Resp 1 Flashcards
Visceral Pleura:
Attaches to
the surface of the lung
Parietal Pleura:
Covers the
surface of the chest wall,
diaphragm, and mediastinum
Pleural Space:
Contains a very thin layer of pleural fluid under negative pressure.The pressure in this space is referred to as the Intrapleural Pressure (PIP)
PIP is subatmospheric
pressure, which ensures that
the lungs are held to the
chest wall and will move with
the chest wall during
inspiration & expiration.
A pleural effusion is
excess fluid in the pleural space, which makes lung
Expansion difficult so the person will
breathe shallow and fast.
The right lung has — lobes and the
left has —.
three
two
Each lung has zones that differ in the (2)
amount of air (ventilation; V) and blood
(perfusion; Q) that they receive.
There is greater ventilation (V) of alveoli and blood flow (Q) into
capillaries in zone – compared to the other zones.
3
Best region for
gas exchange. Normally, most of the lungs are zones (2)
3 and 2
The respiratory system is divided into two functional
zones:
Conducting Zone and Respiratory Zone
The diameter of the tubes --- as you move down, but the number of each ---
decreases
increases
There is a large increase in --- as you move deeper into the conducting zone and exchange surfaces.
surface area
Airways have a --- in cartilage and an --- in smooth muscle as you move along the airways.
decrease
increase
In the Conducting Zone, air is (3)
warmed, humidified and filtered
function of cartilage and smooth muscle
Cartilage prevents its collapse
smooth muscle alters resistance to
airflow (Beta 2 receptors, Muscarinic
receptors, Allergen Activation –
Asthma).
The Respiratory Zone has a
Greater
Surface Area to Optimize the Surface
Area Available for Gas Exchange
velocity equation
flow/cross-sectional area
Total cross-sectional area greatly increases in
the — zone, so velocity of air flow this
zone is —
respiratory
low
Cells Types in Alveoli (3)
1. Type I Cells (Simple Squamous Epithelial Cells) 2. Type II Alveolar (Produce Surfactant) 3. Macrophages
The basement membrane of the endothelium
and of the alveolar epithelium are
fused
The typical transit time at rest for an erythrocyte through an alveolar capillary is
0.75 seconds.
Gas exchange is
usually complete in
0.25 seconds
Gas exchange is usually complete in 0.25 seconds, so even during exercise when the capillary transit time is faster, there is still time for
gas exchange to reach diffusion equilibrium (PAO2 & PaO2 = 100 and PACO2 & PaCO2 = 40).
Respiratory muscles are —
muscles
skeletal
Neurons in the medulla and pons
control their
alpha motor neurons.
nspiratory Muscles: (2)
– Diaphragm, external intercostals
– Contraction INCREASES the size of
the thorax and lungs (causing decrease PALV)
Expiratory Muscles: used for
forced expiration only
Expiratory Muscles: (2)
– Internal Intercostals, abdominal
muscles
– Contraction DECREASES the size
of the thorax and lungs (causing increased PALV)
The — is the primary inspiratory
muscle.
diaphragm
The diaphragm is the primary inspiratory
muscle. It arches over the liver and moves
down like a piston when it contracts,
which (2)
increases the size of the thoracic
cavity and reduces the pressure in the
thorax/lungs.
Expiratory muscles
ONLY contract with
— expiration
ACTIVE
The — push
abdominal contents up against
the diaphragm (compressing
the lungs) and the — depress the ribs.
abdominal muscles
internal intercostals
Air is a mixture of —
gases
Gases have different —
pressures
Air moves from
high pressure to low pressure
Boyle’s Law
P1V1 = P2V2 In a sealed container, pressure times volume equals a constant. If pressure increases, volume decreases and vice versa.
For air to
ENTER the
lungs,
the pressure in the alveoli (PALV) must be lower than atmospheric pressure (PATM)
For air to LEAVE
the lungs,
the pressure in the alveoli (PALV) must be higher than atmospheric pressure (PATM)
The chest wall and the lung
both wish to recoil apart (2)
– Chest outward recoil
– Lung inward recoil (due to
alveoli)
The elastic recoil of the lungs favors a
decrease in lung volume or compression
the elastic recoil of the chest wall favors an
increase in lung volume or expansion.
The intrapleural fluid
overcomes that
recoil, keeping
the two attached together, so when the chest (thorax) moves, the lungs move with it.
Transmural or Transpulmonary Pressure
PTP = Palv – Pip
Must increase to produce I and decrease to produce E.
If PIP = PATM, then PTP is 0 and
there is no longer a force to keep
the lungs open (Pneumothorax).
Nearly half of the energy expended for I is stored in — and during E this stored potential
energy is
elastic recoil
released and overcomes airway resistance.
inspiration begin at rest when
Patm = Palv
Inspiration:
Inspiratory Muscles contract and the VOLUME of
the thorax (and lungs) —.
increases
The decrease in PIP (from -5 to -7.5 mmHg) causes PTP to increase ( to 7.5
mmHg) and this causes lung volume to increase.
Inspiration:
Because volume has increased, the pressure in the
lungs (Palv)
decreases (to -1 mmHg).
Inspiration:
When Palv < Patm, air flows – the lungs
into
Inspiration:
When Palv < Patm, air flows into the lungs (3)
a. As air enters the lungs, Palv begins to increase again.
b. Air flow continues until Palv = Patm.
c. No difference in pressure, no difference in flow.
Inspiration:
These pressure changes lead to movement of
500 mL (Tidal Volume) of air. Moving a larger volume of air would require more muscle contraction leading to greater volume and pressure changes.
