the most important muscle that raises the rib cage?
External intercostals
List the four muscles that raise the ribcage
External intercostals
sternocleidomastoid
anterior serrati
Scaleni
Which two muscle groups pull the rib cage downward?
Abdominal Recti
Internal Intercostals
The external intercostals are _____ muscles
The internal intercostals are ______ muscles
Inspiratory
Expiratory
What maintains the suction between the visceral pleura and the parietal pleura?
Lymph suction!
What is normal/resting pleural pressure?
During inspiration?
- 5 cmH20
- 7.5 cm H20
What is resting alveolar pressure?
During inspiration?
During expiration?
0 cm H20
-1 cm H20
+1 cm H20
What is the transpulmonary pressure?
The difference between the alveolar pressure and the pleural pressure
What is lung compliance?
The extent to which the lungs will expand for each unit increase in transpulmonary pressure
What is normal lung compliance?
200ml of air for every 1 cm H2O change in transpulmonary pressure
What is the surface tension of alveoli without surfactant?
With surfactant?
50 dynes/cm
5-30 dynes/cm
What is the compliance of the lungs in the thorax?
Why is it different from the lungs alone?
110 ml/cm H2O
The thorax is heavier and much less elastic
Vital Capacity Definition
Calculation
maximum amount of air a person can expel from the lungs after filling the lungs to a maximum extent
Inspiratory reserve + expiratory reserve + tidal volume
Total Lung Capacity Definition
Calculation
Maximum volume to which the lungs can be expanded with the greatest possible effort
vital capacity + residual volume
Tidal Volume Definition
air inspired or expired with each normal breath
Inspiratory Reserve Volume
extra volume of air that can be inspired over and above the normal tidal volume
Expiratory Reserve Volume
max extra air that can be expired by forceful expiration
Residual Volume
Air remaining in the lungs after the most forceful expiration
Inspiratory Capacity Definition
Calculation
amount of air a person can breathe in after a normal exhalation
tidal volume + inspiratory reserve volume
Functional Residual Capacity Definition
Calculation
amount of air that remains in the lungs at the end of normal expiration
expiratory reserve volume + residual volume
What is phsyiologic dead space?
All dead space including alveolar dead space
What is the calculation for alveolar ventilation?
VA = RR x (VT - VD)
Bronchioles usually have a diameter less than _______
1.5 mm
What keeps bronchioles from collapsing?
NOT their rigidity, but rather the same transpulmonary pressure that keeps alveoli open
The trachea and bronchi are made up of ______ and ______
The bronchioles are made up of ________
Cartilage plates and smooth muscle
smooth muscle
What is the respiratory bronchiole?
What is it made of?
Most terminal bronchiole
made up mainly of pulmonary epithelium and underlying fibrous tissue
Where does the greatest resistance of airflow occur during normal breathing?
The larger bronchioles and bronchi near the trachea
In pathologic conditions, smaller bronchioles do have higher resistance than larger ones because of: (3)
muscle contraction in their walls
edema in the walls
mucus collecting in the lumens
How does sympathetic stimulation of the bronchioles occur: locally or hormonally?
Hormonally
Very few sympathetic nerve fibers penetrate into the central lung
Which causes more bronchodilation: norepinephrine or epinephrine?
Why?
Epinephrine
More beta adrenergic activity
In the bronchioles, sympathetic stimulation causes _____
parasympathetic causes
dilation
constriction
What drug would attenuate parasympathetic constriction of bronchioles with underlying asthma?
Atropine
blocks the effects of acetylcholine
Which two secrety factors cause bronchiolar constriction during allergic reactions?
Histamine
Slow reactive substance of anaphylaxis
Cilia in the lungs beat ______
Cilia in the nose beat _______
upward
downward
All mucous in the ciliary tract moves toward the ______
pharynx
is either coughed out or swallowed
The ____ and ____ are especially sensitive to to light touch/irritation
larynx
carina
What triggers the cough reflex?