Expiration
Begin after
inspiration when Patm = Palv
Expiration:
in relaxed breathing, it is a passive process due to
relaxation of inspiratory muscles
a. Can increase the rate and volume of expiration by
contracting expiratory muscles (active expiration).
Expiration: The thorax (and thus the lungs) --- in volume.
decrease
Lung volume decreases because the decrease in thorax volume causes an increase in PIP (from -7.5 mmHg to -5 mmHg) which causes PTP to decrease (from 7.5 mmHg to 5 mmHg).
Expiration:
Because volume decreases, lung pressure (Palv)
increases (to +1 mmHg)
Expiration:
As soon as Palv > Patm,
air flows down pressure
gradient and out of the lungs
Expiration:
As soon as Palv > Patm, air flows down pressure
gradient and out of the lungs (2)
a. As air leaves the lungs, Palv decreases.
b. When Palv = Patm, air flow stops
LUNG COMPLIANCE
a. Definition:
ability of the lung to stretch
compliance= equation
deltaV/deltaP
i. High compliance:
ii. Low compliance:
Lung stretches easily
Difficult for lung to stretch
Alveoli in the base of the lungs are more (2)
compliant and
undergo greater expansion during inspiration
Opposite of compliance is elasticity—
lung’s ability to return to its
normal, resting position.
High compliance =
Easy
Stretch
High elasticity =
Easy Recoil
Lungs with lower compliance (ex. Pulmonary Fibrosis)
require
a larger transpulmonary pressure (PTP) to increase volume
Obstructive Lung Disease (ex.
Emphysema)
Elastic fibers destroyed
increase compliance: Will breathe
deep and slowly to reduce the
work of breathing.
Restrictive Lung Disease (ex.
Pulmomary Fibrosis)
decrease compliance: Will breathe
shallow and fast to reduce the
work of breathing.
Surface Tension:
Force that occurs at any gas-liquid
interface due to the cohesive forces between liquid molecules.
Liquid has a strong attraction for itself and alveoli are covered with a
thin layer of fluid.
This means that the fluid covering of alveoli exerts a
constant
force favoring contraction (which means collapse of alveoli).
The Law of LaPlace describes the relationship between
surface tension and radius of an alveolus.
If two alveoli are connected and the
surface tension of each is equal, the
pressure in the small alveolus is
—.
greater
If two alveoli are connected and the surface tension of each is equal, the pressure in the small alveolus is greater. Because of this, air will flow
into the alveolus.
Surfactant fxn (2)
reduces surface
tension and equalizes pressure
between alveoli of different sizes.
P=
2T/r
P = Collapsing Pressure T = Surface Tension r = Radius
Pulmonary surfactant is secreted by
Type II alveolar
cells.
Pulmonary surfactant is secreted by Type II alveolar cells. It — surface tension (thus elasticity) and — compliance.
decreases
increases
Surfactant is primarily made up of
phospholipids. It
spreads over the fluid lining of the alveolar surface to
disrupt surface tension forces.
Some components of surfactant are components of
innate immunity
Surfactant is particularly important for
reducing surface
tension in small alveoli.
Surfactant is particularly important for reducing surface
tension in small alveoli.
i. This — the likelihood of alveolar collapse.
decreases
Surfactant decreases the work of —.
inspiration
Surfactant production is increased with (3)
hyperinflation of the lungs (sighing and
yawning), exercise and Beta-adrenergic agonists.
Multiple pathologies are associated with decreases in surfactant production – (3)
Infant Respiratory Distress Syndrome, Acute Respiratory Distress Syndrome,
Chronic Smoking
Air Flow =
(Patm – Palv)/Resistance (R)
R = 8nl/pir^4
R = Resistance n = Viscosity of air l = length of airway r = radius of airway
Determinants of Resistance: (3)
i. radius of bronchi/bronchioles
ii. Viscosity of substance
iii. Length of tube
radius of bronchi/bronchioles (3)
a. Bronchodilation: EPI on β2, decrease O2, increase CO2
b. Bronchoconstriction: ACH on M, increase O2, decrease CO2, Histamine
c. Mucus accumulation
The airways with the smallest radius (r)
have the highest individual resistance
(R), but the total resistance (R) of that
generation is the smallest. Why?
Pathologies that increase airway resistance -
OBSTRUCTIVE
DISEASES (ex. Asthma, Emphysema, Bronchitis)
Inspiratory Reserve
Volume.
3000 ml
Tidal Volume.
500 ml
Expiratory Reserve
Volume.
1100 ml
Residual Volume.
1200
ml
Anatomic Dead Space
~ 1ml of Anatomic dead
space per pound of ideal
body weight, which is the
conducting zone of the
respiratory system.
Physiologic Dead Space
Physiologic Dead Space =
Anatomic DS + Alveolar DS
alveolar DS in a healthy young person vs low cardiac output
A healthy young person has little or no alveolar dead
space. However, someone with low cardiac output
might have a lot of alveolar dead space due to low
perfusion and thus a higher V/Q ratio.
Vital Capacity.
a. VC = IRV + ERV + TV
Total Lung Capacity.
a. TLC = VC + RV
Inspiratory Capacity
a. IC = TV + IRV
Functional Residual Capacity
a. FRC = ERV + RV
A normal respiratory rate is between — breaths/minute at rest.
12-20
Minute, Pulmonary or Total Ventilation =
Tidal volume (ml/breath) X Respiration Rate (breaths/minute)
Alveolar Ventilation =
(Tidal volume – Dead Space Volume) X Respiration Rate
It is better to breathe deeper
instead of faster as
deeper
breaths get more air into the
respiratory zone for gas
exchange!
The amount of
air in the
conducting
zone is
~150
mL (ANATOMIC
DEAD SPACE).