Irritant -> Vagus Nerve -> Medulla -> Cough
The sneeze reflex is the same as the cough reflex except _______
the uvula is depressed, allowing air to pass through the nose
What are the three major organs of articulation?
lips
tongue
soft palate
What are the four resonators?
Mouth
Nose/Nasal Sinus
Pharynx
Chest cavity
The lung has two circulatory systems:
High Flow/_________
Low Flow/ _________
Low pressure
High Pressure
Which pulmonary system supplies systemic arterial blood to the structures of the lung?
The high pressure/low flow
Which pulmonary system provides blood to the alveoli and returns the blood to the heart?
Low pressure, high flow
How thick is the pulmonary artery?
1/3 of the aorta
Why does the pulmonary arterial tree have such large compliance?
Vessels have short branches and large diameters
Where does de-oxygenated blood from lung structures go?
Into the LA and out to the circulation
This is the reason for the baseline physiologic shunt
How are plasma proteins and particulates removed from the lung?
Lymph
What is a normal RV SBP and DBP?
25/0
What is the normal mean pulmonary capillary pressure?
7mmHg
What is the blood volume of the lungs?
450ml
The lungs are a blood resevoir. How much blood can they expel?
250ml with forced high pressure expiration (blowing a trumpet)
Blood flow through the lungs is essentially equal to _______
cardiac output
What happens to pulmonary alveolar arterioles when [O2] is low?
They constrict
The exact OPPOSITE of what systemic arterioles do
In low O2 states, alveolar arterioles secrete ________
and inhibit _______
endothelin, ROS
nitric oxide release
Describe zone 1 pattern of pulmonary blood flow
No blood flow during all portions of the cardiac cycle
Alveolar air pressure is always higher than pulmonary capillary pressure, so flow is cut off
Describe Zone 2 Pattern of Pulmonary Blood Flow
Intermittent Blood Flow
systolic bp is higher than capillary prefusion pressure, but diastolic is not
So flow ceases during diastole
Describe Zone 3 Pattern of Pulmonary Blood Flow
Continuous blood flow
Alveolar pressure is always lower than pulmonary capillary pressure, and flow occurs durng systole and diastole
Zone 2 Flow is found in the ________
Zone 3 flow is found in the ________
Apices
Bases
Where does zone 2 flow begin in normal lungs?
10cm above the midlevel of the heart to the top of the lungs
Where does zone 3 flow occur in normal lungs?
everywhere below 10cm above the midlevel of the heart
How do blood flow zones change when a person is lying down?
All areas receive zone 3 flow
When does zone 1 flow occur in a normal lung?
It doesn’t
What two factors cause zone 1 flow?
Abnormally low capillary perfusion pressure
Abnormally high alveolar pressure
What happens to flow in the apices during exercise?
Receive zone 3 flow d/t increased capillary pressure
How do the lungs increase perfusion during exercise?
- increases the number of open capillaries
- distends all the capillaries and increases rate of flow
- increases pulmonary arterial pressure
How much does pulmonary arterial pressure increase during exercise?
hardly at all
capillary dilation and recruitment is usually sufficient
What is a normal LA pressure?
1-5 mmHg
What LA pressure is likely to cause pulmonary edema?
> 30
Pulmonary capillary pressure is ________ than systemic capillary pressure
lower
7 vs 17
Interstitial fluid pressure in the lungs is _______ than in the systemic system
more negative
pulmonary capillary oncotic pressure is _______ than systemic capillary oncotic pressure
higher (14 v 7)
Why don’t alveoli fill with fluid?
pulmonary capillaries and pulmonary interstitial fluid maintain slight negative pressure
sucks fluid out of the alveoli and into the interstitium or epithelium
What are the most common causes of pulmonary edema?
L heart failure
Damage to pulmonary blood capillary membrane (infection, noxious substance)
Pleural fluid has a _______ characteristic
mucoid
makes it nice and slippery
The pleural space is really a _______ space
potential
